In order to predict the secondary structure and B cell epitopes of peanut allergen Ara h 2.02, the gene of Ara h 2.02 was searched in Genbank and its amino sequence was deduced. Meanwhile, its secondary structure was predicted with DNAStar and SOMPA, and antigenicity. hydrophilicity, surface probability and flexibility was predicted using the methods of Jameson- Wolf, Kyte-Doolittle, Emini and Karplus-eSchulz, respectively. B-cell epitopes of Ara h 2.02 were further predicted based on the comprehensive prediction analysis. Results indicated that B-cell epitopes had the high probability in the regions of 28－31, 56－73, 76－90, 92, 148, 156－158, and 168－169. These investigations will be beneficial to epitope localization of Ara h 2.02 and monoclonal antibody preparation in the future.
Microwave treatment and hot-air treatment were separately applied to the drying of orange skin. The drying rate, temperature distribution, water-holding capacity, fat-absorption capacity, and appearance of orange skin dried by both drying methods were investigated. Meanwhile, effects of both drying methods on quality of treated samples were also compared. Results indicated that less time consumption was required to achieve the same water content in treated samples using microwave drying. In addition, microwave drying provided higher temperature in the center and lower temperature in the edge of the samples; in contrast, hot-air drying provided the even temperature distribution in the samples. Significant effects on waterholding capacity, fat-absorption capacity and appearance of treated samples using both drying methods were also observed. Better water-holding capacity and fat-absorption capacity were revealed in the samples treated by lower hot-air temperature or lower microwave power. The uneven texture and quality of the treated samples could be resulted from higher hot-air temperature and stronger microwave power.
Cashew perry wine was treated by individual or combined use of different clarifying agents such as chitosan, bentonite, gelatin and diatomite. The clarification effects were evaluated based on the analyses of relationship between amount of added clarifying agents and optical transmittance of cashew perry wine and changes in sensory attributes and chemical compositions. Results indicated that the best effect on optical transmittance up to 94% was observed in cashew perry wine treated with chitosan at the concentration of 0.17 g/100 ml. However, the combined treatment with 0.1 g/100 ml bentonite and 0.05 g/100 ml chitosan could result in enhanced clarification effects with optical transmittance up to 95%, excellent retention of physiochemical properties and no obvious influence on flavor components in cashew perry wine.
Aqueous, 50% ethanol and absolute ethanol extracts from burdock roots or peel were investigated for in vitro antimicrobial activity. Meanwhile, the thermal stability, pH stability and ultraviolet (UV) illumination stability of the extracts were also discussed. Results showed that all these extracts revealed the potential antimicrobial activities against Escherichia coil, Bacillus subtil, Staphylococcus aureus, Aspergillus niger and Saccharomyces cerevisiae. A higher antimicrobial activity was observed in 50% ethanol extracts in comparison with aqueous and absolute ethanol extracts. In addition, the extracts from burdock peel exhibited higher antimicrobial activity than those from burdock roots. Microorganisms tested were inhibited in the following order of S. aureus > B. subtilis > E. coil > Asp. niger > S. cerevisiae. The 50% ethanol extracts exhibited excellent antimicrobial activities under acidic conditions (pH 3－5), whereas both high-temperature (higher than 100 ℃) treatment and long-time (longer than or equal to 5 min) UV illumination could attenuate the antimicrobial activities.
Effects of polysaccharide concentration, temperature, heat treatment time, pH, NaOH, VC, H2O2 and metallic ions on viscosity of Chinese wolfberry polysaccharides, which was measured using a viscometer, were examined in this study. Results revealed these factors could affect viscosity of Chinese wolfberry polysaccharides to differ entextent.
Significant changes of cooking properties and taste value are always observed in lotus seeds stored due to deterioration of internal attributes. In order to understand the causes of the changes, fresh and stale lotus seeds from Guangchang were comparatively investigated for water absorption capacity, oil absorption capacity, emulsifying ability and emulsion stability, foaming ability and foam stability, and gel property. Results indicated that no significant differences in contents of moisture, protein, crude fat and HPLC fingerprint of 80% methanol extract were found in fresh and stable lotus seeds. However, fresh and stale lotus seeds exhibited significantly different functional properties. Compared with fresh lotus seeds, the water absorption capacity, oil absorption capacity, emulsifying ability, foaming capacity and gel property of stale lotus seeds were decreased remarkably. These results revealed that staling might lead to structural changes of chemical compositions, which affect the functional properties of lotus seeds.
Total amount of bacteria, amount of coliform bacteria, amount of pathogenetic bacteria and TBARS value of softcanned chicken paws irradiated with different doses of 60Co-γ were measured at intervals of 20 d up to 60 d of storage. Results showed that the total amount of bacteria in 60Co-γ-treated chicken paws was much lower than that in untreated chicken paws, and 6 kGy dose-treated chicken paws stored for 60 d revealed a value of 155 CFU/g, lower than limit value of relevant Chinese national standard. No coliform bacteria, Staphylococcus aureus, Shigella, Salmonella were detected. The TBARS value was kept at lower levels and no significant increase was observed over the whole storage period. Accordingly, 60Co-γ irradiation can effectively inactivate microorganisms and prolong sheflife of chicken paws.
Based on the chemical topological theory, Kier’s molecular valence connectivity index (mXtv) and Hall’s electrotopological state index (En) of 53 aromatic components in red raspberry wine were calculated. A model corresponding to quantitative structure-retention relationship (QSRR) of retention time (tR) of 53 aromatic compounds with mXtv and En were deduced by Leaps-and-Bounds regression. A satisfactory relationship was expressed to be tR = －1.943 + 5.643X4－ 4.571X5 + 0.518E6 + 0.819E7 + 0.280E13 + 0.383E16 with a coefficient (R) of 0.959. This model exhibited excellent stability and predictability evaluated by Jackknife method and cross-validation procedure. The regression results indicated that the electro-topological state index and molecular connectivity index could characterize molecular structures and demonstrate the essential affecting factors of tR of aromatic components in red raspberry wine.
In order to explore the oxidative stability of coix seed oil, acid value and peroxide value of coix seed oil stored under different conditions such as temperature, light, air and antioxidants were measured. Results showed that temperature, light and air all could accelerate the oxidation of coix seed oil and among them temperature was the most critical factor. Higher stability was observed in coix seed oil with the additions of antioxidants such as vitamin E and TBHQ. Furthermore, vitamin E exhibited stronger antioxidant effect than TBHQ.
Sweet substances, which give a pleasant, cool, sweet taste when eaten, were extracted from “Enqiyetian”, a new variety of Gynostenma Pentaphyllurn with a yield up to 9.3%. Due to non-carbohydrate and low heat, they have wide medical applications in prevention of obesity, diabetes, cardiovascular diseases and dental caries. Apart from this, they also can be used as a new natural sweetener. The optimal procedure for extraction and purification of sweet substances developed in this study was based on the following steps: defatting of dried powder of“ Enqiyetian” leaves as the raw material with ether, ultrasonic cell disruption in 95% ethanol, hot water extraction, centrifugation, impurity removal using ZTC+1, centrifugation, concentration, dissolution in methanol and then precipitation with acetone, redissolution in deionized and then extraction with water-saturated n-butanol, rotary evaporation of the aqueous phase, separation of sweet substances using silica gel column, purification of sweet substances using Sephadex G-10 column, freeze-drying, and LC-MS analysis. The final product was showed to consist of two compounds sharing with the same molecular formula of C11H10N2 and the molecular weight of one was 274 and another of 170. Our findings suggested the potential of these sweet substances as a novel sweet material.
In order to provide experimental evidences for the rapid identification of kudzu starch, 7 brands of commercial kudzu starch and kudzu starch prepared in our laboratory were subjected to morphological observation and determination of physiochemical properties such as transparency, solubility, viscosity, retrogradation, swelling power, and puerarin, amylose and amylopectin contents and freeze-thaw stability. Results indicated significant differences in physiochemical properties were observed among 8 kudzu starch samples.
Two Monascus metabolites with strong fluorescence, named MFA and MFB, were investigated for stability under different conditions such as strong acid, strong alkali, heat and light. Results showed that the alkali, heat and light stability of MFA and MFB was poor, but the stability of MFA and MFB for strong acid was better than for strong alkali.
Porcine longissimus muscles were used as materials to conduct treatments with polyphosphate, hexametaphosphate and pyrophosphate at various concentrations. Effects of the phosphates on tenderness and water-holding capacity (Honikel's drip loss method and centrifugation loss and cooking loss) of pork muscles were investigated using orthogonal array design. Results indicated polyphosphate had a significant (P < 0.05) effect on tenderness of pork muscles. The best tenderness of pork muscles was obtained through a combined treatment using the three phosphates with respective concentrations of 0.3%, 0.3% and 0.2%. According to cooking loss, the optimal combination consisted of 0.2% pyrophosphate, 0.3% polyphosphate and 0.2% hexametaphosphate.
Investigations on the rheological property of high-amylose cornstarch paste with glycerol (0－40%) were carried out. High-amylose cornstarch paste with glycerol revealed a film-forming characteristic. The film obtained was evaluated for crystal structure and acid resistance. Furthermore, thiamine micro-pills coated with this starch film were prepared to study the controlled release in simulated in vitro gastrointestinal digestion. Results indicated that larger amount of glycerol addition resulted in a reduction in viscosity of high-amylose cornstarch paste, crystallization capability and acid resistance. The micropills with the coating of this film could enhance the resistance to degradation in gastric acid and the controlled release of core functional factor through adjusting amount of glycerol addition and thickness of coating film.
The antioxidant activities of honeysuckle extract and chlorogenic acid were evaluated by ferric ion reducing antioxidant power (FRAP) assay, hydroxyl free radical array and DPPH free radical assay using vitamin C as the reference. Results showed that honeysuckle extract had strong scavenging capacity for hydroxyl and DPPH free radicals. The IC50 of honeysuckle extract for scavenging hydroxyl free radicals was 0.0273 mg/ml. The scavenging rate of honeysuckle extract for DPPH free radicals was 80% when its chlorogenic acid content was 0.006 mg/ml. Meanwhile, the reducing power of chlorogenic acid standard was 2.66- fold and 2.42-fold stronger than that of honeysuckle extract and vitamin C, respectively. Therefore, chlorogenic acid is the major antioxidant component in honeysuckle extract.
Pigments in Brassica oleracea var. acephala D.C. leaves were extracted and purified for the investigations of chromatographic and spectral characteristics and stability. Results showed that the pigments were mauve in color, soluble in water and revealed a maximum absorbance at 540 nm in aqueous solution at pH 2. The color and maximum absorbance wavelength of the pigments were remarkably affected by pH. The pigments in aqueous solution at pH 2 was stable toward sunlight at room temperature, but degraded at temperatures above 50 ℃. Citric acid, malic acid, lactic acid, sucrose, glucose, lactose and SDS exhibited hyperchromic and protective effects on the pigments. However, prolonged storage period (after 6 d) resulted in the attenuation of hyperchromic and protective effects of sucrose, glucose and lactose, and even hypochromic effects were exhibited.
Polysaccharides as the major components in Salicornia were extracted using different solvents such as water and ethanol. The antioxidant activities of water extract and ethanol extract from Salicornia, crude Salicornia polysaccharides and purified Salicornia polysaccharides were evaluated by ferric reducing antioxidant power assay, hydroxyl (·OH) free radical scavenging capacity assay and superoxide anion (O2·) free radical scavenging capacity assay. Results indicated that water extract, ethanol extract and polysaccharides from Salicornia all had strong scavenging capacity for hydroxyl free radicals, which was weaker than that of VC. The reducing power and ·OH scavenging capacity of water extract were stronger than those of ethanol extract at the same concentration. Likewise, crude polysaccharides exhibited stronger reducing power and ·OH scavenging capacity than purified polysaccharides. Although water extract and polysaccharides did not exhibit scavenging capacity for superoxide anion free radicals at the experimental concentration range, ethanoll extract revealed certain scavenging capacity for superoxide anion free radicals.
Different solvents such as methanol, ethanol, chloroform and distilled water were used to extract propolis. The contents of total flavonoids and total phenols in different solvent extracts were analyzed. Meanwhile, reducing power and DPPH free radical scavenging capacity were determined to compare antioxidant activity of four different solvent extracts. Results indicated that methanol and ethanol extracts had strong antioxidant activity. The reducing power of methanol extract was as high as 1.162 at 0.25 mg/ml concentration of and scavenging rate of methanol extract for DPPH free radicals was 64.676% at 0.05 mg/ml concentration of. The sequential extractions using petroleum ether, chloroform, ethyl acetate and acetone were applied to ethanol extract of propolis. A maximum extraction efficiency was achieved using chloroform. The reducing power of chloroform-soluble extract reached 2.087 and the scavenging capacity for DPPH free radicals as high as 87.724% at 0.05 mg/ml concentration.
Nitrite content in Toona tissues of dormant seeds, sprouting seeds, young seedlings at cotyledon stage, and fully grown seedlings was determined by nitrite-N-(1-naphthyl)ethylene diamine dihydrochloride spectrophotometric method. Meanwhile, nitrite content in different parts of seedlings grown indoors and outdoors was also determined at different developmental stages. Endogenous nitrite content exhibited a decrease trend during sprouting stage and growth stage of seedlings. Nitrite level was the highest in Toona seeds, and the lowest in Toona seedlings. At cotyledon stage, nitrite content in root was higher than in shoot, whereas at late seedling stage, nitrite content in shoot was higher than in root. Nitrite content in the buds and newly formed shoots of Toona grown indoors was higher than those grown outdoors.
Effects of protein concentration (25, 20, 15, 10, 5 mg/ml) diluted using phosphate buffer at pH 6.5 containing 0.6 mol/L KCl on heat-induced gel properties (ultramicrostructure, water holding capacity, hardness and elasticity) of myosin from rabbit psoas major muscles were investigated. Protein concentration revealed a significant effect on the gel properties. In gels formed at increasing myosin concentration, the gel networks became tighter, and the network diameter decreased from 6－10μm to 2 μm. When the myosin concentration reached a value above 15 mg/ml, protein aggregates appeared. Moreover, with the increasing of protein concentration, remarkable increases in water holding capacity, hardness and elasticity were observed from 28.38% to 86.96%, 7.07 to 36.23 g, and 0.25 to 0.80, respectively.
The oxidation stability of Swida wilsoniana oil stored under different conditions such as temperature and antioxidants was evaluated. Results showed that temperature could remarkably accelerate the oxidation deterioration of Swida wilsoniana oil. The protective effects of different antioxidants on Swida wilsoniana oil were different and TBHQ provided excellent protection against oxidation. Both citric acid and VC could synergize with TBHQ to protect against the oxidation of Swida wilsoniana oil and a stronger synergistic effect of citric acid and TBHQ was observed compared with VC and TBHQ. Additionally, the combined use of 0.02% TBHQ and 0.005% citric acid revealed a high effectiveness in inhibiting the rancidification of Swida wilsoniana oil occurring during its storage and sale so that its shelf life could be extended from 4 to 9 months at 20℃.
Chicken eggs were loaded under two modes (flat, ring) for the measurement of eggshell strength. Based on this, finite element analysis was conducted using two models and their effectiveness was compared. Combined static test and finite element analysis gave the following conclusions: (1) the horizontal diameter of chicken eggs exhibits a higher load-bearing capacity than the small and big ends under the same loading conditions and the load-bearing capacity of the small end is higher than that of the big end; (2) the carrying capacity is elevated with the increasing of horizontal diameter along the longitudinal axis.
Central composite design combined with response surface analysis was employed to explore interactive effects of pectinase treatment conditions such as treatment time (16－134 min), temperature (20－70 ℃), enzyme dose (0.005%－0.105%) on rheological characteristics of sweet potato slurry. Results showed that both sweet potato slurry with and without pectinase treatment behaved as non-Newtonian, pseudoplastic fluid with yield stress. The correlation between shear rate and shear stress could be well fit using the Herschel-Bulkley model. Sweet potato slurry gradually lost its non-Newtonian characteristics due to pectinase treatment and its apparent viscosity decreased with the increasing of enzyme concentration. A minimum apparent viscosity of 71.56 mPa·s was observed in pectinase-treated sweet potato slurry under the optimal treatment for 70.56 min at 42.34 ℃ with an enzyme dose of 0.1%.
In order to compare chemical properties of extruded oat bran and unextruded oat bran, they were hydrolyzed using alkaline or proteinases, and the hydrolysates were analyzed for protein isoelectric point, protein and b-glucan contents, and aromatic components in Maillard reaction product. Besides, IR spectral analysis and microstructure observation under scanning electron microscopy (SEM) were also conducted. Results showed that higher protein and β-glucan contents were exhibited in oat bran hydrolysates compared with extruded oat bran hydrolysates. There were obvious differences in microstructure between extruded oat bran and unextruded oat bran. Native oat bran revealed a simple dispersion microstructure with smooth and flat surface, while extruded oat bran exhibited a complex microstructure with rough surface and meanwhile obvious extrusion characteristics were observed. Totally 28 and 29 aromatic compounds were found in Maillard reaction product of native oat bran and extruded oat bran hydrolysates by GC analysis, respectively. Furthermore, the major aromatic compounds showed a great difference in content.
Based on the determination of minimum inhibition concentrations (MICs) of 8 food preservatives against Escherichia coli in vitro, the structural optimization and vibrational frequency analysis were carried out for these food preservatives with density functional theory B3LYP in Gaussian 98 program, and the stable structures were acquired. Meanwhile, the frontier molecular orbital (FMO) and Mulliken population of these antimicrobial molecules were also investigated. Results showed that carboxyl, phenolic hydroxyl or carbonyl, including aldehyde group, comprised the active sites of these antimicrobial molecules. The antimicrobial activity of preservatives could be improved when carbon-carbon double bond, alternate carbon-carbon double bonds or phenyl was linked to the active sites. There was a close correlation between FMO energy and antimicrobial activity of preservatives, which could be described by the following formula: Y ＝ －4.4506－1.8819X1＋2.9969X2 [Y represents MIC (μmol/ml) of preservatives, andX1 and X2 represent EHOMO(eV) and ELUMO(eV), respectively] with a standard error of 0.6256 and a significance level, α = 0.05, a correlation coefficient (R) of 0.929, and a determination coefficient of 0.863.
The mechanical properties of lotus-seed starch gels formed under different conditions, including starch milk concentration, pH value, and additions of NaCl, sugar and Tween-80 concentration were studied. Results showed that the gel strength, elastic modulus of lotus-seed starch gels increased linearly with increasing starch milk concentration, while the gel elasticity changed little. The gel strength and elastic modulus of lotus-seed starch gels first increased and then decreased, whilethe gel elasticity exhibited a decreasing trend with increasing NaCl concentration. All the mechanical properties of lotus-seed starch gels decreased with the increasing NaCl concentration when pH value was between 4.0 and 7.2. The gel strength was also significantly increased by adding sugars, with fructose most effective, followed by glucose and sucrose. Meanwhile, the gel elasticity and elastic modulus were slightly increased. The addition of Tween-80 of less than 0.5% resulted in a sharp decrease in gel strength and elastic modulus and a slight increase in gel elasticity, while little changes were observed in all the mechanical properties when the addition of Tween-80 was more than 0.5%.
Phenolic compounds, including 11 phenolic acids, 5 flavan-3-ols, 10 flavonols and 2 flavones in freshly-brewed red wines of “Shiraz”, “Cabernet Gernischet” and “Cabernet Sauvignon” grape varieties (Vitis vinifera L. cv.) from the same geographical origin and freshly-brewed red wines of“ Cabernet Sauvignon” from different geographical origins (Tianshui, Heshuo and Manasi of Xinjiang, Yanqing of Beijing, and Huailai of Hebei) were analyzed by high performance liquid chromatography (HPLC). Results showed that a significant difference in contents of phenolic compounds was observed among red wines fermented from different grape varieties from the same geographical origin and the same results were also observed in the same variety from different geographical origins. The contents of phenolic compounds in “Cabernet Sauvignon” wine were the highest among wines fermented from the 3 grape varieties. Among 5 geographical origins“, Cabernet Sauvignon” wine from Yanqing of Beijing, Heshuo of Xinjiang and Huailai of Hebei exhibited the highest contents of phenolic acids, flavan-3-ols, and flavonols, respectively.
A method using high-performance size-exclusion chromatography (HPSEC) equipped with multi-angle laser-light scattering (MALLS) and refractive index detector (RID) was presented for determining molecular features of starch. Results indicated that the weight-average molecular weight (Mw), z-average radius of gyration (rz) and polydispersity index could be obtained using the Berry extrapolation method with a third-order polynomial fitting. The Mw (rz) of common maize starch, waxy maize starch, wheat starch, sticky rice starch, rice starch and potato starch were measured to be 17.94 × 107 g/mol (79 nm), 18.11 × 107 g/mol (81.1 nm), 7.86 × 107 g/mol (50.4 nm), 13.04 × 107 g/mol (62.9 nm), 64.3 × 107 g/mol (64.3 nm), and 7.73×107 g/mol (75.9 nm), respectively. This method can provide a convenient and easy approach for starch molecule structure analysis.
Crude polysaccharide from Dendrobium candidum (DSP) was successively fractionated with different concentration ethanol and three polysaccharides named DSP1, DSP2 and DSP3 were obtained at the concentrations of 90%, 70% and 40%, respectively. Subsequently, DSP and its three fractions were tested for antioxidant activity in vitro. Results showed that DSP1 had the strongest DPPH radical scavenging activity, total antioxidant activity, inhibition against Fe2+-VC-induced lipid peroxidation and inhibition against erythrocyte hemolysis induced by H2O2, DSP and DSP3 took the second place and DSP2. had the weakest biological activities. The hydroxyl radical scavenging capacity of these test samples followed the order of DSP > DSP3 > DSP1 > DSP2. In addition, all fractions of Dendrobium candidum polysaccharides showed potential for protecting against DNA damage mediated by hydroxyl radicals. These results suggested that polysaccharides from Dendrobium candidum had antioxidant potential, which might be closely associated with their molecule weight.
Filter paper diffusion method and plate coating method were separately used to determine inhibitory effect and minimum inhibitory concentration (MIC) of volatile oil from peppers against bacteria, molds and yeasts. Results indicated that volatile oil from Zanthoxylum bungeanumm Maxim or Zanthoxylum bungeanumm Mei could inhibit the growth of gram-negative bacteria, gram-positive bacteria, mould and fungi. The maximum inhibitory effect on Penicillium sp. and Aspergillus niger was observed. Therefore, volatile oil from peppers will be promising in the filed of medicine as a natural antimicrobial agent.
The antioxidant activity of red pigment extracted from purple sugarcane was evaluated by superoxide radical scavenging assay, hydroxyl radical scavenging assay, DPPH radical scavenging assay and NO2 scavenging assay and determination of inhibitory effects against peroxidation of lard and soybean oil. Results indicated that the red pigment had excellent scavenging effects against superoxide radicals, hydroxyl radicals and DPPH radicals while unremarkable scavenging effect against NO2. Moreover, this pigment also had certain inhibitory effects against peroxidation of lard and soybean oil and a stronger inhibitory effect was observed against peroxidation of lard in comparison with soybean oil.
Pork longissimus dorsi (LD) was used as the experimental subject to investigate gel properties of transgluminase (TG) treated porcine myofibrillar protein (MP). Effects of TG concentration on gel strength and water-holding capacity of heatinduced porcine myofibrillar protein were investigated under different pH levels. Meanwhile, the microstructure of porcine myofibrillar protein gel was also observed. Results indicated that the gel strength of porcine myofibrillar protein was significantly improved with TG treatment. The optimal treatment was based on TG-catalyzed hydrolysis with an enzyme dose of 0.3% in a 0.6 mol/L NaCl environment. However, TG additions under different pH levels exhibited obvious different effects on cooking weight loss of protein, including an enhancement effect on cooking weight loss of protein at pH 5.8－6.4 and a reduction effect at pH 6.4－6.7. An improvement in microstructure of heat-induced myofibrillar protein gel was observed under scanning electron microscopy. In conclusion, the textural properties of porcine myofibrillar protein gel can be promoted by TG treatment.
In order to construct a set of technical systems for protein profile analysis of skeletal muscle of fugu (Takifugu rubripes), total proteins extracted from fugu skeletal muscle were separated using high resolution two dimensional polyacrylamide gel electrophoresis and developed by silver staining in polyacrylamide gel for computer assisted analysis of electrophoresis patterns using software IMAGEMASTERTM. Subsequently, matrix assisted laser desorption ionization time of flight mass spectrometry (Maldi TOF MS ) was applied for identifying the major protein spots on the 2D profile. Of the 112 protein spots detected in a silver-stained 2D polyacrylamide gel, 33 were analyzed using Maldi TOF MS, and 21 were identified using MASCOT against takifugu or zebrafish data in NCBI nr, MSDB, and UniProtKB/TrEMBL, which included structural proteins such as tropomyosins, enzymes or proteins involved in metabolism and signal transduction and apoptosis etc.
Spectrofluorimetric technique was employed to study the inclusion interaction of brilliant blue (BB) with β - cyclodextrin (β-CD) and its derivatives (CDs), including mono[2-O-(2-hydroxyethyl)]-β-CD (HE-β-CD) and mono[2-O- (2-hydroxypropyl)] -β-CD (HP-β-CD). Linear Hildebrand-Benesi plots with a high correlation coefficient demonstrated that CDs could react with BB to form a 1:1 host-guest complex. A significant enhancement of fluorescence intensity in BB was observed due to its inclusion interaction with β-CD and its CDs which exhibited an enhancement effect in the following order of β-CD < HE-β-CD < HP-β-CD. In addition, the optimum inclusion reaction time and pH value were determined to be 30 min and from 4 to 10, respectively.
The antibacterial activity of ethanol extracts from 27 plant spices was tested against P1 strain isolated from deteriorated salted duck. In order to obtain the highest antibacterial activity, ethanol extracts from 3 plant spices with higher antibacterial activity were compounded and the compound proportion was optimized in terms of antibacterial activity against P1 strain and other bacteria, including Staphylococcus aureus, Pseudomonas sacastanoi, Salmonella, Escherichia coli, Bacillus subtilis. Subsequently, the optimal compound antibacterial ethanol extracts were evaluated for minimum inhibitory concentration (MIC) and effect of temperature on their biological activity. Results showed that ebony, clove and liquorice were chosen due to high antibacterial activity of ethanol extracts and their compound with the mixing proportion of 1:8:1 (V/V) yielded significantly higher antibacterial activity than individual ebony extract. Moreover, no obvious change was observed in inhibitory effect of the compound ethanol extracts when exposed to high temperature (up to 100 ℃) for a long time.
The processing of Jinhua ham by modern processing technology was traced by examining free amino acid (FAA) content in 5 replicate samples of biceps femoris taken as the material for Jinhua ham production at 9 processing stages, namely, green ham, end of pre-curing, end of curing, mid-drying, end of drying, 3 fermentation stages (early stage, medium stage, late stage) and end of post-aging. Results showed that the contents of FAAs in biceps femoris displayed a gradual increase during processing and a sharp rise was observed at the fermentation stages. The total content of FAA in Jinhua ham was about 5 times higher than that in precuring sample and the contents of majority of FAA were increased by 10 times. Glu, Leu, Ala and Arg had relatively high contents and Glu, Thr, Val, Ile and Pro exhibited a large increase.
The goal of the present study was to develop a microbial fermentation method for producing milk-derived ACE inhibitory peptides using a strain of Lactobacillus helveticus TS6024 preserved in our laboratory. Based on the determination of the optimal fermentation substrate for production of ACE inhibitory peptides, the optimal fermentation parameters were investigated using one-factor-at-a-time method and central composite design combined with response surface analysis. Results showed that a mixture of skim milk powder and vegetable protein consisting of half volume of soybean protein isolate and half volume of peanut protein isolate with a ratio of 9:1 (V/V) was chosen as the optimal fermentation substrate. The optimal values of fermentation parameters were skim milk concentration 9.67% (m/V), substrate sterilization time 30 min, inoculation amount 3% (V/V), and fermentation temperature 38.82 ℃ for a fermentation period of 6.26 h. The ACE inhibitory peptides under such conditions revealed an ACE inhibitory activity of 92.26%.
Purified endoinulinase from Aspergillus ficuum was used for inulo-oligosaccharides production at the optimal condition obtained with orthogonal experiments, including pH 5.0, 45 ℃, 50 g/L inulin, and enzyme concentration of 10 U/g substrate. With pure inulin as substrate, the inulin-hydrolyzing degree was up to 75% and the total inulo-oligosaccharides yield was 70.37% after 72 h. The hydrolysis products consisted of DP2 to DP8 determined by HPLC, DP3 and DP4 exhibited a relatively high content. With Jerusalem artichoke powder as substrate, the inulin-degrading extent was 62.38% and the inulooligosaccharides yield was 41.72% after 72 h. DP3 to DP6 were liberated as the main products with a great amount of fructose in the reaction mixtures. With Jerusalem artichoke juice as substrate, the inulin-hydrolyzing extent reached 89% and the maximum inulo-oligosaccharides production was up to 79.80% after 72 h. Various inulo-oligosaccharides with different DPs (mainly DP2, DP3, DP4, DP5, DP7, DP8) were evenly distributed in final reaction products. Therefore, the juice was the most suitable for inulo-oligosaccharides production by A. ficuum endo-inulinase.
Mechanisms and kinetic models of enzymatic hydrolysis of protein in rice dregs by trypsin at pH 7.6 and 53 ℃ were investigated using the combined method of experimental analysis and mathematic deduction. Results indicated that the overall rate of hydrolysis decreased exponentially during the hydrolysis process due to dual functions of the substrate for accelerating and inhibiting enzymatic activity. Based on experimental data, a kinetic model equation was deduced to demonstrate trypsin hydrolysis of protein in rice dregs and inactivation constant of trypsin. Therefore, hydrolysis degree can be effectively controlled through the adjustment of trypsin/substrate ratio, and reaction time, which can provide guidance to peptide industrialization from rice dregs by means of enzymatic technology.
The investigations on calcium enrichment in mycelia of three species of edible fungi: Pleurotus nebrodensis, Pleurotus eryngii and Pleurotus citrinopileatus Sing subjected to plate culture were conducted using calcium chloride as the calcium source. Results indicated that different fungus species, carbon sources and Ca2+ concentrations had a significant effect on the enrichment of calcium. In the same culture medium, the highest calcium enrichment in Pleurotus nebrodensis was observed. In addition, when calcium enrichment in three fungi was investigated in culture media with different carbon sources, the calcium enrichment from high to low revealed an order of lactose, maltose and sucrose. The highest calcium concentration of Pleurotus nebrodensis was obtained in the medium with lactose as the carbon source and 0.6% calcium.
This paper mainly deals with effects of different carbon sources, carbon source amount and medium pH on accumulation of acidic polysaccharides in Tremella fuciformis mycelia during submerged fermentation. Along with this, the fractionation of the polysaccharides by DEAE Sepharose Fast Flow chromatography is also discussed in this paper. Results showed that the fermentation medium containing 1% sucrose at pH 7.0 was conducive to the enrichment of acidic polysaccharides. The distribution of polysaccharide in mycelia and fruit body of Tremella fuciformis revealed a significant change.
In order to improve conversion rate of osteocalcin, bovine bone powder was subjected to symbiotic fermentation of Lactobacillus acidophilus GG (LGG) and Lactobacillus rhamnosus (LA). A series of single-factor experiments were conducted to investigate the effects of symbiotic fermentation parameters, including LGG/LA ratio, fermentation time, bovine bone powder amount and glucose amount on conversion rate of osteocalcin. Based on this, the optimal values of these parameters were determined using central composite design combined with response surface analysis. Results indicated that a symbiotic phenomena between both the probiotics was observed, which could convert calcium from bound state to free state. Fermentation time and bone powder concentration were among the most important affecting factors. A maximum calcium conversion rate of 32.21% was obtained under the following optimized fermentation conditions: LGG/LA ratio 1:4.67, fermentation time 69.96 h, bone powder 4.45%, and glucose 12.26%.
In order to understand the effects of engineered yeast MDC on fermentation and quality of red wine, the fermentation of Caberbet Gernischet wine using this strain was simulated in a 2 L flat bottom flask. Saint Georges S101 served as control. Results showed that compared with the control, engineered yeast MDC-fermented wine revealed a lower total acid content and higher contents of dry extract and total phenols and the malic-lactic acid fermentation was accomplished ahead of time. No significant differences in contents of volatile acid, residual sugar and protein were observed between engineered yeast MDC and Saint Georges S101-fermented wines.
A high trehalose-producing strain of Saccharomyces cerevisiae was bred via combined nitrosoguanidine (NTG)/UV mutagenesis. This strain had good genetic stability and a trehalose content of 19.8% (m/m dry yeast), which revealed the enhancement of 39.43%, 10.0% and 6.45% compared with the original strain, the strain screened by alone UV mutagenesis, and the strain screened by alone NTG mutagenesis, respectively.
Lactobacillus spp. and Staphylococcus spp. strains were isolated from Beihai light cured fish using MRS and MSA media and identified in terms of physiological and biochemical characteristics. Thirteen strains of Lactobacillus spp. and 10 strains of Staphylococcus spp. were obtained, and 3 strains (L1, L7, L9) of Lactobacillus spp. and 2 strains (S5, S8) of Staphylococcus spp. were selected by physiological and biochemical analysis. All the 3 strains of Lactobacillus spp. were identified as Pediococcus pentosaceus, and S5 and S8 Staphylococcus carnosus and Staphylococcus xylosu ,respectively.
In an attempt to optimize the culture medium for fibre degradation of brewers’grains by Neurospora crass, Plackett-Burman design and central composite design combined with response surface methodology were employed in this work. First, the effects of soybean residues, (NH4)2SO4, urea, KH2PO4, CaCl2 and MgSO4 on fibre degradation by Neurospora crassa were evaluated by a Plackett-Burman design leading to 8 experiments and the most important affecting factors were screened. Subsequently, the interactive effects of the screened factors on fibre degradation were determined using response surface methodology based on a five-variable, five-level central composite design involving 32 experiments. Results indicated that CaCl2, KH2PO4, soybean residues, (NH4)2SO4 and MgSO4 were among the most important affecting factors of fibre degradation. The optimal culture medium consisted of 26.08% soybean residues, 3.71% (NH4)2SO4, 1.53% KH2PO4, 0.24% CaCl2 and 0.08% MgSO4. Three replicate fermentations using the optimized culture medium all gave a value of fibre degradation rate which was in good agreement with the predicted value.
This study was designed to understand the effects of different carbon sources and its various concentrations on growth of Pholiota adiposa and exopolysaccharide production in plate culture and liquid culture. Results indicated that the optimal carbon sources and their concentrations for mycelia growth in plate culture were 3.0% fructose, 2.5% maltose, 3.0% glucose, 3.0% lactose, 2.5% brown sugar and 2.5% sucrose; glucose was determined to be the optimal carbon source for mycelia growth in liquid culture and its optimal concentration 3.0%; and the optimal carbon source for exopolysaccharide yield was maltose and its optimal concentration 2.0%.
In order to explore the protection effect of wheat providing the matrix for production of probiotic foods on Lactobacilli, the effect of wheat extracts on viability of selected stains of Lactobacilli, including Lactobacillus johnsonii JJB3, SNZ10, and Lactobacillus reuteri MNZ8, KNZ4 was investigated under the circumstance of simulated bile juice. The viability of these strains was detected during exposure to 10 g/L bile for 4 h at pH 7.0. In additions, the effects of glucose and free amino nitrogen (FAN) on their bile tolerance with increasing concentration were also examined. In the absence of wheat extracts KNZ4 showed the greatest resistance to bile with a reduction of viable count of only 1.16 lg (CFU/ml), whilst MNZ8 displayed the greatest sensitivity with a reduction of viable count of up to 1.74 lg (CFU/ml). Addition of wheat extracts significantly improved the tolerance of all four strains (p＜0.05), and JJB3 showed the highest bile tolerance and the viable population was decreased by 0.11 lg(CFU/ml). The extent of improvement was positively correlated with the concentration of soluble sugars and FAN present in the extracts. Glucose revealed a better effect than FAN. The results presented in this study indicate that wheat extracts exhibit a significant protective effect on the viability of four Lactobacilli strains under simulated bile conditions, especially for L. johnsonii JJB3.
This study aimed to screen and breed an edible strain of Candida utilis exhibiting high protein content via UV mutagenesis. Results showed that the exposure to 15 W UV light (at a distance of 30 cm) for 120 s led to a lethal rate of up to 89% and a new mutant strain B2 was obtained with a high protein content of 33%, which was higher than before mutagenesis (22.9%) by 37.12%. Analysis on protein content showed high genetic stability of this mutant strain after 10 passagings. The optimal B2 fermentation, which resulted in high protein content in mycelia (37%) and biomass of Candida utilis was achieved through culture at 32 ℃ with a shaking speed of 160 r/min using glucose as carbon source and (NH4)2SO4 and yeast extract powder as nitrogen sources.
In order to prepare highly specific rabbit anti-ovotransferrin polyclonal antibody, New Zealand rabbits were immunized with commercial ovotransferrin or laboratory-purified ovotransferrin. The titer and specificity of antisera prepared were analyzed by ELISA and Western blotting, respectively. Results showed that all the antisera reached a titer of 1:819200 and exhibited a high specificity. Therefore, target products have been successfully prepared, which might be useful for the further investigations of egg allergy.
After accomplishing fermentation, recombinant E.coli cells were disrupted via ultrasonic treatment for the release of thermostable α-amylase from them. Subsequently, the enzyme was purified by GST affinity chromatography and subjected to enzymological characterization. This enzyme exhibited a molecular weight of 170 kD, an optimum temperature ranging 60－ 70 ℃, an optimum pH value of 6.6 and a Km value of 0.14352 mol/L. Stable activity was observed at pH 5.4－7.8. In addition, only 50% activity was lost after 2 weeks of storage at 4 ℃, 35 ℃ storage for 3 d led to an activity loss of more than 50%, whereas this enzyme was inactivated rapidly when the storage temperature was more than 70 ℃. Mn2+ revealed a strong promotion effect on the enzyme activity, K+ and Ca2+ only a weak promotion effect, Mg2+ no effect, Cu2+ the strongest inhibition effect, and other metal ions, including Co2+, Zn2+, Fe2+ various inhibition effects. Organic ions such as EDTA, SDS, urea and Tris were all inhibitors of this enzyme, among which SDS was the strongest one.
Fibrinolytic enzyme from Cordyceps militaris was extracted by ammonium sulfate precipitation and ion exchange chromatography and its enzymological properties wee also investigated. Results indicated that optimal pH and reaction temperature of this fibrinolytic enzyme were 8.0 and 37 ℃, respectively. This enzyme was stable at pH from 6.0 to 10.6, but sensitive to high temperature. Its activity could be inhibited by EDTA, which suggested this enzyme was a metalloproteinase. Moreover, its activity could be enhanced by Fe2+ and Ca2+ at a low concentration of 0.01 mol/L and inhibited by them at a high concentration of 0.1 mol/L. However, Na+ and NH4+ had little effect on the activity of this enzyme.
High pressure-induced mutation of beer yeast (Saccharomyces cerevias) was studied. The optimal values of mutagenesis parameters were determined. Meanwhile, the original and mutant strains of bear yeast were compared for differences in fermentation performance and RAPD fingerprint. Results indicated that a mutant strain, MS-3, was obtained under the optimal technological conditions of treatment with 300 MPa for 15 min. Totally 7 arbitrary primers and 4 arbitrary primers could result in relatively high DNA amplification and obvious mutant characteristics. Therefore, these investigations are helpful to provide a basis for screening and breeding of excellent bear yeast strains by mean of high-pressure mutagenesis.
Enzyme is a major factor involved in the process of cell metabolism, which also contributes to food preservation. Six kinds of pollens from apricot flower, peach blossom, lotus, rape, lalayang, and sunflower contain a variety of enzymes. The activities of catalase, peroxidase, lipoxygenase, superoxide dismutase and phenylalanine lyase in 0.2 mol/L phosphate buffer extracts from these pollens were determined so that the activity level of these enzymes was used as criteria for evaluating the freshness of pollens.
In order to establish growth kinetics models for L. monocytogenes in chilled pork, L. monocytogenes were inoculated to contamination-free longissimus muscles to monitor the growth of this species of bacteria during storage. Samples were placed at 2, 15 and 28 ℃ for storage, and total L. Monocytogenes count was determined during different storage periods. Growth kinetics models for L. monocytogenes were developed at various temperatures using Gompertz equation. The relationship between temperature and μmax (maximum specific growth rate) or λ(lag phase) of L. monocytogenes growth in temperature range of 0 －30 ℃ revealed a good linearity evaluated by the square root model with correlation coefficients of 0.716 and 0.972, respectively. The absolute values of model residuals were less than 0.03 and fluctuated around zero, which revealed an absolute reliability of this model. Therefore, this square root model can describle the effect of temperature on growth of L. monocytogenes.
Totally 120 yeast strains were isolated from longan grapes harvested from Shacheng region during spontaneous fermentation process. Five unique colonies were identified through culture and clustering analysis using WL medium. Five different genotypes were also identified through RFLP analysis of 5.8S rDNA-ITS region. The species of four yeast strains were identified through sequence analysis and another one still needs to be further identified.
A probiotic strain with an excellent cholesterol-reducing ability of 50.83 % was screened from 5 strains of lactic acid bacteria, which were isolated from fresh cattle feces. This strain was identified as Lactobacillus fermentum with API identification system and 16srRNA sequence alignment and was nominated as Lactobacillus fermentum DF-4. It exhibited a strong tolerance to 0.3% bile salt and low pH and an antagonistic effect against both enteropathogenic E.coli and S.aureas when incubated in the simulated gastroenteric environment. These results indicate that Lactobacillus fermentum DF-4 is a potential probiotics with an excellent cholesterol-reducing effect.
Eight Lactobacillus acidophilus strains were cultivated in batch, and the activities of 10 enzymes involved in lactic acid fermentation pathway were measured, and the metabolic fluxes of lactic acid were analyzed at the logarithmic growth phase. Path analysis was used to investigate the direct and indirect influence of enzyme activity on lactic acid metabolic flux, followed by the establishment of a determination coefficient (R2(i)) which quantified the control effect similar to metabolic control coefficient. Results showed that pyruvate kinase(R2(PK) = 0.3705), hexokinase(R2(HK) = 0.3053), triosephosphate isomerase(R2(TPI) = 0.2733) and lactate dehydrogenase (R2(LDH) = 0.2601) exhibited higher determination coefficients, which suggested that they played a dominant role in control of lactic acid production. However, the determination coefficient of gylceraldehyde-3-phosphate dehydrogenase was negative (R2(GAPDH) = 0.1320), which suggested that GAPDH had a negative effect on lactic acid production.
In order to prepare highly active peptides derived from goat s milk casein (GMC), the enzymolysis technology for GMC with neutral protease, trypsin, papain or alkaline protease was optimized using orthogonal array design. Based on this, these enzymes were combined pairwise for achieving a maximum amino nitrogen content in GMC hydrolyaste. Meanwhile, the antioxidant activity of GMC hydrolyastes prepared via single enzyme or double enzyme hydrolysis was also evaluated by DPPH radical scavenging assay. Results showed that a content of total peptide substances of 8.5379 mmol/g was exhibited in GMC. For single enzyme hydrolysis, neutral protease and trypsin could hydrolyze GMC with higher degree of hydrolysis when compared to alkaline protease; for double enzyme hydrolysis, the combination of trypsin with neutral protease or alkaline protease exhibited higher degree of hydrolysis than other combinations, and the corresponding values of degree of hydrolysis, average peptide chain length and average relative molecular weights were 17.34%, 5.77 and 692 for neutral protease + trypsin and 16.40%, 6.10 and 732 for trypsin + alkaline protease, respectively. Additionally, neutral protease and trypsin + alkaline protease hydrolysates of GMC displayed stronger DPPH radical scavenging activity than other hydrolysates.
In order to reveal the change law of microecology in cellar mud, different aged cellar mud (0, 2, 16, 33 years) from Hunan Xiangjiao liquor Co. Ltd was sampled to investigate changes in characteristics of microecology in wall cellar mud and bottom cellar mud, such as sensory and physiochemical qualities and microbial flora quantity during aging. Results indicated that with increasing age, cellar mud progressively exhibited the typical sensory quality of naturally ripe cellar mud. The moisture content in cellar mud showed a slowly decreasing trend, while a reverse trend was observed in the pH value of bottom cellar mud and the contents of organic substances, total nitrogen, available phosphorus and potassium in cellar mud. The contents of moisture and available phosphorus in bottom cellar mud were slightly higher than those in wall cellar mud. Moreover, the total counts of different species of microbes in cellar mud, including bacteria, actinomycetes and fungi also exhibited a increasing trend, with a following order of bacteria fungi actinomycetes. Therefore, with increasing age, the quality of cellar mud can be gradually improved due to interactions between physiochemical factors and functional microbes.
A -mannanase producing bacterial strain HDYM-04 was isolated from laboratory-prepared flax retting liquor. HDYM-04 was identified as Bacillus licheniformis according to physiological and biochemical tests and phylogenetic analysis based on16S rDNA sequence. Single factor and orthogonal array design experiments were performed to obtain the optimum fermentation conditions for -mannanase production: culture with an inoculation size of 2% for 48 h at 37 in a 250 ml shaking flask filled with 100 ml liquid medium consisting of 60 g/L konjac powder utilized as carbon source, 30 g/L peptone utilized as nitrogen source, 0.2 g/L MgSO4 7H2O, 5 g/L K2HPO4 at initial pH 8.0. Under these optimum conditions, a -mannanase activity of 4890 U/ml fermentation broth was achieved, which was 3.2 times higher than before the optimization.
The optimal fermentation conditions of recombinant Diasporangium sp. strain D-A1 for Se accumulation in its mycelia were investigated in this study. First, single factor experiments were conducted for exploring the effects of various factors including kinds of carbon source and nitrogen source, carbon source concentration, culture temperature, shaking speed, pH, inoculation amount and culture medium volume poured into 250 ml flask on selenium accumulation in D-A1 mycelia. Subsequently, the most important affecting factors such as kinds of carbon source and nitrogen source, culture temperature and shaking speed were optimized using orthogonal array design. Results showed that after fermentation at 18 with a shaking speed of 120 r/min in a culture medium consisting of 100 g/L maltose and 10 g/L yeast extract with an initial concentration of sodium selenite of 90 g/ml, D-A1 mycelia exhibited a Se content of 3266.79 g/g dry weight and a percentage of organic Se accounting for total Se of 85.08%. Compared with non-Se-enriched mycelia, Se-enriched mycelia had higher unsaturated fatty acids content with 1.20, 1.24 and 1.71-fold enhancements for linoleic acid, arachidonic acid and EPA, respectively.
Spontaneously fermented Pu er tea and solid-state fermented Pu er tea using artificial inoculation of fungi species, including Aspergillus niger, Penicillium and yeast were compared for differences in sensory, chemical and microbiological attributes and health care functions such as hypoglycemic effect and anticancer, and so on. Results showed that when compared with spontaneous fermentation, artificial fungus-inoculated solid-state fermentation could not only maintain the main flavor quality of spontaneouslly fermented Pu er tea, but also result in excellent sensory characters including infusion color, taste and aroma, higher contents of water extract and tea polyphenols and lower coliform count, below 30 MPN/100 g ( no pathogenic bacteria were detected), which could satisfy the requirement for microbiological safety stipulated in the Yunnan province standard DB53/103 2006. Both Pu er tea showed significant protective effects on diabetes, obesity, immunodeficient, leukemia, stomach cancer and blood diseases and the effects of spontaneouslly fermented tea were slightly stronger.
According to the results of physiological and biochemical tests and microbial counterevidence experiments, microorganisms isolated from deteriorated canned peaches mainly consisted of facultative anaerobic bacteria, including Bysscochlamys ulva, B. coagulans and B. cereus. Based on experimental results, their growth curves were also plotted in this study.
Peptides with high antioxidant activity were prepared from casein by a two-step method, i.e., first preparation of casein hydrolysates by papain-catalyzed, and then modification of these hydrolysates by plastein reaction with papain. The antioxidant activities of casein hydrolysates and their modification products were evaluated by DPPH assay and ABTS assay. The optimum conditions for casein hydrolysis were casein concentration 5%, papain concentration 500 U/g casein, pH 4.5, temperature 45 for a hydrolysis duration of 2 h, and the optimal plastein reaction conditions were substrate concentration 50%, papain concentration 500U/g substrate, and temperature 30 for 5.5 h reaction. Capillary electrophoresis analysis confirmed that the compositions of antioxidant peptides were changed as a result of plastein reaction. The DPPH and ABTS scavenging activity of casein peptides were remarkably enhanced after enzymatic modification.
A mannanase-producing bacterial strain F1-5 that isolated and preserved in our laboratory was identified as Bacillus subtilis (Genebank accession number FJ392725) according to the results of morphological observations, physiological and biochemical tests and 16S rDNA sequence homology analysis. The optimal fermentation conditions of F1-5 for producing mannanase were determined to be fermentation for 48 h at 35 ℃ with an inoculation size of 6% in a 250 ml flask with a shaking speed of 180 r/min containing 60 ml of culture medium consisting of 4.8% yeast cell wall as carbon source and 0.5% NH4NO3 as nitrogen source by one-factor-at-a-time and orthogonal array design methods. Under such conditions, the mannanase activity was up to 330 U/ml, which was 3.4 times higher than before the optimization. Furthermore, our 5 L fermentor experiments gave a mannanase activity as high as 582 U/ml. Therefore, these optimal conditions are reliable.
A fermented kudzu beverage was developed using the starter composed of Bifidobacterium, Thermophil streptocoaus and Bulgaria lactobacillaceae with a ratio of 1:1:1. The optimal fermentation process for kudzu beverage production was determined to be fermentation for 10 h at 40 ℃ with an inoculation size of 6.0% using kudzu milk solution with 70% milk and 1.5% glucose as fermentation substrate by one-factor-at-a-time and orthogonal array design methods. The acidity and total amount of viable Bifidobacteria in products fermented under these optimal conditions were 0.52% and 7.14 × 107 CFU/ml. Meanwhile, the obtained products exhibited a nice taste.
In order to increase number of Aspergillus oryzae spores in seed koji and neutral protease activity in soy sauce koji, carbon source, nitrogen source and inorganic salts were added to seed koji culture medium and their addition levels were optimized. Results indicated that the number of Aspergillus oryzae spores reached (15.77 ± 0.49)×109CFU/g (dry weight) in seed koji cultured in medium with the additions of 1.00% glucose, 0.10% CaCl2, 0.05% ZnSO4 and 3.00% bean cake powder, which was higher than that in the blank group by 84.87%. Furthermore, increases of neutral protease activity of 25.04% and 17.04% were observed in seed koji cultured under these optimized conditions and soy sauce koji made from this seed koji when compared to the blank group, respectively.
The effect of 60Co-γ irradiation with different doses and dose rates on mycelial growth of Pleurotus citrinopileatus was investigated in this study. Mutant strains of Pleurotus citrinopileatus with high growth rate were obtained through 60Co-γ irradiation at 600 Gy and 43.5 Gy/h dose rate. After the regeneration of mycelia, a novel strain having the highest growth rate was screened, which showed an average increase of 21.1% when compared with that of the parental strain. Results of antagonistic test, esterase isozyme and peroxidase isozyme electrophoresis revealed significant genetic differences between the mutant strain and its parent stain. After six generations of continuous cultivation, the mutant strain kept the good growth vigor, thereby displaying high genetic stability.
In order to effectively detect minocycline (MNC) residues, a complete antigen of MNC was developed by glutaraldehyde synthesis and diazotization methods. MNC was coupled with bovine serum albumin (BSA) to obtain a complete antigen of MNC-BSA. Infrared and ultraviolet scanning spectral analysis confirmed that the complete antigen of MNC-BSA had been successfully coupled by both methods, with average conjugation ratios of 9.9 and 5.9, respectively. The serum titer of rabbit immunized with MNC-BSA competent antigen prepared by glutaraldehyde synthesis method was 16000, which indicated that the synthesized complete antigen could not only be used as the immunogen to prepare the corresponding antibody, but also act as the coating antigen for enzyme linked immunosorbent assay (ELISA) kit.
A Lactobacillus fusant with high activity was constructed through electro-fusion between L. helveticus SR288 with slim-producing activity and L. bulgaricus NR902 with acid-producing activity. Results indicated that the optimal electro-fusion parameters were alternative electric field intensity 300 V/cm, impulse intensity 6 kV/cm, impulse time 40 μs, and impulse number 4. The obtained fusion strain revealed excellent genetic stability up to 10 generations. Biological activity tests suggested that the fusant was superior to parental strains in acid-producing activity, apparent viscosity, and water-holding capacity.
Fractional factorial design was used to evaluate effects of related factors on astaxanthin production by Phaffia rhodozyma fermentation. Based on this, central composite design combined with response surface methodology was employed for optimizing the most important affecting factors of astaxanthin production. Results showed that the factors including initial pH, yeast extract amount, concentrations of glucose and fructose exhibited the most important effects on astaxanthin yield. The optimal fermentation medium composition for high astaxanthin yield consisted of 5.6 g/L yeast, 24 g/L glucose and 21 g/L fructose with an initial pH value of 8.5. This optimization resulted in an increase of astaxanthin yield from 10900 to 5890 μg/L. Moreover, enlarged fermentation in a 7.5 L fermentor gave an astaxanthin yield as high as 18300 μg/L with an enhancement of 68% when compared with shake flask fermentation.
The optimal carbon source in the fermentation medium for L-lactic acid production by an acid-resistant and high L-lactic acid-producing strain (Lc-F34) of genome-shuffled Lactobacillus was determined to be glucose with an initial concentration range of 90－110 g/L by one-factor-at-a-time method and starch hydrolysates also could be used as carbon source. In addition, the optimal nitrogen source was determined to be yeast extract, followed by corn steep liquor, which was able to partially or completely replace yeast extract. Furthermore, moderate addition of MgSO4·7H2O or MnSO4 could stimulate L-lactic acid fermentation with optimal concentrations of 0.3% and 0.05% respect to each.
Spontaneously-fermented (at 30 or 35℃) and L. sanfranscensis-fermented oat sourdough was compared for differences in changes in content and molecular weight distribution of β-glucan during fermentation. Results indicated that the highest content of β-glucan was determined in 35 ℃ spontaneously fermented oat sourdough, and the lowest content of β-glucan in L. sanfranscensis-fermented oat sourdough. The molecular weight distribution and molecular weight peak (Mp) in L. sanfranscensis-fermented oat sourdough did not exhibit significant change. Molecular weight of β-glucan ranging 55－2.5 × 104 kD exhibited the highest population in L. sanfranscensis-fermented oat sourdough, which reached 41%. The population of molecular weight of β-glucan of higher than 20 kD in 30 ℃ spontaneously fermented oat sourdough was close to 40%. In addition, the lower molecular weight distribution of β-glucan in 35 ℃ spontaneously fermented oat sourdough was the widest.
In order to prepare functional peptides from black chicken through immobilized trypsin hydrolysis, the optimal immobilization process for trypsin, stability of immobilized trypsin and hydrolysis of black chicken were investigated. The trypsin immobilization was conducted using sodium acetylide as the carrier and glutaraldehyde as the cross-linking agent. Results indicated that the optimal trypsin immobilization conduced at pH 7.5 and 70 ℃ with 4% sodium acetylide and 10% trypsin resulted in an activity recovery of 38.84%. A maximum amino nitrogen content of 2.18 mg/ml was achieved under optimized hydrolysis conditions, including material/liquid ratio 1:3, pH 7.5, temperature 60 ℃ and immobilized trypsin dose 10%. Immobilized trypsin still had above 50% activity after being used repeatedly 8 times.
This study was designed to explore effects of addition of Streptococcus thermophilus phages on physiochemical and sensory qualities of direct vat set (DVS)-fermented yogurt including viscosity, mouth-feel, post-acidification, syneresis and ratio of Streptococcus thermophilus to Lactobacillus bulgaricus. Results showed that low concentration of S. thermophilus phage could inhibit acid production, apparently change ratio of S. thermophilus to L. bulgaricus and result in decrease of viscosity, deterioration of mouth-feel, and aggravation of syneresis and post-acidification. In conclusion, addition of S. thermophilus phages exhibits serious hazard to yogurt production with DVS.
Aspergillus oryzae can directly ferment swim bladder homogenate to produce protease that can hydrolyze swim bladder protein into peptides. Based on the principle, this study was designed to perpare peptides from variegated carp swim bladder. The polypeptide concentration in products was determined at intervals of 8 h during 64 h of fermentation. Apart from this, the antioxidant activities of products at different fermentation time and ultrafiltration fractions of 40 h fermentation product were tested by superoxide anion radical scavenging array, hydroxyl radical scavenging array and linoleix acid autooxidation assay. Results showed that 40 h fermentation product with (22±0.8)% degree of hydrolysis exhibited stronger antioxidant activiry than 24 h and 56h fermentation products and VE. The ultrafiltration fraction of 12 amino acid residues in average length with 1000 D molecular weight revealed the strongest antioxidant activity among all fractions. In addition, peptides obtained from variegated carp swim bladder by fermentation also had strong scavenging activity against superoxide anion and hydroxyl radical radicals and could significanty inhibit linoleic acid autooxidation
In order to evaluate the antitumor activity of red wood ants (Formica aquilonia) from Changbai mountain, ethyl acetate extract from this species of red wood ants and its ethyl acetate-soluble and water-soluble fractions were investigated for effects on proliferation and apoptosis of dRLh-84 cells using MTT assay and fluoroscopic observation, respectively. The ethyl acetate extract was able to inhibit the proliferation of dRLh-84 cells in a dose-dependent manner. Active components in the extract were transferred into ethyl acetate phase in ethyl acetate-water extraction due to low polarity so that the ethyl acetate phase also exhibited a significant inhibitory effect on the proliferation of dRLh-84 cells, which depended on dose with an IC50 of 60 μg/ml. Fluoroscopic observation indicated that the extract had an obvious apoptosis-promoting effect on dRLh-84 cells.
In order to study the effect of Lactobacillus helveticus on intestinal immunity in mice, cytokines in intestinal mucosa and tissue of mice were analyzed. Totally 60 mice were randomly divided into four groups: normal diet group, normal saline control group, Lactobacillus helveticus group, and E. coli group. All mice except the normal diet control group were orally administered corresponding probiotics for continuously15 days, and then cytokines in intestine mucosa and tissue of mice were detected using ELISA to analyze immunoregulatory function of Lactobacillus helveticus. Lactobacillus helveticus-administered mice had a significantly higher level of four cytokines when compared to control groups (P < 0.05). The highest level of cytokines was observed at 3 days post-administration for IL-2 and IFN-γ, and at 5 days post-administration for IL-4 and IL-6. Meanwhile, no obvious change in population of Th1 and Th2 type T cells in intestinal mucosa and intestinal tissue of Lactobacillus helveticus-administered mice was observed; in contrast, the balance of Th1 and Th2 type T cells in E. coli-administered mice was disturbed, which revealed that Lactobacillus helveticus had a protective effect on intestinal immune.
Kunming male mice (about 6 weeks old, (20 ± 2) g) were used as experimental animals for measuring free radical scavenging activities and hypoglycemic effects of aqueous extracts of 4 species of edible fungi, including Pleurotus citrinopileatus, Stropharia rugoso-annulata, Pleurotus cornucopiae and Agrocybe aegerita. Meanwhile, active components in the aqueous extracts, including total flavonoids, total phenols and polysaccharides were quantified by spectrophotometric methods. Alloxaninduced diabetic mouse models were constructed by intraperitoneal injection and intragastrically administered with a dose of 400 mg/kg for continuously 28 d, using phenformin-treated mice (100 mg/kg) as positive group and normal mice as control group. Fasting blood glucose level was determined on the 0, 6th, 14th, 21st and 28th d, and glucose tolerance level was determined on the 28th d. After scarification, mice were subjected to blood sampling for assaying glycated hemoglobin and blood lipid levels. These aqueous extracts exhibited a total flavonoids content ranging 2.37－6.89 mg/g, a total phenols content ranging 2.5－4.96 mg/g and a polysaccharides content ranging 20.30－44.02 g/100 g. The EC50 values of Pleurotus citrinopileatus, Stropharia rugosoannulata, Pleurotus cornucopiae and Agrocybe aegerita extracts (PCTE, SRE, PCNE, AAE) were 0.32, 0.24, 0.36, 0.13 mg/ml for scavenging superoxide radicals, 2.36, 3.71, 2.60, 3.95 mg/ml for scavenging hydroxyl radicals, and 14.51, 15.32, 15.36, 11.20 mg/ml for scavenging DPPH radicals, respectively. The 28-day continuous administration of each of these aqueous extracts could result in a significant improvement in clinical symptoms of diabetes mellitus and a significant decrease in the levels of fasting blood sugar and glucose tolerance expressed as blood glucose area under the curve (P < 0.01). A decrease in blood glucose level of above 15% was observed in PCTE-, PCNE- and AAE-treated diabetic mice. In addition, GHB levels in blood serum came back normal. Furthermore, PCTE-, SRE-, PCNE- and AAE-treated diabetic mice exhibited normal levels of TC and HDL-C.
High, medium and low doses of luteolin were administered to high fat diet-induced hyperlipidemic rat model established in adult Sprague-Dawley rats for investigating its effects on the levels of blood lipid and antioxidant indexes in hyperlipidemia rats, including MDA content, T-AOC, and SOD and CAT activities. Results showed that all three dose groups exhibited significantly lower levels of TC, TG and MDA and higher levels of HDL-C, T-AOC, SOD and CAT when compared with model control group (P < 0.05). In conclusion, luteolin might contribute to improve the serum antioxidant capability and reduce the lipid peroxidative damage in hyperlipidemic rats.
This study was designed for understanding how Glycyrrhiza polysaccharide (GP) affects the expression of iNOS mRNA and the generation of NO and iNOS in mouse peritoneal macrophages. iNOS mRNA was isolated by RT-PCR and NO production was assessed by spectrophotometric method based on Griess reaction. Results showed that GP could induce the increases of NO content and iNOS activity in mouse peritoneal macrophages in a dose-dependent manner. A maximum NO and iNOS production and iNOS mRNA expression were observed when the concentration of added GP in culture solution was 400 μg/ml, or when the incubation time was 48 h at a fixed GP concentration of 100 μg/ml. This indicated that the regulation of GP on the production of NO in mouse peritoneal macrophages might occur at the transcriptional level of iNOS, thereby stimulating its large-quantity production and release. Furthermore, antitumor and immuno-regulation functions of GP might be associated with the increased NO production resulting from the ab initio synthesis of iNOS in stimulate macrophages.
A strain of endophytic Chaetomium globosum with high antixoxidant activity was isolated from Eucommia ulmoide, and its fermentation broth was extracted for the evaluation of in vitro inhibitory effects on automatic and H2O2-induced lipid peroxidation and hemolysis of red blood cells (RBCs). Results showed that the extract exhibited a dose-dependent inhibitory effect against lipid auto-peroxidation in mouse heart and spleen tissues and H2O2-induced lipid peroxidation in liver tissue, with inhibition ratios of 71.55%, 71.68% and 92.50% at 1 mg/ml, respectively. Moreover, the extract also inhibited 68.48% of autooxidative hemolysis of RBCs at 0.3 mg/ml and 96.12% of H2O2-induced hemolysis of RBCs at 0.75 mg/ml, and the inhibitory effect against H2O2-induced hemolysis of RBCs exhibited an increase with increasing concentration. In conclusion, this extract has significant in vitro anti-lipid peroxidation activity and protective effects on red blood cells resulting from decrease in oxidative hemolysis.
The aim of this study was to investigate the sedative and hypnotic effect of ethyl acetate extract from male flowers of Eucommia ulmoides Oliv and to determine its optimal effective dose using Kunming male mice as experimental animals. The effect of the extract on spontaneous activity in mice, possible synergetic effect with pentobarbital sodium and anticonvulsant effect of with different doses were analyzed. Results showed that the ethyl acetate extract was able to significantly induce sleep in mice, inhibit the spontaneous activity, enhance the percentage of sleeping mice with the treatment of subthreshold dose of pentobarbital sodium, prolong the sleeping time induced by superthreshold dose of pentobarbital sodium and the convulsion latency, shorten the sleep latency, and reduce the eclamptia ratio in mice. In summary, ethyl acetate extract from male flowers of Eucommia ulmoides Oliv possess obviously sedative and hypnotic effects in mice.
This study was conducted for examining if soybean dregs rich in dietary fiber would enhance the alleviating effect of resistant starch on estrogen deficiency-induced hypercholesterolemia in ovariectomized rats. Total 32 adult female Wistar rats were subjected to bilateral ovariectomy and randomly divided into 4 groups: control group, soybean dregs (SD) group, resistant starch (RS) group and soybean dregs + resistant starch (SD + RS) group, which were fed diets containing total dietary contents of 2.6%, 41.7%, 39.8% and 40.5%, respectively. After 5 weeks of feeding, rats were sacrificed and anatomize and the levels of triglyceride and cholesterol in serum and liver, cholesterol 7α-hydroxylase activity in liver, bile acid pools in small intestine and cecum, and excretion of bile acid in feces were measured. Results showed that RS and RS + SD groups exhibited a significant decrease in total cholesterol content in serum and liver (P < 0.05), SD and SD + RS groups exhibited a significant decrease in serum triglyceride content (P < 0.05), and SD + RS group exhibited significant increases in intestinal bile acid pool, fecal excretion of bile acids and cholesterol 7α-hydroxylase activity in liver when compared to control group (P < 0.05). In conclusion, soybean drags can significantly enhance the hypolipidiamic effect of resistant starch, and the hypocholesterolemic effect of resistant starch appeared to be mediated by accelerated fecal excretion of bile acids and increases in intestinal pools.
Objective: To investigate the effect of combined administration of carboxymethyl chitosan (CM-CTS) and adriamycin (ADR) on proliferation of human cervical carcinoma cell line (Hela) in vitro. Methods: Effects of both drugs on proliferation of tumor cells were evaluated by MTT assay. Results: Alone administration of CM-CTS or ADR revealed an inhibitory effect on proliferation of tumor cells and a synergistic effect on inhibition of tumor cell proliferation was observed under simultaneous administration of both drugs. In addition, sequential administration of ADR followed by CM-CTS had a synergistic effect; in contrast, sequential administration of CM-CTS followed by ADR exhibited an antagonistic effect. Conclusion: Simultaneous administration of CM-CTS and ADR revealed a synergistic effect and sequential administration of CM-CTS and ADR exhibited an unidirectional synergistic effect.
Objective: To investigate hepatoprotective effect of germanium-rich barley seedling (GRBS) in mice with acute hepatic injury induced by CCl4. Methods: Mice model with acute hepatic injury was established through induction of CCl4. The mice with acute hepatic injury were orally administered GRBS at different doses (low, medium and high-doses). ALT activity in serum and immune organs index were determined and pathological changes of livers were examined to evaluate the hepatoprotective effect of GRBS. Results: GRBS at three doses significantly inhibited ALT activity in serum (P < 0.05, P < 0.01) and promoted the recovery of hepatic tissue injury, which was in a dose-dependent mode. Moreover, GRBS also obviously improved liver index (P < 0.01) and spleen index (P < 0.01, P < 0.05). Conclusion: GRBS has hepatoprotective function for mice with acute hepatic injury induced by CCl4.
Kunming male mice ((20 ± 2) g) were used as experimental animals for exploring the protective effects of grape seed proanthocyanidins (GSPs) against oxidative damage in brain tissue of mice. Oxidative brain damage models of mice were established with D-galactose induction. Mice with brain damage were orally administered with GSP at doses of 10, 20 and 40 mg/kg serving as low-, medium- and high-dose groups, respectively or identical doses of normal saline serving as model control group once a day for 6 weeks and normal mice also administered with normal saline served as normal control group. After 6 weeks, all mice were sacrificed and anatomized for assaying the activities of total superoxide dismutase (T-SOD) and glutathione peroxidase (GSHPX), and the content of malondialdehyde (MDA) in brain tissue and observing cerebral cortex ultrastructure under transmission electron microscopy (TEM). Results showed that GSP was able to significantly inhibit the decrease of T-SOD and GSHPXactivities and the increase of MDA content in brain tissue of mice with oxidative damage induced by D-galactose, and alleviate the ultrastructural pathological changes in cerebral cortex. Therefore, GSP has protective effects against oxidative damage in brain tissue of mice induced by D-galactose.
Mice with acute liver injury were modeled through CCl4 induction and orally administered with soybean polypeptides at doses of 3, 1.8 and 0.6 g/kg·d for 30 d, respectively. Effects of soybean polypeptides on glutamic-oxaloacetic transminase (GOT), glutamic-pyruvic transminase (GPT) and alkaline phosphataes (ALP) in serum and triglyceride (TG), total cholesterol (TC), malondialdehye (MDA) and glutathione peroxidase (GSH) levels in liver were investigated. Results indicated that CCl4- induced mice model with liver injury was successfully established. Soybean polypeptides significantly decreased the levels of GOT, GPT and AST in serum and TG, TC and MDA in liver, and obviously increased the level of GSH in liver in a dosedependent manner. Therefore, soybean polypeptides have an excellent protective capability against acute liver injury in mice induced by CCl4.
Due to nutrition-rich in pollen, its research and applications have been gained extensive attention. However, the outer cell wall of pollen is an obstacle to limit the development and utilization of its nutrition. In this paper, a variety of methods including mechanical, physical and biological methods for cell disruption of pollen are reviewed. Meanwhile, the future development trend for cell disruption of pollen is also proposed.
Peanut is one of the common sources of food allergens, which poses a serious threat to the quality of life of allergic population. Meanwhile, the allergenic cross-reactivity between peanut and other nuts is prevalent. This paper introduces the material basis of peanut allergens and the mechanisms for cross-reactivity between peanut and other nuts with an aim to present some insights for advanced studies of peanut allergy.
In this paper, background, development, basic concept and basic structures of cell-based biosensors are introduced. Research methods and applications of cell-based biosensors in the field of food are also demonstrated. Meanwhile, the future strategies for developing cell-based biosensors are put forward based on their current problems.
In this paper, current analytical methods for plant hormone including spectroscopy, gas chromatography, high performance liquid chromatography and pre-treatments of samples are reviewed. Meanwhile, sample pretreatment methods are also summarized.
The labeling technology using quantum dots has gained quick development in recent years. Due to the characteristics of accuracy, high sensitivity, good stability and high specificity, this technology has been extensively used in the field of biomedicine. In this paper, properties and detection strategies of quantum dot technology are reviewed, which will extend its application in rapid detection for food safety.
Polysaccharides have attracted tremendous attention due to the abundance with a variety of species and quantities in nature and extensive application in wide-range fields. In this paper, current problems related to polysaccharide research, concepts and purposes for polysaccharide modification, mechanisms and methods for polysaccharide molecular modification by radiation technology are reviewed. Meanwhile, practical applications of radiation technology in molecular modification of polysaccharides including chitosan, starch, carrageenan, sodium alginate and cellulose are also discussed.
Numerous studies have reported that bioactive peptides have many physiological functions to human including immune regulation on gut mucosa with tremendous surface area. Current research progress of bioactive peptides is reviewed here. Effects of bioactive peptides on SIgA, Th cells, cytokines and immune signaling pathways are discussed on the basis of structures and immune mechanisms of gut mucosa. The future development prospects of bioactive peptides are proposed.
Water is extremely vital for successful extrusion operation and the formation of unique properties of extrudate. In this review, the movement and change of water during extrusion process and the effects of feed moisture on extrusion system parameters and extrudate properties were discussed in detail. Meanwhile, encountered problems in current studies are summarized and analyzed the necessity for extensive and systematic study of action of water during food extrusion process is also pointed out.
The advantages and disadvantages of present analytical methods for the qualification and quantification of plantderived polysaccharides are summarized in this paper. Thin layer chromatography has gained a widespread application in the preliminary analysis of plant-derived polysaccharides due to the merits of rapidness, convenience and low cost; in contrast, HPLC has become the most popular method and HPLC coupled with MS has an extensive application prospect. Current analytical methods for plant-derived polysaccharides need further improvement and in-depth studies will tremendously favor the development of plant-derived polysaccharides as a great potential and valuable healthy food or medicine.
The formation and cooling mechanisms of rennet-induced casein gels are reviewed in this article. Previous investigations have revealed that emulsifying salts can promote the solubility of casein, the contents of protein and fat have effects on the composite modulus and viscoelasticity of casein gels, appropriate temperature and pH can benefit gel structure formation, while increased calcium concentration exhibits an adverse effect on the rennet-induced gelation of casein. Apart from these, applications of rennet-induced casein gels in cheese processing are also summarized.
Curcumins are a class of edible yellow pigments from rhizome of Curcuma longa Linn with multiple pharmacological functions, including anti-oxidation, anti-inflammation and anti-cancer. In this overview, neuroprotection effects of curcumins, research approaches and potential mechanisms are comprehensively summarized, which will provide valuable information for the development of curcumin-related health care products and the chemoprevention of neurotoxic damage.
Favorable and unfavorable reactions occurring during food extrusion determine the quality of final products. Feed materials are heated and sheared simultaneously during extrusion, and experience a non-isothermal process and, in addition, their residence time in extruder is distributed. All these lead to tremendous difficulties in elucidating the kinetic process of reactions induced by extrusion. Therefore, this paper states how to describe food extrusion kinetically and simply, and reviews the kinetics of starch conversion/gelatization and degradation, protein polymerization, nutrition and toxin loss, changes in physicochemical properties, and enzyme inhibitor inactivation. Meanwhile, the main trends of further research are also predicted.
Ferulic acid (FA) and p-coumaric acids are phenolic antioxidants present in a variety of plants, which have been widely used in food and cosmetic industries and others. Massive work has been reported to obtain both acids from agricultural waste such as maize bran, rice bran, wheat bran, wheat straw, sugar cane bagasse, pineapple peels, orange peels, and pomegranate peels. With the aim to provide useful knowledge for high value-added utilization of agricultural and forest fibrous by-products, particularly cereal bran in China, this paper briefly introduces the physiological functions of both acids and their applications in various industries and stressly summarizes recent achievements in the investigation of their preparation process consisting of acid pretreatment, alkaline hydrolysis, separation, purification and identification.
With the purpose of offering useful guidance for the selection of an optimal method for quantitative determination of polysaccharides in various samples, this paper reviews methods for quantitative determination of polysaccharides, mainly including chemical assay, gas liquid chromatographic (GC) method, high pressure liquid chromatographic (HPLC) method, anion ion exchange chromatographic (AEC) method, size exclusion chromatographic (SEC) method, thin layer chromatographic (TLC) ethod, capillary electrophoresis (EC) method, infrared spectroscopic (IR) method and so on.
In this paper, the current status and possible reasons of heavy-metal contamination of vegetables grown in Chinese suburb are analyzed. The corresponding prevention strategies to heavy-metal contamination on vegetables are proposed, which can provide a theoretical basis and reference for further investigations on the attenuation of heavy-metal contamination of vegetables.
Tremendous attention has been paid to the analysis and determination of melamine due to the melamine accident that broke out in China in 2007. With the aim to offer useful guidance for the determination of melamine in foodstuffs and animal feed, this article summarizes chemical and toxicological properties of melamine, relevant regulations at home and abroad and detection technologies, stressly introduces national standard analytical methods of various countries for the determination of melamine, and discusses characteristics and affecting factors of various pretreatment and detection technologies.
“The paradox of acquisition humoral immunity” was propased in the book-food immunity published in 2008. This review summarizes the current understanding of the FcRn-mediated IgG metabolism and transport. Based on the results, the acquisition of the humoral immunity, especially Fc binding with Fc receptors is able to mediate the humoral immunity through maternofetal transmission of immunogolubins and antibody-dependent cellular cytotoxicity (ADCC), but also establish an essential association from acquisition immunity to innate immunity. One of the important Fc receptors, FcRn, is involved in transferring maternal immunity and protecting IgG from fast degradation throughout life. FcRn also mediates bidirectional transport of IgG across mucosal, the intestinal epithelial and placenta barriers. All the data have presented a good answer to the “paradox of acquisition humoral immunity”, and meanwhile provided the scientific bases for food immunity and infant formula milk powder.
Cork taint, a musty off-odor in affected bottles, is among the most serious problems affecting wine sensory quality. And the main responsible factor for this organoleptic defect is attributable to 2,4,6-trichloroanisole(TCA). This paper mainly introduces methods for the extraction, concentration and detection of TCA from wine and wine corks. The application prospects of analytical methods for TCA are also predicted.
Tuna is rich in protein and omega-3 fatty acids, which is honored as a nutritional food. And the nutritional quality of frozen tuna is closely related to thawing methods. This article summarizes thawing methods for frozen tuna that have been reported recently at home and abroad, including conventional air thawing, cold-storage thawing, salt water thawing and several newly emerging methods, such as microwave thawing and low frequency thawing and makes a detailed comparison among them, which can provide a credible theory foundation for in-depth investigations of tuna, such as the establishment of standards for quality assessment.
Due to abundance in nutrients, low-temperature meat products will be one of the promising development goals in China. Predicting microbiological quality of low-temperature meat products is very helpful to the improvement of their edible safety. This paper describes dominant microbial colonies and sources and controlling measures of microbial contamination in low-temperature meat products. An overview of present predictive models at all levels is presented and their strengths and weaknesses as well as practical applications are included.
Egg white is usually used as a food ingredient in meat and surimi and other products due to its excellent gelling properties. The gel strength of egg white powder depends largely on its structure and accordingly the high gel strength of egg white powder could be gained by modifying protein structure. Previous studies indicated that glycosylation between egg white protein and polysaccharide to improve gelling properties of egg white protein is superior to other modification methods. Thus, correct understanding of the correlation between structure of protein glycosylates and gel strength can tremendously favor the extensive applications of glycosylated protein. This conclusion will provide some theoretical bases for industrial applications of glycosylation modification technology in the production of egg white protein-related products.
Animal blood is one of the important byproducts from meat industry. However, less has been utilized in meat processing and most has been abandoned as waste, which causes environmental pollution and resource waste. This article describes methods for the extraction and determination of main proteins from animal blood plasma (fibrinogen, immunoglobulin and BSA) and their applications, which will present some insights for the comprehensive utilization of animal blood plasma.
To guarantee the quality and safety of aquatic products is crucial for people’s health and the national economy. The main reasons for current aquatic product problems in China are analyzed in this paper. Detailed discussions are also presented on countermeasures and controlling methods for heightening the quality of aquatic products and therefore facilitate their export trade.