Compared with hydrochloric acid used in traditional alkaline-extraction and acid-precipitation method, rice bran protein was prepared by the acid-precipitation at condition of tartaric acid, malic acid, and citric acid at pH of 4.0, 3.5, 3.0, and 2.0, respectively. Effects of acid-precipitation by organic acids on structural characteristics of rice bran protein were investigated. The results indicated that when the same organic acid was used to acid-precipitate at different pH, as acid-precipitation pH value decreased, total sulphydryl and α-helix content of rice bran protein changed insignificantly, free sulphydryl and random coil content gradually increased, β-sheet and β-turn content decreased, intrinsic fluorescence intensity and surface hydrophobicity of rice bran protein firstly increased, then decreased. There was no significant difference in total sulphydryl, secondary structure composition, and surface hydrophobicity of rice bran protein between hydrochloric acid and organic acids acid-precipitation at the same pH. Compared with hydrochloric acid, rice bran protein which acid-precipitation by organic acids had lower free sulphydryl content and higher intrinsic fluorescence intensity. The results of molecular weight distribution, particle size distribution, and electrophoresis indicated that acid-precipitation at low pH resulted in partial dissociation and aggregation of rice bran protein, but not form new subunits and high molecular weight aggregates.

Maillard reaction products of sodium caseinate with glucose, lactose, galactooligosaccharides and polydextrose were prepared by a small UHT device. The development of Maillard reaction and the emulsifying properties of Maillard reaction products during different heat treatment time were compared and analyzed. The results show that a slower reaction rate among high molecular weight saccharides and protein as compared to lower molecular weight saccharides. With the reaction of Maillard reaction, the browning index of each system increased, the emulsifying activity and degree of graft both increased at first and then decreased, but there is no linear relationship between them, the maximum value of each emulsifying activity was 0.624, 0.506, 0.5486 and 0.4764 respectively. The sodium caseinate-glucose solution has the highest emulsifying activity at 130℃ heat treatment 15s, significantly higher than other groups (p<0.05), that is equivalent to the water bath at 90 ℃ heat treatment 90min, and the emulsion stability also showed a higher level of 123.88 min. Used it as emulsifier to prepare DHA algae oil emulsion, the dynamic instability index is 1.5, were significantly less than the other groups （P<0.05）.Moreover,this method is continuous,it greatly shortens the reaction time, improves the production efficiency and has significant guidance for industrialized production.

Abstract：The structures of proanthocyanidins from root, stem and leaf of Tetrastigma hemsleyanum Diels et Gilg have been analyzed with 13C nuclear magnetic resonance (13C NMR), reversed-phase high performance liquid chromatography electrospray ionization mass spectrometry (RP-HPLC-ESI-MS) and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). The results showed that these proanthocyanidins from T. hemsleyanum were mainly composed of procyanidin (PC) and prodelphinidin (PD), the terminal units were mainly composed with catechin, epicatechin and epigallocatechin were the dominant of the extension units. The mean degree of polymerization (mDP) of proanthocyanidins from root, stem and leaf of T. hemsleyanum were found to be 4.89 ± 0.33, 3.77 ± 0.19 and 4.45 ± 0.48 respectively. Proanthocyanidins from trimers to decamers were detected within proanthocyanidins from root and stem, while proanthocyanidins up to undecamer were detected within proanthocyanidins from from leaf of T. hemsleyanum by MALDI-TOF MS. (Epi)catechin and (epi)gallocatechin monomer units individually and together with galloyl substituents and A type linkages prevalently existed within each single polymeric cluster. Proanthocyanidins from root, stem and leaf of T. hemsleyanum were structurally similar. The results of this study may provide some reference for the fundamental study and further development of T. hemsleyanum.

To establishes a method for the determination of polyphenols in Osmanthus fragrans by extractive electrospray ionization-mass spectrometry (EESI-MS), Osmanthus fragrans var. semperflorens was used as experimental material, the main polyphenolic compounds in the methanol extracts were determined by high performance liquid chromatography (HPLC) and EESI-MS. The results showed that the total phenols and total flavonoids in the methanol extracts of O. fragrans var. semperflorens were 133.38±0.12 mg/g. md and 72.49±0.09 mg/g. md, respectively. Fifteen kinds of polyphenolic compounds were detected in the methanol extracts of the O. fragrans var. semperflorens by HPLC. The contents of myricetin, morin, rutin, naringenin and (+)-catechin were abundant. EESI-MS detection in positive ion mode directly from the O. fragrans var. semperflorens methanol extract detected p-protocatechuic acid, coumaric acid, caffeic acid, epicatechin; negative ion mode to detected cinnamic acid, morin and myricetin. The EESI-MS method in this study has the advantages of less sample consumption, no complex separation, pretreatment and rapid analysis. It can be used for the analysis of polyphenols in food.

Abstract: Purpose: glyceraldehyde -3- phosphate (GAP) is an intermediates metabolite in glycolysis, which can be catalyzed to form NADH by GAPDH，and NADH will improve metmyoglobin reduction resulting in improved meat colour stability. However, it is not clear whether the formation of NADH catalyzed by GAPDH can be directly used for the reduction of metmyoglobin. Therefore, the purpose of this study was to investigate the effect of adding GAP on the stability of meat color and its pathway. Methods: in situ and in vitro model were used in the present study, and GAP was added to the mutton sample in situ model, then the instrumental colour and NADH content were determinated; the myocardial mitochondria extracted of from sheep, and the mitochondria were incubated with metmyoglobin and GAP incubation, respectively, then the metmyoglobin proportion was measured in vitro model. Results: The addition of GAP to mutton significantly increased the redness and NADH content of the sample in situ model. The proportion of metmyoglobin was reduced significantly after incubated with GAPDH and GAP in vitro model with mitochondria meanwhile, the oxygen consumption rate increased during the incubation. Conclusions: The addition of GAP to the mutton increased the colour stability of the sample were due to the formation of NADH which was catalyzed by GAPDH, and NADH was used to reduce the metmyoglobin directly, and inhibited the accumulation of metmyoglobin led to higher color stability.

By using aptamer as capture probe and gold nanoparticles-invertase-complementary DNA conjugates as detection probe, a competitive dopamine hydrochloride(DH) aptasensor was constructed based on the detection of glucose meter. In the absence of DH, the detection probe was captured on 96-well plate by the aptamer through complementary base pairing. When it was in presence, DH interacted with its aptamer with a stronger affinity forcing the detection probe away from the 96-well plate to catalytic sucrose into glucose, then indirect detection of dopamine hydrochloride concentration was performed by measuring glucose concentration with a glucose meter. When dopamine hydrochloride incubation time and enzymatic reaction time were 30min and 120min respectively, the glucose meter signal intensity increase linearly with the increase of DH concentration in the range of 0.45~10 mmol/L with the correlation coefficient up to 0.997, and the relative standard deviations (RSD) were 0.9%, 1.4% and 4.8% at 8.0 mmol/L, 3.0 mmol/L and 0.8 mmol/L (n=5), respectively. The prepared sensor has the advantages of simple operation, good stability and high selectivity, which not only broadens the detection of other non-glucose targets using glucose meter, but also has potential application in the detection fields of health care and food safety.

Effects of different tea polyphenols additions on the gel properties of egg white protein and the mechanism of interaction between protein and tea polyphenols were investigated. The results showed that the gel strength and water holding capacity of egg white protein increased with the increase of tea polyphenols，the gel strength of egg white protein increased by 130.2%, while expressible moisture content of the gel decreased from 29.41% to 19.29% as 0.8% tea polyphenols added. The gel network structure of egg white protein modified by tea polyphenols was more compact, and the surface of gel was more smooth and uniform .The surface hydrophobic and surface SH content of the modified egg white protein increased, while the total SH content decreased. Further differential scanning calorimetric (DSC) and fourier transformed infrared spectroscopy (FTIR) analysis showed that the modification of tea polyphenols increased the thermal stability of egg white protein and the secondary structure of protein changed, the structure of protein changed from order to disorder, the content of α-helix and β-sheet decreased, while the content of β-turn and irregular curl increased. These results illustrated the intrinsic reasons that tea polyphenols improved the gel strength and water holding capacity of egg white protein.

The optimum conditions for the immobilization of tannins by tannin microspheres were studied by using the tannin derived from Aspergillus niger as raw material,and study on the immobilized enzyme in Lonicera edulis fruit juice colored hydrolysis ability.The result shows,the optimum process conditions for immobilized enzyme were enzyme concentration 0.03mg/mL, glutaraldehyde mass fraction 0.10%, pH 5.4, and immobilization time 40min. Under this condition, the recovery rate of enzyme activity was 71.78%, and the specific activity was 724.72U/mg.The SEM and IR spectra showed that the tannin was immobilized on tannin microspheres.ΔE * ab was 3.49 when the amount of immobilized enzyme was 4 mg;Coloring ability significantly weakened.Microscopic observation showed that the juice treated with the immobilized enzyme could significantly reduce the coloring ability of the pig mucosa.

The aim is to explore the differences of the carbon source utilization and kinetics parameters of Dominant Spoilage Bacteria under different temperatures of fresh Pseudosciaena crocea.Under the condition of 5, 25 ° C degrees, determined the shelf life by sensory, physical and chemical indicators, first used the MIDI ststem to identified the spoilage bacteria, and than determined the dominant spoilage bacteria by the microbial succession, and used 16 sRNA identification to identified the dominant Spoilage bacteria. Biolog system was applied to the determination of the difference of the carbon source utilization, while Gompertz equation was used to fit the growth curve and solved the kinetic parameters. Results showed: the shelf life of fresh Pseudosciaena crocea at 5°C were 9.0±1.0,while under 25°C the shelf life was 1.0±0.11 days, and the dominant Spoilage Bacteria were Shewanella putrefaciens and Vibrio fluvirus. The average carbon use efficiency at 5°C was less than which at 25°C , and the average well color development (AWCD) of Shewanella putrefaciens at 5°C was higher than Vibrio fluvirus, while at 25°C which was lower than Vibrio fluvirus. At 5°C Shewanella putrefaciens mainly use monosaccharides, polysaccharides, carboxylic acids, esters while Vibrio fluvirus mainly used the monosaccharides, polysaccharides, amino acids and carboxylic acids and under 25°C Shewanella putrefaciens and Vibrio fluvirus mainly used the monosaccharides, polysaccharides, amino acids and carboxylic acids; Conclusion: The temperature effected the utilization of carbon source of spoilage bacteria and the carbon source utilization of different spoilage bacteria are different. By adjusting the temperature, change the substrate carbon source and other environmental factors can achieve the purpose of antibacterial, thereby extending the shelf life of fresh Pseudosciaena crocea

In order to improve the gel properties and amino acid composition of Brewer's Grains Protein, Modification Process of Brewer's Spent Grains Protein and Soybean Protein Mixtures by Transglutaminase (transglutaminase，TGase) have been researched by the single factor experiment and response surface method. The effects of Brewer's Spent Grains protein additional proportion,TGase enzyme concentration,water bath temperature,bath time and pH on gelling characteristic have been investigated.The results showed that the Brewer's Grains Protein with a protein content of 52.23% was obtained through wet milling,which was dominated by amino acids called glutamate and proline, on condition of the Brewer's Spent Grains protein additional proportion 30 %,TGase enzyme dosage 15 U/g protein，pH 7.0，the water bath temperature 48 ℃ and the bath time 132 min,transglutaminase had the strongest improving effect on gelling property of Brewer's Spent Grains Protein and Soybean Protein Mixtures with the maximum gel strength as 218.55 g.This study could provide a basis for the deep proces of Brewer's Spent Grains protein.

The aim of this work was to improve the enzymatic hydrolysate flavor of Mactra veneriformis by Maillard Reaction. The effects of the type, addition ratio and the addition amount of sugar, and the temperature, time and pH of reaction on the sensory score, the degree of reaction and the color difference were investigated, to obtain the better parameters of Maillard Reaction. Meanwhile, the changes of free and total amino acids, and volatile compounds of enzymatic hydrolysis before and after reaction were also analyzed. The results showed that all the reaction parameters, including the type, addition ratio and the addition amount of sugar, and the temperature, time and pH of reaction, showed significant influence on the flavor of enzymatic hydrolysate. the optimal conditions of Maillard Reactions were obtained as follow: the 1:2 ratio of xylose and glucose were into the enzymatic hydrolysate, the addition amount was 4%, the pH of reaction system was 6.5, the reaction temperature and time were 105℃, 90 min respectively. After reaction, all the 18 amino acids showed a certain of losses in concentration, among which alanine, glycine, taurine and glutamic acid suffered worst, flowed by histidine, arginine, methionine, phenylalanine, leucine and lysine, indicating those amino acids might mainly take part in the Maillard Reaction and the flavor of reaction product. The species and relative content of flavor components after Maillard Reaction were different form that of before reaction. The content of aldehydes, ketones and esters increased after reaction, while the hydrocarbons decreased.

Three headspace extraction methods including purge & trap (P & T), solid-phase micro-extraction (SPME) and dynamic headspace extraction (DHS) were utilized to analyze the volatile compounds in three kinds of Sachimas combined with the technology of gas chromatography-olfactometry-mass spectrometry (GC-O-MS). Forty-five and thirty-five compounds were identified respectively, including alcohols, aldehydes, ketones, esters and heterocyclic compounds. Meanwhile, due to the high concentration and lower threshold, the overall profile of Sachima was contributed by the aldehydes and heterocyclic compounds. What’s more, 17 aroma compounds were captured by sniffing that were regarded as the aroma-active compounds in Sachima which present the characteristic of green, coca, malty, grass, citrus, bread, mushroom, cheesy, green bean, popcorn, peanut, roasted nut, peanut butter. The further analysis combined with sensory evaluation were concluded that the characteristic of 17 aroma compounds were consistented with the profile of Sachima including roasted, malty, fat, green, sweet, burn, and rosted egg. From partial least squares (PLS) analysis, the statistically compared among three kinds of Sachima was showed that the aroma compounds in classic and whole-egg Sachima were less than premium Sachima, and more pyrazines were existed in premium Sachima, more aldehydes were presented in the other two samples.

In this work, molecularly imprinted polymers (MIPs) for the numb-taste compounds were prepared by using the molecular structure analogs of acid amides (LM) as dummy template molecule. In order to optimize the preparation conditions of the dummy molecularly imprinted polymer for the numb-taste components of Zanthoxylum, UV spectra was applied to study the effect intensity and the optimal concentration ratio between the dummy template and the functional monomer. With ethylene glycol dimethacrylate (EDMA) as the cross-linker, acetonitrile as the pore-foaming agent, 2,2-azobisisobutyronitrile(AIBN) as the initiator, 16 kinds of MIPs were prepared by method of bulk polymerization. Then a best kind of MIPs was chosen out from the several kinds of MIPs to adsorb the numb-taste components from the extraction liquor of Zanthoxylum bungeanum, the result showed that the selected MIPs had the specific recognition and selectivity for the numb-taste components of Zanthoxylum, the relatively pure numb-taste components of Zanthoxylum can be obtained by the MIPs. The results of the research showed that with the dummy template (LM), the MIPs could achieve a good imprinting effect for the numb-taste components. The research also provides an available method for the molecular imprinting technique of substances with similar structural characteristics.

The critical medium components of the phycocyanin production by recombinant E. coli using response surface methodology were optimized, and their optimal levels were determined. Factors affecting the phycocyanin yield by recombinant E. coli were first evaluated by the 2-level factorial design. The key factors with significant effect were screened, and their optimal levels were determined by response surface methodology. The screened key factors with significant effect were peptone, yeast extract and K2HPO4?3H2O, and their optimal concentrations were 23.8 g?L-1, 13.4 g?L-1 and 9.4 g?L-1, respectively. The yield of phycocyanin was up to 15.28 mg?L-1 under the above conditions, 2.15-fold higher than that under the original conditions. This study lays a good foundation for the future production and use of phycocyanin.

The present study was designed to screen for potential probiotics based on high alpha-glucosidase inhibitory activity from cell-free excretory supernatants (CFS) and cell-free extracts (CFE) of 77 probiotic strains. Meanwhile, probiotic properties such as tolerance to the low pH, simulated saliva (SS), simulated gastric juice (SGJ), simulated intestinal juice (SIJ), transporting, bile salts tolerance as well as adhesion to HT-29 cell assays were also examined. Most cell-free excretory supernatants (CFS) showed alpha-glucosidase inhibition, ranging from 2.53% to 15.76%, but all cell-free extracts (CFE) did not. The strain ST-2, 1.1881, GS-3 and BLP12 showed strong ability of α-glucosidase inhibition. The strain ST-2 showed 75.97% survival rate after 3 h of incubation at pH 2.0, and the strain ST-2 expressed strong adhesive abilities to HT-29 cells; the strain GS-3 showed a survival rate of 89.49% after the complete gastrointestinal transit. Principal component analysis (PCA) showed that the strain BLP12 displayed the best combination characteristics: its alpha-glucosidase inhibition rate was 15.10%; the survival rate of resistance to pH 2.0 was 71.04%; its survival rate was 77.14% in the presence of bile salts (2.0%); the transporting survival rate of the strain BLP12 through SS/SGJ/SIJ was 88.27%; but the rate of adhesion to HT-29 cell was only 1.93%. In general, BLP12 display strong adaptability to simulated environment. BLP12 strain was identified as Lactobacillus plantarum by 16S rDNA sequencing methods. It could be used as potential anti-diabetic probiotics in the development of functional food.

The antioxidant activity and interaction of polyphenols extracted from tea seed oil and VE in stored lard were explored by using Schaal oven test at (63 ± 1) ℃. The aim of this study was to assess the impact and interaction of polyphenols extracted from tea seed oil and VE on the oxidative stability of tea seed oil and to provide a simple and feasible method to study the influence and interaction of the antioxidant components on the oxidation stability of tea seed oil. The results revealed that the polyphenols and VE could greatly delay the oxidation rancidity in lard during accelerated oxidation storage. After 30 d of accelerated oxidation, peroxide value, acid value, anisidine value and malondialdehyde (MDA) content were decreased by 72.97%, 3.83%, 54.62% and 47.83% with VE addition, and by 80.54%, 2.87%, 72.26%, and 71.74% with polyphenol addition, respectively, as compared to the blank lard group, indicating that both the polyphenols and VE possess strong antioxidant activity, with the former being superior to the latter. An analysis of their interaction effect showed that VE was synergistic with the polyphenols during the accelerated oxidation process of lard.

The effect of separate addition of the natural antioxidants tocopherol, β-carotene and rosemary extract on the stability of purified corn oil was evaluated by Schaal oven accelerated oxidation test and kinetic equations for oxidation reaction were established. The experimental results showed that the antioxidant capacity of three antioxidants was in the descending order: rosemary extract > β-carotene > tocopherol. Kinetic models for corn oil added with tocopherol, β-carotene and rosemary extract at 0.02 g/100 g, respectively, were , and , while that for purified corn oil was . It was speculated that the shelf-lives of corn oil added with the antioxidants and nothing were 15, 19, 24, and 27 months, respectively. Therefore, rosemary extract as an antioxidant can significantly improve the shelf life of corn oil.

The effect of adding different amounts of tea polyphenols on the gel properties of egg white protein was examined and the mechanism underlying the interaction between protein and tea polyphenols was investigated. The results showed that the gel strength and water-holding capacity of egg white protein increased with the increase of tea polyphenols; the gel strength increased by 130.2%, while expressible moisture content of the gel decreased from 29.41% to 19.29% when 0.8% of tea polyphenols were added. The gel network structure of egg white protein modified by tea polyphenols was more compact with a smoother and more uniform surface. The surface hydrophobic and surface SH content of the modified egg white protein increased, while the total SH content decreased. Furthermore, differential scanning calorimetric (DSC) and Fourier transformed infrared spectroscopy (FTIR) analysis showed that modification with tea polyphenols increased the thermal stability of egg white protein and changed the secondary structure; it changed the structure of protein from a state of order to disorder, and resulted in a decrease in α-helix percentage and an increase in β-sheet percentage.

The Maillard reaction has been reported to be capable of improving the functional properties of soybean protein isolate (SPI). In this work, the effects of temperature, reaction time and mixing ratio on the Maillard reaction between SPI and glucose/maltose were studied, and the changes in solubility, emulsifying activity, solution pH, ζ potential, structure and molecular mass of Maillard reaction products were measured. The results indicated that the optimum reaction conditions were determined as mass ratio between SPI and sugar 4:1, temperature 80 ℃ and duration 6 h. The reaction markedly improved the solubility of SPI and maltose was more effective than glucose in improving this parameter. The reaction reduced the emulsifying activity and affected the ζ potential of SPI. As the Maillard reaction proceeded, the negative charge carried by SPI decreased obviously. The Maillard reaction reduced the pH of SPI solution. Thermal analysis revealed that the modification decreased the thermal stability of SPI. Fourier transform infrared spectroscopy confirmed the introduction of new groups into SPI. Moreover, the Maillard reaction enhanced the fluorescence intensity of SPI. Sodium dodecyl sulfate polyacrylamide gel electropheresis (SDS-PAGE) showed the formation of large molecules.

The present study aimed to evaluate the antioxidant and antiglycation activities of quercetin methyglyoxal (MGO) adducts, including mono- (MM-1) and di-MGO (DM-2) adducts. The antioxidant abilities were assessed through ferric reducing assay and the measurement of oxidation induction time of lard. The inhibitory effect of MGO-quercetin adducts on the formation of MGO and glyoxal (GO) in oil system at high temperature was explored. Ovalbumin (OVA)-glucose system under simulated food processing conditions and bovine serum albumin (BSA)-glucose system under simulated physiological conditions were applied for the measurement of antiglycation activity by gas chromatography and fluorescence spectroscopy. The results indicated that both mono- and di-MGO quercetin adducts had antioxidant capacity and inhibitory activity on the formation of MGO/GO in the oil system. Meanwhile, MGO-quercetin adducts inhibited glycation under simulated Maillard reaction in food processing and physiological conditions in a concentration-dependent fashion, in the increasing order of DM-2 < MM-1 < quercetin. Therefore, MGO-quercetin adducts still played an important role in antioxidation and antiglycation during the process of protein glycosylation.

The aim of this paper was to explore the synergistic effect of adding glycine and starch coating on reduction of acrylamide in bread crust. The inhibitory effect of glycine was significant. The percentage inhibition of acrylamide was 80.5% when glycine was added at 0.1% to flour and no acrylamide was detected at an addition level of 3%. Starch coating on the surface of the fermented dough prior to baking decreased acrylamide content by more than 20%. The inhibitory effects of different starch coatings were in the decreasing order of mixed starch coating > potato starch coating > corn starch coating. The inhibitory effect of corn starch coating was increased to 85.1% when the addition level of glycine was 0.1% while maintaining the attractive color of bread. The significant decrease in the acrylamide content in bread was due to substrate competition between glycine and asparagine in the Maillard reaction and the reduction of a significant amount of the limiting precursor asparagine in coating-forming solutions.

In order to assess the effect of acid precipitation with different organic acids on the structure of rice bran protein, tartaric, malic, and citric acid were separately used to prepare rice bran protein at varying pH values (4.0, 3.5, 3.0, and 2.0) in comparison with hydrochloric acid as control. The results indicated that for each organic acid, total sulphydryl and α-helix content of rice bran protein did not significantly change with decreasing pH, whereas free sulphydryl and random coil content increased, β-sheet and β-turn content decreased and intrinsic fluorescence intensity and surface hydrophobicity firstly increased and then decreased. Total sulphydryl content, secondary structure composition and surface hydrophobicity of rice bran protein prepared with organic acids did not significantly differ from those of rice bran protein obtained with hydrochloric acid, whereas a decrease in free sulphydryl content was observed together with an increase in intrinsic fluorescence intensity. The results of molecular mass distribution, particle size distribution, and electrophoresis indicated that acid precipitation at low pH resulted in partial dissociation and aggregation of rice bran protein without leading to the formation of new subunits and high molecular weight aggregates.

Germinating brown rice was treated with ultrasonic to enhance the accumulation of γ-aminobutyric acid (GABA). The changes of glutamic acid (GA), GABA content and glutamic acid decarboxylase (GAD) activity during brown rice germination were analyzed and their correlation was investigated. Results showed that GABA and GA content gradually increased obviously with germination time and there was a significant correlation between GABA and GA content (P < 0.05). The activity of GAD increased at first and then decreased with germination time. During the first 48 h of germination, the average activity of GAD (calculated as GABA equivalent) in the control without ultrasonic treatment was 9.25 nmol/g and the GABA content was increased by more than 7 times. GABA content did not significantly increase between 48 and 60 h. Compared with the control, ultrasonic treatment resulted in an about 2-fold increase in GA content and a rapid increase in GAD activity and gave the maximum GABA value of 41.85 mg/100 g at 36 h.

In this study, the emulsifying properties of porcine bone protein hydrolysates (PBPH) with different degrees of hydrolysis (DH) were determined. Porcine bone protein was hydrolyzed by alkaline protease for 0, 1, 2, 3, 4, and 5 h, yielding DH of 0%, 5.6%, 7.8%, 11.1%, 14.3% and 17.2%, respectively. The emulsifying activity, emulsion stability and microstructure, zeta potential, and molecular mass distribution of active peptides of PBPH were measured. The results revealed that the emulsifying activity index and emulsion stability index of hydrolysates were increased at the beginning and then decreased with increasing DH (P < 0.05), and the highest emulsifying stability was obtained at a DH value of 11.1%, which was presumably related to the highest surface hydrophobicity and zeta potential, the smallest mean particle size and the uniform droplet size distribution. The results of size exclusion chromatography proved that the content of large peptides was decreased and the content of small peptides was gradually increased with the increase of DH. The hydrolysis process was accompanied by cleavage of polypeptide chains and aggregation of proteins. The functional properties of PBPHs with different DHs were affected by the changes in protein structure, which may be the reason for the changes of the emulsifying properties. It can be concluded that the PBPH obtained after 3 h hydrolysis (DH = 11.1%) had the best emulsifying properties and could be used as an emulsifier in emulsions with good physical stability.

The objective of this study was to evaluate the effect of different concentrations of NaCl (0.1, 0.2, 0.3, 0.4, 0.5, and 0.6 mol/L) on the properties of turbot myofibrillar protein (MP). MP was extracted and its solubility, emulsifying properties, chemical interactions (ionic bonds, hydrogen bonds and hydrophobic interactions) and sulfydryl contents, secondary structures and rheological properties were measured. The results showed that solubility, emulsifying activity index (EAI), emulsion stability index (ESI), active and total sulfydryl contents increased with the increase in NaCl concentration. Meanwhile, ionic and hydrogen bonds first increased and then decreased, whereas hydrophobic interactions first decreased and then increased. The secondary structures of MP tended to transit from helix to sheet with no significant change being observed for the other secondary structures; storage modulus (G’) was increased, with the highest value being observed at a NaCl concentration of 0.6 mol/L. In summary, 0.6 mol/L NaCl was optimal for improving the properties of turbot myofibrillar protein.

Zein and dextran (DX) with different molecular masses (6, 20, 40 and 70 kDa) were prepared into zein-DX glycosylation products by a wet heating method in the present research. The purpose was to examine the effect of DX with different molecular masses on structural and functional properties of zein glycosylation products. As molecular mass of DX increased, the degree of graft and the browning intensity reduced, which indicated that DX with lower molecular mass was easier to react with zein to form glycosylation products with higher solubility and lower surface hydrophobicity. Glycosylation could improve the emulsifying activity index (EAI) and emulsifying stability index (ESI) of zein. With the increase in the molecular mass of DX, the EAI of zein-DX glycosylation products gradually decreased and the ESI gradually increased. Moreover, the covalent binding affinity of DX with high molecular mass could lead to the transformation of the ordered α-helix structure to the unordered β-sheet and random coil structure, which resulted in more flexible and looser protein conformation.

This study investigated the effect addition of different amounts of sodium nitrite on microbial growth, lipid oxidation and volatile compounds in naturally fermented Harbin air-dried sausages. It was found that the addition of sodium nitrite had no significant influence on the pH value, water activity, or the growth of total bacterial count and lactic acid bacteria (P > 0.05) during the fermentation of sausages, but the growth of Escherichia coli was significantly inhibited (P < 0.05) by addition of nitrite at levels higher than 0.10 g/kg. Sodium nitrite had good coloring effect when added at 0.10 g/kg to sausages. The results of peroxide value and thiobarbituric acid reactive substances (TBARS) value showed that nitrite at 0.10 g/kg was effective in inhibiting lipid oxidation. The residual nitrite level was gradually reduced during fermentation and did not significantly different among different treatments at the end of fermentation (P > 0.05). Meanwhile, the addition of sodium nitrite had no significant influence on the amounts of volatile compounds produced by carbohydrate fermentation and amino acid degradation (P > 0.05), but significantly influenced the amounts of aldehydes and ketones from lipid oxidation (P < 0.05); the more sodium nitrite was added, the stronger inhibition of lipid oxidation was observed.

The aim of this work was to improve the flavor of an enzymatic hydrolysate of Mactra veneriformis by Maillard reaction. The effects of sugar type, mixing ratio and amount of sugars, reaction temperature, time and initial pH on sensory score, the degree of reaction and the color difference were investigated to obtain the optimal reaction conditions. Meanwhile, the changes of free and total amino acids, and volatile compounds before and after reaction were also analyzed. The results showed that all the reaction parameters significantly influence the flavor of the enzymatic hydrolysate (P < 0.05). The optimal conditions of Maillard reaction were obtained as follow: ratio of xylose to glucose 1:2, 4.0% reducing sugar, initial pH 6.5, temperature 100 ℃ and time 90 min. The Maillard reaction resulted in loss of all 18 amino acids especially alanine, glycine, taurine and glutamic acid followed by histidine, arginine, methionine, phenylalanine, leucine and lysine in the hydrolysate, indicating that these amino acids may take part in the Maillard reaction and contributed to the flavor of reaction products. The species and relative contents of flavor components were different after the Maillard reaction. The contents of aldehydes, ketones and esters increased, while those of hydrocarbons decreased.

The oxidative polymerization of hydroxytyrosol was catalyzed by laccase. The resultant products were characterized by UV-Vis spectroscopy, FTIR spectroscopy, gel permeation chromatography (GPC) and high performance liquid chromatography-mass spectrometry (HPLC-MS). The results showed that the products were polydisperse (D = 2.1), and mainly consisted of trimer, tetramer and hexamer. Meanwhile, the antioxidant activity and thermal stability of the polymers were assessed by 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging assay and thermogravimetry-Fourier transform infrared spectroscopy (TG-FTIR) with VC and dibutyl hydroxy toluene (BHT) as positive control. The results indicated that the antioxidant activity of hydroxytyrosol polymers was 2.28 and 5.7 times as strong as HT and BHT, respectively and was similar to VC (72% as strong). On the basis of DTG peak temperature (315.1 ℃) and residual percentage (66.09%), the polymers had better thermal stability than VC (228.1 ℃), BHT (236.2 ℃) and HT (314.9 ℃). 3D-FTIR spectra indicated that HT polymers together with the other tested compounds began with O–H bond breaking, forming a quinoid structure by dehydrogenation or carbon-carbon double bond by dehydration. All these findings will provide a good theoretical and practical foundation for deep hydroxytyrosol utilization.

Maillard reaction products of sodium caseinate with glucose, lactose, galactooligosaccharides and polydextrose were prepared in a small-scale ultra-high temperature (UHT) device. The development of Maillard reaction was analyzed and the emulsifying properties of Maillard reaction products at different intervals were compared. The results showed that small sugars were more susceptible to Maillard reaction. A positive correlation existed browning index with the extent of Maillard reaction. Both the emulsifying activity and the degree of graft increased at first and then decreased, but there was no linear relationship between them. The maximum values of activity of Maillard reaction products of sodium caseinate with glucose, lactose, galactooligosaccharides and polydextrose were 0.63, 0.51, 0.55 and 0.48, respectively. The Maillard reaction products from sodium caseinate with glucose produced by heat treatment for 15 s at 130 ℃ had the highest emulsifying activity, which was significantly higher than that of other groups and equivalent to that obtained by water bath heating at 90 ℃ for 90 min together with a high emulsion stability of 123.88 min. The kinetic stability index of DHA-rich algae oil emulsion containing these Maillard reaction products was 1.5, significantly lower than that of the other groups (P < 0.05). In conclusion, glucose can be used as a promising glycosyl ligand for Maillard reaction to prepare a novel and efficient emulsifier. Moreover, this method can realize continuous production, greatly shorten the reaction time and improve the production efficiency and therefore it can provide a significant guidance for industrialized production.

In this research, changes in polyphenols content and antioxidant capacity during in vitro digestion of brown rice were studied. The total phenolic content in brown Japonica rice was significantly higher than that in brown Indica rice (about 1.5 times). During simulated in vitro gastrointestinal digestion, the release of polyphenols (calculated as gallic acid equivalent) was increased significantly for both rice varieties (P < 0.05), with the maximum value (460.9 mg/100 g) of Japonica rice being significantly higher than that (401.1 mg/100 g) of Indica rice. The release of polyphenols versus digestion time was fitted to a power function. The results of ferric reducing antioxidant power (FRAP) and oxygen radical absorbance capacity (ORAC) showed that the polyphenols released during in vitro digestion of brown Japonica and Indica rice possessed potent antioxidant activity. Both FRAP and ORAC were calculated as trolox equivalent. The maximum FRAP values of digested Japonica and Indica rice were 10.76 and 8.44 μmol/g, and the maximum ORAC values were 6.82 and 6.23 μmol/g, respectively.

Purpose: Glyceraldehyde-3-phosphate (GAP) is an intermediate metabolite of glycolysis, which can be catalyzed into NADH by glyceraldehyde-3-phosphate dehydrogenase (GAPDH), and NADH can improve metmyoglobin reduction resulting in improved meat color stability. However, it is not clear whether the formation of NADH catalyzed by GAPDH can be directly used for the reduction of metmyoglobin. Therefore, the purpose of this study was to investigate the effect of adding GAP on the stability of meat color and to elucidate the underlying mechanism. Methods: In situ and in vitro models were used in the present study. GAP was added to mutton samples in the in situ model, and then instrumental color parameters and NADH content were determined; the myocardial mitochondria isolated from sheep were incubated with metmyoglobin and GAP, respectively, and the proportion of metmyoglobin was measured in in vitro model. Results: The addition of GAP to mutton significantly increased redness and NADH content in in situ model. The proportion of metmyoglobin was reduced significantly in in vitro model; meanwhile, the oxygen consumption rate increased during the incubation. Conclusion: The addition of GAP could increase the color stability of mutton, which was catalyzed by GAPDH into NADH to directly reduce metmyoglobin, thereby inhibiting the accumulation of metmyoglobin and consequently leading to higher color stability.

This study aimed to optimize the conditions for the immobilization of tannase with tannin microspheres. Besides, the structure of tannase before and after immobilization was characterized, and the application of immobilized tannase hydrolyze Lonicera edulis fruit juice was investigated. The results showed that the optimum processing conditions were determined using response surface methodology as follows: enzyme concentration 0.03 mg/mL, glutaraldehyde concentration 0.10%; pH 5.4 and immobilization time 40 min, under which, the recovery of enzyme activity and the specific activity were 71.78% and 724.72 U/mg, respectively. Tannase was well immobilized onto tannin microspheres through SEM and IR spectroscopy. The content of ellagic acid in fruit juice increased by 29.12% after adding immobilized tanninase. ΔE*ab was 3.49 when 4 mg of immobilized enzyme was added, indicating a significant decrease in the staining effect. The juice treated with immobilized enzyme showed significantly reduced staining of the mucous membrane of the tongue when consumed by microscopic observation.

In this study, composite organogels were prepared from refined sunflower oil as base oil added with monoglycerides, oryzanol and sitosterol. The effect of gelator ratio on the structure and property of organogels were examined to analyze the role of monoglycerides in the formation of composite organogels. Results showed that the weak non-hydrogen bonding forces between monoglycerides and sitosterol, such as Van der Waals force, structured sunflower oil to form composite organogels under their critical gel concentration. It was also found that monoglycerides had great influence on thermodynamic properties and rheological properties of composite organogels. The microscopic structure and infrared spectra were significantly changed with the addition of monoglycerides. With the increase of monoglycerides content, the hydrogen bonding forces gradually diminished and finally disappeared. The microstructure was changed from fibrous network to spheroidal and finally needle-shaped crystal. The results also showed that the oxidation of organogels was slower with the addition of monoglycerides.

The objective of this study was to determine the differences in the structure and properties of oil bodies from diverse oilseed crops (soybean, peanut, and sunflower). The structure, composition, protein molecular mass, zeta potential, particle size distribution, emulsifying properties, and circular dichroism (CD) spectra of proteins of oil bodies were analyzed and compared under the same conditions. The experimental results showed that the oil bodies from different oilseed crops had similar composition and structure. The ratio of protein to fat in soybean oil bodies (0.086:1) was significantly higher than that in peanut oil bodies (0.018:1) and sunflower oil bodies (0.028:1) (P < 0.05). The average particle size of soybean oil bodies, (0.93 ± 0.07) μm, was significantly smaller than that of peanut oil bodies, (2.58 ± 0.06) μm, and sunflower oil bodies, (1.64 ± 0.03) μm (P < 0.05). The total amount of hydrophobic amino acids in soybean oil bodies was the highest, while the lowest value was observed in peanut oil bodies. The zeta potential, emulsifying activity and emulsion stability of soybean oil bodies were significantly higher than those of peanut oil bodies and sunflower oil bodies (P < 0.05). The α-helix content of proteins in soybean oil bodies ((43.58 ± 0.12)%) was significantly higher than that in peanut oil bodies ((35.43 ± 0.06)%) and that in sunflower oil bodies ((37.00 ± 0.09)%) (P < 0.05); however the β-sheet and random coil content of proteins in peanut oil bodies were the highest. The results show that there are differences in the properties of oil bodies from diverse oilseed crops (soybean, peanut, and sunflower) although they have similar composition and structure, which can provide a theoretical basis for future application of oil bodies in the food industry.

The effect of protease and lipase added individually and in combination on fermentation characteristics and flavor of cream and whey mixture was investigated by determining the changes in viable cell number of lactic acid bacteria, titratable acidity, pH value and volatile flavor components. After 60 h fermentation, the volatile flavor components were extracted by using headspace solid-phase microextraction (HS-SPME) and analyzed by gas chromatography-mass spectrometry (GC-MS) combined with principal component analysis and sensory evaluation was also performed. The results showed that carboxylic acids, ketones and esters were the main volatile flavor components isolated by GC-MS. Protease promoted the growth of lactic acid bacteria, acid production and the formation of ketones and improved the flavor quality. Lipase significantly increased titratable acidity, suppressed the growth of lactic acid bacteria acid production, pronouncedly promoted the generation of carboxylic acids, resulted in the formation of esters, evidently improved and enriched the flavor of the fermented system. Protease and lipase added in combination increased the production of esters, significantly enhanced the aroma, remarkably improved the flavor and attenuated the sour taste of carboxylic acids, had the biggest influence as revealed through principal component analysis. Protease and lipase could improve the quality of flavor, and their combination mitigated sour taste by the sensory evaluation.

γ-Aminobutyric acid (GABA) production of lactic acid bacteria in chickpea milk was enhanced by compound mutagenesis, aiming to lay a basis for the development of functional foods rich in GABA. Ultraviolet (UV) irradiation and combined UV-LiCl were used for the mutagenesis of Lactobacillus plantarum M-6. The optimal UV irritation time was 240 s, and the optimal LiCl concentration was 1.25%. A total of 21 mutants with higher GABA production ability were screened out by paper chromatography, MRS plate with 138 g/L monosodium glutamate (MSG), berthelot colorimetry and high performance liquid chromatography (HPLC) determination. Among them, strain UL-4, obtained by combined UV-LiCl mutagenesis, exhibited the highest GABA production (899.27 mg/L in MRS fortified with 1% MSG and 369.53 mg/L in chickpea milk fortified with 0.2% MSG, which were increased by 64.25% and 30.46% as compared to those of the original strain, respectively). The strain had good genetic stability.

In order to explore the reason for reduced exopolysaccharide (EPS) production by a mutant strain 2# compared with Lactobacillus kefiranofaciens ZW3, we conducted comparative genome-wide analysis of the wild and mutant strains by bioinformatics methods. We also analyzed the role of the mutant genes in metabolic pathways. To evaluate their correlation with EPS production from lactic acid bacteria, we analyzed the relative expression levels of the mutant genes that may be associated with polysaccharide production using RT-qPCR, and constructed a recombinant plasmid carrying the genes with significantly different expression levels and transformed it into Escherichia coli, and then determined the expressed serine/threonine protein kinases (STPKs) activity. The whole genome analysis showed that there were 60 genes mutated in the CDS or the promoter regions, and at least six of them were associated with catalytic domains, namely WANG_0173, WANG_0174, WANG_0175 (encoding dihydroxyacetone kinase or its subunit), WANG_1108 (serine threonine protein kinase), WANG_0292 (synonymous mutation, beta-galactosidase small subunit), and WANG_0840 (udp-n-acetylmuramoylalanine-d-glutamate ligase, MurD). The results showed that the relative expression of WANG_1108 was significantly down-regulated as revealed by RT-qPCR. Therefore, we chose this gene as the target gene related to EPS synthesis to further study the molecular mechanism. It was expressed in E. coil BL21 (DE3) with plasmid pET28a as plasmid vector to identify its function. The expressed product was then detected by SDS-PAGE and the enzyme activity was measured. It was found that the mutant STPKs activity was 37% lower than that of the wild strain, indicating that the mutation of WANG_1108 could partially account for decreased EPS production.

The critical medium components for phycocyanin production by recombinant Escherichia coli were selected and optimized using response surface methodology. The medium components with significant influence on phycocyanin yield were identified using a fractional factorial design and their levels were optimized using response surface methodology. Peptone, yeast extract and K2HPO4·3H2O were recognized as the critical medium components, and their optimal levels were determined as 23.8, 13.4 and 9.4 g/L, respectively, which gave a phycocyanin yield of 15.28 mg/L. This study can pave a good foundation for future production and use of phycocyanin.

In this paper, the solid state fermentation of whole oat grains was carried out by simultaneous inoculation with Lactobacillus plantarum 70810 (L. plantarum 70810) and Rhizopus oryzae (R. oryzae). Our aim was to evaluate fermentation characteristics and the effect of mixed fermentation on the protein nutritional quality of oat. Bacterial growth and ergosterol content were investigated by plate count method and high-performance liquid chromatography (HPLC), respectively. Proteolysis during the fermentation process was measured using sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), the Bradford assay and the o-phthaldialdehyde (OPA) method. Results showed that the number of viable bacterial cells and ergosterol content gradually increased during mixed culture fermentation, reaching (8.46 ± 0.04) (lg(CFU/g)), 7.14% higher than that of pure culture fermentation with L. plantarum 70810, and (137.04 ± 6.13) μg/g at 72 h, respectively. pH value decreased from 5.34 ± 0.12 to 3.74 ± 0.04, and total acidity increased from (0.23 ± 0.02)% to (1.08 ± 0.08)%. As significant proteolysis occurred at 72 h , the soluble protein content (calculated as bovine serum albumin equivalent) was raised to (11.58 ± 0.16) mg/g, and the content of peptides (calculated as casein tryptone equivalent) with molecular mass lower than 10 kDa reached its highest value of (366.51 ± 1.30) mg/g. Fermented oat had higher protein nutritional value and improved amino acid composition with a significant increase in lysine content. In addition, the essential amino acid index (EAAI) increased to 75.63 ± 0.10, and the protein biological value (BV) to 70.74 ± 0.13 after mixed culture fermentation as compared to pure culture fermentation.

This study aimed to explore the differences in the carbon source utilization and kinetic parameters of the dominant spoilage bacteria in fresh Pseudosciaena crocea stored at different temperatures. At 5 and 25 ℃, the shelf life was determined by sensory, physical and chemical indicators. MIDI gas chromatography was used to preliminarily identify the spoilage bacteria isolated, and the dominant spoilage bacteria were determined through changes in the microflora and they were identified up to species level by 16s RNA gene sequencing. The difference in their carbon source utilization profiles were measured by Biolog system, and the carbon source utilization curves were fitted to the Gompertz equation to obtain the kinetic parameters. Results showed that the shelf-life of fresh P. crocea at 5 ℃ was (9.0 ± 1.0) days, while at 25 ℃ the shelf life was (1.0 ± 0.11) days. The dominant spoilage bacteria were Shewanella putrefaciens and Vibrio fluvirus at 5 and 25 ℃, respectively. The average carbon utilization efficiency at 5 ℃ was lower than that at 25 ℃; the average well color development (AWCD) of S. putrefaciens at 5 ℃was higher than that of V. fluvirus, while the opposite was observed at 25 ℃. At 5 ℃ S. putrefaciens mainly utilized monosaccharides, polysaccharides, carboxylic acids, and esters while V. fluvirus mainly utilized monosaccharides, polysaccharides, amino acids and carboxylic acids, and at 25 ℃ S. putrefaciens and V. fluvirus mainly utilized monosaccharides, polysaccharides, amino acids and carboxylic acids. Conclusion: Temperature affected the carbon utilization efficiency of spoilage bacteria and the carbon source utilization efficiencies of different spoilage bacteria were different. By adjusting temperature, carbon source substrate and other environmental factors the spoilage bacteria can be inhibited, thereby extending the shelf life of fresh P. crocea.

This study was designed to determine the distribution of bacterial populations in raw milk by Illumina MiSeq high-throughput sequencing method. The bacterial diversity and the distribution of pathogenic bacteria in raw milk samples collected from 14 dairy farms were determined by means of DNA sequencing with operational taxonomic unit (OTU) clustering analysis, Alpha diversity analysis and species classification analysis. The results showed that bacterial diversity was found in the milk samples from different farms with the genera Enterococcus, Bacillus, Acinetobacter and Lactococcus being the most diverse. At the same time, Staphylococcus aureus and Shigella were detected in only a few milk samples.

The present study was designed to screen 77 probiotic strains based on α-glucosidase inhibitory activity of cell-free excretory supernatants (CFS) and cell-free extracts (CFE). Meanwhile, probiotic properties such as tolerance to low pH, simulated saliva (SS), simulated gastric juice (SGJ), simulated intestinal juice (SIJ), and bile salts as well as adhesion to HT-29 cells were also examined. Comprehensive evaluation was carried out by principal component analysis. Most cell-free excretory supernatants (CFS) showed α-glucosidase inhibition, ranging from 2.53% to 15.76%, but all cell-free extracts (CFE) had no α-glucosidase inhibitory activity. Strains ST-2, 1.1881, GS-3 and BLP12 showed strong ability to inhibit α-glucosidase. Strain ST-2 showed a 75.97% survival rate after 3 h of incubation at pH 2.0, and exhibited strong acid tolerance and adhesion to HT-29 cells; GS-3 showed a survival rate of 89.49% after the complete gastrointestinal transit and three strains differed in their survival rate. Principal component analysis (PCA) showed that overall, BLP12 displayed the best probiotic characteristics: its α-glucosidase inhibition rate was 15.10%; the survival rate was 71.04% after incubation at pH 2.0, 0.70% in the presence of bile salts (2.0%) for 24 h, and 88.27% after sequential digestion with SS, SGJ and SIJ; but the rate of adhesion to HT-29 cell was only 1.93%. In general, BLP12 displays strong adaptability to simulated environment. Strain BLP12 was identified as Lactobacillus plantarum by 16S rDNA sequencing. It could be used as a potential anti-diabetic probiotic strain for the development of functional foods.

This research adopted the isobaric tags for relative and absolute quantitation (iTRAQ) method for qualitative analysis of the whole proteins of Spirulina and employed a reasonable overall categorization method to categorize them according to practicability. The results demonstrated that a total of 2 085 Spirulina proteins were qualitatively identified including 1 562 known proteins. Totally, 869 annotated proteins could be classified into 233 protein superfamilies and 87 protein (all members are known proteins) families by sequence categorization. Based on their nature, structures and functions, these annotated proteins could be classified into 7 categories. It was found that the protein superfamilies had vital functions such as antioxidant, anticancer, antitumor and immunoregulation, and could be widely used in food, medicinal, chemical industry and other fields. Thus, active proteins of Spirulina have has promising prospects.

In this study, Cordyceps militaris (L.) Fr.-fermented rice was obtained by solid-state fermentation of rice with C.?militaris?(L.)?Fr., and its antioxidant activity was studied. The optimization of fermentation conditions was carried out using one-factor-at-a-time and orthogonal array design. The contents of cordycepic acid and water-soluble non-starch polysaccharides (SNSP) were used as response variables. The in vivo anti-aging activity of fermented rice was assessed by measuring the lifespan of Drosophila melanogaster, and antioxidant enzyme activities and malondialdehyde (MDA) content in this organism. Results showed that the optimum fermentation conditions were determined as follows: ratio of material to water 1:1.0, inoculum amount 20 mL/100 g, fermentation temperature 22 ℃, and fermentation time in the dark 8 days. For each dietary supplementation level, the half death period, average life expectancy, maximum life expectancy of Drosophila melanogaster given the fermented rice were higher than those of the blank control group and the rice control group. The activities of superoxide dismutase and catalase in the experimental group were higher than those in the control group, and the enzyme activities increased with increasing supplementation level. MDA content in the experimental group was lower than that in the blank group, and it decreased with increasing addition of C.?militaris?(L.)?Fr.-fermented rice.

T4 DNA polymerase (T4 DP) is an indispensable tool in genetic engineering and other related fields. To obtain a large quantity of high purity and bioactive soluble T4 DP, the recombinant expression vector pET-22b(+)-T4 dp was constructed by cloning the T4 dp gene from the T4 bacteriophage genome into pET-22b(+) plasmid, which was then transformed into Escherichia coli Transetta (DE3) competent cells after the positive clones were confirmed by sequencing. The expression of soluble T4 DP was efficiently and accurately detected by magnetic beads. The temperature and time of auto-induction were optimized to be 30 ℃ and 10 h, respectively. The auto-inducing recombinant bacteria were disrupted by ultrasonic treatment, ultrasonic treatment after preincubation with lysozyme and chemical cleavage, and chemical cleavage was determined as the optimal disruption method. The soluble T4 DP in the supernatant after disintegrating recombinant bacteria was purified by Ni SepharoseTM 6 Fast Flow affinity column or MagNi magnetic beads. High purity T4 DP was efficiently purified to a concentration of 3 073.960 μg/mL by MagNi magnetic beads. The high purity soluble T4 DNA polymerase was successfully applied in the construction of low background cloning vector demonstrating its terminal blunting activity.

This study aimed to establish a method for the determination of polyphenols in Osmanthus fragrans flowers by extractive electrospray ionization-mass spectrometry (EESI-MS). The main polyphenolic compounds in the methanol extract of O. fragrans var. semperflorens flowers were determined by high performance liquid chromatography (HPLC) and EESI-MS. The results showed that the contents of total phenols and total flavonoids in the methanol extract were (133.38 ± 0.12) and (72.49 ± 0.09) mg/g, respectively. Fifteen polyphenolic compounds were detected by HPLC, with myricetin, morin, rutin, naringenin and (+)-catechin being abundant. p-Protocatechuic acid, coumaric acid, caffeic acid, and epicatechin were detected by EESI-MS in the negative ion mode while cinnamic acid, morin and myricetin were detected in the positive ion mode. The EESI-MS method in this study had the advantages of low sample consumption, no complex pretreatment and short analysis time and could be used for the analysis of polyphenols in food samples.

This study aimed to simultaneously, rapidly and nondestructively detect anthocyanins, soluble solid content (SSC) and total sugar (TS) in commercial fresh purple sweet potato by visible and near infrared (VIS/NIR) spectroscopy. The infrared spectra of 52 purple potato cultivars were recorded with the VIS/NIR spectroscopy system set up in our laboratory and Savitzky-Golay (SG) smoothing, standard normal variate (SNV) transformation and first derivative (FD) were separately used to preprocess the original spectra. Partial least squares regression (PLSR) models were established. The best predictive model for anthocyanins and TS was obtained with SG smoothing combined with FD, whereas SNV transformation gave the best predictive model for SSC. Furthermore, new models were developed with the selected optimal pretreatments by competitive adaptive reweighed sampling (CARS) algorithm. For anthocyanins, the correlation coefficient of prediction was 0.942 1, and the root mean square error of prediction was 0.225 9 mg/g; for SSC, the correlation coefficient of prediction was 0.943 1, and the root mean square error of prediction was 0.878 7 °Brix; for TS, the correlation coefficient of prediction was 0.925 3, and the root mean square error of prediction was 0.244 3%. These results showed that using visible/near infrared spectroscopy could achieve the simultaneous, rapid and nondestructive detection of anthocyanins, SSC and TS in fresh purple sweet potato, which is of great practical importance for rapid non-destructive quality testing of fresh purple sweet potato.

In order to analyze the differences in the composition of volatile substances of honeys from different floral sources in the Western Sichuan Plateau, the volatile compounds of rape, Angelica sinensis, Sophora davidii and multifloral honeys were determined using an electronic nose (E-nose) and headspace solid-phase micro extraction coupled with gas chromatography-mass spectrometry (HS-SPME-GC-MS) and the E-nose sensor response data were analyzed by principal component analysis (PCA) and linear discriminant analysis (LDA). The results showed that the E-nose was sensitive to detect the differences in volatile components of four honey samples. A total of 40, 51, 39 and 46 volatile substances were detected by HS-SPME-GC-MS in these samples, respectively, mainly including alcohols, esters, ketones, aldehydes and hydrocarbons. In addition, 7 volatile components were found common to all the tested samples, exclusively containing 22, 27, 26 and 19 compounds, respectively. In conclusion, E-nose combined with GC-MS analysis can successfully distinguish among the volatile components of honey from different sources.

Volatile flavor composition is an important indicator for evaluating the quality of mushroom. The composition and relative contents of volatile flavor compounds in 14 species of the genus Pleurotus were investigated using headspace solid-phase micro-extraction (HS-SPME) combined with gas chromatography-mass spectrometry (GC-MS), and the contribution of different volatile components to the overall flavor was studied based on their relative odor activity value (ROAV) by principle component analysis. The results showed that a total of 41 flavor compounds belonging to aldehydes, alcohols, ketones, esters, carboxylic acids and furans were identified in 14 Pleurotus species. Eight volatile flavor compounds were common to all 14 species: hexanal, 2-butyl-2-octenal, 1-hexanol, 1-octen-3-ol, 1-octanol, 2-octen-1-ol, 3-octanone and 1-octen-one. In addition, esters were far more abundant than other compound classes in these mushroom species. P. florida PF6 contained 3 principal volatile flavor components including 1-octen-3-one, 1-octen-3-ol and octanal, while only 2 principal components, 1-octene-3-one and 1-octen-3-ol, were found present in other species. Furthermore, principle component analysis carried out on the volatile flavor compounds common to 14 Pleurotus species showed that the first three principal components cumulatively contributed to 83.627% of the total variation and that the main representative components were 1-hexanol, hexanal, 2-butyl-2-octenal, 1-octanol, 2-octen-1-ol, 1-octen-3-one and 3-octanone, which were the key flavor components of Pleurotus mushrooms.

The structures of proanthocyanidins from the root, stem and leaves of Tetrastigma hemsleyanum Diels et Gilg were analyzed with 13C nuclear magnetic resonance (13C NMR), reversed-phase high performance liquid chromatography electrospray ionization mass spectrometry (RP-HPLC-ESI-MS) and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). The results showed that the proanthocyanidins from T. hemsleyanum were mainly composed of procyanidin (PC) and prodelphinidin (PD). The terminal units were mainly composed of catechin while epicatechin and epigallocatechin were the dominant extension units. The mean degree of polymerization (mDP) of proanthocyanidins from the root, stem and leaves of T. hemsleyanum were found to be 4.89 ± 0.33, 3.77 ± 0.19 and 4.45 ± 0.48, respectively. Trimers to decamers of proanthocyanidins were detected from the root and stem, while trimers to undecamers of proanthocyanidins from the leaves of T. hemsleyanum by MALDI-TOF MS. (epi) Catechin and (epi) gallocatechin monomer units individually and together with galloyl substituents and a-type linkages prevalently existed in each polymeric cluster. The proanthocyanidins from the root, stem and leaves of T. hemsleyanum were structurally similar. The results of this study may provide useful data for the fundamental study and further development of T. hemsleyanum.

The changes of nutrients of the muscle and hepatopancreas of Portunus trituberculatus during chilled storage were analyzed using nuclear magnetic resonance (NMR)-based metabolomics. The results showed that a total of 30 nutrients were detected in swimming crab muscle and 27 nutrients in hepatopancreas. The levels of muscle nutrients changed mainly during the first two days of chilled storage; glutamate, glutamine, arginine, taurine, and ATP significantly increased while lactic acid, trimethylamine-N-oxide, inosine, inosine monophosphate, and adenosine monophosphate significantly decreased. The levels of hepatopancreas nutrients mainly changed during the first day of storage; the levels of the hepatopancreas amino acids, betaine, taurine, glucose, trimethylamine-N-oxide, choline-O-sulfate, and 2-pyridinemethanol significantly decrease while lactic acid significantly increased. As a result of these changes the taste and nutritional value of swimming crabs changed significantly.

Three headspace extraction methods including purge & trap (P&T), solid-phase micro-extraction (SPME) and dynamic headspace extraction (DHS) combined with gas chromatography-olfactometry-mass spectrometry (GC-O-MS) were utilized to analyze the volatile compounds in three kinds of sachima. A total of 45 and 38 compounds were identified by SPME and DHS, respectively, mainly including alcohols, aldehydes, ketones, esters and heterocyclic compounds. Meanwhile, due to their high concentration and lower threshold, aldehydes and heterocyclic compounds greatly contributed to the overall aroma profile of sachima. Furthermore, 17 aroma-active compounds were detected in sachima, responsible for green, coca, malty, grass, citrus, bread, mushroom, cheesy, green bean, popcorn, peanut, roasted nut, and peanut butter aroma, respectively. Sensory evaluation revealed that the aroma profile of sachima consisted of roasted, malty, fattay, green, sweet, burned, and egg aroma, consistent with the aroma characteristics of 17 odor-active compounds. Statistical comparison of three kinds of sachima with partial least squares (PLS) analysis showed that classic and whole-egg sachima contained less aroma compounds and pyrazines but more aldehydes than premium sachima.

In this work, molecularly imprinted polymers (MIPs) with specific binding affinity for the numb-taste compounds of Zanthoxylum bungeanum were prepared by using structural analogs of alkyl amides (LM) as dummy template molecule. In order to optimize the preparation conditions, UV spectroscopy was applied to study the effect of intensity of interaction and molar ratio between dummy template and functional monomers. With ethylene glycol dimethacrylate (EDMA) as the cross-linker, acetonitrile as the pore-foaming agent, 2,2-azobisisobutyronitrile (AIBN) as the initiator, 16 MIPs were prepared by bulk polymerization and the best MIP was selected and used to separate numb-taste compounds from the extract of Z. bungeanum. The results showed that the selected MIP had specific recognition and selectivity for the numb-taste components and exhibited an adsorption capacity of (14.64 ± 0.80) mg/g as determined by high performance liquid chromatography (HPLC). The peak area percentage of numb-taste component increased by approximately 21.95% after adsorption by the MIP.

The effects of four independent variables, namely microwave intensity, extraction time, ethanol concentration and solid-to-solvent ratio, on the extraction efficiency of anthocyanins from blueberry were investigated by one-factor-at-a-time method. Subsequently, these variables were optimized using response surface methodology (RSM) and genetic algorithm-artificial neural network (GA-ANN) based on Box-Behnken design. The results showed that the extraction efficiency increased to a maximum followed a decrease with increasing level of each variable in the experimental range. GA-ANN showed better prediction and optimization abilities than RSM with lower relative error value (1.43% versus 2.71%) and higher determination coefficient R2 (0.904 4 versus 0.877 3). The optimal process parameters were obtained by using GA-ANN as follows: microwave intensity 155 W/g, extraction time of 53 s, ethanol concentration 56% and solid-to-solvent ratio 1:30 (g/mL). The yield of blueberry anthocyanins extracted was 85.12%, under the optimized conditions, which was higher than that (83.32%) calculated by RSM. The results from this research can provide an effective method for the optimization of process parameters in food processing.

In order to improve the gel properties and amino acid composition of brewer’s spent grains (BSG) protein, the modification of BSG protein and soybean protein mixtures with transglutaminase (TGase) was optimized using one-factor-at-a-time method and response surface methodology. The gel strength of modified proteins was investigated with respect to proportion of BSG protein, enzyme dosage, water bath temperature and heating time. The results showed that BSG protein with a protein content of 52.23% was obtained through wet milling, and that its amino acid composition was dominated by glutamate and proline. The optimal modification condition of BSG protein was determined as follows: 30% BSG protein, 15 U/g of TGase, pH 7, and water bath heating at 48 ℃ for 132 min. The gel strength of the modified proteins was 218.55 g. The approach presented in this study can provide an experimental basis for the deep processing of brewer’s spent grains protein.

A method was established for the determination of four progesterones (progesterone, melengestrol acetate, megestrol acetate and chlormadinone acetate) by ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) with dispersive solid-phase extraction. The samples were extracted with n-hexane and then the extract was redissolved with methanol solution after being evaporated to dryness by nitrogen blowing. The solution was then purified with primary secondary amine (PSA) solid phase adsorbent. Using binary mobile phase gradient with water containing 0.1% formic acid and methanol, the centrifugal supernatant was separated on an ACQUITY UPLC BEH C18 column (2.1 mm × 100 mm, 1.7 μm) and the target compounds were detected under a multiple reaction monitoring (MRM) mode with a positive electrospray ionization source. The results showed that the calibration curves for the four progesterone hormones exhibited good linear relationships in the range of 0.4–100 μg/L with correlation coefficients (r2) of more than 0.996. The limit of detection was 0.2 μg/kg and the limit of quantification was 0.6 μg/kg. The average recoveries at three spiked levels were 79.5%–99.7% with relative standard deviations (RSD, n = 6) of less than 10.0%. This method proved to be simple, rapid, highly sensitive and practical, and thus it could be applicable for routine determination of the 4 progesterone hormones in eggs.

By using aptamer as the capture probe and gold nanoparticles-invertase-complementary DNA conjugates as the detection probe, a competitive dopamine hydrochloride (DH) aptasensor was constructed based on a glucose meter. In the absence of DH, the detection probe was captured on a 96-well plate by the aptamer through complementary base pairing. When it was present, DH interacted with its aptamer with a strong affinity forcing the detection probe away from the 96-well plate to catalyze the transformation of sucrose into glucose. Accordingly, indirect detection of dopamine hydrochloride concentration was performed by measuring glucose concentration with a glucose meter. When the incubation time and the enzymatic reaction time were 30 min and 120 min, respectively, the glucose meter signal intensity increase linearly with the increase of DH concentration in the range of 0.45–10 mmol/L with a correlation coefficient of up to 0.997, and the relative standard deviations (RSDs) were 0.9%, 1.4% and 4.8% at 8.0, 3.0 and 0.8 mmol/L (n = 5), respectively. The prepared sensor has the advantages of simple operation, good stability and high selectivity, which not only broadens the application of glucose meter to the detection of other non-glucose, but also has potential application in the fields of health care and food safety detection.

This study aimed to explore the feasibility of applying near infrared spectroscopy (NIR) and electronic nose (E-nose) for detecting apple watercore. A total of 277 samples of “Qinguan” apples with watercore and healthy apples were tested. NIR spectra of each sample in the range of 12 000 to 4 000 cm-1 and E-nose signals from 10 sensors were collected, The Fisher discriminant model was established with the principal components extracted by different preprocessing methods. Meanwhile, the E-nose data were used for modeling by 3 different chemometric methods. The results indicated that the Fisher discriminant model developed based on the first twenty principal components from the NIR spectra subjected to the first derivative (9-point smoothing) pretreatment worked best with discrimination accuracy rates of 100% for unknown samples. The correct discrimination rates of the discriminant models developed by Fisher discriminant, multilayer perceptron (MLP) neural network and radial basis function (RBF) neural network for unknown samples were 89.7%, 89.5% and 85.7%, respectively. Thus, the combined application of NIR spectroscopy and E-nose with chemometrics can rapidly and nondestructively test watercore apples. NIR spectroscopy combined with Fisher discriminant analysis is an accurate and reliable method for detecting watercore apples with the highest correct recognition rate.

An ion chromatography method for the determination of three sugars, four preservatives and one edulcorant in beverages using valve switching technique was established. After simple pretreatment, the sample was injected into an IonPac? AS11-HC (4 mm × 250 mm) separation column. By setting an appropriate valve switching time, the carbohydrates with weak retention in the AS11-HC column were first washed out and collected in a quantitative loop. The preservatives retained strongly were gradually washed out by the eluent and detected by a UV detector. The carbohydrates collected were then rinsed into a CarboPac? PA10 (4 mm × 250 mm) column and separated using NaOH eluent for electrochemical detection. The experimental results showed that the regression coefficients (r2) of the calibration curves were more than 0.999 0 in the range of 0.5–2.5 mg/L. The reproducibility expressed as relative standard derivation (RSD) was less than 6.72%, and the recovery ranged between 80.0% and 120.0%. The method can be widely applied to quality control or the detection of components in final products in the beverage industry.

A method was developed for determining carvacrol and thymol in modified polylactic acid (PLA) active food packaging film by high performance liquid chromatography (HPLC). Samples were analyzed by HPLC on a Sunfire C18 column with 10 μL of a mobile phase consisting of acetonitrile and water (3:2, V/V) at a flow rate of 1 mL/min by gradient elution. The column temperature was set at (30 ± 5) ℃ and the analysis time was 10 min. The detection wavelength was 274 nm and the external standard method was used for quantitative analysis. Good linearities for the analytes were obtained in the concentration range of 5–100 mg/L with correlation coefficients of more than 0.996. The recoveries from samples spiked with carvacrol and thymol were 71.6%–93.7% and 73.1%–103.6%, with relative standard deviations (RSDs) of 5.2%–8.3% and 5.0%–8.8%, respectively. The limits of detection (LODs) for the analytes were 200 μg/kg and limits of quantification (LOQs) were 500 μg/kg. The method proved to be rapid, simple and highly sensitive, and it could provide a foundation for gaining further insight into the release mechanism of carvacrol and thymo from active food packaging materials and ensuring the safe application of active food packaging film.

This study aimed to develop a technique to trace the geographical origin of protected geographical indication (PGI) rice grown in different years for the purpose of protecting the brand benefits of PGI rice. Near-infrared diffuse reflectance spectroscopy was used to detect rice samples from experimental fields and the characteristic bands related to the growing area were selected. The geographical origin of 291 rice samples from Sanjiang and Wuchang areas, collected during 2013 to 2015 was analyzed using the characteristic bands. There were significant differences among the experimental filed grow rice samples in terms of geographical origin in the range of 5 136–5 501 cm-1. In this range, the qualitative analysis model and the cluster analysis model established by the factorization method showed a correct recognition rate of higher than 97.00% for Sanjiang and Wuchang rice; the correct recognition rates of the quantitative analysis model established by partial least squares (PLS) were 95.83% and 94.00%, respectively. Therefore, this method was proved feasible for tracing the geographical origin of rice harvested in different years.

In this paper, a rapid, non-destructive and accurate method for detecting the contents of aflatoxin B1 (AFB1) and zearalenone (ZEN) in maize using hyperspectral imaging was established by developing predictive models. Among 5 spectral pretreatments tested, standard normal variate (SNV) was found to be the best method for preprocessing the original spectral data. Sample set partitioning based on joint x-y distance (SPXY) algorithm combined with partial least squares regression (PLSR) was used to screen the differences in the predicted contents of AFB1 and ZEN from different calibration set samples, and 130 and 140 calibration set samples were selected for AFB1 and ZEN, respectively. On the basis of dimensionality reduction by the uniform spectral spacing (USS) method, the two variable extraction methods: successive projections algorithm (SPA) and competitive adaptive reweighted sampling algorithm (CARS) were compared. The results showed that 17 characteristic wavelengths were selected for AFB1 and ZEN, respectively and the PLSR model established based on fewer calibration set samples with the characteristic wavelengths had better predictive performance. The correlation coefficients (R2pre) and root mean square error of prediction (RMSEP) for AFB1 and ZEN content were 0.997 3 and 0.681 5, and 0.997 7 and 1.144 1, respectively, while the initial R2pre and RMSEP values were 0.994 4 and 0.984 6, and 0.991 6 and 2.320 9, respectively. The results indicated that despite reducing the reducing the complexity of the model, the predictive accuracy could be improved. Therefore, it is feasible to non-destructively predict the AFB1 and ZEN content in maize by applying hyperspectral imaging technology.

In this study, a rapid, accurate and stable direct competitive ELISA (dcELISA) for the detection of chloramphenicol residue in honey was developed. The anti-chloramphenicol monoclonal antibody was used as coating antigen, chloramphenicol-horseradish peroxidase conjugate as marker and 3,3’,5,5’-tetramethyl benzidine (TMB) as chromogenic substrate. Six main experimental conditions, including buffer for chloramphenicol standard, coating temperature, and dilution of coating antibody were optimized. In addition, the accuracy and stability of the method were also investigated. The obtained standard curve equation was y = ?17.425x + 97.509 (R2 = 0.991 2), and the IC50 was 0.63 ng/mL. The limit of detection (LOD) and linear rang were (0.04 ± 0.01) ng/mL and 0.10?4.17 ng/mL, respectively. The whole detection process required about 40 min. In honey samples, the LOD, LOQ and spiked recovery were 0.15 ng/g, 0.33 ng/g and 97.58%?100.94%, respectively. The intra-batch and inter-batch coefficients of variation were both less than 11%. These results indicated that the developed dcELISA method possessed high accuracy and stability.