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15 June 2021, Volume 42 Issue 11
Basic Research
Antioxidant Activity and Electron-Donating Capacity of Tyr-Containing Dipeptides in Liposomal Systems
CHEN Chong, ZHAO Mouming, SUN Weizheng
2021, 42(11):  1-7.  doi:10.7506/spkx1002-6630-20200617-232
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The ultraviolet (UV) absorption characteristics of five Tyr-containing dipeptides (Tyr-Tyr, Tyr-Phe, Phe-Tyr, Tyr-Ala, and Tyr-Ser) were investigated, and their antioxidant activities were evaluated and compared using reducing power assay, cyclic voltammetry and 2,2’-azobis(2-amidinopropane)dihydrochloride (AAPH)-induced liposomal oxidation system. The aim was to explore their influential factors and the distinction and correlation between the antioxidant activities in a homogeneous system and those in a heterogeneous system. The results showed that the amino acid composition and sequence of these dipeptides had a significant influence on their UV absorption characteristics, electron-donating capacity and lipid oxidation inhibitory effect, while the amount of phenolic hydroxyl group played a determinant role in the antioxidant activity. Compared with Tyr-Phe, Phe-Tyr exhibited higher activity in the three antioxidant assays. In the liposomal system, the inhibition of lipid oxidation by these dipeptides were significantly correlated (P < 0.05) with their electron-donating capacity as well as their lipophilicity or hydrophilicity.
Effects of Different Thawing Methods on the Functional Properties, Physicochemical Properties and Protein Structures of Frozen Egg Yolks
DU Qingpu, ZHAO Ying, WANG Ruihong, CHI Yujie
2021, 42(11):  8-16.  doi:10.7506/spkx1002-6630-20200612-172
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This study aims to mitigate the deterioration of egg yolk quality caused by freezing-thawing treatment. The functional and physicochemical properties of frozen egg yolk samples thawed by four thawing methods such as standing at room temperature, immersion in warm water, ultrasonic and microwave were investigated and compared with those of fresh egg yolk. Furthermore, under various thawing conditions changes in protein structures were explored by Raman spectroscopy. The results indicated that natural thawing brought about the highest turbidity in egg yolk, the lowest C=C stretching vibration intensity of lipoprotein alkyl chains as indicated by Raman spectroscopy, and the highest percentage of β-sheet, demonstrating the highest degree of protein cross-linking. The protein solubility, emulsifying activity and emulsion stability of egg yolk thawed in warm water bath were significantly lower than those of egg yolk thawed by ultrasonic treatment (P < 0.05). Among the four thawing methods, the surface hydrophobicity of egg yolk thawed in water bath was the strongest. The disulfide bond content of proteins in egg yolk thawed by microwave treatment was significantly higher than that in egg yolk thawed by ultrasonic treatment (P < 0.05). The highest asymmetric C-H bending vibration intensity of aliphatic amino acids and the lowest proportion of α-helix structure were observed in the microwave-thawed sample, together with the formation of microgel particles. By contrast, the ultrasonic-thawed egg yolk was characterized by superior emulsifying activity and emulsion stability as well as the smallest particle size and the most concentrated distribution. Moreover, the hardness, cohesiveness and viscosity were low, being not significantly different from those of fresh egg yolk (P > 0.05). In conclusion, ultrasonic thawing is a suitable thawing method for frozen egg yolk.
Effect of Heat Treatment on Juice Sac Granulation of Harvested Guanxi Honey Pumelo (Citrus grandis (L.) Osbeck) Fruit and Its Association with Cell Wall Metabolism
ZHANG Shen, ZHANG Yixiang, YE Hong, NIE Ke, WU Guangbin, NI Hui, ZHANG Zongcheng, CHEN Fahe
2021, 42(11):  17-25.  doi:10.7506/spkx1002-6630-20200714-178
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Juice sac granulation is a major quality deterioration of harvested pumelo fruit. This study investigated the effect of heat treatment on the fruit quality of Guanxi honey pumelo during postharvest storage and its inhibitory effect on juice sac granulation, and explored the appropriate conditions. Furthermore, this study analyzed the correlation between the inhibitory effect and the metabolism of lignin synthesis and polysaccharide degradation in the cell wall. Spraying with 35, 42, 49 and 56 ℃ water was employed as postharvest handling. The appropriate temperature was selected based on the granulation index and the contents of moisture, total soluble solids and titratable acid during cold storage, and its impacts on the lignin content, lignin synthetic enzyme activities, cell wall polysaccharide contents and cell wall polysaccharide-degrading enzyme activities in fruit juice sacs were evaluated. The results suggested that compared with other treatments, spraying with water at 42 ℃ for 15 min effectively retarded the increase in juice sac granulation index and the decrease in moisture content, and maintained the contents of total soluble solids and titratable acid. Meanwhile, it suppressed the activity of phenylalnine ammonialyase, cinnamyl alcohol dehydrogenase and peroxidase in the juice sac, delaying the increase in lignin content; and inhibited the activities of cellulase, pectin methylesterase, polygalacturonase and β-galactosidase, delaying the increase in cellulose and hemicellulose contents, the decline in covalently bound pectin content and the accumulation of ion-soluble pectin and water-soluble pectin in the juice sac during storage. The above results indicated that spraying with water at 42 ℃ could retard juice sac granulation and maintain the quality of harvested Guanxi honey pumelo fruit, and the inhibitory effect on juice sac granulation might be associated with inhibited enzyme activities related to lignin synthesis and cell wall polysaccharide degradation, resulting in delayed juice sac fibration, lignification and pectin degradation, which maintained the cell wall composition and structure.
Curcumin Loading Properties of Folic Acid and Octenyl Succinic Anhydride Modified Inulin Micelles
LI Ruohua, YANG Hua, LEI Lin, YE Fayin, ZHAO Guohua
2021, 42(11):  26-33.  doi:10.7506/spkx1002-6630-20200425-330
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Folic acid conjugated with amphiphilic polysaccharide has been regarded as an effective carrier to delivery hydrophobic pheytochemicals to the colon. In our present study, the stability of self-assembled micelles of folic acid octenylsuccinate inulin (FA-OS-inulin) loaded with curcumin to thermal treatment, freeze-thaw treatment and simulated gastrointestinal digestion was investigated by the particle size and polydispersity index (PDI) of micelles as well as the retention of curcumin. Results showed that the micelles exhibited good thermal and storage stability with enhanced retention of curcumin. However, the particle size and PDI changed significantly during thermal processing and storage (P < 0.05). In the end of the gastrointestinal digestion, the percentage release of curcumin from the micelles was lower than 2% and 10% in simulated gastric and intestinal fluids respectively, indicating good controlled release properties. Therefore, FA-OS-inulin may be used as a potential vehicle for colon-targeted delivery of bioactive compounds like curcumin.
Antioxidant Interaction of Different Forms of Phenolic Compounds Extracted from Camellia Seed Oil
LIU Guoyan, LI Sitong, LIANG Li, ZHU Wenqi, ZHOU Wanli, XU Xin
2021, 42(11):  34-39.  doi:10.7506/spkx1002-6630-20210111-113
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The contents and major compositions of free phenolics (FP), esterified phenolics (EP) and insoluble-bound phenolics (ISP) from camellia seed oil were analyzed. The ferric ion reducing antioxidant power, 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonate) (ABTS) cation radical scavenging capacity, 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging capacity and β-carotene bleaching capacity were used to study the antioxidant activity of the three phenolic compounds and their interactions. The results showed that the content of total phenols in camellia seed oil was (137.97 ± 5.14) mg/kg. ISP was significantly more abundant than FP and EP (P < 0.05), which accounted for 47.74% of the total phenols in the oil. In addition, benzoic acid derivatives (mostly isovanillin and methyl vanillin) were the dominant component in FP, salicylic acid was the dominant component in EP, and 3,4-dihydroxymandelic acid was the dominant component in ISP. The three forms of phenolic compounds showed different antioxidant capacities with different mechanisms in a concentration-dependent manner. FP + ISP and EP + ISP showed a synergistic and additive interaction in the antioxidant tests, the antioxidant activity of the latter combination being stronger than that of the former. However, FP + EP and FP + EP + ISP showed an antagonistic or additive effect.
Effect of 12-Hydroxystearic Acid as Organogelator and Thermal Processing on Oxidation of Soybean Oil Organogel
LUO Jing, YAN Mengting, LI Peixu, ZHANG Cuiping, FU Hong
2021, 42(11):  40-46.  doi:10.7506/spkx1002-6630-20200715-200
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The effect of 12-hydroxystearic acid (12-HSA) as an organogelator on oxidation indices of soybean oil organogels prepared with it was investigated together with the role of the functional groups of 12-HSA in promoting lipid oxidation. Further, the mechanism of the effect of the thermal processing of 12-HSA on the oxidation of soybean oil organogels was studied based on the difference between the state of organogels at room temperature and that during thermal processing, and the thermal oxidation of organogels was analyzed by 1H-nuclear magnetic resonance (1H-NMR). The results showed that 12-HSA reacted with the titrating alkaline solution, increasing the measured acid value. The true acid value reflected by free fatty acids in the oil should be calculated by subtracting the measured acid value with the acid value caused by 12-HSA. 12-HSA had a promoting effect on the oxidation. Under the same condition, the headspace oxygen consumption was in the descending order of stearic acid > stearyl alcohol > 12-HSA > octadecane, implying that the oxidation-promoting effect of hydroxyl and carboxyl group alone was stronger than that of 12-HSA containing both groups. The rheological results showed that at 25 ℃, 12-HSA with 2% addition enabled soybean oil to form a stable gel structure and to be less susceptible to oxidation. When the temperature was greater than 60 ℃, the gel structure was gradually destroyed, and the oxidation-promoting effect of 12-HSA was gradually enhanced. Compared with the blank control group, the headspace oxygen consumption in the 12-HSA group at 90 and 120 ℃ increased by 0.65% and 1.78%, respectively. The results of 1H-NMR showed that the integral peak area ratio of protons between aliphatics and olefins (Rao) and that between aliphatics and diallylmethylenes (Rad) increased with the degree of oxidation, both having a good positive correlation with the total oxidation value of oleogels.
Polyphenol Composition and Antioxidant and Hypoglycemic Activities in Wild Blue Honeysuckle Fruit
QIAO Jinli, ZHANG Yan, LIU Pei, GUO Liangchuan, HUO Junwei
2021, 42(11):  47-55.  doi:10.7506/spkx1002-6630-20200709-123
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The polyphenol composition and antioxidant and anti-starch hydrolase activities in wild blue honeysuckle fruit collected from the Lesser Khingan Mountains in northeast China were analyzed. Anthocyanin and non-anthocyanin fractions were obtained by solid-phase extraction (SPE) and the chemical composition was determined. Total phenolics and total anthocyanins were also determined in the polyphenol crude extracts, and antioxidant activity was measured by determining 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging capacity, ferric reducing antioxidant power (FRAP), 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) cation radical scavenging capacity, and oxygen radical absorbance capacity (ORAC). In addition, the inhibitory activity of α-amylase, α-glucosidase and lipase were determined. The results showed that the fruit contained abundant anthocyanins and non-anthocyanin polyphenols, especially cyanidin-3-glucoside and kaempferol-3-rutinoside. The contents of total phenolics and total anthocyanins in the polyphenol crude extracts were up to 82.7 and 49.8 mg/100 g respectively, indicating strong antioxidant activity. The half-maximum inhibitory concentrations (IC50) for α-amylase, α-glucosidase and lipase were 0.39, 0.933 and 12.31 mg/mL, respectively. This study demonstrates that blue honeysuckle fruit could be used as a promising inhibitor of starch hydrolase.
Changes of Free Radicals during Oxidation of Unsaturated Fatty Acids at Room Temperature
WANG Mengmeng, KOU Yuxing, ZHOU Sheng, WANG Liqian, YU Xiuzhu
2021, 42(11):  56-62.  doi:10.7506/spkx1002-6630-20200610-137
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The pattern of changes in free radicals during the oxidation of unsaturated fatty acids including oleic, linoleic, and linolenic acid at room temperature was investigated by electron paramagnetic resonance (EPR) and nuclear magnetic resonance (NMR). The impact of exogenous substances on it was also evaluated. The results showed that the EPR spectra of oleic acid were dominated by alkyl radicals (R·) during oxidation from 0 to 60 min and then by alkyl peroxyl radicals (ROO·) and alkoxyl radicals (RO·). The radicals formed during the oxidation of linoleic and linolenic acids were mainly R·. During the oxidation process, the fatty acids (RH) were induced to form R· and H·, and then H· combined with ROO· to generate hydroperoxides, which were partly decomposed. The oxidation and degradation of linolenic acid were higher than those of linoleic acid and oleic acid. Addition of either tocopherol (VE) or tert-butylhydroquinone (TBHQ) inhibited the formation of free radicals such as RO· and ROO·. The EPR spectra of fatty acids added with 2,2’-azobis(2,4-dimethyl)valeronitrile (ADVN) were dominated by R· during oxidation, and inorganic carbon-centered free radicals were also introduced. The total number of spins in oleic and linolenic acid added with chlorophyll significantly increased at 150 and 90 min, respectively, and was fluctuated at other times. The higher the degree of unsaturation of fatty acids, the greater the amount of R· radicals produced during oxidation. Addition of VE and TBHQ could provide H·, which combined with lipid free radicals to inhibit the process of chain reaction and particularly inhibit the generation of ROO· and RO·. ADVN and chlorophyll could have a free radical-initiating effect, thus promoting the chain reaction.
Taste Quality of Indica Hybrid Rice Varieties Evaluated by Using Rice Taste Analyzer
YUAN Yujie, ZHANG Siqi, LU Hui, LI Guiyong, ZHU Haiping, TAO Youfeng, CHEN Hong, REN Wanjun
2021, 42(11):  63-70.  doi:10.7506/spkx1002-6630-20200531-381
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This research aimed to explore the effects of different cooking methods on the eating quality of indica hybrid rice produced in two ecological regions of southwest China. Nine medium hybrid rice varieties, each grown in Yongsheng of Yunnan province and Dayi of Sichuan province were used to investigate the effect of different cooking methods (water-to-rice mass ratios of 1.3:1, 1.5:1, 1.6:1, 1.9:1, 2.1:1, 2.4:1 and 2.7:1), soaking times (0, 15, 30 and 60 min), cooking times (20, 30 and 40 min) and holding times (0, 15 and 30 min)) on the taste quality of cooked rice as analyzed by using a rice taste analyzer. The results showed that the taste quality of cooked rice was affected by cooking methods, cultivars and ecological regions individually and interactively, and all factors significantly affected the appearance and taste value (P < 0.01). The interactions of cooking methods with ecological regions and cultivars as well as the interaction among these three factors significantly affected the taste quality of cooked rice (P < 0.01). The results obtained on the rice taste analyzer demonstrated that rice from the area with sufficient light and temperature of Yongsheng had a high taste value under the conditions of water-to-rice ratio of 2.1:1, soaking for 30 min, cooking for 30 min and holding for 15 min; rice from the area with high humidity and weak light of Dayi had a high taste value under the conditions of water-to-rice ratio of 2.1:1, soaking for 15 min, cooking for 30 min and holding for 15 min. Among the nine varieties, ‘Nei 5 You 39’ had the best eating quality, varying little with water-to-rice ratio, closely followed by ‘Yixiangyou 2115’, while the eating quality of ‘Zhongyou 295’ and ‘F You 498’ was poor. Moreover, the taste quality of ‘F You 498’ and ‘Tianyouhuazhan’ varied greatly with cooking methods. In general, cooked rice grown in Yunnan had a better appearance than that in Sichuan, while the latter exhibited the a higher taste value under specific cooking conditions.
Preparation, Physicochemical Properties and Anticoagulant Activity of Heparinoid from Shrimp Head
CHEN Jing, DU Zhenxing, CHEN Jianping, JIA Xuejing, LIU Xiaofei, LI Rui, ZHONG Saiyi
2021, 42(11):  71-77.  doi:10.7506/spkx1002-6630-20200422-282
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In this study, heparinoid was separated and purified from an enzymatic hydrolysate of shrimp heads by anion exchange column chromatography and alcohol precipitation and was identified by cellulose acetate film electrophoresis. Its purity and molecular mass were analyzed by ultraviolet (UV) spectroscopy and high-performance gel permeation chromatography (HPGPC), its functional group structure by Fourier transform infrared spectroscopy, and its monosaccharide composition by high performance liquid chromatography (HPLC) after pre-column derivatization. Its anticoagulant activity was evaluated by in vitro coagulation test. The results showed that the heparinoid contents of fractions F1.1 and F1.5 were 83%, indicating their high purity, and their molecular masses were 7.8 and 19.8 kDa, respectively. The electrophoretic mobility of F1.1 was similar to that of chondroitin sulfate, and F1.5 was close to the heparin standard. Both had the absorption peaks of carboxyl, acetamido, and sulfuric acid groups. Monosaccharide composition analysis demonstrated that they were composed of glucuronic acid, iduronic acid, N-acetylgalactosamine, galactose and fucose in different proportions. F1.1 and F1.5 exerted a significant anticoagulant effect through the endogenous coagulation pathway and the common coagulation pathway, and F1.5 had better anticoagulant activity than F1.1 and could be used as a potential anticoagulant agent.
Effect of Phenolic Acids on Color and Volatile Flavor Compounds of Red Bayberry Wine during Storage
CAO Yuxi, WU Zufang, WENG Peifang
2021, 42(11):  78-85.  doi:10.7506/spkx1002-6630-20200712-161
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In an effort to investigate changes in the color and flavor of red bayberry wine as a function of storage time, the effect of added phenolic acids on the color, volatile flavor substances and sensory attributes of red bayberry wine was determined by gas chromatography-ion mobility spectrometry (GC-IMS), colorimetry, electronic tongue and sensory evaluation. The results showed that added tannic acid, ferulic acid or sinapic acid had a color-protecting effect on red bayberry wine, slowed down the changes in a*, C*, and total color difference ΔE*, and significantly enhanced the color stability of red bayberry wine during storage. From the two-dimensional and three-dimensional spectra and fingerprints for the volatile flavor substances of red bayberry wines with and without added phenolic acids established by GC-IMS, it was found that addition of phenolic acids showed no significant influence on the volatile flavor of the wine. Electronic tongue analysis could distinguish the control group from the wines added with phenolic acids. The sensory quality of the wine added with sinapic acid was closer to that of the control group. Therefore, sinapic acid is more suitable as a copigemnt for red bayberry wine.
Roasting Suitability of Different Beef from Different Cuts
LIU Xuefei, YOU Jiawei, CHENG Kexin, YOU Mengjiao, LIU Dengyong
2021, 42(11):  86-93.  doi:10.7506/spkx1002-6630-20200608-105
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Roasting is one of the major ways to cook beef in China, but the roasting suitability of different cuts of beef is not clear yet. In this study, beef high rib, shank, chuck tender, silverside, striploin, tenderloin, topside and rump were analyzed for differences in their nutritional quality, physicochemical quality, color, water-holding capacity and muscle fiber characteristics as well as in sensory quality and texture properties after roasting. The key quality indexes of roast beef were determined by multivariate statistical analysis, and a comprehensive quality evaluation equation was established as follows: Y = ?0.138 9X1 + 0.114 3X2 + 0.355 9X3 + 0.262 2X4 + 0.240 3X5 + 0.166 2X6 (X1 through X6 respectively represent fat content, gel hardness, muscle fiber diameter, shear force, raw meat yellowness value b*, and roast beef redness value a*). The roasting suitability of different cuts was determined by K-means cluster analysis on the basis of the calculated comprehensive quality scores. The results showed that the high rib was more suitable for roasting than silverside, striploin, tenderloin and topside, while shank, chuck tender and rump were not suitable for roasting. A regression equation to predict the overall acceptability as a function of the comprehensive quality scores was developed as follows y = 1.633 7x ? 0.243 1 (R2 = 0.831 9), further proving that the comprehensive quality evaluation model could well reflect the suitability of different cuts of beef for roasting. This study can provide a theoretical basis for rational and standardized beef processing.
Food Engineering
Ultrasound-Assisted Encapsulation of Astaxanthin within Ferritin Nanocages with Enhanced Efficiency
ZHANG Chenxi, ZHANG Xiaorong, LÜ Chenyan, ZHAO Guanghua
2021, 42(11):  94-101.  doi:10.7506/spkx1002-6630-20200604-055
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Astaxanthin is a natural carotenoid pigment with a variety of bioactivities, but its poor water-solubility and high sensitivity to temperature or light limit its application. Recently, due to its pH-induced disassembly and reassembly property, ferritin, a cage-like protein, has emerged as a new vehicle for the encapsulation of various nutrients. However, during encapsulation, at least 40% of total proteins can be damaged because of harsh pH conditions. Therefore, in this study, an ultrasound-assisted approach was established for the successful encapsulation of astaxanthin within ferritin nanocages, without damage to the protein nanocages. Quantitative analysis by high performance liquid chromatography (HPLC) indicated that one ferritin molecule could encapsulate approximately 40 astaxanthin molecules. The results of light and thermal stability experiments showed that the degradation rate of astaxanthin was reduced from 45% at the end of heat treatment and 31% at the end of light treatment to 3% after being loaded into the protein cavity, respectively. As expected, the encapsulation of astaxanthin within ferritin nanocages pronouncedly improved its water-solubility and photothermal stability as compared to astaxanthin alone. The reported method provides new possibilities for encapsulating and delivering nutrients, thereby facilitating their applications in the food industry.
Effect of Ultra-High Pressure Assisted Shelling on Biochemical Characteristics and Structure of Myofibrillar Protein in Patinopecten yessoensis
CHEN Qihang, WEN Lihua, CHEN Xiao’e, FANG Xubo, LING Jiangang, XUAN Xiaoting
2021, 42(11):  102-107.  doi:10.7506/spkx1002-6630-20200603-040
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This study was undertaken in order to explore the effect of ultra-high pressure (UHP) treatment, applied within 150?350 MPa for 3 min on the shelling efficiency, and biochemical characteristics and structure of myofibrillar protein in Patinopecten yessoensis. Manual shelling and steam shelling were used as controls for comparison. The shelling efficiency was evaluated by measuring the shelling time and flesh yield. The pattern of changes in myofibrillar protein concentration, total sulfhydryl content, carbonyl content, surface hydrophobicity, Ca2+-ATPase activity and secondary structure was investigated. The results showed that high shelling efficiency was achieved by holding at 250 MPa for 3 min, and UHP treatment caused certain changes in the myofibrillar protein from Patinopecten yessoensis adductor muscle. Specifically, after the treatment, the surface hydrophobicity and hydroxyl content increased, whereas total sulfhydryl content and Ca2+-ATPase activity decreased. In addition, the relative contents of α-helix and β-turn decreased, whereas the contents of β-sheet and random coil increased. Overall, UHP treatment had only a limited impact on the myofibrillar protein, maintaining its biochemical properties and consequently maintaining the eating quality and processing performance of Patinopecten yessoensis adductor muscle. These results will provide references for the quality control of shellfish myofibrillar protein during ultra-high pressure treatment.
Physicochemical Properties of Fish Skin Gelatin Prepared by Sequential Microwave and Rapid Freezing-Thawing Pretreatment Coupled to Gelatinization
DU Jie, LIU Tingwei, MA Liang, WANG Hongxia, DAI Hongjie, YU Yong, ZHU Hankun, ZHANG Yuhao
2021, 42(11):  108-115.  doi:10.7506/spkx1002-6630-20200612-161
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The physicochemical properties of fish skin gelatin prepared by sequential microwave and rapid freezing-thawing pretreatment coupled to gelatinization were characterized by measurement of isoelectric point, transmittance, gel strength, rheological properties and amino acid composition as well as using sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and Fourier transform infrared (FTIR) spectroscopy. Different from commercial type A and type B gelatins, the gelatin prepared in this study had an isoelectric point of 7. The transmittance was 57.13% and 78.07% at 450 and 620 nm, respectively, and the gel strength was 524.40 Bloom g, meeting the requirements of the Chinese national standard (transmittance at 450 nm ≥30%, transmittance at 620 nm ≥50%, and gel strength ≥ 50 Bloom g). Compared with that prepared by the traditional acid method, the gelatin had more hydrogen bonds as well as a complete triple helix structure and the proportion of sub-amino acids was similar between both gelatins. However, due to the small proportion of polymer subunits, gel properties were generally inferior to those of the traditional gelatin. In general, the method presented in this study is suitable for the green and clean preparation of gelatin.
Preparation and Characterization of β-Lactoglobulin-Chitosan Covalent Conjugate under High Pressure Processing and Emulsion Stabilized by It
REN Shuang, HE Xiaoye, LIU Jinfang, MAO Like, GAO Yanxiang, YUAN Fang
2021, 42(11):  116-123.  doi:10.7506/spkx1002-6630-20200706-073
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Objective: To explore the impact of ultra-high pressure (UHP) treatment on the Maillard reaction, and to develop a more efficient oil-water interface membrane for improving emulsion stability through protein-polysaccharide covalent complexation. Methods: The Maillard reaction between β-lactoglobulin (β-Lg) and chitosan (CS) at different mass ratios (1:1, 1:2 and 1:4) was initiated under dry-heating conditions after preprocessing at different pressures (200, 400 and 600 MPa). Their physical mixtures were used as a control for comparison. The resultant conjugates were characterized by the degree of browning, fluorescence spectroscopy, and circular dichroism spectroscopy, and the particle size, zeta-potential, and physical stability of the emulsions prepared with the conjugates were measured. Results: When the mass ratio of β-Lg to CS was 1:1 and 1:2, as the pressure increased, the degree of browning first increased and then decreased; when the ratio was 1:4, the degree of browning continued to increase. The fluorescence of β-Lg was quenched after the Maillard reaction, and the higher the CS ratio, the stronger the degree of quenching. The α-helix content of β-Lg was reduced from 19.5%, 21.1% and 22.5% to 18.7%, 16.9% and 15.9%, respectively after the Maillard reaction at β-Lg to CS ratios of 1:1, 1:2 and 1:4, and the α-helix content reached the maximum value of 19.6%, 19.0% and 16.6%, respectively under 400 MPa. The particle size (399.1, 481.5 and 584.4 nm) and 4 h turbiscan stability index (1.60, 2.31 and 0.49) of the emulsions prepared with the covalent conjugates were smaller than those with the physical mixtures, and the former had higher zeta-potential (46–48 mV). Conclusion: UHP-induced Maillard reaction had a positive effect on emulsion stability.
Effect of Ball-Milling Treatment on Protein Structure and Physicochemical and Foaming Properties of Egg White
TAN Wen, ZHANG Qinjun, WAN Pengyu, LIU Xuebo, DUAN Xiang
2021, 42(11):  124-129.  doi:10.7506/spkx1002-6630-20200529-354
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Egg white is widely used in bakery food processing because of its excellent foamability. Therefore, it is of great significance to improve the foamability of egg white proteins. In this experiment, the free sulfhydryl content, surface hydrophobicity, hydrolysis degree, zeta-potential and particle size of egg white proteins were measured after ball-milling treatment, and their thermodynamic properties, secondary structure, foaming characteristics and microstructure were analyzed. The aim was to investigate the effects of ball milling on the structural and foaming properties of egg white proteins. The results showed that ball milling resulted in no significant change in the foaming capacity of egg white proteins, while the foam stability showed a trend of increasing and then decreasing, reaching the maximum value (33.5 s) at 40 min of ball milling treatment, which was nearly four times higher than that of the control group. In addition, ball milling treatment significantly reduced the surface hydrophobicity and denaturation enthalpy (ΔH) of egg white proteins (P < 0.05), increased the hydrolysis degree, particle size and decrease the absolute value of zeta-potential (P < 0.05), but had no significant effect on the free sulfhydryl content or denaturation temperature (P > 0.05). The proportion of β-sheet conformation continued to significantly increase (P < 0.05), the proportion of α-helix declined initially and then rose, while the proportion of β-turn first increased and then decreased with increasing time of ball milling. Scanning electron microscopy (SEM) showed that ball milling treatment caused fragmentation and flocculation of egg white protein particles in a scattered manner. In conclusion, moderate ball milling treatment can change the molecular structure of egg white proteins and thus improve their foaming stability.
Effect of Preparation Methods on Physicochemical Properties of Hawthorn Pectin
FANG Yuan, CUI Nan, DAI Yinyin, LIU Suwen, CHANG Xuedong
2021, 42(11):  130-136.  doi:10.7506/spkx1002-6630-20200529-364
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As a purely natural food additive, hawthorn pectin plays an important role in food production and processing. In this experiment, two different drying methods of hot air drying and freeze drying were used to dry hawthorn fruit before powdering by grinding, shearing or air flow, and the thermal properties of the resulting six powders were investigated. Further, pectins were extracted from these samples and their physicochemical properties were compared in terms of galacturonic acid content, total sugar content, esterification degree, Fourier transform infrared spectra, X-ray diffraction patterns and rheological properties. The results showed that there was no significant difference in the thermal characteristics of the hawthorn powders, while the pectin yield and galacturonic acid content in the freeze-dried group were higher than those in the hot-air dried group. Different pulverization methods had no significant effect on the physicochemical properties of hawthorn pectin prepared using the same drying method (P > 0.05). The physicochemical properties of the pectin prepared from the freeze-dried fruit were better than those of the pectin prepared from the hot air-dried fruit using the same pulverization method (P < 0.05).
Nutrition & Hygiene
Effects of Different Protein Intakes on Adiponectin Signaling Pathway in Liver of Overweight Rats Subjected to Limited Energy
HE Zhiyan, TIAN Ying, PENG Suwen, WANG Qian, CHEN Min, ZHOU Huan
2021, 42(11):  137-143.  doi:10.7506/spkx1002-6630-20200620-271
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Objective: To study the effect of different protein intakes on the adiponectin signaling pathway in the liver of overweight male SD rats with low energy intake. Methods: Six out of 36 rats were randomly selected as normal control group (NC), and the rest were given a high-fat diet. After 9 weeks of feeding, 16 rats with average body mass over 1.1 times heavier than that of the normal diet group were selected and equally randomized into model control (MC), low-energy, low-protein (LP), low-energy, normal-protein (NP), low-energy, high-protein (HP) groups before being subjected to energy and protein controlled feeding for 9 weeks. During the experimental period, body mass, body fat mass, liver mass, liver fat mass, serum adiponectin (APN) concentration, and the levels of liver AMP-activated protein kinase (AMPK), sterol regulatory element binding protein 1c (SREBP-1c), acetyl-CoA carboxylase (ACC), fatty acid synthetase (FAS), peroxisome proliferators-activated receptors α (PPARα) and carnitine palmitoy transferase-1 (CPT-1) in the rats in each group were determined. Results: After 9 weeks of intervention, compared with the MC group, body fat mass, liver mass, liver fat mass, and liver SREBP-1c, ACC and FAS levels in the three intervention groups were significantly reduced (P < 0.05), and serum APN level and liver AMPK, PPARα and CPT-1 levels were significantly increased (P < 0.05). There was no significant difference in body mass, body fat mass, liver mass or liver AMPK level among the intervention groups (P > 0.05). Compared with the LP and NP groups, liver fat mass in the HP group was significantly reduced (P < 0.05), and serum APN and liver SREBP-1c, ACC, FAS, PPAR α and CPT-1 levels were increased significantly (P < 0.05). Conclusion: After energy control, the levels of various factors in the signaling pathways of APN-AMPK and APN-PPARα-CPT-1 in the liver of overweight rats were significantly increased (P < 0.05), thereby reducing body mass, liver mass and liver fat mass to some extent. In the case of consistent energy restriction, high protein intake can promote the activation of APN-PPARα signaling pathway, thus reducing live fat mass in overweight rats, while having no significant influence on the body mass, body fat mass or liver mass (P > 0.05).
Antioxidant Activity of Selenium-Modified Soluble Dietary Fiber from Millet and Its Effect on the Tryptophan-Producing Capability of Mouse Intestinal Flora
WANG Juan, CAO Longkui, WEI Chunhong , WANG Weihao, ZHAO Shuting, LIU Dezhi, QUAN Zhigang, WANG Yifei, WU Yunjiao, SU Youtao, ZHANG Dongjie
2021, 42(11):  144-153.  doi:10.7506/spkx1002-6630-20200709-132
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The present study was undertaken with two aims: 1) to determine the optimal preparation process for selenium-modified soluble dietary fiber from millet and 2) to explore the influence of selenium modification on the structure and antioxidant activity of millet water-soluble dietary fiber (SDF) and on its effect on the ability of intestinal flora to produce tryptophan. SDF was modified by a nitric acid-sodium selenite method, and the selenization conditions were optimized by the Taguchi method. The molecular mass, particle morphology, functional groups and crystallinity of the native and modified SDF were determined by gel permeation chromatography (GPC), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy and X-ray diffraction. In addition, their antioxidant activity was compared with each other, and the change of the tryptophan content in the culture broth of mouse intestinal microbes utilizing Se-SDF as a carbon source was analyzed. The results showed that the optimal conditions of modification were as follows: reaction temperature of 40 ℃, reaction time of 6 h, 3 mL of 5 mg/mL Na2SeO3, and 0.65 g of BaCl2. Under these conditions, the yield of Se-SDF was 10.56% with a selenium content of 2.69 mg/g. The relative molecular mass of the Se-SDF was increased compared with the native SDF, and the surface showed a porous honeycomb-like structure with large pore size. The degree of polymerization was reduced relative to that of the native SDF, and functional groups such as Se=O, Se–OH and Se–O–C were appeared in the Se-SDF. Despite no obvious change in the crystal structure, the crystallinity of SDF was decreased after the modification. The hydroxyl and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging capacity and total antioxidant capacity of SDF as well as its promoting effect on the tryptophan-producing capability of the mouse intestinal flora were enhanced after the modification. In summary, the Se-SDF prepared using the optimized process can be used to produce dietary selenium and tryptophan supplements.
Evaluation of in Vitro Probiotic and Safety Properties of Enterococcus faecium SC-Y112 Producing Bacteriocin
LUO Qiang, ZHANG Ming, LIU Qiao, LUO Fan
2021, 42(11):  154-160.  doi:10.7506/spkx1002-6630-20200602-025
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Enterococcus faecium SC-Y112 is a bacteriocin-producing lactic acid bacterium with broad-spectrum antibacterial properties. In order to better understand it, the in vitro prebiotic and safety properties of Enterococcus faecium SC-Y112 were explored through simulated gastrointestinal fluid tolerance, bile salt tolerance, antioxidant activity, hemolytic activity, gelatin liquefaction and harmful metabolite tests, as well as the evaluation of drug resistance and the virulence gene analysis of Enterococcus. The results showed that SC-Y112 had a strong tolerance to artificial gastrointestinal juice. The survival rate after 3 hours of exposure to it was 73.66% compared to 56.38% after 3 hours of exposure to 0.3 g/100 mL bile salt, and the total antioxidant activity of the 24 h fermentation supernatant was 35.21 U/mL. In addition, this strain could not produce biological amines, indoles, azoreductase or other harmful substances, caused no hemolysis, did not dissolve gelatin, did not carry the virulence genes of Enterococcus, and was sensitive to vancomycin. These results provide a scientific basis for further development and application of the strain.
Effect of Hemp Seed Peptide on Blood Lipids in High-Fat Diet Fed Rats
WEI Lianhui, SONG Shumin, DONG Yan, SHI Jie, WANG Jiaojiao, LI Baolong, SUN Xingrong
2021, 42(11):  161-167.  doi:10.7506/spkx1002-6630-20200421-266
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The hypolipidemic activity of hemp seed peptide was investigated by animal tests. Sixty male SD rats were randomly divided into the normal group with 10 rats and the model group with 50 rats after one week of adaptive feeding. The rats in the normal group were fed a basic diet and the rats in the model group were fed a high-fat diet (HFD) to induce hyperlipidemia for four weeks of feeding. After successful modeling, the model rats were randomly divided into model control, positive control (simvastatin at 10 mg/kg mb), and low-, medium-, and high-dose hemp seed peptide groups (200, 400, and 800 mg/kg mb) with 10 animals each. The route of administration was by intragastric gavage. After 4 weeks of feeding, body mass, visceral organ index, blood rheology, and serum total cholesterol (TC), triglyceride (TG), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), alanine aminotransferase (ALT) and aspartate aminotransferase (AST) were measured, and morphological changes in the liver of the rats were observed. The results obtained showed that hemp seed peptide could inhibit body mass gain in high-fat diet-fed rats, reduce serum TC, TG, LDL-C, ALT and AST and liver index and atherosclerosis index (AI) and augment serum HDL-C. In addition, it could improve blood rheology such as reducing whole blood viscosity and plasma viscosity and the fatty degeneration of the liver. In conclusion, hemp seed peptide has a lipid-lowering effect in HFD rats.
Metabonomic Study on Hypolipidemic Effect of Sparassis crispa Polysaccharides on Hyperlipidemic Rats
GAO Yuan, YANG Yaru, CHANG Mingchang, MENG Junlong, LIU Jingyu, FENG Cuiping
2021, 42(11):  168-175.  doi:10.7506/spkx1002-6630-20200513-146
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Objective: To discuss the effect of Sparassis crispa polysaccharides on blood lipids in hyperlipidemic rats from a metabolomics perspective and to investigate the change of serum metabolites. Methods: The effect of intragastric administration of Sparassis crispa polysaccharides at different doses for eight weeks on serum lipids in hyperlipidemic rats was evaluated. Serum metabolites were detected by gas chromatography-mass spectrometry (GC-MS), and the differential metabolites in serum samples from different animal groups were screened out. The metabolic pathways in which these differential metabolites may be involved were analyzed, and the most influential pathway was verified. Results: Compared with the normal control (NC) group, the levels of serum total cholesterol (TC), low density lipoprotein cholesterol (LDL-C) and total bile acid (TBA) were increased significantly in the high-fat, high-cholesterol model (HFCM) group (P < 0.05), while high density lipoprotein cholesterol (HDL-C) was significantly reduced (P < 0.05). Compared with the HFCM group, serum TC in the high-dose polysaccharide (HFC + HD) group were significantly decreased (P < 0.05), and 14 metabolites such as isoleucine, tyrosine, glycine, threonine, serine, alanine, glucose, glycerol, butanedioic acid, cholesterol and hexadecanoic acid were significantly changes (P < 0.05). Eight metabolic pathways such as glutamic acid and glutamine metabolism, the synthesis of valine, leucine and isoleucine, the synthesis of phenylalanine, tyrosine and tryptophan, and glycerol phospholipid metabolism were related to the lipid lowering activity of Sparassis crispa polysaccharides. Among them, glutamic acid and glutamine metabolism had the greatest influence. Compared with the NC group, serum glutamic acid level in the HFCM group decreased significantly (P < 0.05). Compared with the HFCM group, serum glutamic acid in the low-dose polysaccharide group was significantly increased (P < 0.05), and both glutamic acid and glutamine level in the middle- and high-dose polysaccharide groups were significantly increased (P < 0.05). Conclusion: Sparassis crispa polysaccharides can improve dyslipidemia in hyperlipidemia rats, and its mechanism may be related to amino acid and lipid metabolism, especially glutamic acid and glutamine metabolism.
Myricitrin from Diospyros lotus L. Leaves Induced Apoptosis in Hepatocellular Carcinoma HepG2 Cells and Its Underlying Mechanism
TIAN Yanhua, WU Lei, DU Huizhi, YANG Zhaoyan, ZHANG Liwei
2021, 42(11):  176-185.  doi:10.7506/spkx1002-6630-20200609-131
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Objective: To investigate the effect of myricitrin from Diospyros lotus L. leaves on inducing apoptosis in human hepatocellular carcinoma HepG2 cells and its underlying mechanism. Methods: Cell viability was determined by the methyl thiazolyl tetrazolium assay. Laser confocal microscopy with Hoechst 33342 staining was used to observe cell morphology. Meanwhile, apoptosis, cell cycle arrest, intracellular reactive oxygen species (ROS) levels and monodansylcadaverine (MDC) mean fluorescence intensity in HepG2 cells were detected using a flow cytometer. Finally, Western blot was used to measure the expression levels of proteins associated with apoptosis and autophagy in HepG2 cells. Results: Myricitrin at concentrations of 10–200 μmol/L had no significant effect on human normal liver L-02 cells (P > 0.05), but could significantly reduce the survival rate of HepG2 cells (P < 0.05). Myricitrin could dramatically increase the apoptosis rate, ROS level, MDC mean fluorescence intensity and nuclear fluorescence intensity, and induce cell cycle arrest in the G2/M phase. In addition, myricitrin could up-regulate the expression levels of Bax, cytochrome c, Apaf-1, Caspase-9, Caspase-3, Beclin 1, Atg5 and LC3-II proteins significantly (P < 0.05), and down-regulate the expression levels of Bcl-2 and LC3-I proteins significantly (P < 0.05). Conclusion: Myricitrin has an anti-liver cancer effect, and its underlying mechanism is related to the activated mitochondrial-mediated apoptosis pathway, cell cycle arrest, increased intracellular ROS levels and promoted autophagy. These results lay a foundation for the development and application of myricitrin as a natural anti-hepatoma drug.
Packaging & Storage
Preparation and Characterization of Oregano Essential Oil Microcapsules and Its Effect on Quality Preservation of Apricot Fruit during Storage
SHI Zedong, JIANG Yaping, SUN Yingjie, LI Fujun, MIN Dedong, ZHANG Xinhua, LI Xiaoan
2021, 42(11):  186-194.  doi:10.7506/spkx1002-6630-20200712-155
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In order to further develop the application of plant essential oil in post-harvest sanitation and preservation of fruits and vegetables, oregano essential oil was microencapsulated by the coacervation method using gelatin and arabic gum as the wall material under optimized conditions. The physicochemical and slow-release properties of oregano essential oil microcapsules (OEO-MPs) were characterized using scanning electron microscope (SEM), Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). Finally, the anti-fungal activity of different doses of OEO-MPs on apricot fruit during postharvest storage and its effects on decay incidence and disease resistance-related enzyme activities were evaluated. The results showed that the optimal process conditions were as follows: core-to-wall ratio 1:1, wall material mass ratio (gelatin and gum arabic) 1:1, reaction temperature 45 ℃, and reaction time 30 min. The microencapsulation rate of OEO-MPs prepared by the optimized process was 83.65%, the loading amount of oregano essential oil (OEO) was 74.36%, and the particle size was 147 μm. Compared with oregano essential oil (98% purity), OEO-MPs, spherical with a more regular surface structure, exhibited higher stability, and possessed higher thermal stability and slow-release performance. In addition, 4% OEO-MPs reduced the total number of colonies, total mold count and decay incidence of apricot fruit during shelf life, increased peroxidase, L-phenylalanine ammonia-lyase, β-1,3-glucanase, catalase and chitinase activities, and reduced polyphenol oxidase activity compared with the control. These results provided a new idea for the development of a slow-release bacteriostatic agent based on plant essential oil.
Effects of α-Tocopherol and Vacuum Packaging on the Quality of Sturgeon Surimi Incorporated with Chicken Meat during Frozen Storage
WANG Kangyu, WANG Ruihong, LI Yujin, BAI Fan, GAO Ruichang, WANG Jinlin, XU Peng, ZHAO Yuanhui
2021, 42(11):  195-204.  doi:10.7506/spkx1002-6630-20200527-326
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To delay the deterioration of the quality of composite sturgeon surimi (CSS) with high fat content, prepared by mixing 40% chicken breast meat into non-rinsed sturgeon surimi (NRSS), the gel strength, texture properties, water-holding capacity (WHC), lipid oxidation degree, fatty acid composition and volatile flavor substances of vacuum packaged samples and those added with α-tocopherol were measured during frozen storage. The results indicated that the gel strength, texture properties of CSS were better than those of NRSS. The gel strength of vacuum packaged CSS decreased to a smaller extent compared with all other groups, while it was not significantly different from α-tocopherol treated CSS in hardness and elasticity. Besides, WHC and the percentage of linoleic acid relative to the total fatty acids decreased to a significantly lower extent in vacuum packaged CSS and α-tocopherol treated CSS than in CSS, and the gel structure was uniform, dense and arranged in an orderly manner after 16 weeks of frozen storage. The volatile flavor was dominated by a grassy taste, together with a weak rancid and earthy smell. Thiobarbituric acid reactive substances (TBARS) value increased to a much lower extent in vacuum packaged CSS and α-tocopherol treated CSS than in NRSS after frozen storage for four weeks. After 16 weeks of frozen storage, TBARS value was still significantly lower in vacuum packaged CSS than in the other groups. These results suggested that vacuum packaging and α-tocopherol treatment both could effectively maintain the texture properties of CSS, inhibit lipid oxidation and alleviate quality deterioration.
Effect of Temperature Fluctuation on the Quality of Big-Eye Tuna (Thunnus obesus) during Low Temperature Circulation
LAN Weiqing, LIU Lin, XIAO Lei, MEI Jun, XIE Jing
2021, 42(11):  205-212.  doi:10.7506/spkx1002-6630-20200706-075
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In order to analyze the effect of temperature fluctuation on the quality of big-eye tuna (Thunnus obesus) during low-temperature circulation, changes in texture properties, pH, metmyoglobin (MetMb) content, total volatile basic nitrogen (TVB-N) content, histamine content, total viable count (TVC) and sensory evaluation score were measured during simulated cold chain logistics with constant (control) and fluctuating temperatures (L1: supermarket direct marketing; L2: supermarket retailing). The results showed that pH, MetMb content, TVB-N content, histamine content and TVC rose during the experimental period for all groups. The temperature fluctuation in group L2 was the most obvious compared with the other groups, and group L2 showed the most significant increase in hardness and chewiness as well as the most obvious quality deterioration. After 216 h, the pH of group L2 was as high as 6.66 and the MetMb content was increased up to 35.23%, indicating severe browning. In addition, the TVB-N content was 19.14 mg/100 g, histamine content 89.97 mg/kg, TVC 5.43 (lg (CFU/g)), and sensory score ?2 points. Correlation analysis demonstrated that the MetMb content, TVB-N content, histamine content and TVC were positively correlated with each other for all groups (P < 0.01 or P < 0.05), which could therefore be used to evaluate the quality changes of big-eye tuna during low temperature circulation. Conclusively, temperature fluctuations should be reduced as much as possible during circulation. Particularly, severe temperature fluctuations could affect the quality of big-eye tuna greatly.
Antifungal Effect of ε-Polylysine on Alternaria alternata Isolated from Pears with Black Spot and Its Possible Mechanism
LIU Zhitian, DONG Yupeng, LI Yongcai, BI Yang, LI Baojun, JING Chunyuan
2021, 42(11):  213-220.  doi:10.7506/spkx1002-6630-20200523-275
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The inhibitory effect of ε-polylysine on the vegetative growth of Alternaria alternata isolated from pears with black spot and its effect on black spot control in pears artificially infected with this fungus were determined by the colony diameter and lesion diameter, and the possible mechanism of its antifungal activity was also evaluated by determining cell membrane integrity, mitochondrial membrane potential and related metabolites levels. The results showed that ε-polylysine significantly inhibited the mycelial growth of A. alternata in a concentration-dependent manner (P < 0.05). After 7-day cultured with ε-polylysine at concentrations of 100 and 200 mg/L, the colony diameter was 43.24% and 29.54% as compared to the control group, respectively. The development of black spot in ε-polylysine-treated pears was also inhibited. Further research showed that ε-polylysine treatment severely damaged the integrity of A. alternata cell membrane and mitochondria, and increased the mycelium conductivity. ε-Polylysine treatment promoted the production of melanin and mycotoxins including alternariol, altenuene, andalternariol monomethyl ether, while it inhibited the production of tentoxin in A. alternata. These results suggested that ε-polylysine might reduce the pathogenicity of A. alternata through delaying its growth and destroying the integrity of the cell membrane and mitochondria.
Changes of Lipid Oxidation and Volatile Substances in Dried Salted Eel during Cold Storage
YANG Junping, GU Guizhang, HU Kena, GAO Xingjie, ZHANG Jinjie, YANG Wenge, XU Dalun
2021, 42(11):  221-228.  doi:10.7506/spkx1002-6630-20200630-387
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This research aimed to examine the development of lipid oxidation and the flavor deterioration of dried salted eel under household storage conditions. The changes in peroxide value (POV), thiobarbituric acid (TBA) value, fatty acid composition and flavor composition were determined during four months of storage at 1–7?℃ (simulated domestic refrigerator) and the correlation between fatty acids and flavor compounds was analyzed. The results revealed that lipid oxidation was aggravated with prolonged storage time. POV and TBA both increased at first and then decreased, which peaked after 2 and 3 months of storage, respectively. The contents of saturated fatty acids (SFA) and monounstaturated fatty acids (MUFA) showed an overall upward trend, whereas the content of polyunsaturated fatty acids (PUFA) significantly dropped (P < 0.05). Over the whole storage period, the content of aldehydes exhibited a decrease after an increase while the reserve trend was observed for the contents of hydrocarbonsand alcohols. Moreover, the content of ketones progressively rose. A certain correlation was observed between fatty acids (oleic acid, linoleic acid, linolenic acid, arachidonic acid and eicosapentaenoic acid) and volatiles (hexaldehyde, heptyl aldehyde, octyl aldehyde, nonanal, 1-pentene-3-alcohol, and 1-octene-3-alcohol).
Reviews
A Review of the Protective Effect and Underlying Mechanism of Food Components on DNA Double Strand Breaks in Intestinal Cells
PENG Zhen, XU Xiaoyan, XIONG Tao
2021, 42(11):  229-235.  doi:10.7506/spkx1002-6630-20200508-082
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As the most dangerous type of DNA damage, DNA double strand breaks (DSBs) are a potential factor causing human genome instability and promoting the occurrence of genetic diseases. In many studies, it has been found that many food ingredients can inhibit the formation of DSBs or promote DNA damage repair. This paper mainly summarizes the food ingredients reported in the recent 20 years that have a regulatory function on DSBs. The mechanism of food ingredients in alleviating DSBs in human intestinal cells is expounded from three aspects: antioxidant effect, regulation of DNA damage repair and simultaneous action of both functions. The influence of different intakes and ingestion times of food components on the protective effect on DSBs is discussed as well. The possible protective effect of other potential food components on DSBs is proposed, aiming to provide a theoretical reference for the development of new types of foods that can alleviate DSBs.
Advances in Understanding the Regulation of Meat Tenderness by Peroxiredoxin 6
WANG Xinyi, ZHANG Yimin, LIANG Rongrong, DONG Pengcheng, LUO Xin, MAO Yanwei
2021, 42(11):  236-243.  doi:10.7506/spkx1002-6630-20200427-355
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Tenderness is a key attribute that affecting consumers’ willingness to buy meat. Many scientific articles summarize the factors affecting the tenderness of meat. However, the effect of peroxiredoxin 6 (Prdx6) on meat tenderness and the underlying mechanism are rarely reported. After slaughter, the physiological environment of skeletal muscles changes, resulting in the production of more cellular reactive oxygen species and breaking redox homeostasis and survival/apoptosis balance. These changes are closely related to meat tenderness. Therefore, this article reviews the current research on the effect of Prdx6 on scavenging reactive oxygen species and repairing peroxidized cell membrane, and its relationship with meat tenderness. In addition, it summarizes the mechanisms by which Prdx6 affects meat tenderness including regulating protein and lipid oxidation, cell apoptosis, the expression of small heat shock protein and autophagy as well as reducing phospholipid peroxide membrane, and it clarifies the related pathways. This review will enrich the current knowledge of the mechanism of meat tenderization.
Advances in Understanding the Theoretical Mechanism of the Interaction between Antifreeze Proteins and the Ice-Water Interface Layer
WU Jinhong, YANG Danlu, ZHOU Mi, CHEN Xu, CAI Xixi, SHI Yi, YANG Fujia, WANG Shaoyun, XU Jingshen, ZHANG Heng
2021, 42(11):  244-252.  doi:10.7506/spkx1002-6630-20200420-262
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Antifreeze proteins (AFPs) have thermal hysteresis activity and recrystallization-inhibiting activity, and have potential applications in a wide range of areas such as the quality control of frozen foods, low temperature protection of bacteria, and plant protection against frost injury. This paper focuses on the theoretical problem of how AFPs, containing a wide variety of components with complicated structures, can inhibit the growth of ice crystals and exert thermal hysteresis and recrystallization-inhibiting activity by regulating the structure of the ice-water interface and interacting with or binding to ice crystals in the cryogenic freezing environment. Meanwhile, this review also systematically describes the principles and characteristics of some related theoretical models, including adsorption-inhibition model, dipole-dipole model, lattice matching and possession model, rigid body energy model, anchored clathrate model, and affinity interaction coupling and aggregation model, and it reveals the mechanism by which AFPs bind to or interact with the ice-water system by regulating the structure of the ice-water interface layer and its driving force characteristics. This review will provide theoretical guides for the elaboration of the antifreeze mechanism and the screening for application in the food industry of AFPs.
Recent Understanding of the Lag Phase of Foodborne Pathogens: A Review
FANG Taisong, WU Yufan, SHI Ningxin, CHANG Min, HU Bin, LIU Yangtai, LI Hongmei, DONG Qingli, WANG Xiang
2021, 42(11):  253-260.  doi:10.7506/spkx1002-6630-20200504-024
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Foodborne pathogens are the primary factors causing foodborne illness. In order to quantitatively evaluate the food safety risks associated with foodborne pathogens and the effectiveness of food processing technology in controlling these risks, it is necessary to establish predictive microbiology models to estimate the growth or inactivation parameters of foodborne pathogens. The lag phase is an important parameter in the description of the growth of foodborne pathogens, which is known to be influenced by multi-factors. Especially the growth variability of foodborne pathogens at low concentrations makes it difficult to obtain the lag phase accurately. In this article, based on a review of the relevant worldwide studies in recent years, we systematically summarize the methods used to determine the lag phase of foodborne pathogens and the factors that may affect it, and we describe the cellular events that can be used as physiological markers for the lag phase of foodborne pathogens. Finally, we propose future trends in this area of research.
Application of Magnetic Solid-Phase Extraction in the Analysis of Mycotoxins in Foods: A Literature Review
XU Hongwen, XU Hua, ZHU Yu, YE Yongli, SUN Jiadi, SUN Xiulan, ZHANG Xiaojuan
2021, 42(11):  261-270.  doi:10.7506/spkx1002-6630-20200425-331
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Mycotoxins are common in foods and various food crops and have health hazards such as carcinogenicity, mutagenicity and teratogenicity, which seriously threaten the health of humans and animals. Since mycotoxins exist in a wide variety, low concentration and wide polarity range in food matrix, developing a rapid and efficient sample pretreatment method is important to the analysis of trace amounts of mycotoxins in foods. Magnetic solid-phase extraction (MSPE) is a sample preparation technique based on magnetic interaction, which has been widely applied in the analysis of mycotoxins in foods by virtue of its simple, rapid, green, safe and economical characteristics. This article briefly describes the process of MSPE and the preparation and modification of magnetic nanomaterials, and summarizes the application of this method using inorganic materials (oxidized silica-based and carbon-based), organic materials (imprinted molecules, organic polymers, surfactants and small organic molecules) and other materials (ionic liquids and monocolonal antibodies) as representative MSPE adsorbents in the detection of mycotoxins in food samples. At the same time, it discusses future trends in the development of MSPE.
Recent Progress in Inhibition of Microbial Biofilm Formation by Cold Plasma
HU Yue, CHEN Qian, LIU Qian, KONG Baohua, DIAO Xinping
2021, 42(11):  271-277.  doi:10.7506/spkx1002-6630-20200415-203
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The increasingly serious problem of biofilm pollution has posed a great threat to the safety of foods and medical products. Different from planktons in foods, biofilms formed by microorganisms are more resistant to bactericidal treatment due to their unique structures and functional properties. Therefore, discovering a green anti-biofilm technology has become a growing concern. As a new sterilization technology, cold plasma is simple, effective and low-energy-consuming, and it can well maintain the color, texture and nutritional value of foods, so that it has attracted widespread attention in the food field. This review mainly describes the mechanism by which cold plasma destroys biofilm formation, the factors influencing the effect and the application of cold plasma with a view to providing theoretical support for the application of cold plasma as an anti-biofilm technology in the food industry.
Functional Characteristics of Bioactive Peptides in Dry-Cured Ham: A Review
LI Ping, YANG Ting, ZHOU Hui, NIE Wen, XU Baocai, WANG Zhaoming, CHEN Shuntong
2021, 42(11):  278-283.  doi:10.7506/spkx1002-6630-20200418-238
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During the processing of dry-cured ham, due to the action of endogenous enzymes and microorganisms on them, proteins are broken down into many peptides with diverse biological activities including antioxidant, antihypertensive and antibacterial effects. The biological peptides are of significant interest to researchers and have wide application prospects. This paper reviews the formation mechanism and functional characteristics of bioactive peptides in dry-cured ham.
Progress in Understanding the Effect and Mechanism of Starter Cultures on the Formation of Volatile Flavor Compounds in Fermented Sausage
LIU Yingli, YANG Ziyan, WAN Zhen, YU Qinglin, CAO Yating, JIANG Yixuan, LI Hongyan, LIU Jie, WANG Jing
2021, 42(11):  284-296.  doi:10.7506/spkx1002-6630-20201012-085
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Fermented sausage refers to the sausage products made by mixing minced pork, beef or mutton, animal fat, salt, sugar, a starter culture and spices into the casing followed by fermentation. Due to its unique flavor and high nutritional value, fermented sausage is favored by consumers in China and all over the world. Flavor is considered one of the most important quality attributes of fermented sausage, and the generation and development of flavor are closely related to the metabolic activity of the microbial community during fermentation. In this article, the formation and development of flavor substances and reactions related to microbial metabolism during the fermentation and maturation of fermented sausages are summarized. The effect and mechanism of several major microorganisms on the flavor quality of fermented sausages are also discussed, and future research trends are proposed so as to provide references for studies on the flavor quality of fermented sausages.
Recent Advances in Understanding the Interaction between Dietary Lipids and Allergens
YANG Hui, QU Yezhi, GAO Yaran, WU Junrui
2021, 42(11):  297-303.  doi:10.7506/spkx1002-6630-20200513-148
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Food allergy has become an important public health problem as the number of allergic people increases every year worldwide. Lipids are an important component of foods. Accumulating studies have shown that excessive intake of dietary lipids can enhance allergen sensitization and increase the risk of food allergy. This review presents the current understanding of the relationship between lipids and food allergy, discusses how lipids influence the allergic response and the relationship between high-fat diet and food allergy, and summarizes the types of lipid-binding allergens and the types of lipids involved in food sensitization reported in the literature over the past decade. This review aims to provide new insights for the prevention and treatment of food allergy.
Comparative Analysis of Regulations and Standards for Milk and Dairy Products in China and Abroad with Respect to Main Quality Indices
XU Xiuli, YAO Guihong, NIE Xuemei, CUI Dongwei, ZHANG Feng
2021, 42(11):  304-312.  doi:10.7506/spkx1002-6630-20200416-205
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The quality and safety of dairy products are an important global issue. Many countries have taken various measures including legislation, administration, justice and improving the inspection technology to improve the quality and safety of dairy products. The type and the number of dairy products imported to China have increased steadily recently. However, the differences between the domestic and international dairy products regulations and standards have made it difficult to find out the safety risks of imported dairy products and have frequently caused dairy products exported from China to suffer technical trade barriers. In order to safeguard the lawful rights and interests of Chinese dairy product importers and exporters as well as consumers and to ensure the quality and safety of dairy products, it is urgent to understand the differences between the domestic and international dairy products regulations and standards and improve the pertinence and accuracy of detection methods. This article summarizes the current status of China’s standards for dairy products, compares the differences between them and those in its major trading partners in terms of the main indicators of quality and safety, and points out the differences between China and its major trading countries in terms of regulations and detection limits. Finally, suggestions are provided for the improvement of China’s dairy products regulations and testing method standards.
Advances in Understanding the Regulation of Obesity by Microbiome-Gut-Brain Axis
WANG Yuanwei, LIU Xiong
2021, 42(11):  313-323.  doi:10.7506/spkx1002-6630-20200421-272
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Obesity has become a global epidemic, posing a serious threat to the lives and health of people. The prevention and treatment of obesity have become a major public health challenge all over the world. More and more studies have shown that the gut microbiota is closely related to the occurrence and development of obesity. The regulatory mechanism of the gut microbiota on obesity has become a research hotspot. The microbiome-gut-brain axis is a bidirectional communication system between the intestine and the brain, which provides a path for the mutual integration and regulation between the brain and gut functions. Recent worldwide studies have shown that the microbiome-gut-brain axis plays an important role in the regulation of obesity, and many substances lower lipids and reduce body mass through this axis. This article reviews the current grim situation of obesity, the composition of microbiome-gut-brain axis and the underlying mechanism of obesity regulation, with the aim of providing ideas for the treatment of metabolic diseases such as obesity and providing directions for exploring the lipid-lowering mechanism of some substances.
A Literature Review of the Application of Maillard Reaction and Its Products in the Delivery of Bioactive Substances
WANG Zhi, LIU Haotian, LIU Qian, CHEN Qian, KONG Baohua
2021, 42(11):  324-331.  doi:10.7506/spkx1002-6630-20200507-063
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Bioactive compounds have potential applications as functional ingredients in many foods and medicines. During processing, storage, and gastrointestinal digestion, bioactive substances are easily degraded, which greatly limits their applications. Therefore, researchers have expressed considerable interest in designing a food-grade delivery system. The Maillard reaction occurs naturally without the addition of chemical reagents and has been widely used to improve the functional properties of proteins. The protein-polysaccharide conjugate prepared by the Maillard reaction has high stability, and it has been widely used to deliver bioactive substances in recent years. This article reviews the effect of the Maillard reaction on the functional properties of proteins, and the applications of the protein-polysaccharide conjugate in delivery systems for bioactive substances such as emulsions, nanoparticles, nanogels, and microcapsules. Also, how the delivery systems change during digestion is discussed. Moreover, the problems to be solved and future prospects for the application of the Maillard reaction in the preparation of delivery systems are discussed.
A Review of the Mechanism of the Association between Intramuscular Connective Tissue and Meat Tenderness and Related Meat Tenderization Technologies
WANG Yang, WANG Wenhang
2021, 42(11):  332-340.  doi:10.7506/spkx1002-6630-20200427-354
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Intramuscular connective tissue (IMCT) is an important component of muscle tissue, playing an essential role in the texture and quality of meat. The structural composition of IMCT changes during post-mortem ageing and cooking, largely determining the tenderness of meat, in which changes in the perimysium and endomysium play a crucial role. Beginning with an overview of the characteristics of collagen in IMCT, this article reviews the correlation between IMCT and meat tenderness, and analyzes the change of IMCT during the post-mortem ageing and cooking of meat. Additionally, it summarizes the effects of the newly emerging meat tenderization technologies (electrical stimulation, exogenous enzymatic hydrolysis, pulsed electric field, and ultrasound) on IMCT structure and the consequent change of meat tenderness. Hopefully, this review will provide technical support and a theoretical basis for the reasonable regulation of IMCT to effectively improve meat tenderness.
Recent Progress of Nanocarriers for the Oral Delivery of Bioactive Peptides
HAO Xiaoli, Jirimutu, HE Jing
2021, 42(11):  341-348.  doi:10.7506/spkx1002-6630-20200517-196
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Bioactive peptides have been used to prevent or treat various diseases because of their high physiological activity and biocompatibility. Nanocarriers play an important role in the stabilization of bioactive peptides and can provide strong protection for bioactive peptides passing through the gastrointestinal tract. The bioavailability of bioactive peptides is often greatly reduced when they are orally administered. Nanoparticles have been prepared as an oral delivery system to enhance the bioavailability of bioactive peptides and thus improve therapeutic targeting. Accordingly, this article reviews the current status of studies on nanocarrier systems for the oral delivery of bioactive peptides with focuses on the conditions of oral delivery as well as various multifunctional delivery systems and their applications, aiming to provide a reference for maximizing the utilization of bioactive peptides.
Research and Application of Sensors in Intelligent Packaging of Fruits and Vegetables
SHAO Ping, LIU Liming, WU Weina, CHEN Hangjun, GAO Haiyan
2021, 42(11):  349-355.  doi:10.7506/spkx1002-6630-20200520-230
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With the development of society, people’s awareness of food safety and reducing waste of resources is increasing, and the demand for intelligent packaging materials for fruits and vegetables that can be used for perception, tracking, monitoring and detection is increasing. In view of this situation, this paper reviews recent progress in the classification and application of sensors for fruit and vegetable intelligent packaging, analyzes the obstacles to and the main trends in the development of sensors used in fruit and vegetable packaging. Using sensors for intelligent packaging of fruits and vegetables can monitor and detect the quality of fruits and vegetables, which can useful provide information to adjust external environmental conditions to extend the shelf life of fruits and vegetables and has great market value.
Role of Talent Training and Discipline Construction in Improving Food Safety Governance Systems
LU Lei, XU Yuanyuan, YANG Jiao, REN Shan
2021, 42(11):  356-364.  doi:10.7506/spkx1002-6630-20210407-085
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The implementation of food safety strategies and the modernization of food safety governance systems and governance capabilities require the support of a complete food discipline and a large number of professionals. The complexity and particularity of food safety issues determine that food safety governance needs interdisciplinary talents in food discipline. As the primary front for discipline construction and talent training, colleges and universities should play an essential leading role, improve their curriculum, and strengthen discipline construction and talent training in food science. This article summarizes the major trends in the development of talent training in food science and other related disciplines at home and abroad, and the experience of representative foreign colleges and universities in food discipline construction and talent training, which will provide a reference to improve food safety governance talent training system, thereby helping in the modernization of food safety governance systems and governance capabilities.