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Table of Content

15 December 2022, Volume 43 Issue 23
Basic Research
Construction of Amino Acid Pattern of Chinese Human Milk
REN Lele, PANG Jinzhu, MI Lijuan, LI Yixuan, ZHENG Limin
2022, 43(23):  1-9.  doi:10.7506/spkx1002-6630-20220114-136
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Breast milk is considered as the best food for infants and young children, and humanization is the basic principle for formulating infant formula. However, the composition of breast milk is extremely complex, so it is important to fully understand it. Amino acids are important nutrients in breast milk, and their contents are affected by many factors, including lactation stage (colostrum, transitional milk, early mature milk, and late mature milk), region (south and north) and parity. The purpose of this study was to evaluate the effects of different factors on the amino acid composition of Chinese human milk, and propose amino acid patterns of Chinese human milk in different lactation stages and amino acid patterns of early and late mature milk from different regions and seasons. A total of 1 640 breast milk samples were collected from eight cities in China to analyze the changes of amino acid contents in different lactation periods with five factors including region, parity, delivery season, birth situation and delivery mode. The Euclidean distance was used to calculate the similarity in amino acid composition among lactation periods and find the amino acid patterns with the minimum distance and the maximum distance. The breast milk samples were screened by the European distance to determine the recommended amino acid pattern for breast milk in different lactation periods. The results showed that region and delivery season had significant effects on the amino acid patterns of early and late mature milk. Multi-factor analysis would be needed to analyze the effects of delivery frequency, birth condition and delivery mode. The validity of the amino acid pattern of Chinese breast milk was verified by the coefficient of variation method, and the differences in the amino acid pattern in breast milk from different regions and seasons were proposed. The results of this study provide a reference for future research on the humanization of infant formula and nutritional research of breast milk and offer new ideas for the improvement and optimization of infant formula.
Antibacterial Activity and Mechanism of Eugenol, Carvacrol and Thymol against Fusarium graminearum
CUI Xing, ZHU Qiujin, HOU Rui, WAN Jing
2022, 43(23):  10-18.  doi:10.7506/spkx1002-6630-20220107-051
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The inhibitory effects and mechanism of eugenol, carvacrol and thymol against Fusarium graminearum were studied by transcriptomics. The effective concentrations of eugenol, carvacrol and thymol against the mycelium growth, spore germination, and deoxynivalenol biosynthesis of F. graminearum were determined through in vitro antifungal tests. At the cellular level, the action sites were further explored by measuring the conductivity, adenosine triphosphate (ATP) level and malondialdehyde (MDA) level of the mycelium solution treated with each of the three compounds. Thymol had the best antifungal activity among the three compounds. All these compounds could damage the cell membrane integrity of F. graminearum, causing electrolyte leakage and an imbalance in energy metabolism. In addition, they could exert antifungal activity against F. graminearum through regulating the ribosome and mitochondrial structure and enzyme synthesis at the transcriptome level.
Antifungal Mechanism of Sodium Dehydroacetate against Penicillium digitatum
TAN Xiaoli, LONG Chunyan, LI Lu, TAO Nengguo
2022, 43(23):  19-26.  doi:10.7506/spkx1002-6630-20211202-021
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Studies have found that sodium dehydroacetate (SD) can effectively inhibit the growth of Penicillium digitatum but its inhibitory mechanism remains unclear. In this study, the antifungal mechanism of SD was analyzed by measuring the effects of different concentrations of SD on the cell structure and function (cell wall, cell membrane and mitochondria) of P. digitatum mycelia. Results showed that SD entered the cells by active transport after 30 min of treatment and intracellular SD concentration was maintained at a high level during the treatment period. Compared with the untreated control group, the fluorescence intensity of cell wall and the extracellular alkaline phosphatase (AKP) activity of SD-treated mycelial cells were not significantly different, whereas propidium iodide staining showed that SD caused a significant increase in the fluorescence intensity of mycelia (P < 0.05), decreased the total lipid content of mycelia, and increased the extracellular pH, indicating that SD treatment directly damaged the cell membrane without damaging the cell wall. SD treatment also reduced the mycelial mitochondrial membrane potential and energy charge levels and increased Na+/K+-ATPase activity, thereby disturbing cellular energy metabolism. Intervention experiments showed that SD treatment effectively inhibited the incidence of green mold of inoculated kumquat fruit in a concentration-dependent manner. The above results indicated that SD exerts its antifungal effect and reduces the incidence of green mold in postharvest kumquat fruit by damaging the structure and function of the cell membrane and mitochondria of P. digitatum mycelia. These findings can provide a theoretical basis for the application of SD in the green control of postharvest kumquat diseases.
Relationship between Grain Quality Traits and Fermentation Quality of Xiaoqu Liquor from Different Hulless Barley Cultivars
LIANG Lijing, WANG Songtao, JIA Junjie, FENG Zongyun
2022, 43(23):  27-33.  doi:10.7506/spkx1002-6630-20220110-076
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Hulless barley is used as the major raw material to produce a distinctive kind of distilled liquor and hulless barley grain quality plays an important role in the liquor’s quality. In this study, 26 hulless barley cultivars were selected as raw material to make liquor with Xiaoqu, a traditional Chinese liquor fermentation starter. The grain quality traits of hulless barley cultivars, the chemical composition of fermented grains and the yield and sensory quality of liquor were evaluated, and the relationship between them was investigated by principal component analysis (PCA) and path analysis. The results showed there were significant differences in the grain quality traits of the hulless barley cultivars tested. Among these cultivars, ‘F1’ and ‘Ganqing 6’ were the most suitable for making Xiaoqu liquor. A higher amylopectin content in hulless barley contributed to the complete fermentation of liquor and an increase in liquor yield, while the bulk density, 1 000-grain mass and flavonoid content of hulless barley were major factors affecting liquor brewing properties.
Nutritional, Taste and Texture Characteristics of Juvenile and Adult Kelp
NI Hui, WANG Xiaolin, JIANG Zedong, ZHU Yanbing, ZHENG Mingjing, LIU Tao
2022, 43(23):  34-40.  doi:10.7506/spkx1002-6630-20211122-268
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Kelp is an important marine biological resource and food raw material. At present, adult kelp is eaten by people, but there is a lack of systematic studies evaluating the quality characteristics of kelp at different growth periods. In this study, the main nutritional components, amino acid composition, mineral elements, fatty acids, flavor-free amino acids and cooking texture characteristics of juvenile and adult kelp were analyzed. The results showed that the ash, protein and crude fat contents of juvenile kelp were higher than those of adult kelp. The essential amino acid (EAA)/total amino acid (TAA) ratios of juvenile kelp and adult kelp were 0.36 and 0.34, respectively, and the EAA/nom-essential amino acid (NEAA) ratios were 0.57 and 0.53, respectively. The nutrient reference values (NRV) of potassium in juvenile kelp and adult kelp were 70.40% and 41.25%, respectively, and the NRV of iron were 54.60% and 16.00%, respectively. The contents of palmitic acid, myristic acid and elaidic acid in juvenile kelp were higher than those in adult kelp. The taste activity values (TAV) of umami amino acids in juvenile kelp and adult kelp were 3.46 and 0.64, the TAV of sweet amino acids were 0.27 and 0.80, and the TAV of bitter amino acids were 0.26 and 0.00, respectively. The hardness, viscosity, chewiness, adhesiveness, cohesiveness and resilience of blanched juvenile kelp were less than those of blanched mature kelp, while their elasticity was basically the same. The above results indicate that juvenile kelp have better protein nutritional potency, mineral element and elaidic acid contents, and taste and texture characteristics than adult kelp. This study provides useful information for the high-value utilization of kelp in the modern food industry, and offers inspiration for the development of the modern food industry and the kelp industry.
Machine Learning Combined with Multi-Feature Fusion of Vision and Tactile Sensation for Quality Grade Evaluation of Salted Sea Cucumber
ZHU Xinyu, KANG Jiaming, SHAO Weidong, LIU Yang, ZHANG Xu, YANG Jixin, WANG Huihui
2022, 43(23):  41-48.  doi:10.7506/spkx1002-6630-20211125-312
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The results of quality grade evaluation of salted sea cucumber have a direct effect on its economic value. It is difficult to distinguish different grades of salted sea cucumber according to their color, shape and smell. The existing detection methods, which are characterized by offline decentralized operation and dependence on manual experience, cannot meet the requirements of large-scale production lines. A new multi-sensory feature fusion method based on machine visual and mechanical features was proposed for rapid and nondestructive quality grade evaluation of salted sea cucumber in this study. In view of the complex relationship between the salt content and texture properties of sea cucumber, the mechanical information and deformation images of sea cucumber during the stress recovery process were perceived by the quality grade evaluation system developed. The quality grade evaluation of salted sea cucumber was realized by using machine learning algorithm. In order to accurately extract image features related to the change of sea cucumber contours, the traditional image processing method was improved to establish a dynamic energy map for sea cucumber contours. Then, texture features were extracted by histogram (HIS) and gray-level co-occurrence matrix (GLCM). For mechanical information, mechanical statistical features were extracted. All feature data were subjected to dimensionality reduction and fusion by one-way analysis of variance (ANOVA) and principal component analysis (PCA) to obtain the multi-feature fusion of vision and tactile sensation. According to the characteristics of the fused data, the genetic algorithm (GA) was used to optimize the support vector machine (SVM) to establish a grade evaluation model. It was shown that the SVM model had excellent performance, with Accuracy = 1, Precision = 1, Recall = 1, F1-score = 1. The identification accuracy for first-grade, second-grade and qualified salted sea cucumber were all 100%. This method provides a new idea for the grade evaluation of salted sea cucumber.
Suitability of Different Broad Bean Cultivars for Producing Pixian Broad Bean Paste-Meju
LI Xiongbo, FAN Zhiyi, YANG Mei, DENG Weiqin, XIANG Chao, LI Heng
2022, 43(23):  49-56.  doi:10.7506/spkx1002-6630-20211024-261
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To explore the suitability of different broad bean cultivars for producing Pixian broad bean paste-meju, 11 broad bean cultivars were studied for their physical properties and nutritional value. Also, the physicochemical and textural properties and sensory quality of Pixian broad bean paste-meju made from these cultivars were analyzed. Factor analysis was used for comprehensive quality evaluation of Pixian broad bean paste-meju. The results showed that there was significant difference in quality indexes among the 11 cultivars of broad bean and Pixian broad bean paste-meju from them (P < 0.05). Through factor analysis, the dimensionality of the 14 quality indicators of Pixian broad bean paste-meju was reduced to three principal factors, which contributed?cumulatively?to 90.410% of the total variation. A comprehensive evaluation model for Pixian broad bean paste-meju quality was constructed based on the results. The 11 Pixian broad bean paste-meju were divided into three groups by cluster analysis. Group I included Pixian broad bean paste-meju made from the cultivars QY, CDDB and CH, whose quality was evaluated as good. Group II included that made from the cultivar TCX, whose quality was evaluated as medium. Group III included those made from the cultivars YD and SCZG, whose quality was evaluated as poor. Correlation analysis indicated that cultivars with high protein content, low starch content and moderate seed size such as QY, CDDB and CH were more suitable for processing Pixian broad bean paste-meju. This study can provide reference for the comprehensive quality evaluation of Pixian broad bean paste-meju and the selection of special broad bean varieties for processing.
Antibacterial Effect and Mechanism of Mixture of Culture Supernatant of Lactobacillus paracei Z17 with Chitosan against Escherichia coli O157:H7
GU Hengmei, MA Xinmin, ZHAO Yu, YANG Weixing, MENG Feng, KANG Yanping, CHEN Ping
2022, 43(23):  57-62.  doi:10.7506/spkx1002-6630-20211205-055
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To investigate the synergistic antibacterial activity and mechanism of culture supernatant of Lactobacillus paracei Z17 combined with?chitosan against Escherichia coli O157:H7 in strawberry, flow cytometry, Fourier transform infrared (FTIR) spectroscopy, Raman spectroscopy and scanning electron microscopy (SEM) were used to study the damage to the cell membrane of E. coli O157:H7 caused by Lactobacillus paracei Z17-chitosan mixture. The results showed that combined treatment with 1.0% chitosan solution and Lactobacillus parace Z17 could decontaminate E. coli O157:H7 on strawberries by 99%. The extracellular release of DNA from E. coli O157:H7 was (381.00 ± 3.53) ng/μL and the proportion of cells with a damaged membrane was 58.3% after combined treatment for 3 h. Fatty acids, proteins, peptidoglycans, glycoside rings and polysaccharides were destroyed in the cell wall membrane. The cell membrane exhibited local displacement and became thinner, and large molecules were adhered to the cell surface, with holes in it, leading to leakage of intracellular contents and eventually cell death. In conclusion, L. paracei Z17-chitosan mixture can inhibit E. coli O157:H7 on strawberries by targeting the cell membrane of E. coli O157:H7, which may be useful for the biocontrol of E. coli O157:H7.
Predictive Model for Comprehensive Quality Evaluation of Pumpkin (Cucurbita moschata) Fruit Based on Sensory Analysis, Texture Characteristics and Physicochemical Components
ZHAO Siying, LI Lu, LIU Xiaoxi, ZHAO Gangjun, WU Haibin, LUO Jianning, GONG Hao, ZHENG Xiaoming, LI Junxing
2022, 43(23):  63-71.  doi:10.7506/spkx1002-6630-20211011-105
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In this study, a set of methods for comprehensive quality evaluation of pumpkin (Cucurbita moschata) fruit was established in order to provide a theoretic basis for exploring the key sensory quality attributes and breeding new cultivars with excellent fruit quality. Twenty pumpkin fruit samples of different cultivars were used, and their sensory attributes, texture parameters, and physicochemical indicators were measured. The obtained data were subjected to difference analysis, correlation analysis and stepwise regression analysis. The difference analysis showed that sensory attributes, texture parameters and physicochemical indicators were different between these pumpkin samples. The correlation analysis indicated that a higher comprehensive taste score was observed for pumpkin fruit with higher softness, stickiness and sweetness and moister mouthfeel. In addition, higher elasticity and cohesiveness and lower adhesiveness resulted in better overall taste of pumpkin fruit. Higher contents of sugar, pectin and total starch and lower water content contributed to better overall taste. Through stepwise regression analysis, a comprehensive sensory evaluation prediction model was established as follows: Y = ?1.547 + 0.072 × fructose content + 0.052 × soluble pectin content ? 0.053 × amylose content ? 0.022 × adhesiveness + 21.278 × crude fiber content (Y is the predicted value of overall taste score), and this model had good predictive performance. Use of texture parameters and physicochemical indicators as objective measures can better make up for the disadvantage of the subjectivity of sensory evaluation.
Food Engineering
Effect of Low-Voltage Electrostatic Field-Assisted Vacuum Storage on Postharvest Quality and Antioxidant Metabolism of White Hypsizygus marmoreus
MENG Xiaoman, SUN Yanan, CHENG Ruyang, LI Wenxiang, WANG Shuangji, WU Hao, CHENG Fansheng
2022, 43(23):  72-81.  doi:10.7506/spkx1002-6630-20211128-341
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In this study, freshly harvested white Hypsizygus marmoreus was stored at (3 ± 1) ℃ and a relative humidity of 80%–85% under low-voltage electrostatic field (LVEF) conditions (150 V voltage and 1 000 Hz frequency) in vacuum (26–36?kPa pressure). Physiological and biochemical indicators and sensory quality were measured to evaluate changes in the mushroom’s quality and antioxidant mechanism during storage. The results showed that the shelf life of the mushroom treated with LVEF combined with vacuum (LVEF-Vac) was 14 days, the shelf life of the sample treated with LVEF was 12 day, and the shelf life of the control sample (stored at cold temperature and normal pressure) was nine days. Compared with the control group, LVEF and LVEF-Vac treatment significantly inhibited the respiratory intensity, reduced water loss, and improved the sensory quality of white Hypsizygus marmoreus (P < 0.05). Compared with the control and LVEF groups, LVEF-Vac treatment significantly improved antioxidant enzyme activities (ascorbic acid peroxidase, peroxidase, catalase, glutathione reductase and superoxide dismutase) and maintained higher contents of non-enzymatic antioxidant substances (glutathione, oxidized glutathione and ascorbic acid) in white Hypsizygus marmoreus (P < 0.05), which in turn enhanced the antioxidant capacity of the direct and indirect antioxidant systems, significantly inhibited the increase in the contents of hydrogen peroxide, superoxide anion radical and malondialdehyde (P < 0.05), reduced the degree of membrane lipid peroxidation, and maintained cell integrity. Taken together, LVEF-Vac treatment can improve the storage quality of white Hypsizygus marmoreus and delay the postharvest senescence process.
Effect of Low Voltage Electrostatic Field-Assisted Freezing on the Quality of Bamboo Shoots
GUO Jiagang, YANG Song, TONG Guangxiang, WU Yuhan, ZHU Qian, DU Jingjing, PAN Jiuhong, JIANG Jian
2022, 43(23):  82-88.  doi:10.7506/spkx1002-6630-20220127-278
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In order to study the effect of low voltage electrostatic field (LVEF)-assisted freezing on the freezing characteristics of bamboo shoots, freezing curves, texture, drip loss, water migration, ice crystal morphology and microstructure were used as indicators to evaluate the effect of LVEF-assisted freezing (–35 ℃) and regular freezing (–35 ℃) on the quality characteristics of frozen bamboo shoots. The results showed that LVEF-assisted freezing improved the freezing efficiency, changed the shape and distribution of ice crystals, and reduced the degree of microstructural damage and thawing loss of bamboo shoots. The drip loss of bamboo shoot samples subjected to LVEF treatment at 10, 20, 30 and 40 cm away from the electrostatic field generating plate were 14.16%, 12.58%, 9.73% and 10.44%, respectively and were significantly lower than 21.01% for the control group (P < 0.05), and the hardness values were 461.19, 507.48, 496.65 and 455.31 g, respectively and were significantly higher than 350.70 g for the control group (P < 0.05). Low-field nuclear magnetic resonance (LF-NMR) spectroscopy indicated that the thawing loss of bamboo shoots was reduced under LVEF. Scanning electron microscope (SEM) observation showed that the bamboo shoot fibers were arranged neatly and the microstructure of bamboo shoots was well maintained. In summary, LVEF-assisted freezing can effectively improve the quality of bamboo shoots, which will provide guidance for utilizing LVEF in the frozen storage and cold chain transportation of fruits and vegetables.
Effect and Possible Mechanism of Ultrasonic Treatment on the Gel Properties of Waxy Rice Flour
YANG Qiuye, LIU Yawei, LIU Jie
2022, 43(23):  89-96.  doi:10.7506/spkx1002-6630-20211104-056
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This study was undertaken in order to explore the effect and possible mechanism of action of ultrasonic treatment on the gel properties of waxy rice flour. An orthogonal array design was applied to optimize the conditions of ultrasonic treatment based on loss tangent (tan δ) as a measure of gel viscoelasticity. The optimum process parameters were determined as follows: 130 W of ultrasonic power, 20 min of ultrasonic time, and 1:2 of solid-to-liquid ratio. The tan δ value of the rice flour gel treated under the optimized conditions was 0.82. The scanning electron micrographs showed that starch granules in waxy rice flour (WRF) were aggregated and became dispersed after ultrasound treatment. Moreover, the storage modulus (G’), loss modulus (G’’), hardness and springiness of WRF decreased, while the peak viscosity, and adhesiveness rose. The starch content of WRF was 84.34%. Ultrasound treatment had no significant effect on the granular morphology, gelatinization properties, freeze-thaw stability, rheological properties or texture properties of starch from WRF. The structure of proteins from ultrasound-treated WRF was looser with more holes in it, the relative contents of β-sheet and random coil significantly increased, and the disulfide content and the thermal stability significantly decreased as compared to proteins from WRF (P < 0.05). In conclusion, ultrasound treatment can change the gel properties of WRF by changing the conformation of proteins in it.
Nutrition & Hygiene
Preventive Effect of Zizania latifolia Shell Extract on Ulcerative Colitis in Mice
YAN Yuan, WU Weijie, GAO Haiyan, FANG Xiangjun, HAN Yanchao, LIU Ruiling, NIU Ben, CHEN Hangjun
2022, 43(23):  97-105.  doi:10.7506/spkx1002-6630-20220602-027
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In this study, Zizania latifolia shell extract (Zlse) was obtained by ethanol extraction and silica gel chromatography, and its effect on ulcerative colitis in mice was evaluated. The underlying mechanism was analyzed by network pharmacology. Six groups of mice were established: normal control (NC), model control (MC), positive control (PC), low-dose Zlse (Zlse-L), medium-dose Zlse (Zlse-M) and high-dose Zlse (Zlse-H). Ulcerative colitis was induced by intragastric administration of 3.5% sodium dextran sulfate solution in the MC, PC and Zlse groups. The PC and Zlse groups were intragastrically administrated with mesalazine and Zlse, respectively. The NC and MC groups were intragastrically administrated with 0.5% sodium carboxymethylcellulose (CMC-Na) solution. The health status of mice was recorded daily, and the disease activity index (DAI) score was calculated. The percentage body mass change, DAI score, colon length, hematoxylin and eosin (HE)-stained colonic sections, colonic histopathology score, serum inflammatory factors (IL-6, IL-8, IL-1β, and TNF-α) levels, and the activities of colonic myeloperoxidase (MPO) and superoxide dismutase (SOD) were compared between the six groups. Based on the key targets and the important Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways obtained from the GeneCards, OMIM, TTD and DAVID databases, a ‘active ingredient-target-KEGG pathway’ network diagram was constructed. The results showed that compared with the MC group, the trend of body mass loss in the Zlse treatment groups was significantly slowed down (P < 0.05), the colon length was restored, and the colon injury was reduced. In addition, the levels of serum proinflammatory factors in the Zlse groups were significantly decreased (P < 0.05); colonic MPO activity was significantly decreased (P < 0.05), while SOD activity was increased (P < 0.05). Eight active components, 77 intersection targets and 119 KEGG pathways were obtained by network pharmacology analysis. The key active components were tricin and tricin-4’-O-syringyl alcohol, and the important pathways included the P13K/Akt signaling pathway, receptor activation and reactive oxygen species accumulation, which were confirmed by animal experiments. The results showed that Zlse can concentration-dependently prevent DSS-induced ulcerative colitis in mice by inhibiting the release of proinflammatory factors and regulating the antioxidant defense capacity of the colon.
Quantum Chemical Calculation for the Antioxidant Mechanism of Two Peptides from Naked Oat
FU Yuan, ZHANG Meili, ZHANG Yu, GAO Shaohui
2022, 43(23):  106-112.  doi:10.7506/spkx1002-6630-20211202-013
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In order to study the in vivo antioxidant mechanism of two bioactive peptides I and II from naked oat, their amino acid sequences were determined, their antioxidant activity was evaluated, and their molecular structure, charge distribution, molecular frontier orbital distribution, energy difference (ΔE) and radical Fukui index (f0(r)) were calculated by quantum chemistry to deduce the active sites for antioxidant activity of the two peptides. Furthermore, animal tests were carried out and the experimental results were compared with the calculated ones. The results showed the energy of the highest occupied molecular orbital (EHOMO) of peptide I was higher, and the energy difference between the EHOMO and the energy of the lowest unoccupied molecular orbital (ELUMO) of peptide I was smaller, which proves that this peptide has better electron delocalization performance, more easily loses electrons, and is easier to oxidize and therefore a more potent antioxidant. In addition, according to the f0(r), the active sites of peptide I for free radical reaction were located at the double bonds of the indole ring of tryptopha, the amino groups of phenylalanine and the carboxyl group of leucine, whereas the active sites of peptide II were located at two quanidyl groups of arginine and the carboxyl group of leucine. The results of quantum chemical calculation were consistent with those from the animal tests. It was found that both peptides could effectively remove free radicals D-galactose-induced subacute aging mice, peptide I being more effective than peptide II. These results will be helpful for the development of antioxidant products from naked oat.
Konjac Glucomannan Ameliorates Hyperlipidemia via Gut Microbiota-Bile Acid Pathway
ZOU Xiaoying, DENG Jie, ZHONG Jing, WANG Qian, HE Fangqing, SUN Yuanming, LI Meiying
2022, 43(23):  113-124.  doi:10.7506/spkx1002-6630-20211224-291
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The hypolipidemic effect and mechanism of konjac glucomannan (KGM) were investigated in hyperlipidemic hamsters from the perspective of the relationship between the gut microbiota and bile acid metabolism. Five-week-old hamsters were divided randomly into control, high fat diet (HFD), 2% (m/m) KGM, 6% KGM and 10% KGM groups. Serum and hepatic lipid levels were assessed, and the effect of KGM treatment on the gut microbiota and bile acid metabolism were analyzed after five-week administration. Our results suggested that 6% and 10% KGM treatments significantly decreased serum total cholesterol (TC), triglyceride (TG), low density lipoprotein cholesterol (LDL-C) and hepatic TC levels. Totally 51 differential metabolites were found between the HFD versus control and KGM groups, and enrichment analysis showed that bile acids accounted for the highest proportion (24%) of the total number of metabolites. Moreover, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis showed a significant alteration in the primary bile acid synthesis pathway. Administration with 6% and 10% KGM significantly reduced the relative abundance of Bilophila and bile salt hydrolase (BSH)-related bacteria, Bifidobacterium and Lactobacillus, and decreased the levels of deoxycholic acid (DCA) and lithocholic acid (LCA) in cecal contents. Besides, the mRNA expression of cholesterol 7α-hydroxylase (CYP7A1) was unregulated in the 6% KGM group. Taken together, KGM treatment significantly decreased the relative abundance of Bilophila and BSH-related bacteria in the gut, upregulated the gene expression of CYP7A1 to regulate the levels of bile acids, thus modulating dyslipidemia.
Inhibitory Effect of Four Bioactive Compounds from Rosemary on Lipopolysaccharide (LPS)-Induced Oxidative Stress and Inflammation in RAW264.7 Cells
DING Zhiqian, XU Min, WU Hua, RAKA Rifat Nowshin, WEI Mengya, WANG Kaiyang, XIAO Junsong
2022, 43(23):  125-133.  doi:10.7506/spkx1002-6630-20211229-325
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Objective: Our aim is to investigate the inhibitory effects of four bioactive compounds from rosemary (carnosic acid, carnosol, rosmanol and rosmarinic acid) against oxidative stress and inflammatory response in lipopolysaccharide (LPS)-induced RAW264.7 cells. Methods: The effects of these compounds on reactive oxygen species (ROS), inflammatory factors and related enzymes were characterized by various methods including colorimetry, fluorescence quantitative polymerase chain reaction (PCR) and Western blot. Results: All four compounds had significant inhibitory effects on the expression or production of ROS, malonic dialdehyde (MDA), nitric oxide (NO), tumor necrosis factor-α (TNF-α), interleukin (IL)-1β, IL-6, inducible nitric oxide synthase (iNOS) and cyclooxygenase 2 (COX-2) in LPS-induced cells. They had a significant protective effect on the activity of superoxide dismutase (SOD) and catalase (CAT) in a concentration-dependent manner. Carnosic acid at 10 μg/mL had a better inhibitory effect on the LPS-induced increases in relative ROS levels, NO release, TNF-α mRNA expression and MDA levels, and a better protective effect on SOD and CAT activity. Rosmanol at 10 μg/mL had a better inhibitory effect on the LPS-induced increases the relative mRNA expression levels of IL-1β and IL-6 and the relative protein expression levels of iNOS and COX-2. Conclusion: All four compounds from rosemary have antioxidant and anti-inflammatory effects and alleviates inflammatory responses. The effective concentration of water-soluble rosmarinic acid is significantly higher than that of the other three compounds.
Effect of Processing Method on Immunogenicity and Allergenicity of Fish Cake Parvalbumin
ZHOU Linjie, LU Jiada, SHI Wenzheng, LU Ying
2022, 43(23):  134-140.  doi:10.7506/spkx1002-6630-20220125-255
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In this study, silver carp muscle was processed into fish cakes by heating, autoclaving, Lactobacillus paracasei fermentation, or L. paracasei fermentation combined with autoclaving. Changes in the immunogenicity and secondary structure of parvalbumin (PV) from fish cakes were evaluated by enzyme-linked immunosorbent assay (ELISA) and Fourier transform infrared (FTIR) spectroscopy. The effect of processing methods on the allergenicity of PV from fish cakes in BALB/c mice was analyzed in terms of allergy symptom scores, and changes in serum immunoglobulin E (IgE) antibody, histamine and cytokine levels. The results showed that compared with heating, autoclaving, L. paracasei fermentation and their combination reduced the reduction rate of PV immunoglobulin G binding capacity from fishcakes by 50.6%, 34.7% and 68.5%, respectively. Compared with natural PV (from silver carp muscle), the α-helix content was reduced by 10.7%, 13.3% and 17.3%, and the β-sheet content was increase by 7.8%, 5.1% and 14.8% by autoclaving, L. paracasei fermentation and their combination, respectively, while there was no significant change in the heating group. All processing methods except heating alleviated allergic symptoms in sensitized mice, and significantly reduced the serum levels of histamine and Th2 cytokines including interleukin-4 (IL-4), IL-5 and IL-13 (P < 0.05). Serum IgE antibody levels were significantly higher in the heat treatment group than in the other treatment groups (P < 0.05), and L. paracasei fermentation combined with autoclaving was the most effective in reducing the allergenicity of PV. In summary, the single treatments were less effective than their combination in reducing the α-helix content, increasing the folding degree, and mitigating the immunogenicity and allergenicity of PV, but they all alleviated Th2 cell responses in immunized mice, in turn inhibiting allergic reactions. Among them, autoclaving combined with fermentation had the most significant effect on the immunogenicity and allergenicity of the major fish allergen PV.
Polyphenols Extracted from Hizikia fusiformis Relieves Lipopolysaccharide-Induced Inflammation in RAW264.7 Cells via the Nuclear Factor-κB/Mitogen-Activated Protein Kinase Signaling Pathways
HUANG Ping, HONG Jingxia, MI Jie, ZHANG Panxue, LI Chao, YANG Wenge
2022, 43(23):  141-148.  doi:10.7506/spkx1002-6630-20211230-348
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Objective: To study the effect of Hizikia fusiformis polyphenols (HFPs) on lipopolysaccharide (LPS)-induced inflammatory response in RAW264.7 cells. Methods: The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) method was used to examine the cellular viability. Nitric oxide (NO) was measured by the Griess method. Quantitative real-time polymerase chain reaction (qPCR) was applied to analyze the gene expression of interleukin (IL)-6, IL-1β, tumor necrosis factor (TNF)-α, cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS). Flow cytometry was used to determine macrophage phagocytosis. The expression of the key proteins involved in the mitogen-activated protein kinases (MAPKs) and nuclear factor (NF)-κB signaling pathways was investigated by Western blot. Results: HFPs at concentrations of 0–160 μg/mL had no cytotoxic effect on RAW264.7 cells. Compared with the LPS-induced group, HFPs dose-dependently inhibited the phagocytic capacity of macrophage and NO production. Besides, the mRNA levels of several inflammatory mediators, including IL-1β, IL-6, TNF-α, iNOS and COX-2 were down-regulated, and this effect was dependent on the dose of HFPs and LPCS stimulation time. The expression of these inflammatory mediators may be related to the inhibition of the activation of the activation of p38 MAPK and NF-κB p65 by HFPs. Conclusion: HFPs alleviates LPS-induced inflammation in RAW264.7 cells by down-regulating the activation of the p38 MAPK and NF-κB p65 signaling pathways and inhibiting the transcription and expression of downstream inflammatory mediators.
Hypoglycemic Effect and Mechanism of Polysaccharides from Finger Citron from Guangdong Province Based on Enzyme Activities and Cell Model
YANG Yujie, LIU Huan, WANG Shuhui, LIU Chunhong, CHEN Shuxi, ZHOU Aimei
2022, 43(23):  149-157.  doi:10.7506/spkx1002-6630-20220104-024
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Finger citron (Citrus medica ‘Fingered’) is a medicinal and edible plant belonging to the genus Citrus of the family Rutaceae. Finger citron grown in Guangdong is called Guang Foshou. The present study explored the in vitro hypoglycemic activity and mechanism of polysaccharides extracted from Guang Foshou by measuring enzyme activities as well as using cell model. The results showed that the half-maximal inhibitory concentrations (IC50) of the polysaccharide fraction FCP-2-1 for α-glucosidase, α-amylase and angiotensin converting enzyme (ACE) were 2.74, 0.87 and 0.85 mg/mL, respectively. All the polysaccharides remarkably promoted glucose transport in 3T3-L1 adipocytes, improved lipid metabolism and reduced the secretion of tumor necrosis factor (TNF)-α. The mechanism might be that FCP-2-1 could promote the expression of phosphatidylinositol 3-kinase (PI3K), glucose transporter 4 (GLUT4), protein kinase B (PKB or AKT) and phosphorylated AKT (p-AKT) in the PI3K/AKT signaling pathway to alleviate insulin resistance and restore normal cellular metabolism.
Lactobacillus plantarum KSFY04 Inhibits Thrombosis in Mice by Regulating the Nuclear Factor Kappa B (NF-κB) Signaling Pathway
ZHAO Xin, LIU Jia, YI Ruokun, QIAN Yu, YANG Zhennai
2022, 43(23):  158-167.  doi:10.7506/spkx1002-6630-20211107-076
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This study observed the effect of Lactobacillus plantarum KSFY04 (LP-KSFY04) against carrageenan-induced thrombosis in mice by regulating the NF-κB signaling pathway. Commercial biochemical kits and quantitative polymerase chain reaction (qPCR) were used to detect related indexes in mouse serum and tissues, and hematoxylin-eosin (HE) staining was used for histopathological examination. The composition of intestinal microbiota was examined as well. The results showed that LP-KSFY04 could effectively reduce the degree of black tail in thrombotic mice, prolong the activated partial thromboplastin time (APTT), and reduce the prothrombin time (PT), thrombin time (TT) and fibrinogen (FIB) level. LP-KSFY04 could also reduce the levels of inflammatory cytokines including tumor necrosis factor alpha (TNF-α), interleukin-6 (IL-6) and interleukin-1 beta (IL-1β) in the serum, kidney and liver of thrombotic mice. Pathological observation showed that LP-KSFY04 could reduce liver and kidney lesions caused by thrombosis and the accumulation of tail vein thrombosis. qPCR results showed that LP-KSFY04 could down-regulate the mRNA expression of nuclear factor kappa-B p65 (NF-κB p65), IL-6, TNF-α, intercellular cell adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1) and E-selectin. Moreover, LP-KSFY04 increased the relative abundance of Bacteroidetes, Lactobacillus and Bifidobacterium and decreased the relative abundance of Firmicutes. These results showed that LP-KSFY04 can reduce inflammation and inhibit thrombosis in thrombotic mice, and the effects of high concentration of LP-KSFY04 were most pronounced, which were close to those of dipyridamole.
Non-Antioxidant Pathway for the Ameliorative Effect of Fucoxanthin against Phagocytic Disturbance of Retinal Pigment Epithelial Cells
GUO Zixin, LIU Yunjun, LIU Yixiang, WANG Yanbo
2022, 43(23):  168-173.  doi:10.7506/spkx1002-6630-20211231-358
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In this work, the ameliorative effect of fucoxanthin on visible light-induced phagocytic disturbance of differentiated retinal pigment epithelial (RPE) cells was investigated in a polyunsaturated fatty acids-rich environment and the non-antioxidant pathway involved was explored. The results showed that when exposed to visible light at 3 500 lx, the phagocytic capacity of RPE cells was significantly reduced, and the expression of phagocytic receptors (including Mer tyrosine kinase (MerTK), αV integrin protein, β5 integrin protein and CD36 receptor) on the cell membrane was inhibited to varying degrees. Pretreatment with different concentrations (10.0 and 20.0 μg/mL) of fucoxanthin significantly ameliorated the phagocytic capacity of RPE cells and effectively up-regulated the expression of the above four phagocytic receptors. Specific antibody testing further confirmed that fucoxanthin enhanced the phagocytic capacity of RPE cells mainly by regulating the expression of MerTK, αV integrin protein and β5 integrin protein receptors. In addition, the L-type Ca2+ channel was also shown to be an important pathway for fucoxanthin to improve the phagocytic capacity of RPE cells. These findings provide a theoretical basis for the development of vision-protective functional foods containing fucoxanthin.
Comparison of Hepatoprotective Effects of Wild and Cultivated Kudzu Root (Pueraria lobata Ohwi) on Mice with Chronic Alcoholism
YAO Yuan, GAI Yongqiang, CHEN Tiejun, WANG Zhe, PIAO Meizi
2022, 43(23):  174-179.  doi:10.7506/spkx1002-6630-20211107-079
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Objective: To compare the hepatoprotective effects of wild and cultivated kudzu root (Pueraria lobata Ohwi) on a mouse model of chronic alcoholic liver injury. Methods: Specific pathogen free (SPF) mice were divided into nine groups randomly to evaluate and compare the effects of different oral doses of wild and cultivated kudzu root on aminotransferase and dehydrogenase activities, antioxidant indexes and inflammatory signaling indexes in the liver and blood of mice. Results: Compared with the model group, serum aminotransferase levels decreased, and the activities of hepatic alanine aminotransferase (ALT) and aspartate aminotransferase (AST) increased and decreased significantly in the kudzu root treated groups, respectively (P < 0.05). Serum dehydrogenase levels increased significantly (P < 0.05). Moreover, the activities of hepatic catalase and glutathione peroxidase increased significantly (P < 0.05). The contents of NO, tumor necrosis factor α and interleukin (IL)-1β in the liver decreased significantly (P < 0.05), while the content of IL-10 increased significantly (P < 0.05). Conclusion: Both wild and cultivated kudzu root at certain doses can protect against chronic alcoholic liver injury in mice, and the protective effect of wild kudzu root is more pronounced at the same dose. These experimental results provide a theoretical basis for further development and utilization of wild and cultivated kudzu root.
Effects of Modified Okara on Physiology and Intestinal Flora in Hyperlipidemic Rats
XIANG Qinxue, TIAN Rui, WU Bo, SUN Guogen, CHEN Limei, MO Kaiju
2022, 43(23):  180-186.  doi:10.7506/spkx1002-6630-20220504-036
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In an effort to evaluate the ameliorative effect of modified okara on obesity and hyperlipidemia, hyperlipidemic rats were orally administered with natural and modified okara and evaluated for body mass, blood lipids, visceral organ indexes and intestinal microbial abundance. The results showed that compared with the high-fat control group, the body mass, the serum levels of total cholesterol, triglyceride, low-density lipoprotein cholesterol (LDL-C) and liver index of rats administered with modified okara were decreased by 6.3%–13.3%, 19.7%–32.0%, 47.0%–59.3%, 43.2%–55.3%, and 5.4%–12.8%, respectively. Serum high density lipoprotein-cholesterol (HDL-C) concentration was increased by 20.9%–48.5%, and the structure of intestinal microbiota was different between the two groups. Okara proved helpful to improve obesity and hyperlipidemia in rats, and Na2HPO4 modified okara was more effective than raw and NaOH modified okara. The relative abundance of beneficial bacteria, such as Bacteroides, Lactobacillus and Lactobacillus murinus, was increased, and the relative abundance of harmful bacteria, such as Proteobacteria and Shigella, was decreased after administration of okara. Firmicute has no significant correlation with body mass or blood lipid indexes. The relative abundance of Lactobacillus was positively correlated with body mass and HDL-C concentration, and negatively correlated with TC, TG, and LDL-C concentrations. However, its effects on body mass and blood lipids were not synchronous. Bacteroidetes and Bacteroides were beneficial for blood lipid indexes. Proteobacteria and the genus Escherichia Shigella in this family have negative effects on blood lipids. In summary, modified okara improves obesity and hyperlipidemia in rats by regulating the intestinal flora.
Packaging & Storage
Inhibitory Effect and Mechanism of Composite Coating Containing Oleaster Gum and Cuminal on Postharvest Pink Mold Rot of Tomatoes
DAI Xishuang, ZHANG Zhong, BI Yang, William Oyom, ZHANG Zhipeng, XIE Pengdong
2022, 43(23):  187-193.  doi:10.7506/spkx1002-6630-20220106-044
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Pink mold rot is one of the major diseases of tomatoes, which can occur before and after harvest, causing great losses in tomato production, storage and transportation. This study investigated the in vitro inhibitory effect of cuminal against Trichothecium roseum Pers. Link, the fungal pathogen causing pink mold rot of tomatoes. The inhibitory effect of a composite coating consisting of cuminal and oleaster gum on disease incidence in tomatoes artificially wounded and inoculated with T. roseum and the effect of the composite coating on disease resistance in tomato fruit were evaluated. The results showed that cuminal effectively inhibited the spore germination and mycelial growth of T. roseum under in vitro conditions, cuminal at a concentration of 0.1 μL/mL inhibited colony growth by more than 80%. Under in vivo conditions, the composite coating significantly inhibited the growth of T. roseum on tomato fruit, delayed lesion expansion and reduced decay incidence. After 9 days of storage, the lesion diameter and the decay incidence of the fruit treated with the composite coating containing 30 mg/mL oleaster gum and 0.2% (V/V) cuminal were 36.7% and 69.2% of those in the control group, respectively. The composite coating effectively increased the H2O2 content of tomato fruit during the early stage of storage, increased enzyme activities such as peroxidase (POD), phenylalanine ammonia-lyase (PAL) and 4-coumarate-CoA ligase (4CL), and enhanced the accumulation of total phenols and flavonoids in tomato fruit. These results suggest that the composite coating containing oleaster gum and cuminal can effectively inhibit the occurrence and development of postharvest pink mold rot of tomatoes, and its mechanism is not only related to the inhibition of pathogen growth by cuminal, but also to enhanced disease resistance in tomato fruit.
Effect of Cold Chain Storage on Chemical Interactions of Surimi Gel and Structural and Functional Properties of Myofibrillar Protein
CHEN Xu, YU Luhan, CAI Xixi, WU Jinhong, LIU Yongle, HUANG Jianlian, WANG Shaoyun
2022, 43(23):  194-201.  doi:10.7506/spkx1002-6630-20220512-156
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In order to study the effect of cold chain storage on the structural and functional properties of myofibrillar protein and the chemical interactions of surimi gel, the changes in the functional groups and secondary and tertiary structure of myofibrillar protein and the chemical interactions of surimi gel were investigated as a function of cold chain storage time, and the relationship between chemical interactions and myofibrillar protein was evaluated by principal component analysis (PCA) and correlation analysis. Results showed that the salt-soluble protein content, Ca2+-ATPase activity and total sulfhydryl content in surimi gel decreased, while the carbonyl content increased during storage.?In addition, the secondary structures of myofibrillar protein transformed from an ordered to a disordered state, and the fluorescence intensity decreased, indicating changes in the polar environment of the protein. These findings demonstrate that the active groups in myofibrillar protein are closely related to the formation of gel chemical forces.?Therefore, preventing protein oxidation and freeze denaturation at the initial stage of storage is an effective way to maintain the chemical interactions of surimi gel and the gel characteristics. This study can provide basic theoretical support for the quality maintenance of surimi during cold chain storage.
Preparation of Antibacterial Indicator Films Based on Polyvinyl Alcohol and Chitosan and Its Application in Chilled Pork
WU Yanglin, SUN Li, LI Yixin, GAO Yuan, LI Hao, ZHENG Cong, LI Chunwei
2022, 43(23):  202-210.  doi:10.7506/spkx1002-6630-20210925-299
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Multifunctional food packaging films were prepared using polyvinyl alcohol (PVA) and chitosan (CS) as film-forming substrates, montmorillonite (MMT)-supported tea polyphenol (TP) as a bacteriostatic agent, and bromocresol purple (BCP), methyl red (MR) or their combinations as an indicator. The effects of BCP, MR and their combination as well as MMT-supported TP on the physical and functional properties of the films were studied, and they were applied to monitor the freshness of chilled pork. The results showed good compatibility between these components. The addition of the indicator enhanced the crystallinity of the blend film and improved its physical and optical properties. The indicator film could respond to ammonia gas, and the highest sensitivity was obtained with a 1.5:1 (m/m) combination of BCP and MR. The addition of bacteriostatic agent significantly improved the water resistance, water vapor barrier performance, antioxidant performance and bacteriostatic performance of the film. When applying the most sensitive antibacterial indicator film to monitor the freshness of chilled pork, a significantly positive correlation was found between the color changes of the film and the freshness of chilled pork, and compared to the control group, the shelf life of chilled pork in the experimental group was extended by 1 to 2 days, indicating that the antibacterial indicator films can real time monitor the freshness and effectively extend the shelf life of chilled pork.
Chlorine Dioxide Accelerates the Wound Healing Process of Potato Tubers by Eliciting Phenylpropanoid Metabolism
CHAI Xiuwei, KONG Rui, ZHENG Xiaoyuan, ZHU Yatong, LIANG Wei, ZHAO Shijia, LI Baojun, BI Yang, Dov PRUSKY
2022, 43(23):  211-219.  doi:10.7506/spkx1002-6630-20220119-181
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Chlorine dioxide (ClO2) is a safe and effective disinfectant that is widely used for preserving fruits and vegetables as well as controlling microorganisms. However, the mechanism by which ClO2 treatment affects wound healing in potato tubers remains unclear. The half cut potato tubers ‘cv. Atlantic’ were soaked with 25 mg/L ClO2 for 10 min, which were stored for 0, 3, 5, 7, 14, and 21 d at room temperature in dark for wound healing. The mass loss rate and the disease index of wounded tubers inoculated with Fusarium sulphureum were determined, the deposition of suberin poly phenolic (SPP) and lignin at wound sites were observed, and the activities of the key enzymes of phenylpropanoid metabolism and peroxidase (POD) as well as the content of phenylpropanoid metabolism products and H2O2 at wound sites were measured. This result showed that ClO2 at 25 mg/L accelerated SPP and lignin deposition and increased cell layer thickness at wounds. Furthermore, the mass loss rate and disease index (after inoculated with F. sulphureum) of potato tubers significantly was reduced by 20.8% and 45.3%, respectively, on day 14 after ClO2 treatment. Additionally, ClO2 enhanced the contents of five phenolic acids (cinnamic, p-coumaric, caffeic, ferulic, and sinapic acids) and three lignin monomers (p-coumaryl, sinapyl, and coniferyl alcohols) by increasing phenylalanine ammonia-lyase (PAL), cinnamate-4-hydroxylase (C4H), and cinnamyl alcohol dehydrogenase (CAD) activities. Moreover, ClO2 treatment significantly promoted the synthesis of total phenolics, flavonoids and lignin and elevated H2O2 content and peroxidase activity. In conclusion, ClO2 treatment accelerated the deposition of SPP and lignin at wound sites, decreased the mass loss rate and disease index of damaged potato tubers during healing, triggered the phenylpropanoid metabolism pathway, and increased H2O2 content and POD activity. These findings provide evidence that ClO2 treatment can accelerate wound healing in potato tubers.
Effect of Freezing Temperature and Frozen Storage Temperature on Lipid Oxidation of Red Swamp Crawfish
YANG Haiqi, CHEN Jiwang, XU Yan, TIAN Hongwei, LIAO E, WANG Haibin
2022, 43(23):  220-227.  doi:10.7506/spkx1002-6630-20211206-072
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Red swamp crawfish were blanched, vacuum packaged, frozen at three different temperatures (?20, ?40 and ?55 ℃) until the internal temperature reached ?15 ℃, and stored at two different temperatures (?20 and ?40 ℃) for up to 24 weeks. The fat and free fatty acids (FFAs) contents, fatty acid composition, peroxide value (POV), and thiobarbituric acid reactive substance (TBARS) value of crawfish meat were measured to investigate the effect of freezing temperature and frozen storage temperature on lipid oxidation. The results showed that as storage time prolonged, the contents of fat, unsaturated fatty acids (UFAs), and polyunsaturated fatty acids (PUFAs) decreased significantly (P < 0.05), while the contents of FFAs and saturated fatty acids (SFAs) as well as POV and TBARS values increased significantly (P < 0.05). At the same frozen storage temperature, the POV and TBARS values of crayfish meat frozen at –20 ℃ were significantly higher than those of crayfish meat –40 and –55 ℃, while there was not a significant difference in FFAs contents or fatty acid composition; at the same frozen temperature, the fat and FFAs contents, POV, and TBARS values of crayfish meat stored at –20 ℃ were significantly higher than those of crayfish meat stored at –40 ℃, but the contents of UFAs and PUFAs during storage at –20 ℃ were slightly lower than at –40 ℃. In addition, SFAs contents during storage at –20 ℃ was higher than, but not significantly different from, those during storage at –40 ℃. These results indicated that freezing at –40 or –55 ℃ and frozen storage at –40 ℃ alleviated the degree of hydrolysis and oxidation of lipids from crayfish meat.
Effect of Rapid Heat Treatment on Wound Healing and Metabolic Mechanism in Sweet Potato
XIN Qi, SUN Jie, FENG Xinxin, ZHAO Zezhong, LIU Bangdi, JIANG Lihua, HAO Guangfei
2022, 43(23):  228-238.  doi:10.7506/spkx1002-6630-20211111-132
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In order to explore the effect and mechanism of rapid heat treatment (RHT) on promoting callus formation in postharvest sweet potato tubers, ‘Dayehong’ sweet potatoes were artificially wounded and divided into a positive control group, a negative control group, and an RHT group. The positive control group was subjected to traditional heat treatment (35 ℃ for two days), and the negative control group was not subjected to any heat treatment. The RHT group was subjected to heat treatment at 65 ℃ for 15 min. All groups were stored at 13 ℃. The experimental period was seven days, consisting of heat treatment and storage. Lignin and suberin deposition at the wound site were observed during wound healing. The intermediate products and enzyme activities in reactive oxygen species (ROS) metabolism were determined, as well as antioxidant activity and the key enzyme activities in the phenylpropane metabolism pathway and the contents of lignin and phenols. The results showed that RHT could effectively promote lignin and suberin deposition at the wound site, and its effect was similar to that of the positive control. On the 6th day of the experiment, the thickness of lignin and suberin deposition was significantly higher than that in the control groups (P < 0.05). RHT treatment significantly promoted the rapid accumulation of H2O2, hydroxyl radical and superoxide anion radical contents, induced the activities of superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), peroxidase (POD) and polyphenol oxidase (PPO), and significantly increased the scavenging capacity against (1,1-dipheny1-2-picryl-hydrazyl (DPPH) and 2,2’-azinobis-(3-ethylbenzthiazoline-6-sulphonate) (ABTS) cation radical of sweet potato callus during wound healing (P < 0.05). RHT could also induce the increase in phenylalanine ammonia lyase (PAL), cinnamic acid-4-hydroxylase (C4H), 4-coumaryl coenzyme A ligase (4CL) and cinnamyl alcohol dehydrogenase (CAD) activities and make them reach their peak earlier during wound healing, and promoted the accumulation of total phenols, flavonoids and lignin.?Meanwhile, RHT significantly increased the contents of neochlorogenic acid, catechin, chlorogenic acid and epicatechin in sweet potato callus. In conclusion, RHT could not only maintain the dynamic balance of ROS in callus by stimulating the accumulation of ROS and increasing antioxidant activity, but also activate the key enzymes in the phenylpropane metabolic pathway to produce a large number of secondary metabolites and accelerate the deposition of lignin and suberin, thereby promoting rapid wound healing in sweet potato tubers.
Linolenic Acid Treatment Promoted Wound Healing in Apple Fruit and the Underlying Mechanisms
JIA Juyan, LI Baojun, WANG Bin, YU Lirong, ZHAO Shijia, BI Yang, Dov PRUSKY
2022, 43(23):  239-245.  doi:10.7506/spkx1002-6630-20211122-266
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To study the effect of linolenic acid (LA) on wound healing in postharvest apple fruit and to explore the underlying biochemical mechanisms, artificially wounded apple fruit (cv. Fuji) were treated with 1 mmol/L LA or sterile water containing a small amount of ethanol as a control. The wound healing effect of LA was evaluated by measuring disease index and mass loss rate of apple. The key enzyme activities related to phenylpropane metabolism and its metabolite contents, H2O2 content and peroxidase (POD) activity at the wounds were measured. Compared to the control group, LA treatment decreased significantly the mass loss of wounded fruit and the disease index of inoculated fruit during wound healing. LA treatment increased the activities of four key enzymes involved in phenylpropane metabolism (phenylalanine ammonia lyase (PAL), cinnamic acid-4-hydroxylase (C4H), 4-coumaryl coenzyme A ligase (4CL) and cinnamyl alcohol dehydrogenase (CAD)), and elevated the levels of four phenolic acids (erucic acid, ferulic acid, cinnamic acid and caffeic acid) and three lignin alcohol monomers (coniferyl alcohol, cinnamyl alcohol and sinapyl alcohol), as well as total phenols, flavonoids, and lignin at the wounds. LA treatment also enhanced H2O2 content and POD activity. In summary, LA could promote wound healing of apple fruit by activating phenylpropanoid metabolism, and increasing H2O2 content and POD activity.
Transcriptomic Analysis of the Effect of Calcium Chloride on the Postharvest Quality of Green Bell Peppers with Mechanical Damage
ZHOU Xinyuan, SANG Zhaoze, BAI Chunmei, ZHENG Yanyan, JIA Li’e, WANG Qing, ZUO Jinhua, MU Jianlou
2022, 43(23):  246-253.  doi:10.7506/spkx1002-6630-20220610-101
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To explore the effect of calcium chloride treatment on the postharvest quality of green bell peppers with mechanical damage, bell pepper fruit were dropped from a high place to simulate mechanical damage that may occur during transportation and immersed in 1 mmol/L calcium chloride solution. The hardness, color and sensory quality of bell peppers were determined during storage. Meanwhile, transcriptomic analysis was conducted by high-throughput sequencing technology. Experimental results indicated that 1 mmol/L calcium chloride treatment could significantly delay the reddening, softening and decay of green bell peppers, and the color and texture changes and flavor and aroma-related genes were determined. In addition, the key enzymes and transcription factors involved in the plant hormone signal transduction pathway were identified, and the effect of calcium chloride treatment on the storage quality of green bell peppers with mechanical damage was evaluated. Calcium chloride may occur through the inhibition of the bifunctional 15-cis-octahydrolycopene synthase (PSY) and capsaicin/capsaicin synthase (CCS) and other genes to inhibit carotenoid synthesis, by the inhibition of cellulose synthase A (Ces), endo-1,3-β-glucosidase (β-Glu) and endoglucanase 25 (EG25) to alleviate their softening, and influencing the expression of certain transcription factors, phytohormones and aroma flavor related genes in pepper to improve the apparent quality of green round pepper fruit with mechanical damage. Conclusion: Calcium chloride treatment can effectively delay the deterioration of the fruit quality of the green round pepper, and prolong the storage period of the fruit.
Use of Principal Component Analysis for the Evaluation of the Effect of Composite Coatings in Preserving the Quality of Wax Apples (Syzygium samarangenese)
YIN Qingchun, YANG Suishan, PAN Yongbo, XIAO Xuan, WANG Chengye, CHEN Chunquan, DENG Hao
2022, 43(23):  254-260.  doi:10.7506/spkx1002-6630-20211227-311
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Wax apples are susceptible to water loss during postharvest storage, which in turn causes quality deterioration. In this study, three composite coatings (C1–C3) were prepared with multi-strain cultures and chitosan, and their efficacy in preserving the quality of wax apples was evaluated by measuring eight quality indexes as well as using principal components analysis (PCA) and mathematical models. The results showed that the preservative effect of the coating (C3) consisting of a three-strain cocktail (V(Streptococcus lactis):V(Bifidobacterium infantis):V(Bifidobacterium animalis) = 1:2:2) and chitosan at a volume ratio of 3:7 was the best. The percentage of marketable fruit in this coating treatment group was 95% on the 10th day of storage and 45% higher than that of the control group. The coating treatments could obviously reduce water loss, and the water loss rates of the three coating treatment groups were 14.87%, 13.81% and 15.64%, respectively and significantly lower than that of the control group (P < 0.05) on the 10th day of storage. After 10 days of storage, the increase in the contents of soluble solids and titratable acid (0.08% and 12.28%, respectively) and the decrease in the contents of vitamin C, glucose and fructose (18.87%, 10.91% and 5.84%, respectively) in the C3 treatment group were the lowest among the three treatment groups. PCA showed that the first two principal components (PC1 and PC2) could represent 69.814% of the information on all quality indexes and comprehensively reflect the effect of coatings on these indexes. The mathematical model analysis showed that the comprehensive score of the control group was ?0.53 on day 0, and became positive on the 4th day, indicating that the quality obviously deteriorated. The score of the C3 group was always near the critical value (zero) during storage, further verifying that C3 is the most effective in preserving wax apple quality, followed in order by C1, C2 and the control. This study provides a reference for research on postharvest preservation and comprehensive quality evaluation of wax apples.
Effect of Precooling Treatments on Postharvest Preservation of ‘Lingwu Long’ Jujube
LI Yan, LIU Guishan, HE Jianguo, LI Yue, CHEN Yapeng
2022, 43(23):  261-268.  doi:10.7506/spkx1002-6630-20211222-250
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In order to explore the effects of different precooling treatments on the postharvest preservation of ‘Lingwu Long’ jujube, harvested fruit were subjected to vacuum precooling, forced-air precooling or cold storage precooling before storage at (1 ± 1) ℃. Changes in the fruit quality and the activities of antioxidant enzymes in ‘Lingwu Long’ jujube were measured during storage. The results showed that compared with the untreated control, the three precooling treatments inhibited the mass loss and softening of jujube fruit, maintained the levels of soluble solids, titratable acids and ascorbic acid in jujube fruit, and effectively delayed the accumulation of malondialdehyde (MDA) and the increase in cell membrane permeability. Moreover, the precooling treatments enhanced ascorbate peroxidase, superoxide dismutase and catalase activities to stimulate the antioxidant defense system and in turn delay the oxidative browning and senescence. Particularly, forced-air precooling significantly inhibited the increase in MDA levels and cell membrane permeability, and inhibited lipid peroxidation of cell membranes to protect the cell structure. In addition, forced-air precooling maintained higher antioxidant enzyme activities, contributed to oxidative stress resistance and inhibited browning, hereby maintaining better storage quality. Principal component analysis further proved that forced-air precooling maintained higher storage stability and provided better preservation of jujube quality compared with vacuum precooling and cold storage precooling. In conclusion, forced-air precooling could effectively maintain the storage quality of jujube fruit and delay its ripening and senescence process.
Reviews
Recent Advances in Understanding Mechanism and Influential Factors of Color Formation in Fermented Vegetables
YANG Shan, WANG Wei, ZHAO Nan, HUANG Fude, ZENG Xueqing, LAI Haimei, MEI Yuan, ZHU Yongqing
2022, 43(23):  269-276.  doi:10.7506/spkx1002-6630-20220121-216
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Fermented vegetables originated in China’s Shang and Zhou Dynasties 3 100 years ago and are one of the traditional fermented foods in China. Color is one of the most important quality attributes of fermented vegetables. Fermented vegetables have a color different from that of fresh ones, which can be ascribed to chemical reactions and microbial metabolism during fermentation. Studying the mechanism of color formation in fermented vegetables is of great practical significance for improving product color. This paper summarizes recent research in this field, focusing on the effect of the color of fermented vegetables on their quality and the mechanism and influential factors of color formation in fermented vegetables. Future research trends are also discussed. This review could provide a theoretical basis for the quality control of fermented vegetables during large-scale industrial production.
Progress in Cross-Contamination Assessment of Listeria monocytogenes Biofilm
WANG Zhen, FANG Taisong, WANG Yuan, ZHAO Jiexiu, LI Zhuosi, QIN Xiaojie, WANG Xiang, DONG Qingli
2022, 43(23):  277-286.  doi:10.7506/spkx1002-6630-20211213-146
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Listeria monocytogenes (L. monocytogenes) is a food-borne pathogen causing listeriosis, a sickness with high hospitalization rate and high mortality rate, and it can adhere to food contact surfaces under various adverse conditions such as cold, heat, dryness and disinfectant to form biofilms that are hard to remove. Cross-contamination is the major transmission route of L. monocytogenes, and biofilm formation increases the possibility of persistent transmission and contamination of L. monocytogenes in factory and kitchen environments, which may lead to the outbreak of food-borne diseases and food recalls, causing health and economic loss. In this article, the extracellular polymeric components of L. monocytogenes biofilms are introduced, and the internal and external factors affecting the cross-contamination and transfer of L. monocytogenes biofilms are summarized. A particular focus is placed on the recent progress in research on 、L. monocytogenes cross-contamination from the perspectives of research type and bacterial collection. In addition, we summarizes the prevention and control strategies for L. monocytogenes in the early stage of biofilm formation. Finally, the future prospects of this research field are proposed. We hope that this review could provide a theoretical basis for the scientific evaluation and accurate early prevention and control of the potential risk of L. monocytogenes biofilm cross-contamination.
Progress in Understanding the Role of Probiotics in Alleviating Alzheimer’s Disease
JIA Longgang, WANG Yuanwang, FANG Wei, GENG Weitao, WANG Yanping
2022, 43(23):  287-295.  doi:10.7506/spkx1002-6630-20211231-356
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Currently, Alzheimer’s disease (AD) is a neurodegenerative disease with the largest number of patients and the widest range of impact in the world, and its pathogenic mechanism has not yet been fully understood. Emerging evidence has shown that the gut microbiota can regulate the development and health of the brain via gut-brain axis. Probiotics are a group of live microorganisms that maintain intestinal microecological balance. In recent years, probiotics and their metabolites or probiotic fermented foods have received great attention for their role in alleviating neurodegenerative diseases including AD. Herein, this paper reviews the progress in the past five years in the application of single-strain or multiple-strain probiotics, probiotic fermented foods, and probiotics combined with other drugs for alleviating AD, and expounds the relevant mechanisms and existing problems. We expect this review to provide new ideas for the application of probiotics in the prevention and treatment of AD.
Progress in Understanding the Structure, Biological Activity and Mechanism of Yam Polysaccharides
LIANG Shan, WANG Kun, LIU Peiyao, HE Xiaotong, ZOU Zebin, LI Pan, DU Bing
2022, 43(23):  296-304.  doi:10.7506/spkx1002-6630-20220106-047
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Yam is an important medicinal and edible plant, rich in various bioactive ingredients such as polysaccharides, allantoin and saponins. Yam polysaccharides have various functional properties like antioxidant, anti-aging, anti-tumor, immunoregulatory, hypoglycemic, and hypolipidemic effect, and are promising for application in the development of health foods and drugs. The structure of yam polysaccharides is complex, and the monosaccharide composition, molecular mass, glycoside and glycochain structure have great influence on the biological activity of yam polysaccharides. Therefore, exploring the structural characteristics of yam polysaccharides is of great significance to understand their bioactive mechanism. In this paper, the structural characteristics and bioactive mechanism of yam polysaccharides are introduced, and the relationship between their structural characteristics and biological activity is also discussed, in order to provide theoretical support for the application of yam in the fields of health foods and drugs.
Progress in Research on Secondary Metabolites and Biological Activity of Medicinal and Edible Citrus Plants
CAO Xiaomin, PAN Siyi
2022, 43(23):  305-315.  doi:10.7506/spkx1002-6630-20220627-302
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Some citrus plants are important medicinal and edible plants. Fructus aurantii, Fructus aurantii immaturus, finger citron, Zhique (the dried fruit of Citrus grandis × junos), Citri Grandis Exocarpium (the dried unripe or almost ripe exocarp of C. grandis ‘Tomentosa’ or C. grandis (L.) Osbeck and Guangchenpi (the dried pericarp of C. reticulata ‘Chachi’) are common medicinal and edible citrus plant products, rich in flavonoids, coumarins, alkaloids, limonoids and volatile oils and having a variety of biological activities, such as antioxidant, anti-inflammatory, hypolipidemic, anti-depressant, antitussive and expectorant activities. They are widely used in the fields of health products, food and medicine. However, they have different bioactive components and clinical efficacies. Nowadays, their bioactive components and clinical efficacies have not been systematically summarized and compared. The bioactive components and bioactivities of these citrus products are systematically compared in this article, in order to provide a theoretical basis for further research and rational utilization of medicinal citrus plant resources.
Progress in the Application of Maillard Reaction Modified-Casein in the Delivery of Bioactive Substances
ZHANG Jingjing, LI Aili, CHENG Jinju
2022, 43(23):  316-325.  doi:10.7506/spkx1002-6630-20211224-284
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Bioactive substances from foods are of great interest to researchers because of their excellent efficacy in health regulation and disease prevention. However, they are easily damaged by environmental conditions and extreme pH in the gastrointestinal tract and thus exhibits extremely low bioavailability in vivo, limiting their applications. Numerous studies have shown that casein modified with polysaccharides by the Maillard reaction has good functional properties and environmental stability and can be used as a delivery system for bioactive substances to improve their stability in the gastric environment and for their targeted release in the small intestine. This paper reviews the structure and properties of casein, the preparation methods for casein modified by the Maillard reaction, the types of casein modified by the Maillard reaction as a delivery vehicle for bioactive substances and its application in delivery systems for bioactive substances, and discusses the release characteristics of bioactive substances in simulated gastrointestinal digestion system. Besides, this article describes future prospects for the application of casein modified by the Maillard reaction in the preparation of delivery systems and discusses the problems to be solved in this field. Hopefully, this review will be helpful to enhance the bioavailability and utilization of food-derived bioactive substances.
Recent Progress in Extraction and Structural and Functional Properties of Banana Tannins
ZENG Xiangquan, LI Qianqian, JIANG Weibo, YANG Qian, XI Yu, LI Xuejie, LI Yan, HUI Bowen, LI Jian
2022, 43(23):  326-335.  doi:10.7506/spkx1002-6630-20220107-053
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As a subgroup of plant polyphenols, tannins have various biological activities, including antioxidant, anticancer and anti-inflammatory properties. Nowadays, tannins have been widely utilized in the food, pharmaceutical and leather industries. Bananas, one of the most widely consumed fruits in the world, are demonstrated to be rich in tannins. However, there have been few reviews of recent research on banana tannins. Most research on the extraction of banana tannins concentrates on solvent extraction, ultrasound-assisted extraction, microwave-assisted extraction and enzyme-assisted extraction. The chemical structure of banana tannins has been researched regarding their molecular mass distribution, degree of polymerization, chemical composition, structural units and linkage types. Most research on the functional properties of banana tannins focuses on their antioxidant, antibacterial, hypolipidemic and hypoglycemic activities, protective effects against pesticide-induced toxicity, metal-binding capacity and ultraviolet-absorbing capacity. Finally, future research directions are discussed, hoping to provide theoretical support for broadening the application of banana tannins in the food industry.
Physicochemical Properties and Physiological Functions of Citrus Dietary Fiber and Its Application in Foods: A Review of Recent Research
CHEN Guiting, HU Tan, XU Yang, XU Gang, TIAN Lei, WU Siyu, DAI Yiyi, PAN Siyi
2022, 43(23):  336-345.  doi:10.7506/spkx1002-6630-20220110-085
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Citrus fruit contains a variety of bioactive ingredients and is particularly rich in dietary fiber (DF) with values of 50.13–68.00 g/100 g dry base. Citrus dietary fiber has excellent physicochemical properties in terms of water-holding capacity, water-swelling capacity and oil-holding capacity, making it widely used in meat products, baked products and dairy products. In addition, citrus dietary fiber has been proven to play a positive role in preventing several diseases such as diabetes, obesity, cardiovascular diseases and intestinal diseases due to diverse functional properties. In this review, the molecular composition, chemical structure, physicochemical properties, physiological activities and food application of citrus dietary fiber are summarized in order to provide a theoretical basis for the development and comprehensive utilization of citrus dietary fiber.
Progress in Research on the Effect of Diet Structure and Nutritional Composition on Depression
XU Huihui, CHEN Xu, ZHAO Fang, MAO Ruoxi, WANG Wenli, CHENG Zhimei, ZHANG Yali
2022, 43(23):  346-355.  doi:10.7506/spkx1002-6630-20211228-317
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Depression is becoming the second biggest killer of mankind after cancer, with an estimated 340 million people worldwide suffering from this disease. Research reports have shown that diet affects depression. This paper reviews the effects of different dietary structures such as high protein diet, vegetarian diet, high-fat diet and ketogenic diet on depression, discusses the effect of nutritional components such as folic acid, dietary fiber, polyphenolic compounds, vitamins and polyunsaturated fatty acids in improving depression, and summarizes the three mechanisms by which dietary structures and nutritional components affect depression: by regulating the metabolism of monoamine neurotransmitters, the digestive tract and the intestinal flora, and neuroendocrine system. This article will provide new inspirations to prevent and interfere in depression through diet.
Research Progress on the Dual-Directional Immunoregulatory Effect of Different Polysaccharide Fractions from Lycium barbarum Fruit
TIAN Yang, GONG Guiping, LU Yu, HUANG Wenqi, LI Cheng, WANG Zhongfu, HUANG Linjuan
2022, 43(23):  356-366.  doi:10.7506/spkx1002-6630-20211126-327
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Lycium barbarum polysaccharides (LBP) are one of the major functional components in the fruit of Lycium barbarum, which have been demonstrated to exert immunomodulatory activity. Most of the existing studies are focused on the immunoenhancing effect of LBP, but in-depth research on its immunosuppressive effect is limited. This article reviews recent research on the immunoenhancing and immunosuppressive effects of different polysaccharide fractions extracted from Lycium barbarum fruit from different perspectives, like intestinal mucosa protection, intestinal flora changes, immune cells and the neuroendocrine immune system. The outcome of this review will be for the application of Lycium barbarum polysaccharides in antiviral therapy, antitumor therapy, vaccine development, immune-enhancing feed formulation and anti-allergic agents or food products.
Preparation and Bioactivity of Walnut Peptides: A Review
MEN Deying, DAI Jiahe, TANG Muguo, LIU Litong, TIAN Yang, TAO Liang
2022, 43(23):  367-376.  doi:10.7506/spkx1002-6630-20220126-272
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Walnut is an important woody oil crop. Walnut meal left after oil extraction is rich in high-quality protein, but it is underutilized, causing a waste of resources. Bioactive peptides derived from walnut meal protein have the potential for food development and are a promising ingredient in functional foods owing to their diverse bioactivities such as antioxidant, cardiovascular protective and memory improving activities. The effective utilization of walnut meal protein, for example by developing bioactive peptides is of great significance to realize the comprehensive utilization of walnut meal and to improve the added value of products. This review summarizes previous studies on the preparation, purification, identification and biological activity of walnut peptides in order to provide a theoretical basis for the high-value utilization of walnut meal protein resources and in-depth studies of walnut protein peptides.
Research Progress on Fruit Surface Wax Synthesis and Its Regulation by APETALA2/Ethylene-Responsive Factors
LI Dan, GUAN Junfeng, HAN Yanan
2022, 43(23):  377-385.  doi:10.7506/spkx1002-6630-20220116-149
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Wax plays an important role in maintaining good appearance, quality and nutrients of fruits, delaying fruit senescence and prolonging fruit shelf life. As an important plant hormone, ethylene participates in stress signaling responses and regulates the process of fruit growth, development, ripening and senescence. At present, the pathway of fruit wax synthesis and transport has been gradually clarified, and the wax synthase and transporter genes involved in this pathway have been gradually identified and verified. The expression of these genes may be regulated by ethylene and the ethylene signaling system. Therefore, this review focuses on summarizing recent progress in research on the synthesis and regulation of fruit wax, ethylene regulation of horticultural crop fruit wax synthesis, and the regulatory effect of APETALA2/ethylene-responsive factors (AP2/ERFs) on fruit wax synthesis in model plants, agricultural crops and horticultural crops, in order to provide useful information for understanding the structural genes and AP2/ERFs transcription factors involved in regulating wax synthesis.