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Table of Content

15 December 2020, Volume 41 Issue 23
Basic Research
Antioxidant and Acrolein Trapping Capacity of Myricetin-Acrolein Adducts
LU Yongling, ZHANG Dingmin, XIAO Liubang, LÜ Lishuang
2020, 41(23):  1-7.  doi:10.7506/spkx1002-6630-20200418-237
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Objective: To evaluate the antioxidant and acrolein (ACR) trapping activity of myricetin-ACR adducts, including mono-ACR (MA) and di-ACR (DA-1) adducts in comparison with those of myricetin. Methods: Total reducing power and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging capacity were determined by using ascorbic acid as a positive control. The Rancimat method was used to measure the effects of myricetin-ACR adducts on the oxidation induction time of oil. The ACR trapping activity of MA and DA-1 was investigated by high performance liquid chromatography (HPLC) with 2,4-dinitrophenylhydrazine as a derivatization reagent. Further, the inhibitory effect of the two adducts on the formation of ACR in an ovalbumin-glucose model, rapeseed oil and cake was investigated. Results: Both MA and DA-1 had strong total reducing power and DPPH radical scavenging capacity equivalent to or even higher than that of ascorbic acid in the concentration range of 0.01–0.1 mmol/L, prolonged the oxidation induction time of oil and slowed the rate of development of rancidity. The inhibition rates of MA and DA-1 on ACR were 80.5% and 60.7%, respectively, and could effectively inhibit the formation of ACR in ovalbumin-glucose model. MA and DA-1 could inhibit up to 43.4% and 34.5% of ACR in rapeseed oil, and up to 41.4% and 31.9% of ACR in cake, respectively. Conclusion: The myricetin-ACR adducts had strong antioxidant and ACR trapping capacity and could reduce the content of acrolein in food systems in a sustained and long-term manner.
Effect of Oxidation on Molecular and Physicochemical Properties of Mutton Myofibrillar Protein
ZHANG Hailu, HUANG Xiang, YANG Ran, AN Fengping, LU Jiankang, HUANG Qun
2020, 41(23):  8-14.  doi:10.7506/spkx1002-6630-20200615-197
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In order to investigate the effect of oxidation on the physicochemical and molecular properties of mutton myofibrillar protein, the carbonyl content, total sulfhydryl content, dimeric tyrosine content, surface hydrophobicity, ultraviolet absorption spectrum, endogenous fluorescence spectrum, Fourier transform infrared (FTIR) spectrum, particle size, and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) profile of myofibrillar protein samples with different oxidation durations were analyzed. The results showed that the carbonyl content, dimeric tyrosine content and surface hydrophobicity increased, while the total sulfhydryl content and fluorescence intensity decreased with the extension of oxidation time. Oxidation increased the particle size of myofibrillar protein and decreased the absolute value of Zeta potential. FTIR analysis showed some changes in the protein secondary structure when the oxidation time increased. The proportion of α-helix increased first and then decreased, the proportion of random coil did not obviously change, the proportion of β-sheet showed a decreasing trend, and the proportion of β-turn decreased first and then increased. SDS-PAGE indicated that oxidation caused cross-linking between protein molecules. The cystine content showed an increasing trend with prolonged oxidation time, while the reverse trend was seen for other amino acids.
Fluorescence Spectroscopic and Molecular Docking Studies of Interaction between [C4mim]BF4 or [C4Py]Cl Ionic Liquids and Papain
TIAN Kangyong, YANG Lüqing, HU Huihui, ZHANG Haide
2020, 41(23):  15-20.  doi:10.7506/spkx1002-6630-20191105-053
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Relevant studies have shown that ionic liquid aqueous two-phase extraction of papain gave a high extraction rate through simple operation, and the construction of a suitable ionic liquid aqueous two-phase system is a research hotspot for the extraction of papain. In view of this, this experiment studied the mechanism of the interaction between ionic liquid and papain through fluorescence quenching, molecular docking and the determination of the partition coefficient of papain in ionic liquid aqueous two-phase systems. Fluorescence quenching analysis showed that the ionic liquids [C4mim]BF4 and [C4Py]Cl could bind to papain with one binding site through hydrophobic interaction, forming a complex, and the quenching effect of [C4Py]Cl was higher than that of [C4mim]BF4. Further molecular docking results indicated that the binding site of [C4mim]BF4 was located in the hydrophobic pocket of the active region of papain and interacted non-covalently with many surrounding amino acid residues through hydrophobic interaction, van der Waals force and π-π interaction. According to the partition coefficient of papain in ionic liquid aqueous two-phase systems, the extraction efficiency of papain with [C4Py]Cl was better that with [C4mim]BF4 under the same conditions, which was consistent with the results of fluorescence spectroscopy and molecular docking. This study can theoretically guide the selection of suitable ionic liquids for aqueous two-phase extraction of papain.
Discrimination of Chilled Lamb from Different Carcass Parts at Different Storage Times Based on Mobile Phone Images
MENG Lingfeng, ZHU Rongguang, BAI Zongxiu, ZHENG Minchong, GU Jianfeng, MA Benxue
2020, 41(23):  21-26.  doi:10.7506/spkx1002-6630-20191104-041
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In order to realize the rapid identification of different cuts of chilled lamb at different storage times by using mobile phones, images of back, hind leg and front leg were collected over a storage time of 12 days. Color features such as the mean value in different color spaces and the color moments in the red, green and blue (RGB) color space were extracted and analyzed for significant differences, and 7 color features with significant differences among meat cuts were obtained. Considering the differences in color features among meat cuts as well as different color spaces, four combinations of color features were selected as the inputs for the extreme learning machine (ELM), back propagation (BP) and support vector machine (SVM) models, respectively, and modeling analysis and comparison were carried out to classify different lamb cut. The results showed that upon using each color feature combination as the model input, the classification performance of the BP model established was better than that of the SVM and ELM models. When the 12 color mean features were chosen as the input, the BP model showed the best classification performance with a discrimination accuracy of 96.13%, 95.11% and 91.44% for the training, cross-validation, and test set, respectively, allowing rapid discrimination of lamb cuts at different storage times. The research provides a theoretical basis and technical support for future development of mobile phone applications to rapidly discriminate chilled lamb cuts at different storage times.
Effect of Adding Heat-Moisture Treated or Dry-Heat-Treated Highland Barley Flour on the Quality of Noodles
XU Hanshan, LI Lin, CHEN Ling, ZHENG Bo
2020, 41(23):  27-34.  doi:10.7506/spkx1002-6630-20191016-148
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In this study, the effect of partial replacement of wheat flour with native and thermally processed whole grain highland barley flour on the quality of noodles was investigated by scanning electron microscopy and texture analyzer. Further, we examined the effect of addition of wheat gluten on improving the quality of noodles incorporated with highland barley flour. The results showed that the resistant starch content of highland barley flour was increased from 21.95% to 39.17% and 34.08% after heat moisture treatment and dry heat treatment, respectively. Decreasing the substitution level from 70% to 30% increased the microstructure compactness of noodles incorporated with native, heat-moisture-treated or dry-heat-treated highland barley flours, reduced the cooked breaking rate, and improved the cooking and texture properties. The cooking and texture properties of noodles incorporated with 50% highland barley flour and 5% wheat gluten were comparable to those of pure wheat flour noodles, confirming the feasibility of partially replacing wheat flour with heat-moisture-treated or dry-heat-treated highland barley flours in noodle making. This study provides a theoretical basis and basic data for developing high-quality, nutritious noodles incorporated with highland barley flour.
Correlation Analysis between Contents of Chemical Components in Different Rice Cultivars and Quality Characteristics of Cooked Rice
LI Zhifang, YAO Yijun, ZHANG Lei, WANG Lifeng
2020, 41(23):  35-41.  doi:10.7506/spkx1002-6630-20191029-327
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Rice is one of the most important food crops in China. The chemical components of rice vary greatly with production areas and varieties and have different effects on the processing quality of rice. In this study, 15 different rice cultivars were compared for differences in chemical components and processing quality, and the correlations of chemical components of rice with starch gelatinization properties and cooked rice texture were systematically analyzed. Further, we identified the characteristic components with the most significant impact on starch gelatinization properties and cooked rice texture. The results showed that significant differences existed among cultivars in the contents of total protein, albumin, globulin, gliadin, gluten and amylose, with variation coefficients of 10.84%, 30.33%, 12.36%, 18.12%, 26.18%, and 23.73%, respectively. Moreover, the contents of protein and starch were found to be the most important factors that determine starch gelatinization characteristics and cooked rice texture quality. This study provides theoretical data for rice processing suitability evaluation.
Analysis of the Quality and Suitability for Fresh Rice Noodle Processing of Rice at Different Storage Times
ZHANG Yurong, ZHOU Xianqing, PENG Chao, LI Jianfei
2020, 41(23):  42-48.  doi:10.7506/spkx1002-6630-20191217-193
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Objective: This study aimed to understand the difference in the quality of fresh rice noodles processed from rice with different storage times, so as to provide a basis for the selection of raw materials for fresh rice noodles. Methods: Totally 40 samples of indica rice and 40 samples of japonica rice with different storage times were selected to process fresh rice noodles, which were then tested for cooking loss rate, the rate of broken noodles during cooking, sensory score and texture parameters. Further, descriptive statistical analysis, analysis of variance, principal component analysis and cluster analysis were used to explore the processing quality of the two kinds of rice. Results: With the prolongation of storage time, the cooking loss rate of indica rice noodles showed a gradually decreasing trend, while that of japonica rice noodles showed a trend of first declining and then rising. For both rice types, the rate of broken noodles during cooking decreased first and then increased, the color and odor of rice noodles showed a decreasing trend, while the appearance, chewiness, smoothness, and total sensory score increased first and then decreased. The sensory quality of indica rice noodles was better than that of japonica rice noodles. The hardness and chewiness of both kinds of rice noodles showed an upward trend, reaching a significant level when the storage time was 4 years (P < 0.05), and the stickiness also showed an upward trend. There was no significant change in other texture indexes. Through cluster analysis, the quality of rice noodles was classified into three grades, and statistical analysis of the number of samples in each storage year demonstrated that indica rice was more suitable for fresh wet rice noodle processing than japonica rice, and the quality of noodles processed from indica rice stored for 3 years was the best.
Effect of Coagulation Temperature on Gelling Properties and Chemical Forces of Tofu Coagulated with Glucono-δ-lactone
JIN Yang, LIU Lisha, ZHANG Xiaofei, ZHANG Qing, BAI Jie, GUO Hong, PENG Yijiao
2020, 41(23):  49-55.  doi:10.7506/spkx1002-6630-20200602-027
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This study aimed to investigate the effect of coagulation temperature on gelling properties and molecular forces of tofu coagulated with glucono-δ-lactone. Through dynamic rheological and texture analysis, the dynamic viscoelastic properties and texture properties of tofu were studied during its coagulation process. The effect of coagulation temperature on chemical forces of tofu was explored by using a sequential extraction procedure. The results showed that with the increase in coagulation temperature, the elastic modulus (G’) and viscosity modulus (G”) increased rapidly. At 85 ℃, the coagulation reaction only took about 1.8 s to reach maximum gel strength and the final G’max was 143.5 kPa. Hydrophobic interaction, disulfide bonds, hydrogen bonds and ionic bonds were the major chemical forces in tofu. With the increase in coagulation temperature, the proportions of ionic bonds and hydrogen bonds decreased significantly, while the proportions of hydrophobic interactions and disulfide bonds increased. The chemical forces were significantly related to the textural properties of tofu gels. At higher coagulation temperature, the main chemical forces were hydrophobic interaction and disulfide bonds, and higher gel elasticity, hardness, adhesiveness and cohesiveness were obtained. This study provides theoretical support for the development of high temperature coagulated tofu processing technology.
Effect of ε-Polylysine on Cell Structure and Energy Metabolism of Saprophytic staphylococcus
LAN Weiqing, ZHANG Nannan, CHEN Mengling, XIE Jing
2020, 41(23):  56-62.  doi:10.7506/spkx1002-6630-20191112-155
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The effect of ε-polylysine (ε-PL) on the cell structure and energy metabolism of Saprophytic staphylococcus was investigated in this paper. The minimal inhibitory concentration (MIC) was determined by broth dilution method, and the impact of ε-PL on cell morphology was evaluated according to the growth curve, the activities of alkaline phosphatase (AKP) and adenosine triphosphatase (ATPase), electrical conductivity, ultraviolet (UV) absorbance and scanning electron microscope (SEM) observation. The impact of ε-PL on cell metabolism was investigated by cell protective enzyme activities such as peroxidase (POD) and catalase (CAT), tricarboxylic acid metabolic enzyme activities such as succinodehydrogenase (SDH) and malic dehydrogenase (MDH), and cell metabolic activity. The results showed that the MIC was determined to be 1.0 mg/mL. ε-PL was able to inhibit bacterial growth, destroy the integrity of the cell wall and increase the permeability of the cell membrane. SEM revealed that the bacterial cells were distorted and deformed with rough surfaces after being treated with ε-PL at MIC, while after being treated with ε-PL at 2 MIC, some cells were adhered to each other and obvious morphological damage was observed. The activities of ATPase, POD, CAT, SDH and MDH were significantly decreased by treatment with ε-PL in a concentration-dependent manner (P < 0.05), indicating ε-PL to be effective in inhibiting the energy metabolism of Saprophytic staphylococcus. Moreover, ε-PL could damage the morphology of bacterial cells, and alter the cell membrane permeability, thereby affecting bacterial growth and metabolism and finally causing bacterial death.
Activity and Mechanism of Perilla Essential Oil in Inhibiting Aspergillus glaucus
Yuan Kang, HU Zhenyang, CHEN Kexin, LU Chen, DU Lihui
2020, 41(23):  63-69.  doi:10.7506/spkx1002-6630-20191103-022
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Perilla essential oil (PEO) is a natural, healthy and highly effective plant essential oil which is widely used in the food industry. In this paper, the minimum inhibitory concentration (MIC) and minimum bactericidal concentration of PEO against Aspergillus glaucus in rice were studied. The antifungal activity of different concentrations of PEO was tested by measuring the dry mass of hyphae and percentage spore germination. The change of ergosterol content in the plasma membrane of Aspergillus glaucus was determined. The effect of PEO on the surface morphology of Aspergillus glaucus was observed by scanning electron microscope (SEM). The activity of mitochondrial ATPase was measured. The spores were stained with propidium iodide (PI) to detect the effect of PEO treatment on cell membrane integrity by flow cytometry. The change of functional groups in Aspergillus glaucus hyphae was detected by Fourier transform infrared spectroscopy (FTIR), and the antifungal mechanism of PEO was explored. The results showed that the MIC of PEO against Aspergillus glaucus was 0.5 μL/mL. The growth of Aspergillus glaucus was significantly inhibited by all concentrations of PEO, and the percentage spore germination rate and dry hyphal mass were decreased. The percentage of hyphal growth inhibition by PEO at 0.5, 1 and 2 MIC increased from 81.75% to 93.07%, and the ergosterol content decreased significantly with increase in essential oil concentration. Scanning electron microscopy showed that the PEO-treated myceliaof Aspergillus glaucus exhibited pits and pores. As the concentration of essential oil increased, the mycelia appeared to shrunken and distorted. PEO treatment decreased mitochondrial ATPase activity. PI staining indicated that the cell membrane integrity was reduced and the amount of stained spores increased with increase in PEO concentration. FTIR demonstrated significant changes in organic ligand groups in the mycelia in response to PEO treatment, suggesting damage to phospholipids, proteins and lipids.
Synergistic Antibacterial Mechanism of Phenyllactic Acid Combined with Acetic Acid against Listeria monocytogenes
NING Yawei, FU Yunan, HE Jianzhuo, SU Dan, HOU Linlin, WANG Zhixin, JIA Yingmin
2020, 41(23):  70-76.  doi:10.7506/spkx1002-6630-20191106-071
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Objective: To investigate the synergistic antibacterial activity and mechanism of phenyllactic acid (PLA) combined with acetic acid (ACE) against L. monocytogenes. Methods: The double broth dilution method was used to measure the minimum inhibitory concentration (MIC) and the fractional inhibitory concentration index. The time-killing curve was constructed by plate counting method. The antibacterial mechanism was studied by measuring Zeta potential, membrane depolarization, membrane integrity, cell morphology and DNA damage. Results: The MICs of PLA and ACE were 2.25 and 1.75 mg/mL, respectively, and the fractional inhibitory concentration index of PLA in combination with ACE was 0.5, suggesting that combination of PLA (1/4 MIC) and ACE (1/2 MIC) can exert a synergistic effect against L. monocytogenes. Zeta potential results showed that PLA and/or ACE effectively changed the cell surface charge. DiSC3(5) fluorescent probe labeling results indicated that PLA and ACE could dissipate membrane potential. Flow cytometry and fluorescence microscopy analysis showed that PLA, ACE and their combination could disrupt cell membrane integrity. After treatment with PLA at MIC, ACE at MIC or PLA (1/4 MIC) plus ACE (1/2 MIC), L. monocytogenes cells became deformed and adhered together, and the contents leaked out. Gel electrophoresis images showed that PLA and ACE could damage DNA. Conclusion: Combination of PLA and ACE shows a synergistic antibacterial activity by reducing cell surface charge, causing membrane depolarization, destroying the integrity of the cell membrane and consequently entering into the cells to interact with DNA, and finally lead to cell death. This investigation can provide a theoretical basis for applying PLA in food preservation.
Structural Properties of Starches from Various Root Crops and Their Effect on Vermicelli Quality
ZOU Jinhao, LI Yan, OUYANG Huafeng, GUO Shiyin, SU Xiaojun, SONG Yong, LI Qingming
2020, 41(23):  77-82.  doi:10.7506/spkx1002-6630-20191123-271
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The microstructure, particle size, molecular structure and crystalline structure of tapioca starch (from the cultivars SC9, SC205 and LMC), sweet potato starch (from the cultivar XSSP) and yam starch (from the cultivars GY2, SFY and MPY) were studied, and the correlation between starch structural properties and vermicelli quality was analyzed. The results showed that the root crops significantly differed in the microstructure, granule size, molecular structure and crystalline structure of starch. The granule size, 1 045 cm-1/1 022 cm-1 peak intensity ratio and crystallinity of yam starch were larger than those of tapioca starch and sweet potato starch. Starch structural properties had significant effects on the quality of vermicelli. Starch granule size was positively correlated (P < 0.05) with swelling index of vermicelli. Root-mean-square rotation radius (Rg) was significantly positively correlation with breaking rate (P < 0.01) and swelling index (P < 0.05) of vermicelli, but negatively correlated with comprehensive evaluation score (P < 0.05). Polydispersity coefficient was significantly negatively correlated with hardness (P < 0.05), but positively correlated with tensile work of vermicelli (P < 0.05). There was a significant negative correlation between 1 045 cm-1/1 022 cm-1 peak intensity ratio and cohesiveness of vermicelli (P < 0.01). Starch granule size, Rg, polydispersity coefficient, and 1 045 cm-1/1 022 cm-1 peak intensity ratio had a significant impact on the quality of vermicelli. This study provides theoretical reference for the selection of raw materials for vermicelli and quality improvement.
Antioxidant and Antibacterial Activities of β-Acid Homologue Mixtures with Different Ratios from Hops
YANG Jingwen, LIU Zechang, CHEN Pei, DU Weidong, FAN Xiaolan, SHI Ming, LIU Yumei
2020, 41(23):  83-90.  doi:10.7506/spkx1002-6630-20191112-157
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Hops soft resin contains three homologues of β-acids: co-, n- and ad-lupulone, and the ratio among these homologues varies depending on hops varieties. In this experiment, five β-acid homologue mixtures were obtained from the crude β-acid from hops by crystallization, and their antioxidant activity in vitro were investigated comparatively by measuring the inhibitory activity against xanthine oxidase, 1,1-diphenyl-2-picrylhydrazyl (DPPH) and OH radical scavenging activity, total antioxidant activity and inhibition zone diameter. The results showed that the antioxidant activity of these β-acid homologue mixtures were significantly different. Among them, the 1:4 mixture of co-lupulone with n-lupulone + ad-lupulone possessed the strongest antioxidant activity, indicating that the antioxidant activity of n-lupulone + ad-lupulone was stronger than that of co-lupulone. At high concentrations (≥ 40.00 mg/L), mixtures with higher proportion of co-lupulone had stronger antibacterial activity. The antibacterial activity of all samples except the 1:4 mixture of co-lupulone with n-lupulone + ad-lupulone at a concentration of 160.00 mg/L was similar to or even stronger than that of amoxicillin. The sample with the highest proportion of n + ad-lupulone showed the lowest minimum inhibitory concentration (5.00 mg/L) against Staphylococcus aureus. In addition, although the minimum inhibitory concentrations of all samples against Escherichia coli were equally 10.00 mg/L, this one exhibited a bigger diameter of inhibition zone.
Identification of Dominant Peptides from Hydrolyzed Tuna Dark Muscle and Their Antioxidant and Angiotensin-Converting Enzyme Inhibitory Activities
WANG Rui, ZHANG Diya, LI Ye, SU Xiurong
2020, 41(23):  91-99.  doi:10.7506/spkx1002-6630-20191102-015
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In order to obtain highly bioactive peptides and to achieve high-valued utilization of aquatic product proteins, this study determined the optimal conditions for the hydrolysis of tuna dark muscle by a mixture of trypsin and alcalase using combination of one-factor-at-a-time method and response surface methodology. The molecular mass of peptides in the prepared hydrolysate was measured by matrix-assisted laser desorption/ionization time-of-flight tandem mass spectrometry (MALDI-TOF MS/MS), and the functions of the dominant peptides were predicted using the CDocker module in Discovery Studio. The 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging capacity and angiotensin-converting enzyme (ACE) inhibitory activity of the peptides synthetized in vitro were compared with those of the hydrolysate. The optimal processing conditions that provided maximal degree of hydrolysis of 61.01% were determined as 1:1, 1:4, 51 ℃, 2% and 5 h for mass ratio between the two enzymes, solid-to-liquid ratio, hydrolysis temperature, enzyme concentration and time, respectively. Molecular docking showed that the dominant peptides VSSK and EPR could separately bind to Kelch-like ECH-associated protein 1 (Keap1) and ACE to exert antioxidant and hypotensive effects, respectively. Further, in vitro tests showed that the half maximal inhibitory concentration (IC50) values of the hydrolysate, VSSK and EPR were 0.204, 3.050 and 3.368 mg/mL for DPPH radical scavenging activity; and 2.321, 2.914 and 4.857 mg/mL for ACE inhibitory activity, respectively. These data illustrated that the hydrolysate had stronger antioxidant and hypotensive effects. The results of this study provide a theoretical basis for the high-value utilization of tuna dark muscle.
Combined Antimicrobial Effect and Mechanism of Antimicrobial Peptide from Grass Carp Scale and Cinnamon Essential Oil
WANG Xueyan, CHEN Ying, ZHANG Jiamin, SHI Yongqing
2020, 41(23):  100-106.  doi:10.7506/spkx1002-6630-20191106-079
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In this study, tricine-sodium dodecyl sulfate-polyacrylamide gel electrophoresis (TSDS-PAGE) was used to determine the molecular mass of an antimicrobial peptide from grass carp scale. Chessboard dilution method was used to determine the combined antimicrobial effect of the peptide and cinnamon essential oil on common foodborne pathogenic bacteria, and the growth curves, cell membrane permeability, and extracellular lactate dehydrogenase activity of the tested strains when exposed to combinations of the two antimicrobials were measured. In addition, flow cytometry was used to analyze the membrane penetration efficiency. The results showed that combination of the peptide, with a molecular mass of 14.3 kDa, and cinnamon essential oil exerted a synergistic effect against Staphylococcus aureus, Vibrio parahaemolyticus and Penicillium chrysogenum and additive effect against Salmonella choleraesuis, Escherichia coli, Aspergillus niger, Mucor wutungkiao, Rhizopus and Saccharomycetes, but had no antagonistic effect on all tested bacteria. Through flow cytometry analysis, it was found that the membrane penetration efficiency of the antimicrobial combination was 72.76% for Staphylococcus aureus, 61.56% for Penicillium chrysogenum, and 51.04% for Vibrio parahaemolyticus, all of which were significantly higher than those of either antimicrobial alone. The antimicrobial mechanism may be by shortening the logarithmic growth period, accelerating the occurrence of the decline period, changing the permeability of the cell membrane, and consequently leading to leakage of intracellular electrolytes and lactate dehydrogenase and subsequent cell death.
Food Engineering
Effect of Ultrasonic-Assisted Immersion Freezing on the Quality of Pork Dumpling Filling
WU Yutong, ZHANG Chao, KONG Baohua
2020, 41(23):  107-113.  doi:10.7506/spkx1002-6630-20191123-267
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This study investigated the effects of ultrasound-assisted immersion freezing (UIF) under different ultrasonic powers on the freezing rate and quality of pork dumpling filling. The results showed that UIF significantly (P < 0.05) increased the freezing rate, and the sample treated with ultrasonic power of 90 W (UIF-90) took the shortest time to freeze. Compared with air freezing, UIF showed significantly lower levels of oxidation and cooking loss (P < 0.05). As the ultrasonic power increased, the L* and a* values increased first and then decreased, while no significant differences were observed in b* value (P > 0.05). The T21 and T22 relaxation times of the UIF-90 sample were the shortest, indicating that proper ultrasonic power levels could reduce the mobility of free water and immobilized water. To sum up, UIF significantly reduces the freezing time of pork dumpling filling at an appropriate ultrasonic power (P < 0.05) and improves the quality of meat filling.
Effect of High Hydrostatic Pressure Treatment on Morphological, Thermal and Rheological Properties of Oat Starch
ZHANG Jing, ZHANG Meili
2020, 41(23):  114-121.  doi:10.7506/spkx1002-6630-20190908-106
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The properties of starch directly affect the appearance and eating quality of starch-based foods. In order to investigate the effect of high hydrostatic pressure (HHP) treatment on the properties of oat starch, changes in the morphological, textural, thermal and rheological properties of oat starch were determined after being treated under pressures of 100–600 MPa for 30 mins. The results showed that after HHP treatment at pressures of 100–300 MPa, the average particle size of oat starch granules decreased without significant changes in the surface morphology. In contrast, the particle size increased and the granule surfaces became rough, collapsed and adhered together after HHP treatment at 400–600 MPa. HHP treatment could significantly reduce the hardness, gumminess and chewiness of starch gels, and increase the resilience, springiness and cohesiveness. Differential scanning calorimetric (DSC) analysis indicated that starch gelatinization occurred after treatment at 500 or 600 MPa. The dynamic rheological studies revealed that the G’, G’’ and tan δ values of HHP treated starch paste were significantly higher than those of the original starch, indicating that this treatment enhanced the viscoelasticity of starch, and after treatment at 100 MPa, starch showed the best viscoelasticity. In the static rheological studies, both raw and treated starch were pseudo-plastic fluids. HHP treatment at 500 or 600 MPa reduced the thixotropy loop area and greatly improved the shear stability. This study will provide theoretical reference for research on the effect of ultrahigh pressure on starch properties.
Effect of Low-Frequency and High-Intensity Ultrasound Treatment on Characteristics of Chicken Breast Myofibrillar Protein
LI Ke, LI Sanying, FU Lei, ZHAO Yingying, ZHANG Yanyan, ZHAO Dianbo, BAI Yanhong
2020, 41(23):  122-129.  doi:10.7506/spkx1002-6630-20191205-067
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This study investigated the stability and interfacial tension of soybean oil emulsions stabilized by chicken breast myofibrillar protein (MP) subjected to ultrasonic treatment (frequency of 20 kHz, power of 450 W, and intensity of 30 W/cm2) for different durations (0, 3 and 6 min), as well as the zeta potential, solubility, turbidity, viscosity, sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) profile, secondary structure and morphplogical structure of the treated MP samples. Also, this study explored the mechanism by which ultrasonic treatment may improve the emulsifying properties of MP. The results showed that ultrasonic treatment reduced the Turbiscan stability index (TSI) and interfacial tension of the MP-stabilized emulsions. The solubility and the absolute value of zeta potential were increased significantly (P < 0.05), while the turbidity and viscosity were significantly reduced by ultrasonic treatment (P < 0.05). SDS-PAGE analysis showed that ultrasonic treatment had no effect on protein bands. Circular dichroism (CD) spectroscopy showed that the content of ordered α-helices in MP was significantly decreased, while the contents of loose β-turn, β-sheet and random coil were significantly increased (P < 0.05). Atomic force microscopy (AFM) showed that the structure of MP was destroyed, the morphology was characterized by dispersed particles with smaller particle size, and the surface roughness was significantly reduced. These results indicated that the low-frequency and high-intensity ultrasonic treatment made the MP structure more disordered, promoting the breakup of MP aggregates to form small soluble ones. Moreover, it enhanced the electrostatic interaction and fluidity, enabling the protein to quickly adsorb oil droplets during the emulsification process and consequently reducing the oil-water interfacial tension and enhancing the emulsion stability. This study provides a theoretical basis for the application of ultrasonic in the processing of emulsified meat products.
Effect of Ultrasonic Modification on Physicochemical Properties and Structure of Oat Dietary Fiber
NIU Xi, SHI Qiankun, ZHAO Chengbin, YIN Huanhuan, XU Xiuying, WU Yuzhu, CAO Yong, ZHANG Hao, LIU Jingsheng
2020, 41(23):  130-136.  doi:10.7506/spkx1002-6630-20191118-201
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This study investigated changes in the physicochemical properties and structural characteristics of oat dietary fiber before and after ultrasonic treatment. Results showed that the water-holding capacity, water-swelling capacity and oil-holding capacity of oat dietary fiber were significantly improved by ultrasonic treatment. Particle size and scanning electron microscopic analysis showed that ultrasonic treatment reduced the particle size and loosened the surface structure, resulting in the appearance of honeycomb-like pores. X-ray diffraction and Fourier transform infrared spectroscopy analysis showed that the relative crystallinity of oat dietary fiber increased after ultrasonic modification, being partially redistributed and transformed into soluble dietary fiber. Differential scanning calorimetry (DSC) analysis showed that the thermal enthalpy (ΔH) of oat dietary fiber significantly increased after ultrasonic modification, indicating its improved thermal stability. Therefore, ultrasonic treatment can be used as an excellent method to modify dietary fiber, which will help to improve the utilization rate of oat dietary fiber and to further explore its nutritional value.
Effects of Different Thawing Methods on the Quality of Frozen Horse Mackerel
WANG Xuesong, XIE Jing
2020, 41(23):  137-143.  doi:10.7506/spkx1002-6630-20191105-050
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In order to improve the quality of frozen-thawed horse mackerel, frozen fish were thawed by five different methods (refrigerator thawing, ?owing water thawing, ultrasonic-assisted flowing water thawing, ultrasonic-assisted still water thawing and microwave thawing) in this study, and the changes in physicochemical indicators including water-holding capacity, color, texture, metmyoglobin (MetMb) content, malondialdehyde (MDA) content, total sulfhydryl content and protein tertiary structure were analyzed. The water mobility in fish was investigated by pulsed nuclear magnetic resonance spectroscopy, and the microstructure of fish tissue was observed by optical microscopy. The results showed that frozen fish maintained good water-holding capacity and color after refrigerator thawing, and its muscle tissue remained intact to the greatest extent. Refrigerator thawing could effectively alleviate the oxidation of protein and fat, but was the most time-consuming. Ultrasonic-assisted flowing water thawing was completed within 10 minutes, being suitable for large-scale thawing. Compared with the other thawing methods except refrigerator thawing, ultrasonic-assisted flowing water thawing could effectively slow down the oxidation of fish protein and fat, and better maintain the quality of fish.
Preparation of Green Coffee Oil Microcapsules by Complex Coacervation Method and Its Physicochemical Properties
TAN Rui, SHEN Jin, DONG Wenjiang, ZHANG Zhong, LONG Yuzhou, HU Rongsuo, CHEN Zhihua, JIANG Kuaile
2020, 41(23):  144-152.  doi:10.7506/spkx1002-6630-20191128-273
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In this paper, microcapsules were prepared by complex coacervation method using gelatin (G) combined with arabic gum (GA), pectin (P) or sodium hydromethyl cellulose as the wall material and green coffee oil as the core material. The effects of the three wall material combinations on the morphology, moisture, yield, microencapsulation efficiency, particle size and structure of green coffee oil microcapsules were studied. Results showed that the as-prepared empty microcapsules and green coffee oil microcapsules were?spherical?and?intact with uniform distribution under optical microscopy and revealed yields and microencapsulation efficiencies of 90.0% and 85.0%, respectively, but they had different utilization rates of wall materials, with the highest value being observed for G/P combination (76.6%). Fourier transform infrared spectroscopic (FTIR) analysis confirmed that the interaction between gelatin and each of the polysaccharides was through electrostatic interaction rather than chemical interaction. The condensation reaction only took place between the wall materials, and no other chemical reaction occurred between the core material and the wall materials. The curve-fitting of amide I bands in the FTIR spectra demonstrated that the relative contents of β-sheet and random coil in the coacervates were reduced, whereas the relative contents of α-helix and β-turn were increased. Thermal gravimetric analysis revealed that the thermal stability of the complexes was related to that of the wall materials, and the gelatin/sodium carboxymethyl cellulose (CMC) complex had the best thermal stability; microencapsulation with this wall material significantly increased the thermal stability of coffee oil. This study can supply a theoretical basis and technical support for high-valued application of green coffee oil.
Effect of Drying Temperature on Drying Efficiency, Energy Consumption and Flavor Quality of Xiangcha, a Kind of Green Tea
LIN Zhiyuan, SHI Jiang, TAN Junfeng, LIN Zhi
2020, 41(23):  153-158.  doi:10.7506/spkx1002-6630-20191201-001
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Temperature is the most significant parameter in the drying process of Xiangcha, a kind of green tea. In this study, tea samples were prepared at various drying temperatures (90, 110, 130 and 150 ℃). During the drying process, changes in moisture content and leaf temperature were monitored continuously. Energy consumption and flavor composition were analyzed at the end of drying. The results indicated that drying temperature differently influenced the drying efficiency, energy consumption and aroma composition of tea. Higher drying temperature accelerated the rate of water loss and the highest drying efficiency was obtained at a drying temperature of 150 ℃. Both excessively high (150 ℃) and excessively low (90 ℃) drying temperature were not beneficial for energy saving. The lowest energy consumption was found upon drying at 130 ℃, which was reduced by approximately 1/4 when compared with those at 150 and 90 ℃. The amount of total aroma components in tea dried at higher temperature (150 and 130 ℃) was significantly higher than in tea dried at lower temperature (110 and 90 ℃) (P < 0.05). The contents of linalool with floral and citrus-like aroma, geraniol with floral and rosy aroma, phenylacetaldehyde with floral and chocolate-like aroma, and furfural with baked aroma were 35%, 20%, 64% and 36% higher at 150 ℃ than at 90 ℃, respectively. On the basis of the best compromise among drying efficiency, energy consumption and flavor quality, the optimal drying temperature was 130 ℃.
Nutrition & Hygiene
Effects of Soybean Cultivars on Nutrient Composition and Quality of Sufu Fermented by Mucor
MU Delun, WU Rina, CUI Liang, YANG Hui, SUN Xueting, ZHU Xinyuan, WU Junrui
2020, 41(23):  159-165.  doi:10.7506/spkx1002-6630-20191113-167
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Although there are many kinds of sufu available in the market nowadays, the quality of sufu varies from inferior to superior. There are few studies reported in the literature on the correlation between soybean cultivars and the quality of sufu. In this study, soybean seeds of nine cultivars were measured for protein content, fat content, moisture content, 100-grain mass, diameter and color. The taste and flavor characteristics, texture properties, protein, fat and moisture contents, yield and color of Mucor fermented sufu made from each cultivar were determined by gas chromatograph-mass spectrometry, an electronic tongue, a texture analyzer and conventional analysis methods. Then correlation analysis and cluster analysis were used to explore the effects of soybean cultivars on the quality of sufu. The results showed that the nutrition and physical properties of sufu were significantly different among the cultivars. The protein content of soybeans was significantly positively correlated with the protein content (r = 0.965), yield (r = 0.761) and elasticity (r = 0.748) of sufu. The fat content of soybean was significantly negatively correlated with the protein content and yield of sufu (r = ?0.713 and ?0.721, respectively). The 100-grain mass of soybean was significantly negatively correlated with the salty taste of sufu (r = ?0.679) but significantly positively correlated with the acidity (r = 0.775). The yellowness of soybean was positively correlated with that of sufu (r = 0.705). ‘Liaodou 66’ and ‘Handou L2’ were found to be more suitable for sufu processing. This study provides reference for the processing of high-quality sufu.
A Risk Assessment Method for Total Bacterial Count in Wheat during Storage Based on Monte Carlo Simulation
WANG Xiaoyi, CHEN Qian, ZHAO Zhiyao, XIONG Ke, SHI Ce, PEI Penggang
2020, 41(23):  166-171.  doi:10.7506/spkx1002-6630-20190927-337
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Wheat is an important food crop, and research on food safety issues regarding wheat is of great significance. In the wheat supply chain, wheat storage has a high risk of producing biological hazards, and the risk level should be effectively monitored for early-warning. Development of risk assessment techniques is being strongly promoted to assess potential health risks associated with direct exposure to biological, chemical or physical hazards in foods. Considering the advantages and disadvantages of the existing qualitative and quantitative risk assessment methods and the lack of reasonable risk assessment metrics, a comprehensive risk assessment method for biological hazards was explored based on total bacterial count during wheat storage. First, a dynamic bacterial growth model that can adapt to different growth environments was established. Then, Monte Carlo simulation was used to quantitatively predict the distribution characteristics of total bacterial count during wheat storage. Finally, “hazard degree” was proposed as a metric for risk evaluation and used to quantitatively estimate the risk of total bacterial count during wheat storage. The proposed risk assessment method can provide real-time and intuitive risk assessment results for risk management and decision making authorities, and offer theoretical support for risk prevention and control.
Inhibitory Effect of Glucosinolates from Brassica juncea var. integlifolia on HCT116 Human Colon Cancer Cells
TIAN Yan, DENG Fangming, ZHAO Lingyan, LIAO An, LAI Dengni, CHEN Qiujia
2020, 41(23):  172-180.  doi:10.7506/spkx1002-6630-20200223-245
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In this study, we determined the content of total glucosinolates in fresh Brassica juncea var. integlifolia by UV spectrophotometry, identified the structures of glucosinolates by high performance?liquid chromatography of quadrupole time of flight-tandem mass spectrometry (HPLC-Q-TOF-MS), and evaluated the effects of glucosinolates extracted from Brassica juncea var. integlifolia on the proliferation and apoptosis of human colon cancer cell line HCT116 by flow cytometry, Western blot and quantitative real-time PCR. The results showed that the content of total glucosinolates in fresh Brassica juncea var. integlifolia was 15.45 mg/g. Three major glucosinolates were identified from the extract (the total glucosinolates content was 73.7%) including 2-allyl glucosinolate, 4-methyl thiobutyl glucosinolate and 4-methoxy 3-indolemethyl glucosinolate. The glucosinolate extract had no inhibitory effect on normal human colonic myofibroblasts CCD-18Co cells, but led to cell cycle arrest in HCT116 cells by down-regulating cell cycle genes and related signaling proteins (cyclin B, cyclinD1, and led to the apoptosis of HCT116 cells cyclinE) by up-regulating apoptotic genes and related signaling proteins (caspase-3, and cleaved caspase-3), thereby inhibiting cell proliferation.
Packaging & Storage
Preservation Effect of in-Situ Synthetic Nano-SiOx/Lysozyme/Teapolyphenols/Chitosan Composite Coatings on Sea Bass Fillets
WU Jiao, YANG Hua, ZHANG Jiatao, ZHANG Ran, SUN Tong, XIE Jing, GUO Xiaohua, YU Jianyang, LI Jianrong
2020, 41(23):  181-189.  doi:10.7506/spkx1002-6630-20191026-293
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Composite coating films with good preservation performance were prepared by a casting method based on the modification of chitosan (CS) as the film-forming matrix by in-situ synthetic nano-SiOx with the addition of lysozyme (LZM) and tea polyphenol (TP) as additives, and they were characterized by Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD) and scanning electron microscopy (SEM). Meanwhile, their physicochemical properties were determined. The preservation effect of the coatings was evaluated on sea bass fillets. The results showed that the addition of nano-SiOx, LZM and TP increased intermolecular interactions in CS coatings, resulted in a more compact structure, and improved the microstructure and physicochemical properties. After being modified by nano-SiOx, the preservation performance of CS coatings was enhanced, extending the shelf life of fish fillets by 3–4 days compared with the untreated fish fillets. After adding LZM or TP to the modified SiOx/CS coatings, the preservation performance was further improved, inhibiting the increase in the total number of colonies, pH, thiobarbituric acid (TBA) value, K value, and total volatile basic nitrogen (TVB-N) content in fish fillets, and slowing the changes in texture properties, and consequently extending the shelf life by 4–7 days compared with the untreated fish fillets. The best preservation performance was obtained upon their addition together, extending the shelf life by 8–10 days. Therefore, the in-situ synthetic nano-SiOx/LZM/TP/CS coatings had improved physicochemical and preservation performance, and could be potential for applications in the field of food preservation.
Effect of Ozone Micro-nano-bubble Treatment on Postharvest Preservation of Spinach
WANG Xueqing, ZUO Jinhua, YAN Zhicheng, SHI Junyan, WANG Qing, GUAN Wenqiang
2020, 41(23):  190-196.  doi:10.7506/spkx1002-6630-20191102-014
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In order to explore the effect of ozone micro-nano-bubbles (MNBs) on the postharvest quality of fruits and vegetables, spinach was treated with 4 mg/L ozone MNBs for 5 min and stored at (20 ± 1) ℃ for 8 d. By measuring and analyzing the changes of physiological indexes during storage, the effect of this treatment on the quality of spinach was studied. The results showed that ozone MNB treatment could effectively alleviate cell membrane damage, reduce the accumulation of malondialdehyde (MDA) and maintain the integrity of cell structure. This treatment could inhibit respiration and ethylene release and slow down the consumption of nutrients and the senescence process, thereby improving the storability of spinach. It also could delay the loss of chlorophyll and vitamin C, reduce the deterioration of sensory quality and nutrient quality of spinach, and alleviate oxidative damage by reducing the accumulation of hydrogen peroxide and enhancing peroxidase, catalase and ascorbic acid peroxidase activity. To sum up, ozone MNBs can preserve the quality of spinach with a low mechanical damage, and the experimental results from this study provide a theoretical basis for the application of ozone micro-nano-bubbles in the preservation of postharvest fruits and vegetables.
Effect of Tree-Hanging Pre-storage on Postharvest Storability and Cold Sensitivity of ‘Xuxiang’ Kiwifruits
QU Wei, GAO Meng, RAN Bian, LI Huan, SHU Xueyao, RAO Jingping
2020, 41(23):  197-204.  doi:10.7506/spkx1002-6630-20191104-027
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To evaluate the effect of tree-hanging pre-storage on the postharvest storability and cold sensitivity of kiwifruits, pre-stored ‘Xuxiang’ kiwifruits (Actinidia deliciosa) with different tree-hanging times were harvested and cold stored on the same day. Normal fruits stored under the same conditions as above were taken as the control group. The results showed that tree-hanging pre-storage reduced the hardness and starch content of kiwifruits at harvest, and resulted in earlier appearance of the respiratory and ethylene peaks, but reduced the respiratory peak. Tree-hanging pre-storage could improve the content of soluble solids in freshly harvested fruits, significantly reduce the content of titratable acids during storage as well as mass loss at the end of storage (P < 0.05), and shortened the shelf life to varying degrees, and the effect was more significant with increasing tree-hanging time. Fruits pre-stored for one week showed higher pulp L* value over the storage period, VC content at the end of storage, and sensory evaluation scores than any other treatment group and was not significantly different from the control group. Moreover, this group exhibited the longest shelf life, lowest chilling injury rate at the end of storage, and the highest catalase (CAT) and superoxide dismutase (SOD) activities. Therefore, tree-hanging pre-storage for one week can effectively maintain the storability and quality and reduce the cold sensitivity of kiwifruits, helping to alleviate the stress of coincidence between harvest and putting on the market.
Effect of 1-Methylcyclopropene Treatment on Respiration Rate and Reactive Oxygen Species Metabolism during Postharvest Storage of ‘Younai’ Plum Fruit
LIN Jingying, LI Hui, YUAN Fang, LIN Yuzhao, LIN Hetong
2020, 41(23):  205-211.  doi:10.7506/spkx1002-6630-20200302-031
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The effect of 1-methylcyclopropene (1-MCP) treatment on respiration rate and reactive oxygen species (ROS) metabolism during postharvest storage of ‘Younai’ plum (Prunus salicina Lindl. cv. Younai) fruit was investigated in the present study. Freshly harvested fruit were treated with 1.2 μL/L 1-MCP, and then stored at (25 ± 1)℃. The results showed that compared with the untreated control, 1-MCP treatment effectively reduced respiration rate, the production rate of superoxide anion radical (O2-·), and the content of malondialdehyde (MDA, a product of membrane lipid peroxidation), and maintained higher activities of ROS scavenging enzymes including superoxide dismutase (SOD), peroxidase (POD), catalase (CAT) and ascorbate peroxidase (APX), and higher contents of endogenous antioxidant substances such as total phenols, ascorbic acid (AsA) and glutathione (GSH) in ‘Younai’ plums during postharvest storage. Therefore, 1.2 μL/L 1-MCP treatment could effectively reduce fruit respiration rate, increase ROS scavenging capacity, reduce ROS accumulation and suppress membrane lipid peroxidation, consequently improving the storability and extending the storage period of harvested ‘Younai’ plum fruit.
Effect of Chitosan-Tea Polyphenols Composite on Microbiota Composition and Quality of Penaeus vannamei during Refrigerated Storage
GAN Hui, MI Qiang, WEI Kaili, YANG Mingwei, LU Xiaohua, CHEN Shifu, LÜ Min, MA Huawei
2020, 41(23):  212-220.  doi:10.7506/spkx1002-6630-20191010-067
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Microbial spoilage is one of the most important causes of decline in the quality of aquatic products during processing and storage. In order to elucidate the microbiota composition and quality of Penaeus vannamei treated by chitosan-tea polyphenols composite during refrigerated storage, shrimp samples were treated with 3 g/100 mL chitosan + 3 g/100 mL tea polyphenols (CP), and 3 g/100 mL chitosan (CH), 3 g/100 mL tea polyphenols (TP) or sterile water (CG) and then stored at 0 ℃ for 8 days. The microbial flora was investigated by high throughput Illumina-MiSeq 16S rRNA sequencing, and changes in sensory attributes, total volatile basic nitrogen (TVB-N) content, ATP complex content, K value, biogenic amine content and total viable count (TVC) were measured. The sensory shelf-lives of CG, TP, CH and CP treatments were 5, 7, 7 and 8 days, respectively. At the end of shelf life, Pseudoalteromonas, Candidatus Bacilloplasma and Psychromonas were the dominant spoilage bacteria in CG treatment, while Pseudoalteromonas, Psychromonas, Candidatus Bacilloplasma and Aliivibrio were the dominant spoilage bacteria in CP treatment. Aliivibrio, Moritella and Pseudoalteromonas were the dominant spoilage bacteria in both CH and TP treatments. The preservative treatments affected the microbiota and consequently chemical quality attributes. Compared with CH and TP, CP showed lower TVB-N, putrescine, cadaverine and hypoxanthine contents over the entire storage period but higher contents of inosine 5’-monophosphate and hypoxanthine riboside at the late stage of storage. In conclusion, chitosan-tea polyphenols composite preservative altered the microbiota composition and delayed quality deterioration of P. vannamei during refrigerated storage at 0 ℃.
Antibacterial Effect and Mechanism of Antimicrobial Peptide PAF26 on Monilinia fructicola in Postharvest Plums
CAI Die, LI Xindan, DENG Lili, ZENG Kaifang
2020, 41(23):  221-227.  doi:10.7506/spkx1002-6630-20191231-376
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This work studied the antibacterial effect and mechanism of antimicrobial peptide PAF26 on Monilinia fructicola in postharvest plums. In this experiment, in vitro experiments and inoculation methods were used to study the antimicrobial peptide PAF26’s in vitro antibacterial effect on M. fructicola and the control effect on plum fruit brown rot. The effect of the antibacterial peptide on the structural integrity of M. fructicola and its hemolytic activity were also tested. The results showed that PAF26 could significantly inhibit the growth of Monilinia fructicola, and its minimum inhibitory concentration (MIC) was 64 μmol/L, which could significantly reduce the survival rate of spores. PAF26 could also effectively control the occurrence of Monilinia fructicola in plum fruit. Fluorescent staining with SYTOX Green (SG) and propidium iodide (PI) showed that PAF26 could enhance the permeability of hyphal and conidial membrane. In addition, the extracellular conductivity of Monilinia fructicola mycelia treated with PAF26 was significantly increased. PAF26 at 64 and 128 μmol/L hardly resulted in hemolysis of human red blood cells. The above results indicate that PAF26 can effectively control postharvest brown rot in plums by destroying the integrity of the cell membrane structure and consequently accelerating the death of Monilinia fructicola.
Inhibitory Effect of L-Cysteine against Alternaria alternata Rot of Grapes
KANG Huifang, QIAO Yongjin, LIU Chenxia, ZHANG Yi, SUN Dapeng
2020, 41(23):  228-235.  doi:10.7506/spkx1002-6630-20191010-058
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This work aimed to study the inhibitory effect of L-cysteine against Alternaria alternata rot of grapes. The fungus was treated with different concentrations (0.4, 0.6, 0.8, 1.0, 1.2, 1.4, 1.6, 1.8, 2.0, 2.2, 2.4, 2.6, 2.8 and 3.0 g/L) of L-cysteine, and that without any treatment was regarded as the control group. The antifungal effect of L-cysteine was evaluated by determining the inhibition rates of colony growth, spore germination and germ?tube?elongation as well as using inverted microscopy to observe mycelial morphology. The appropriate concentrations of L-cysteine were selected to treat grapes inoculated with Alternaria alternate, which were subsequently stored in an incubator at 25 ℃. The inhibitory effect of L-cysteine on Alternaria alternata rot was researched by measuring the diameter of lesions, incidence and related enzyme activities. Results showed that compared with?the control?group, L-cysteine at all concentrations could significantly inhibit mycelial growth and germ tube elongation and reduce the rate of spore germination. In addition, L-cysteine could decrease the diameter of lesions and the rot rate of fruits, delay the accumulation of malondialdehyde (MDA) and maintain high antioxidant activity as well, being the most effective at a concentration of 2.8 g/L.
Effects of High Oxygen Modified Atmosphere Packaging on Quality of Beef Semimembranosus Muscles during Postmortem Aging
FU Qingquan, WANG Haiou, LI Kun, YANG Ping, CHEN Quanzhan, WANG Tingting
2020, 41(23):  236-242.  doi:10.7506/spkx1002-6630-20200512-126
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The aim of the study was to investigate the effects of high oxygen modified atmosphere packaging on the quality of beef semimembranosus muscle during postmortem aging. Four Simmental cattle were slaughtered and semimembranosus muscles from each carcass were excised, packaged in high oxygen modified atmosphere (80% O2 + 20% CO2) or in vacuum at 24 h postmortem and then stored at 4 ℃. Meat tenderness, color, protein solubility, thiobarbituric acid reactive substances (TBARS) value, and the proteolysis of troponin-T were determined after 0, 4, 7 and 10 days of storage. The distribution of protein carbonyl groups in muscle cells was observed by confocal laser scanning microscopy. The results showed that meat tenderness, the solubility of sarcoplasmic protein on day 7 of storage and total protein solubility in high oxygen modified atmosphere packaged samples were significantly lower than those of vacuum packaged samples (P < 0.05), while TBARS value was significantly higher (P < 0.05) and the fluorescence signal of protein carbonyl groups was similarly higher in the former, which penetrated?from the exterior to the interior of?the cells with increasing storage time. Moreover, the rate of proteolysis of troponin-T significantly decreased compared with the vacuum packaging group (P < 0.05). However, high oxygen modified atmosphere packaging maintained higher surface redness values (P < 0.05) in comparison with vacuum packaging during the 10-day storage period. In conclusion, high oxygen modified atmosphere packaging increased the level of lipid and protein oxidation, thereby inhibiting μ-calpain degrading of troponin-T and finally decreasing the tenderness of beef samples.
Reviews
A Review of Cross-Adaptation and Underlying Molecular Mechanism of Foodborne Pathogens
CHEN Xin, HU Lingping, YING Yubin, LIU Jialin, HU Yaqin, DING Tian
2020, 41(23):  243-254.  doi:10.7506/spkx1002-6630-20200630-380
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Foodborne pathogenic bacteria are prone to cross-adaptation under food processing and storage-related stresses. This phenomenon leads bacteria subjected to sublethal stress develop tolerance to other stresses so that they can survive in subsequent sterilization or bacteriostatic treatment, posing a potential risk to food safety. This article reviews the current understanding of cross-adaptation in common foodborne pathogens, the factors influencing it and its molecular mechanism in order to provide a basis for reducing bacterial cross-adaptation to enhance microbial food safety.
Recent Progress in Plant-Derived Natural Products as Antibiotic Adjuvants
GUO Qin, ZHANG Chunyan, PENG Kai, CAI Jiahui
2020, 41(23):  255-265.  doi:10.7506/spkx1002-6630-20191030-340
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The overuse of antibiotics and resulting multi-drug resistance of bacteria have seriously jeopardized human health and the development of the food industry. There are many difficulties in the development of new antibiotics, although fortunately there are abundant resources of plant-derived natural products as antibacterial adjuvants, which can be used to inhibit bacteria in combination with antibiotics, thereby effectively reducing the dosage of antibiotics and alleviating the impact on the environment and society. In this paper, the antibacterial effects and mechanisms of plant-derived natural products alone and in combination with antibiotics as well as their application in the food industry are reviewed, which will provide reference for the development of new antibiotic adjuvants to reduce the abuse of antibiotics.
Recent Progress in Nucleic Acid-Microfluidic Chips Used for Detection of Foodborne Pathogens: A Review
XIN Liang, ZHANG Lanwei
2020, 41(23):  266-272.  doi:10.7506/spkx1002-6630-20191227-335
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Outbreaks of foodborne diseases caused by pathogenic bacteria have become a global health concern. Relying on plate culture and biochemical analysis, traditional microbiological assays are time-consuming and labor-intensive and thus cannot meet the growing demand of food safety testing. Therefore, an efficient detection method is urgently needed. With high sensitivity and short time, nucleic acid amplification-based methods have been developed to detect various foodborne pathogenic microorganisms. With the characteristics of small size, high specific surface area and flexible design, the microfluidic chip is a portable, reagent-saving and high-throughput method. In order to further apply the nucleic acid detection method in situ and in resource-constrained environments, researchers have combined it with microfluidic chips, which provides a convenient and efficient tool for food safety detection. In this paper, we summarize recent progress in the development of polymerase chain reaction (PCR)-microfluidic, loop-mediated isothermal amplification (LAMP)-microfluidic, recombinant polymerase amplification (RPA)-microfluidic, nucleic acid sequence-based amplification (NASBA)-microfluidic and helicase dependent amplification (HDA)-microfluidic chips methods for the detection of foodborne pathogens. In conclusion, the combination of nucleic acid amplification technology and microfluidic chips provides a new, simple and efficient method for the detection of foodborne pathogenic microorganisms.
Recent Progress in Understanding the Contribution of Lactic Acid Bacteria to Flavor Formation in Salami: A Review
LIU Yingli, WAN Zhen, YANG Ziyan, YU Qinglin, LI Lei, WANG Jing
2020, 41(23):  273-282.  doi:10.7506/spkx1002-6630-20200416-204
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Salami is a kind of meat product with special flavor, color and texture as well as long shelf life, which is made from pork or beef by microbial fermentation. The flavor of salami greatly affects its overall quality and sensory acceptability. Compared with natural fermentation, the application of artificial starter cultures can reduce the interference of environmental factors and ensure the stability of flavor substances. In particular, lactic acid bacteria can further reduce the acidity of salami through the metabolic activity in meat matrix, imparting a unique flavor to the product. This article discusses the factors that may influence flavor formation in salami. The contribution of lactic acid bacteria to the formation of flavor and the underlying metabolic mechanism are analyzed in detail from three aspects including protein metabolism, fat metabolism, and carbohydrate metabolism. We expect that this review will provide a theoretical basis for further studies on the flavor quality of salami.
Progress in Resistant Starch Prepared via Multi-Physical Fields
TANG Junyu, ZHOU Jianwei, GAO De, CHENG Huan, XU Enbo, LIU Donghong
2020, 41(23):  283-292.  doi:10.7506/spkx1002-6630-20191020-204
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Resistant starch types 3 to 5 (RS3–5) are modified starch with reorganized structures and are widely used as a new type of dietary fiber because of their multiple functions such as preventing colon cancer, decreasing cholesterol levels, regulating blood sugar metabolism, and promoting mineral absorption (like Ca2+ and Fe3+). Therefore, it is of great significance to prepare safe and edible RS as well as its derivatives using microstructural manipulation strategy. Physical fields combined with chemical or enzymatic treatment can improve the preparation efficiency of RS, reduce the risk of introduction of exogenous agents, and simplify the operating procedure, being highly efficient, safe and green. Herein, this review illustrates the effect and mechanism of single physical field (SPF) such as temperature field, pressure field, shear field, ultrasonic field, electric field and electromagnetic field as well as multi-physical fields (MPFs) on the preparation of RS3–5. Furthermore, the effect of different physical fields (like field superposition, energy distribution, and field parameters) is discussed on the structures and properties of RS products, and the applications and innovation of RS3–5 in food, pharmaceutical and other fields are summarized.
Application of Mass Spectrometry-Based Metabolomics in Meat Science: A Review
WANG Juanqiang, LI Yingying, LI Shilei, ZHAO Wentao, JIANG Rui, WANG Shouwei
2020, 41(23):  293-302.  doi:10.7506/spkx1002-6630-20200430-405
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With the improvement of living conditions, people have increasingly higher requirements for food safety, quality and traceability, continuously promoting the development of efficient, sensitive, selective and information-rich analytical methods. Mass spectrometry (MS)-based metabolomics plays an important role in the fields of disease diagnosis, environmental monitoring and pharmaceutical analysis, and has been demonstrated to be able to solve some important challenges in food science such as food certification, food nutrition and food origin traceability. This review discusses the design ideas for MS-based metabolomics methods, including sample preparation, analysis platform and data processing. Recent advances in the application of MS-based metabolomics methods in meat quality and safety evaluation, authenticity identification, geographical origin tracing, processing and storage are also summarized in this review, and future directions and prospects are discussed. We hope that this review can provide a basis for further research on the effects of small molecular metabolites on the quality of meat products and to promote the development of high-quality meat products.
Sleep-Improving Food and Medicinal Resources and Their Application in Health Foods: A Review
ZHANG Fangming, ZHENG Hui, ZHENG Tao, ZENG Yiqiong, FAN Yubing, LI Weizhen, ZHOU Nan, HE Jinxu, YANG Yong
2020, 41(23):  303-310.  doi:10.7506/spkx1002-6630-20200614-192
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Sleep is the foundation of health. Good and adequate sleep is conducive to accumulate body energy reserves, maintain brain function, improve human immunity, etc.. Improving sleep is very important to maintain human health and improve the quality of life. Compared with psychotropic chemical drugs used to treat insomnia, the application of natural food and medicinal resources to improve sleep disorders is safer with less drug resistance and drug dependence, and is a sustainable slow conditioning mode. Based on a large number of literature reports, this paper systematically summarizes and analyzes the main types of sleep-improving food and medicinal resources, such as common foods, Chinese medicinal materials for both culinary and medicinal purposes, and Chinese medicinal diets, as well as their functional mechanisms and applications in health foods. The purpose of this review is to provide a reference for the high value utilization of sleep-improving food and medicinal resources and the research and development of sleep-improving health foods.
Recent Progress in Post-Mortem Meat Tenderization Techniques and Their Mechanisms of Action
SHI Haibo, ZHU Yongzhi, FANG Rui, ZHANG Xinxiao, ZOU Ye, WANG Daoying, XU Weimin
2020, 41(23):  311-321.  doi:10.7506/spkx1002-6630-20191106-075
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Tenderness is a key index for characterizing the eating quality of meat and good tenderness contributes to enhancing consumers’ repurchase intentions. The conversion of muscle to meat involves complex physiological and biochemical processes, and post-mortem aging and tenderization can improve meat quality effectively. This paper reviews the mechanism of the postmortem aging of muscle, as well as existing meat tenderization techniques (e.g., biological, chemical and physical methods) and their mechanisms of action, with the aim to provide a theoretical basis for semi-/full processing technologies of post-mortem muscle.
A Review of Emulsifying Properties of Polysaccharides and Their Applications in Enhancing Textural Attributes of Emulsion-Based Foods
LI Anqi, YANG Xi, ZHANG Han, GUO Yurong
2020, 41(23):  322-328.  doi:10.7506/spkx1002-6630-20191011-085
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In addition to extensive sources and renewability, polysaccharides possess significant functional properties including thickening, gelling, emulsifying, and dispersing abilities, and consequently play significant roles in the food industry. This paper reviews the emulsifying mechanism of polysaccharides and the mechanism by which they stabilize emulsions, with a focus on the effects of various factors on the emulsifying properties of polysaccharides. Moreover, the emulsifying mechanism of coexisting systems containing polysaccharides and proteins or small molecular mass emulsifiers is discussed, and the strategies commonly used to improve the stability of polysaccharide-stabilized emulsions are summarized. Finally, the applications of polysaccharide emulsifiers in enhancing textural attributes of emulsion-based foods are outlined. This review highlights the great potential of polysaccharide emulsifiers in the food industry.
Recent Progress in Fe2+/Fe3+ Chelating Peptides Derived from Foods
LIN Shanting, HU Xiao, LI Laihao, YANG Xianqing
2020, 41(23):  329-337.  doi:10.7506/spkx1002-6630-20191205-059
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Iron ion is a necessary micronutrient for constituting human tissues and maintaining normal physiological functions. Iron deficiency in the body is prone to cause many nutritional deficiencies. Fe2+/Fe3+ chelating peptide is a kind of peptide that has the ability to chelate Fe2+/Fe3+ forming a soluble conjugate, which can promote the absorption of iron in the body. This paper summarizes the food sources, preparation, separation and purification, and structural characteristics of Fe2+/Fe3+ chelating peptides, as well as the formation and chelating sites of peptide-Fe2+/3+ complexes and the mechanism for promoting Fe2+/Fe3+ absorption, in order to provide a theoretical basis for the research and product development of Fe2+/Fe3+ chelating peptide.
Legal Governance of Quality and Safety of Edible Agricultural Products Produced and Operated by Small Farming Households
CAO Junjin, RUAN Zanlin
2020, 41(23):  338-346.  doi:10.7506/spkx1002-6630-20200105-044
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The production and operation of edible agricultural products are regulated by many laws such as the Food Safety Law and the Agricultural Products Quality and Safety Law. However, the governance of the quality and safety of agricultural food products produced and operated by small farming households needs to be strengthened. These agricultural food products are put under the regulation of the Agricultural Products Quality and Safety Law (Revised Draft) released by the Ministry of Agriculture and Rural Affairs, which stipulates the obligations of producers and operators to strengthen the enforcement actions against violations of the law. In view of great difficulties in holding agricultural food quality and safety violators accountable, small farming households’ weak ability to bear legal responsibilities and ensuring social equity, whole-process supervision of the production and operation of agricultural food products by small farming households should be further strengthened, and the agricultural assistance system should be specified to improve small farming households’ capacity to ensure the quality and safety of agricultural products, provide institutional opportunities for the integration of agricultural social services into the safe production of agricultural products by small farming households, and develop a self-governance system for agricultural product quality and safety in rural areas so as to strengthen areas of weakness in government supervision.
Recent Progress in the Preparation and Application of Chitosan Nanoparticles as an Antimicrobial in Foods
TAN Xiao, QIU Tingting, LI Ruonan, ZHOU Lisha, ZHAO Yanyun, CHEN Shunsheng, ZHANG Hongcai
2020, 41(23):  347-353.  doi:10.7506/spkx1002-6630-20191203-044
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In recent years, chitosan nanoparticles have been widely applied in materials, medicine, biology and foods because of their non-toxic effects, high biocompatibility, easy biodegradation, and strong antibacterial properties. Nowadays there are many methods available for the preparation of chitosan nanoparticles including ionic cross-linking, coacervation, chemical cross-linking, spray drying and layer-by-layer self-assembly. Ionic cross-linking is widely used in the food field due to its simple operation, high efficiency and non-toxic properties. The main objective of this paper is to review the principles, advantages and disadvantages of these preparation methods. In addition, this paper summarizes recent progress in the application of chitosan nanoparticles as an antibacterial agent in foods.