Volume 37,Issue 12,2021 Table of Contents

1 Lipid-lowering Effect and Pharmacokinetic Analysis of Natto-monascus Complex

QI Mingming , ZHANG Wenmeng , YIN Shuxia , SUN Jianbo

2021, 37(12):1-6. DOI: 10.13982/j.mfst.1673-9078.2021.12.0278

[Abstract](317) [HTML](315) [PDF 899.52 K](621)

Abstract:
The lipid-lowering effect of natto-monascus complex (NMC) and the pharmacokinetic characteristics of its component lovastatin was investigated. SD rats were divided into normal group, model group, NMC low-, medium- and high-dose groups, and positive drug lovastatin group. Except for the normal group, the rats in the other groups were fed a high-fat diet to induce hyperlipidemia. The contents of total cholesterol (TC), total triglycerides (TGs), high density lipoprotein cholesterol (HDL-C) and low density lipoprotein cholesterol (LDL-C) in the sera of rats in each group were measured after 4 weeks of continuous intragastric administration, and the liver tissue sections were stained with hematoxylin-eosin for analysis. In this study, the changes in the content of lovastatin in plasma of beagle dogs after oral administration of NMC were measured by LC-MS. The results showed that the administration of low-, medium- and high-doses of NMC decreased significantly (p<0.01) the levels of LDL-C and TG in high fat diet-induced rats, and the level of TC decreased significantly (p<0.01) in the high-dose group. Moreover, medium- and high-doses of NMC could ameliorate lipid accumulation in the livers by high fat diet in rats. In addition, after a single oral administration of NMC, the time for lovastatin in beagle dogs to reach the peak amount was 1.17 h, with the maximum plasma concentration being 62.33 mg/mL, the elimination half-life being 5.95 h, and the retention time being 7.83 h. This study proves that NMC can reduce the level of blood lipids in rats induced by the high-fat diet, and provides apreliminary analysis of the pharmacokinetic characteristics of lovastatin in beagle dogs. The research results can provide abasis for the research and development of natto-monascus foods.

2 Protective Effect of Polyphenol of Houttuynia cordata on Ulcerative Colitis Induced by Sodium Dextran Sulfate (DSS) in Mice

DONG Jing , WANG Shuaike , WU Ping , WANG Shuo , LIU Jinqian , JI Lusha , CHEN Fang

2021, 37(12):7-13. DOI: 10.13982/j.mfst.1673-9078.2021.12.0336

[Abstract](271) [HTML](258) [PDF 889.32 K](671)

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In the current study, the ameliorating effect of total polyphenol from Houttuynia cordataon mice with ulcerative colitis was studied. 50 male KM mice were randomly divided into control group, modelgroup, low-, medium- and high-dose groups of polyphenol in Houttuynia cordata. The model group was induced by administering 3.5% dextran sodium sulphate (DSS) for 9 days. On third day, the polyphenol groups were infused to stomach after DSS administration for another 10 days. The changes of mice body weight, colonic histomorphology and the disease activity index (DAI) of each group were observed. The levels of TNF-α, IL-1β, IL-6, IFN-γ in serum were detected by ELISA. The expressions of aspartate aminotransferase (AST), aspartate transaminase (ALT), creatinine (Cr) and blood urea nitrogen (BUN) in serum were measured. Compared with the DSS group, polyphenol groups significantly reduced symptoms with bloody stool. Disease activity index (DAI) decreased to 29.83%, 46.45% and 54.82%, respectively. The mice colon increased to 8.35 cm (in low dose group), 9.53 cm (in medium dose group), and 10.87 cm (in high dose group) on average. Also, treatment with polyphenol considerably the ALT and AST level and the expression of tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), interleukin-6 (IL-6) were decreased. These results demonstrate that polyphenol in Houttuynia cordata has an ameliorative effect on colonic damage, and decrease the level of serum proinflammatory factor. The mechanism may be related to inhibiting the activation of NF-κB.

3 Interference Effect of Hemerocallis citrina Baroni Methanol Extract on Glycolipid Damage

QIN Xiyue , ZHANG Lei , WEN Yanbin , LI Jingming , ZHANG Yali

2021, 37(12):14-22. DOI: 10.13982/j.mfst.1673-9078.2021.12.0430

[Abstract](162) [HTML](219) [PDF 916.02 K](482)

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Caenorhabditis elegans (C. elegans) was used as a model organism to study the interference effects of methanol extract from Hemerocallis citrina Baroni on glycolipids damage. UPLC-QQQ-MS/MS was used to analyze the ingredients in methanol extract of Hemerocallis citrina Baroni, and based on the wild-type N2 C. elegans, sugar damage model was induced by 100 µmol/mL sucrose, lipid injury model was induce by100 µg/mL stearic acid. To observe the interference effects of methanol extract from Hemerocallis citrina Baroni, the three models were added with 0, 400, 800, 1200 µg/mL methanol extract of Hemerocallis citrina Baroni, egg production, body length and lifespan of C. elegans were detected. The results showed that the main component of methanol extract in Hemerocallis citrina Baroni was rutin with a content of 5721.11 ng/mg. For common N2 C. elegans, the total progeny and body length of the nematodes fed with 800 µg/mL Hemerocallis citrina Baroni methanol extract increased by 24.76% and 7.73%, respectively, compared with the blank group; for sugar-damaged C. elegans, fed with 800 µg/mL Hemerocallis citrina Baroni methanol extract, the lifespan and total progeny number of nematodes were increased by 24.47% and 3.40% respectively than those of the blank group; for lipid-damaged C. elegans, the lifespan, body length and total progeny number of nematodes fed with 1200 µg/mL Hemerocallis citrina Baroni methanol extract were increased by 30.04%, 10.36% and 97.32%than those of the blank group, respectively. Therefore, the results showed that the mid-to-high concentration of Hemerocallis citrina Baroni methanol extract had a certain interference effect on C. elegans glycolipids damage.

4 Quality Analysis and Evaluation of Different Parts of Phallus impudicus L. of Guizhou

ZHENG Xiuyan , MENG Fanbo , WU Cailing , HUANG Daomei , LU Yingying , CHEN Xi , TANG Pengyu , LIN Mao

2021, 37(12):23-32. DOI: 10.13982/j.mfst.1673-9078.2021.12.0563

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The quality and nutritional evaluation of three parts of Phallus impudicus L. of Guizhou were carried out from the perspectives of nutrient composition, texture characteristics and microscopic characteristics. The results indicated that the protein content of Phallus impudicus L. was 16.30 g/100 g~19.50 g/100 g with the ranking stipe>fruiting body>pileus, the fat content was about 1.30 g/100 g. There were 16 kinds of amino acids in different parts, with 45% of essential amino acids accounting, and the contents of glutamic acid and methionine were the highest. The total flavor amino acids was 7.88 g/100 g~9.31 g/100 g with the order stipe>fruiting body>pileus. Protein evaluation results showed that lysine was the first restricted amino acid of Phallus impudicus L. The analysis results, including SRCAA, U, EAAI and CS, were pileus>fruiting body>stipe with the exception of IN. The texture test results showed that the maximal tensile force and maximum shearing force of different parts of Phallus impudicus L. were ordered as: stipe>pileus and dried>reconstituted, respectively. The hardness, adhesion, elasticity, adhesiveness and chewiness of pileus of Phallus impudicus L. were higher than those of stipe, while the hardness, adhesion, adhesiveness and chewiness of pileus were lower than those of stipe. Besides, there were obviously different microstructural features in the stipe and pileus of Phallus impudicus L. This study could provide theoretical basis for edible, standard establishment and product development of Phallus impudicus L.

5 In-vivo Anti-tumor Effects of the Proteins of Apriona swainsoni Larvae on 4T1 Tumor-bearing Mice

HOU Peiying , SUN Xu , HUANG Xiufeng , WANG Yi , BAO Qinghua , OUYANG Dongxing , XU Huachao

2021, 37(12):33-39. DOI: 10.13982/j.mfst.1673-9078.2021.12.0157

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4T1 tumor-bearing mice models were established to examine the in-vivo anti-tumor effects of proteins extracted from Apriona swainsoni larvae. Changes in the body weight and tumor growth of the mice treated with different protein concentrations were observed during the experiments. The growth of the 4T1 tumor cells was detected by bioluminescence imaging. All mice were sacrificed after treatment administration, and the tumor inhibition rate and indexes of main organs were subsequently calculated. Compared with the tumor model control group, the tumor-bearing mice treated with different concentrations of proteins of Apriona swainsoni larvae showed no significant changes in their body weights or the weights and indexes of main organs, whereas the tumor weights significantly reduce (p<0.05). The tumor inhibition rates in the groups treated with the Apriona swainsoni larval protein at low, medium, and high doses were 23.08%, 36.06%, and 21.63%, respectively. The fluorescence signals of the 4T1 tumor cells in these three treatment groups were attenuated in comparison with those of the control group. The result was consistent with the tumor growth observations. It was preliminarily concluded that the proteins of Apriona swainsoni larvae have certain in-vivo anti-tumor effects, and they have no obvious toxic and side effects on the body and the main organs of the 4T1 tumor-bearing mice.

6 Expression of the Acid-resistant Xylanase Gene from Bacillus velezensis P7 in Bacillus subtilis and Optimization of Its Production

HUANG Xueqin , ZUO Yong , ZHANG Qiang , XU Jia , YANG Jianfei , YI Yuan

2021, 37(12):40-48. DOI: 10.13982/j.mfst.1673-9078.2021.12.0158

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To obtain a xylanase protein that can adapt to acidic environments (e.g., in distiller’s grains), the endogenous xylanase gene from acid-resistant Bacillus velezensis P7 was successfully cloned using the polymerase chain reaction. The xylanase gene fragment and the pHT43-HIS shuttle plasmid were first digested with the restriction enzymes Bam HI and Xba I. After purification of the xylanase gene fragments with a gel recovery kit, they were then ligated with the vector fragments using T4 DNA ligase, and the recombinant plasmid was subsequently transfected into Bacillus subtilis WB800 cells. SDS-PAGE analysis of the purified xylanase revealed that it was a 40 ku polypeptide. To increase the extracellular production of xylanase by Bacillus subtilis WB800-P7 in high-density fermentation, the effects of temperature, pH, inoculum size, rotation speed, and other individual factors on the production process were studied, and orthogonal experiments were then used to determine the interactions among the factors and to predict the optimal fermentation conditions for promoting the secretion of the recombinant protein. The results suggested the optimal fermentation conditions of strain WB800-P7 to be as follows: inoculum OD600 of 0.8, IPTG concentration of 1.2 mmol/L, fermentation pH of 6.0, culture temperature of 35 ℃, inoculum size of 2%, and rotation speed of 160 r/min. Among these factors, the culture temperature had the most significant effect on enzyme production. Under these optimal conditions, the enzyme activity reached 4.21 IU after 16 h of fermentation, which was 64.45% higher than that before optimization. The acid resistance of the recombinant xylanase was analyzed, whereupon its residual enzymatic activity was found to be more than 80% of that of the original enzyme under strongly acidic and neutral conditions (pH 5.0~7.0). In conclusion, a modified B. subtilis strain with better protein expression capability and which produces a highly acid-resistant xylanase was successfully engineered in this study.

7 Fermentation Characteristics of Litchi Craft Beer and Optimization of Brewing Parameters

MIAO Yanlong , GONG Shimei , WANG Kai , ZHAO Lei , TU Jingxia , YANG Qing , WANG Yuhai , HU Zhuoyan

2021, 37(12):49-56. DOI: 10.13982/j.mfst.1673-9078.2021.12.0401

[Abstract](307) [HTML](176) [PDF 1.16 M](560)

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In order to develop a litchi craft beer, the effects of original gravity, level of litchi pulp addition and hop addition on the fermentation characteristics and sensory score of litchi beer were investigated. The brewing conditions were optimized using response surface methodology (RSM) with a Box-Behnken design. The results showed that the degree of fermentation, alcohol content, form-stability, bitterness of litchi beer were significantly affected by original gravity and level of litchi pulp addition (p<0.05); the form-stability and bitterness of litchi beer were significantly affected by level of hop addition (p<0.05). The optimum fermentation conditions to obtain desirable sensory score ≥78.00 were found at the original gravity of 9~11 oP, litchi pulp addition of 11~15% (V/V), hop addition of 0.39~0.44 g/L. The average sensory score (78.10) from the verification experiments at original gravity of 10 oP, litchi juice addition of 15% V/V, and hop addition of 0.40 g/L were in good agreement with the predicted value. The results suggested that adding litchi to traditional brewing process could increase style of beers and improve the sensory characteristics of beers.

8 Analysis of Fungal Diversity and Communty Structure in Rice with Different Moisture Content

LI Xinwei

2021, 37(12):57-64. DOI: 10.13982/j.mfst.1673-9078.2021.12.0408

[Abstract](176) [HTML](167) [PDF 1.50 M](632)

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To explore the original state of fungal community of rice with different water content before warehouse storage, Illumina MiSeq high-throughput sequencing was used to analyze the fungal community structure and diversity of newly harvested early japonica rice from Northeast China with different water content in this study. The result showed that the fungal communities in the two rice samples belonged to 2 phyla, 26 classes, 51 orders, 85 families, 112 genera and 188 species according to the 97% sequence similarity level. At the phylum level, the dominant fungal communities in rice with different water content were Ascomycota and Basidiomycota. At the genus level, the contents of Cryptococcus 0.07% and Papiliotrema 3.81% were relatively high in high-moisture rice and relatively low in low-moisture rice. It was found that there were a large number of the same species in rice with different water content, but there were differences among species richness. And the species and number of fungi in rice with high water content were higher than those in rice with low water content. Therefore, it could be concluded that the specific bacteria, such as Filobasidium, Sarocladium and Mycosphaerella, which have significant differences between the two groups of rice in water content, can be inhibited by reducing the rice water content. In conclusion, this study provides theoretical support for water control of paddy rice before entering storage.

9 Changes in Tea Quality Components in the Yellowing Process of Wild Baiyun Yellow Tea and the Isolation and Identification of Microbial Strains

LIU Zhanliang , WU Xiaorong , HUANG Yiju , HUANG Xipeng , HUANG Xueya , WU Xiyue , LIN Yuechun , CHEN Ling , ZHOU Qiaoyi

2021, 37(12):65-71. DOI: 10.13982/j.mfst.1673-9078.2021.12.0200

[Abstract](310) [HTML](194) [PDF 546.27 K](563)

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In order to investigate the factors influencing the processing s of yellow tea from fresh leaves of wild Baiyun tea species, the main quality components of yellow tea, roasted green tea and half- baked and half-fried green tea processed from wild Baiyun tea were analyzed. The changes of culturable strains in the 8 tea samples (green tea, pan-fried green tea, rolling leaves, refried leaves (dehydrated leaves), leaves with 24 h smothering, leaves with 48 h smothering, leaves with 72 h smothering, and raw tea) withdrawn from the yellow tea processing of the fresh leaves of wild Baiyun tea were examined. The comparison of the wild Baiyun tea with the baked green tea, and the half-baked and half-fried green tea revealed that in addition to the slight decreases in amino acid and caffeine contents, the wild Baiyun tea had a higher water extract content (increased by 4.80% and 7.11%, respectively) , a higher soluble sugar content (increased by 0.41% and 0.36%, respectively), but lower tea polyphenol content and total catechin content (ester-type catechin content decreased by (21.62 mg/g and 19.08 mg/g, EGCG content decreased by 9.99 mg/g and 6.98 mg/g, and GCG content decreased by 14.23 mg/g and 13.80 mg/g, respectively). All these changes were significant (p<0.05). There were no significant changes in the contents of the non-ester catechins and the total content of non-ester catechins, except that C was reduced by 2.49 mg/g and 1.75 mg/g, respectively (p<0.05). After smothering for 24 hours, a significant number of yeast was detected, and fungi became dominant (3.5×105 CFU/g) after smothering for 72 hours. Eight microbial strains were isolated and identified, including 1 Pestalotiopsis strain, 4 Penicillium strains, 1 Cladosporum strain and 2 yeast strains, with Penicillium exsudans being isolated and identified for the first time from tea processing and tea leaves. The results indicated that smothering of tea increased the water-soluble and soluble sugar contents of tea, decreased the contents of tea polyphenols and ester-type catechins. Microbial reproduction occurred in the yellowing stage and participated in the formation of yellow tea quality.

10 Structural Characteristics and in vitro Antioxidative Activity of Wheat Oligopeptides

LIU Wenying , FENG Xiaowen , CHENG Qingli , ZHAO Xiaohan , LI Guoming , GU Ruizeng

2021, 37(12):72-79. DOI: 10.13982/j.mfst.1673-9078.2021.12.0075

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The structural characteristics of wheat oligopeptides were elucidated using scanning electron microscopy imaging as well as analyses of their basic physicochemical composition, relative molecular weight distribution, amino acid composition, and ultraviolet and circular dichroism spectra. The in vitro antioxidative activity of the oligopeptides was investigated by determining their oxygen radical absorbance capacity (ORAC) and their abilities to scavenge hydroxyl, DPPH, and ABTS free radicals. The wheat oligopeptides were in the form of spherical granules and had irregular folds and pores on the surface. Their protein and peptide contents were 95.86% and 83.74% (both on a dry basis), respectively, and 92.22% of the components had a molecular weight of less than 1000 u. Their contents of essential amino acids and hydrophobic amino acids were 20.46% and 33.38%, respectively. The maximum absorption peak was at 270 nm. The α-helix, parallel β-fold, antiparallel β-fold, β-turn, and random coil contents of the oligopeptides were 5.83%, 3.14%, 37.57%, 20.32%, and 33.14%, respectively, indicating the coexistence of multiple secondary structures. The IC50 values of wheat oligopeptides for hydroxyl and DPPH free radicals were 9.6 and 1.5 mg/mL, respectively. Moreover, their ABTS free radical-scavenging activity was 3.53 mmol Trolox/g and their ORAC was 1035.52 μmol Trolox/g. In summary, these findings indicating the strong antioxidative capacity of wheat oligopeptides provide a theoretical basis for their use in the development of antioxidant-containing foods.

11 Non-covalent Interactions between Ferritin and Chlorogenic Acid

LIU Yuqian , BEN Tingting , ZHANG Fengjiao , SONG Siqi , CHEN Yilun

2021, 37(12):80-86. DOI: 10.13982/j.mfst.1673-9078.2021.12.0131

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The mechanisms by which chlorogenic acid (CA; a phenolic compound) and ferritin [from the recombinant soybean seed H-2 (rH-2)] interact with each other were examined using fluorescence spectroscopy, circular dichroism spectroscopy, transmission electron microscopy, and dynamic light scattering. The results showed that CA could interact with phytoferritin, causing changes in the tertiary/quaternary structure of the iron-storing protein but not in its primary/secondary structure. The phenolic compound did not change the characteristic emission peak of ferritin at 330 nm, the fluorescence intensity of which decreased with increasing CA concentrations. Hydrogen bonds/van der Waals forces played a major role in the non-covalent interactions between CA and ferritin, the binding constants (K) for which were 1.7×104, 1.4×104, and 1.04×104 (mol/L)-1, with 156.8, 132.1, and 93.9 binding sites (n), at 25, 37, and 55 ℃, respectively. These results indicate that the strength of the interaction between CA and ferritin decreases with increasing temperature. According to the dynamic light scattering results, the particle size of ferritin did not change significantly before (7.61) and after (7.67) the addition of CA, indicating that the phenolic compound does not induce the aggregation of ferritin molecules. Additionally, the antioxidative capacity of CA in the ferritin-CA complexes was preserved, albeit slightly decreased. These results further enhance understanding of the interactions between different food components, especially ferritin and phenolic acids.

12 Chemical Components and Antioxidative Activities of Camellia yungkiangensis var. yuanbaoshanica - A New Resources of Camellia sinensis

CHEN Taolin , CHEN Meili , GE Zhiwen , LIAO Yinpin , WANG Xifu , QIAO Xiaoyan , ZHANG Zheng , LUO Junwu

2021, 37(12):87-96. DOI: 10.13982/j.mfst.1673-9078.2021.12.0189

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Camellia yungkiangensis var. yuanbaoshanica (a new resource in Sect. Thea plants) and the Camellia sinensis plants grown locally in Jiuwan Mountain was compared in terms of their main quality-controlling components, using fresh leaf, black tea, and green tea samples. Additionally, the antioxidative activities of the two plants were analyzed using 1,1-diphenyl-2-picrylhydrazyl (DPPH), ferric reducing antioxidant power (FRAP), and 2,2ʹ-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) assays. The contents of the tea polyphenols, soluble sugars, flavonoids, theobromine, gallic acid, and DL-catechin (DL-C) in the fresh leaf sample of Camellia yungkiangensis var. yuanbaoshanica were 31.33%, 10.96%, 0.41%, 2.84%, 0.21%, and 9.28%, respectively, all of which were significantly higher than those of Camellia sinensis (p<0.05). By contrast, the contents of free amino acids, caffeine, total catechins, epigallocatechin, epigallocatechin gallate, gallocatechin gallate, and epicatechin gallate in the fresh leaf sample of Camellia yungkiangensis var. yuanbaoshanica were 1.17%, 0.39%, 12.55%, 0.21%, 1.45%, 0.12%, and 0.86%, respectively, which were significantly lower than those observed for Camellia sinensis (p<0.05). Moreover, for both plants, the IC50 values of the green tea samples against DPPH and ABTS were the lowest, followed by those of the fresh leaf samples. The FRAP IC50 value of the green tea sample of Camellia yungkiangensis var. yuanbaoshanica was the lowest (225.21 μg/mL) whereas that of the black tea sample of Camellia sinensis was the highest (862.63 μg/mL). Furthermore, the DPPH IC50 values of all three types of Camellia yungkiangensis var. yuanbaoshanica samples were all smaller than the respective ABTS and FRAP IC50 values, with the FRAP IC50 values being the highest. Additionally, the correlation analysis revealed that the tea polyphenol, flavonoid, and catechin contents were significantly related to the antioxidative activities of all the samples (p<0.01). In summary, Camellia yungkiangensis var. yuanbaoshanica was shown to be a special resource with high contents of tea polyphenols, DL-C, soluble sugars, and theobromine and a low content of caffeine. Importantly, it exhibited stronger antioxidative activities in vitro compared to Camellia sinensis.

13 A Comparative Study on Nutritional Compositions of Lentinula edodes in Four Main Producing Regions in China

SUN Tian , YAO Songjun , LIU Fengsong , MA Zhen , ZHANG Nan , JING Pu

2021, 37(12):97-103. DOI: 10.13982/j.mfst.1673-9078.2021.12.0146

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To examine the differences in the nutritional composition of Lentinula edodes collected from four main producing regions, including Shiyan in Hubei, Suizhou in Hubei, Lishui in Zhejiang, and Xixia in Henan, in China, the levels of nutritional components, such as proteins, polysaccharides, fats, minerals, ergosterol, and amino acids, in L. edodes were evaluated. The results revealed that the contents of crude proteins, crude polysaccharides, and crude fat in L. edodes of different origins vary. More specifically, the crude protein content in L. edodes from Xixia and the polysaccharide content in L. edodes from Shiyan are the highest. Meanwhile, the levels of potassium, sodium, alcium, and zinc in L. edodes from Xixia are the highest, corresponding to 21773.3, 68.01, 122.09, and 81.52 mg/kg, respectively. The highest ergosterol level of 5.78 mg/g was noted in L. edodes from Shiyan. Amino acid analysis results revealed that L. edodes collected from the four main producing areas possess abundant amount of essential amino acids, and they resemble the WHO/FAO protein standard. Particularly, the contents of glutamic acid and aspartic acid are the highest. Furthermore, L. edodes from Shiyan exhibited the highest polysaccharide content, while L. edodes from Xixia exhibited the optimal amino acid composition. These results suggest that L. edodes from the four regions contain various nutrients, and thus, they are of high nutritional value. These findings will enable further application and research on L. edodes.

14 Computer Evaluation of the Potential of Protein from Arachis hypogaea as A Nutritional Supplement during COVID-19 Pandemic

ZHOU Xianmin , OU Cansheng , DENG Senrong , YANG Saiya , ZHANG Xuewu , ZENG Qiaohui

2021, 37(12):104-111. DOI: 10.13982/j.mfst.1673-9078.2021.12.0370

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The potential of Arachis hypogaea protein as a nutritional supplement during the pandemic of COVID-19 was studied. First of all, the classification of Arachis hypogaea proteins was briefly reviewed, and the representative Arachis hypogaea proteins (Ara h1, Ara h2, Ara h3, Ara h6, conarachin A and conarachin B) were selected. At the same time, six common Arachis hypogaea proteins were hydrolyzed by computer-simulated gastrointestinal protease, and a large number of active peptides were obtained. Then, the active peptides were docked with SARS-CoV-2 Mpro to evaluate their binding ability of the six Arachis hypogaea proteins. Results showed that the degree of hydrolysis of the six Arachis hypogaea proteins ranged from 34.97% to 38.11%, and Ara h2 possessed the best binding effect with SARS-CoV-2 Mpro (F>6.67%), followed by Ara h6 (F=4.73%). In addition, oligopeptides PCAQR, CQSQL, PCEQH and IQQGR were proved to possess good binding effect with SARS-CoV-2 Mpro (docking fraction≤-140). In summary, supplementation of Arachis hypogaea protein during COVID-19 pandemic may be helpful for potential SARS-CoV-2 infection, and the identified oligopeptides have the potential to become inhibitors of SARS-CoV-2.

15 Synergistic Inhibitory Effect of Thymol and Cinnamaldehyde against Salmonella and Applications of the Combination

HU Xinyi , HU Yuhan , PAN Zhenhui , LI Zhicheng , XIAO Xinglong , YU Yigang

2021, 37(12):112-119. DOI: 10.13982/j.mfst.1673-9078.2021.12.0307

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The antibacterial effect of the combined use of thymol and cinnamaldehyde against Salmonella was examined in this study, and the preservation effects of their combinations on salt-baked chickens were also evaluated. The minimum inhibitory concentrations (MICs) and the combined anti-bacterial effect of thymol and cinnamaldehyde against Salmonella were determined by the microdilution method. The results showed that the MICs and minimum bactericidal concentrations (MBCs) of thymol and cinnamaldehyde against Salmonella were 0.25 mg/mL and 0.5 mg/mL, respectively. In addition, the fractional inhibitory concentration index (FICI) of thymol and cinnamaldehyde in combination against Salmonella was 0.75, indicating that the combination of thymol and cinnamaldehyde exhibited a significant synergistic antibacterial effect. The above results were further confirmed by the time-kill curves, SEM analysis and PI staining experiments. That the combined use of thymol and cinnamaldehyde could destroy the integrity of the cell membranes of Salmonella and alter its morphology, causing the leakage of the cell contents and eventually cell lysis and death. These results indicated the potential of the combination as an antiseptic agent and preservative. Therefore, salt-baked chicken was used a model food to examine the antiseptic and preservation effects of thymol and cinnamaldehyde in combination from two aspects, microorganisms and lipid oxidation. The results showed that the combination of thymol and cinnamaldehyde could significantly inhibit the proliferation of bacteria and lipid oxidation in salt-baked chicken. Accordingly, thymol and cinnamaldehyde in combination can be used as a natural compound antibacterial agent for preserving salt-baked chicken and other cooked meat products.

16 Effect of Houttuynia cordata and Syzygium aromaticum and Pullulan Polysaccharide Compound Preservative on Penicillium italicum and Storage Quality of Citrus reticulata

HUANG Jiaoli , LIU Jiaxin , YI Youjin , LIU Rukuan , ZHU Shuqing , DENG Houqin

2021, 37(12):120-126. DOI: 10.13982/j.mfst.1673-9078.2021.12.0414

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In order to develop a new plant-resource Citrus reticulata preservative, the inhibitory effects of water extracts from five plants were evaluated by antibacterial test, and the inhibition effects of Houttuynia cordata and Syzygium aromaticum and pullulan polysaccharide composite on Penicillium italicum after harvest were studied. The results showed that the Syzygium aromaticum and Houttuynia cordata water extracts had better inhibitory effect on Penicillium italicum, the inhibition ratios were 73.45% and 49.85% respectively, and the MIC were 0.60 mg/mL and 1.20 mg/mL respectively. The mixed Syzygium aromaticum and Houttuynia cordata water extracts had higher inhibitory toxicity than that of single water extracts, and the EC50 was 0.36 mg/mL. The decay rate of the compound preservative was 16.67% lower than that of CK group (p<0.05), but the inhibition effect on weight loss rate was not significant (p>0.05) after 9 days storage. The compound preservative could effectively delayed the increase of soluble solid content and titratable acidity content, maintained stable ascorbic acid content and inhibited the respiration intensity. The experimental results indicated that Syzygium aromaticum and Houttuynia cordata water extracts could inhibit spore germination and mycelial growth in Penicillium italicum; the compound preservative of Houttuynia cordata and Syzygium aromaticum and pullulan polysaccharide could improve the resistance of Penicillium italicum of Citrus reticulata. This study provides theoretical support for the development of new safe preservative of Citrus reticulate.

17 Bactericidal Efficacy and Kinetics of Cold Plasma against Staphylococcus aureus and Pseudomonas aeruginosa

LIU Yafu , FU Tengfei , LIU Chencheng , CHEN Gu , WANG Jiamei

2021, 37(12):127-135. DOI: 10.13982/j.mfst.1673-9078.2021.12.0302

[Abstract](164) [HTML](179) [PDF 1.11 M](546)

Abstract:
To study the bactericidal effects of dielectric barrier discharge cold plasma against S. aureus and P. aeruginosa, bacterial suspension (1×108 CFU/mL) was used as the research object to examine its bactericidal effect. Linear, Weibull and Log-linear+Shoulder+Tail models were used to examine the kinetic characteristics of cold plasma sterilization, and root mean square error (RMSE), determination coefficient (R2), accuracy factor (Af) and bias factor (Bf) as the four indices were used to evaluate the fit of the model. The outcome of the sterilization in this experiment showed that under the conditions of O2:N2=65:35, the medium thickness was 2 mm, the treatment voltage was 75 kV and the treatment time was 150 s, the sterilization rates of S. aureus and P. aeruginosa were 90.00% and 98.99%, respectively, just after the treatment (without standing); After the standing for 2 h following the treatment, the sterilization rates for the two strains increased to 90.27% and 99.61%, respectively. The fitting results showed that the Weibull model and the Log-linear+Shoulder+Tail model were more in line with the actual sterilization curves of cold plasma-treated S. aureus and P. aeruginosa than the Linear model, whilst the Log-linear+Shoulder+Tail model has a wider range of applications and can better describe the sterilization process of cold plasma under different standing time periods.

18 Preparation and Characterization of Quaternary Ammonium Salt Modified Chitosan and Its Derived Composite Film

PAN Qingyan , ZHOU Chuang , YANG Ziming , HE Zuyu , WANG Chao , LIU Yunhao , SONG Shuhui , GU Hui , YU Lijuan , LI Xuerui , QU Yunhui , LI Puwang

2021, 37(12):136-144. DOI: 10.13982/j.mfst.1673-9078.2021.12.0318

[Abstract](343) [HTML](449) [PDF 1.26 M](727)

Abstract:
In this study, chitosan was modified with quaternary ammonium salt. The optimal preparation conditions of chitosan quaternary ammonium salt were examined by single factor experiments. Its structure was characterized by Fourier infrared spectroscopy and hydrogen nuclear magnetic spectroscopy. The mechanical properties of the coating film prepared by chitosan quaternary ammonium salt with different degrees of substitution were investigated. Using chitosan quaternary ammonium salt as the raw material, with the introduction of polyvinyl alcohol, nano-titanium dioxide, and glycerol, chitosan quaternary ammonium salt-based composite membrane was prepared by the solution blending method. The structure and performance of the composite film of chitosan quaternary ammonium salt were examined by Fourier infrared spectroscopy, thermogravimetric analysis and contact angle measurements. The results revealed the optimal preparation conditions as follows: the mass ratio of quaternary ammonium salt to chitosan was 3:1, reaction time was 12 h, and reaction temperature was 80 ℃. In addition, when the content of chitosan quaternary ammonium salt was 50% (polyvinyl alcohol as the standard), nano-titanium dioxide content was 1%, and glycerol content was 0.8%, optimal tensile strength and elongation at break of chitosan quaternary ammonium salt-based composite membrane were achieved (19.38 MPa and 55.78%, respectively). The tensile strength of the chitosan quaternary ammonium salt-based composite membrane (19.38 MPa) was also higher than that of the chitosan composite membrane (18.64 MPa). This indicated that the modification of chitosan with quaternary ammonium salt was beneficial to the increase of the mechanical properties of the coating, which provides a certain theoretical reference for subsequent studies on membrane materials containing modified chitosan.

19 Optimization of the Key Processing Parameters of Saozi Meat

MA Yali , QUE Jiajing , YUE Tianli , CUI Lu

2021, 37(12):145-152. DOI: 10.13982/j.mfst.1673-9078.2021.12.0295

[Abstract](173) [HTML](176) [PDF 631.95 K](549)

Abstract:
At present, the rapid development of the Chinese Saozi meat industry is severely limited, because of the large difference in meat processing, low degree of industrialization, absence of well-known brands, and few studies on the changes in aroma components and the evaluation of key physico-chemical indicators during processing. Therefore, the study took Saozi meat as the research object, and sensory evaluation results and changes in aroma components as the inspection indicators. The factors having a significant impact on the quality of Saozi meat were selected through the Plackett-Burman test and determined as pepper, monosodium glutamate (MSG), and light soy sauce. On this basis, the Box-Behnken test was used to optimize the processing parameters of Saozi meat and the optimal processing conditions were: pork 500 g, lean to fat ratio 3:2, rapeseed oil 10 g, salt 5.0 g, pepper 20 g, ginger 30 g, garlic 30 g, cooking wine 10 g, dark soy sauce 5.0 g, light soy sauce 4.0 g, vinegar 200 g, Sichuan pepper 2.0 g, pepper 4.0 g, MSG 3.5 g, high-fire temperature 220 ℃, low-fire temperature 140 ℃, heating time 50 min. This study investigated the aroma and key physico- chemical indicators in the processing of Saozi meat, which is a characteristic product in northern china, and establishes an optimization model, which has local characteristics and application value, as well as a certain degree of scientificity.

20 Quality Factor Analysis and Process Optimization of Textured Pea Protein

ZHANG Guangyao , PENG Huihui , ZHANG Jing , WANG Sihua , QI Mingming , REN Zhishang , HE Zhuangzhuang , MA Chengye

2021, 37(12):153-161. DOI: 10.13982/j.mfst.1673-9078.2021.12.0109

[Abstract](189) [HTML](604) [PDF 3.82 M](533)

Abstract:
Box-Behnken experimental design was employed to investigate the effects of different combinations of screw speed, barrel temperature, and moisture content in a high-moisture textured pea protein extrusion experiment. Correlation analysis and factor analysis were performed on textured pea protein indices such as hardness and degree of texturization. The results showed that the indices could be attributed to four main factors, with factor 1 dominating hardness, water absorption, and ΔE; factor 2 dominating cohesiveness, sensory evaluation, and degree of texturization; factor 3 dominating springiness and oil holding capacity; and factor 4 dominating soluble nitrogen content. Among the various indices, soluble nitrogen content demonstrated a poor correlation with other indices; hardness demonstrated a highly significant negative correlation with water absorption and highly significant positive correlation with ΔE; water absorption demonstrated a highly significant negative correlation with ΔE, cohesiveness, and sensory evaluation; and springiness demonstrated a significantly negative correlation with oil holding capacity, cohesiveness, and degree of texturization. The indices for textured pea protein evaluation and the corresponding weights were hardness (25%), degree of texturization (25%), sensory evaluation (25%), and water absorption (25%). Response surface analysis of hardness, degree of texturization, and sensory evaluation revealed that the extrusion parameters exerted a strong impact on product quality. The optimized process parameter values were as follows: screw speed: 153 r/min, barrel temperature: 170°C, moisture content: 56%. Our results may serve as a basis for further exploration of methods to improve the quality of textured pea protein.

21 Comparative Analysis of Freshwater Fish Surimi Hydrogel Based on the Difference of Raw Materials

YING Yue , YU Jiamei , ZHU Jie , LIU Yujia

2021, 37(12):162-168. DOI: 10.13982/j.mfst.1673-9078.2021.12.0424

[Abstract](268) [HTML](244) [PDF 1.21 M](518)

Abstract:
In this study, the physicochemical and digestibility characteristics of surimi products from 8 kinds of freshwater fish were compared using constructs cluster analysis, principal component analysis (PCA) and self-organizing maps (SOM) mathematical models, and the relationship between the type of differences and product characteristics was explored. The results showed that the pH of the 8 types of surimi gels was between 6.24 and 6.79, and there was no significant difference. The color and Hunter whiteness showed obvious differences. Grass carp, black carp and striped bass had the highest gel strength (about 1100 g•cm). The texture properties of striped bass, such as adhesiveness, chewiness, spring and resilience, were overall better than other fishes. Grass carp and sturgeon surimi gels had a looser structure and faster protein digestibility, but the final digestibility of all surimi tended to be the same. Cluster analysis and PCA results confirmed the subordination of different kinds of surimi, and the constructed 14×8 sets of characteristic parameters were the input layer, and the SOM model with competition layer 5 and output layer 25 was constructed to further show the internal relationship between the main characteristics and species of surimi through the topology. This research aims to provide data reference for the deep processing of freshwater fish surimi in our country.

22 One-step Fabrication and Characterization of Pickering Double Emulsions Stabilized by Soybean Water-insoluble Peptide-chitosan Composite Particles

SHU Xinyi , HUANG Xiaonan , LAI Yangjie , LI Li , YIN Shouwei

2021, 37(12):169-176. DOI: 10.13982/j.mfst.1673-9078.2021.12.1155

[Abstract](232) [HTML](193) [PDF 1.76 M](571)

Abstract:
Enzymatic hydrolysis of soy protein isolate (SPI) afforded water-insoluble peptide aggregates (SWIP), which were sonicated and further compounded with chitosan (CS) to prepare composite colloidal particles (SWIP-CS). These particles were used as emulsifiers to obtain W/O/W Pickering double emulsions in a simple one-step preparation process. The effects of different chitosan concentrations and pH levels on the appearance, particle size, microstructure, and rheological properties of the emulsions were also investigated. Mechanistic studies revealed that the water-insoluble aggregates interacted with chitosan by hydrogen bonding. Stable Pickering double emulsions were prepared using chitosan at concentrations of 0.125%, 0.25%, and 0.5% and an oil phase fraction of 50% at pH 3.0, 3.8, 4.0, and 5.0. The increase in chitosan concentration resulted in a significant decrease in the particle size of the emulsions (from 30.6 to 23.9 μm), and the stability and gel properties of the double emulsions were improved at a relatively high chitosan concentration (0.5%). However, as the pH was increased from 3.0 to 5.0, the number of small droplets inside the double emulsion droplets gradually decreased, which in turn reduced the stability and gel properties of the droplets. Thus, this study provides a simple and effective strategy for the preparation of double emulsions, which can be applied to food, cosmetics, and pharmaceutical industries

23 Establishment and Application of A Product Quality Analysis and Comprehensive Evaluation System for Aronia melanocarpa Juices

LI Haibo , WANG Shujuan , YANG Yaping , GUO Dongwei , BAO Shihan , LAN Tian , SUN Xiangyu , MA Tingting

2021, 37(12):177-186. DOI: 10.13982/j.mfst.1673-9078.2021.12.0331

[Abstract](165) [HTML](207) [PDF 1.07 M](494)

Abstract:
In this study, 14 kinds of commercially available Aronia melanocarpa juice products with a relatively high sales volume were used as the experimental materials, a product quality analysis and comprehensive evaluation system for Aronia melanocarpa juices was established through analyzing 18 quality indexes (including color, physicochemical properties, phenolic content and antioxidant capacity) along with principal component analysis(PCA). This system was used to evaluate commercially available Aronia melanocarpa juice products. The results of PCA showed that the cumulative contribution rate of the first four principal component variances reached 91.88. The h° (0.56), total acid (0.90), sugar-acid ratio (0.54:1), suspension stability (0.48), flavonoids (0.82), condensed tannin (0.82), FRAP (0.57), and DPPH (0.70) had higher load weights among the first four principal components, which were characteristic evaluation indexes of Aronia melanocarpa juices. In general, the concentrated oral liquid and 100% fruit juice products had a higher comprehensive quality, and ZH fruit juices had the best overall quality in its product category. Through establishing a product quality analysis and comprehensive evaluation system for Aronia melanocarpa juices, this study provides a database and theoretical support for the development and utilization of Aronia melanocarpa juice products, which is of great significance for the healthy development of the Aronia melanocarpa industry.

24 Extraction Optimization for the Polysaccharides from Tuber sinense and Their in vitro Antioxidant Activities

GUO Qi , LIANG Shuangmin , GE Changrong , XIAO Zhichao

2021, 37(12):187-196. DOI: 10.13982/j.mfst.1673-9078.2021.12.0263

[Abstract](241) [HTML](199) [PDF 4.55 M](671)

Abstract:
Tuber sinense from Yunan was used as the research object, and the extraction process for extracting polysaccharides from Tuber sinense was optimized. The monosaccharide compositions and in vitro antioxidant activities of the purified polysaccharides were analyzed. The optimal extraction conditions obtained via optimization by the response surface method were as follows: extraction temperature 75.36 ℃, extraction time 1.02 h and material-liquid ratio 1:31.32 (g/mL). Under these conditions, the experimental yield of polysaccharides was 11.79%, whilst the predictive yield was11.86%. Four new polysaccharide fractions (TSP-1, TSP-2, TSP-3, TSP-4) were separated and purified from the crude polysaccharides from Tuber sinense by using the DEAE-sepharose fast flow column. The compositions of the polysaccharides were analyzed by ion chromatography. The monosaccharide components of TSP-1 included galactosamine hydrochloride, glucose and mannose in a ratio of 2.8:77.1:20; TSP-2 included rhamnose, glucosamine hydrochloride, galactose and mannose in a ratio of 18:1.4:44.7:35.9; TSP-3 was composed of rhamnose, glucosamine hydrochloride, glucose, mannose, glucuronic acid and galactose in a ratio of13:3.5:58.4:21.1:2.7:1.2. In the range of 0.25~4 mg/mL, the maximum rates of crude polysaccharide (crud TSP), TSP-1, TSP-2 and TSP-3 were 73.93%, 36.67%, 73.60% and 54.10% for scavenging DPPH radical, 60.47%, 36.20%, 41.87% and 52.73% for scavenging ABTS radical, 61.63%, 27.00%, 52.50% and 43.17% for chelating metal, and 0.39, 0.34, 0.28, 0.56 for the absorbance corresponding to reducing power. This research aimed to provide a theoretical foundation for the study of the bioactive material basis and the development and utilization of Tuber sinense polysaccharides. The research results are of great significance to the research and development of wellness foods.

25 Optimization of Low-temperature Vacuum Fried Process for Shiitake Mushroom Crisps

CHEN Hanyong , XU Guobo , YANG Juan , WANG Jinmei

2021, 37(12):197-204. DOI: 10.13982/j.mfst.1673-9078.2021.12.0387

[Abstract](232) [HTML](274) [PDF 6.60 M](889)

Abstract:
Shiitake mushroom crisps were prepared by fresh shiitake mushrooms. Low-temperature vacuum fried process was optimized and the effect of different shiitake mushrooms cultivars on the quality of crisps was evaluated. The results showed that processing mainly affected the physicochemical property and microstructure. Compared to sugaring/freezing process, the microstructure of freezing/thawing/sugaring process crisps was destructed more seriously, leading to an increase in the oil content from 5.51%to 8.75% and a decrease in the total sugar content from 78.04% to 72.25%, respectively. During sugaring treatment, the irregular and rough pores were formed in the microstructure, the total sugar content was decreased from 72.21% to 59.05%, and the lipid content of the crisps was slightly increased, which were attributed to the addition of sugar cane juice into the malt syrup. The ultrasonic treatment had no discernible effect on the total sugar content but was beneficial for the centrifugal removal of oil, with a decrease of oil content to 5.50%. Overall, the best processing techniques for the production of low-temperature vacuum fried shiitake mushroom crisps were freezing/thawing/ultrasonic-assisted sugaring with mixing sugaring solution of malt syrup and sugar cane juice. Additionally, shiitake mushroom cultivars had a strong impact on the physicochemical property, sensory property, texture property and microstructure of crisps. No distinct influence of the size of fresh shiitake mushrooms on the content of total sugar and lipid was observed. Minor-sized shiitake mushroom crisps presented lower moisture content, better sensory property and crispness than medium and large-sized crisps. Mushroom type 0912 exhibited the best physicochemical and sensory properties, and the market supply of mushroom raw materials is sufficient and stable, which is suitable for industrial production.

26 Analysis of Adsorption Characteristics of Zirconium-loaded Montmorillonite on Gallic Acid in Sucrose Solution

WU Guoyong , PAN Yanmei , WU Hailing , SU Xide , LIU Fujie

2021, 37(12):205-214. DOI: 10.13982/j.mfst.1673-9078.2021.12.0368

[Abstract](159) [HTML](162) [PDF 1.45 M](454)

Abstract:
In this study, zirconium chloride and montmorillonite were used as raw materials to prepare zirconium-loaded montmorillonite by coprecipitation. The effects of modification and adsorption on the surface structure and surface group of zircalmontmorillonite were studied by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and specific surface area analysis (BET). The adsorption properties of the montmorillonite on sucrose solution were investigated. The results showed that the surface of zirconium loaded montmorillonite was coarser than that of montmorillonite, with a specific surface area of 204.47 m2/g, which was 3.39 times of the former; nano particles accumulation was observed on the surface. FT-IR and XPS results showed that zirconia was successfully loaded on the surface of montmorillonite, and the isoelectric point of zirconia loaded montmorillonite was 7.39. The adsorption test showed that the adsorption capacity of zircalmontmorillonite was 102.54% higher than that of montmorillonite, and the optimum pH and equilibrium time of adsorption on gallic acid from sucrose solution were 7.0 and 300 min, respectively. The adsorption process could be described accurately by the quasi second-stage adsorption kinetic model and Langmuir isotherm adsorption model, and the saturated adsorption capacity reached 129.87 mg/g; the thermodynamic research showed that the adsorption process was endothermic and can proceed spontaneously. After 5 times of regeneration, zirconium loaded montmorillonite can maintain more than 80% of the initial adsorption capacity. Gallic acid was mainly adsorbed by electrostatic attraction and coordination ion exchange of zirconia. In conclusion, zircalmontmorillonite exhibited good adsorption performance for gallic acid in sucrose solution, and it may be a promising adsorbent for sugar engineering.

27 Optimization of Microwave Extraction of Ficus carica Polysaccharide

LI Le , CHEN Benshou , YUAN Ying

2021, 37(12):215-220. DOI: 10.13982/j.mfst.1673-9078.2021.12.0692

[Abstract](266) [HTML](160) [PDF 399.45 K](808)

Abstract:
The microwave-assisted extraction method of Ficus carica fruit polysaccharides was studied. The Ficus carica polysaccharides were extracted by several steps, including microwave-assisted extraction, ethanol precipitation, Sevage deproteinization. Then polysaccharides content was determined by phenol-sulfuric acid method. The single factor experiments were used to investigate the influence of four factors, including microwave power, water-to-material ratio, temperature and microwave time on the yield of polysaccharides. On this basis, the orthogonal design of four factors and three levels of experiments were to study the influence of each factor on the extraction rate of Ficus carica polysaccharides, and the extraction conditions of Ficus carica polysaccharides were optimized by microwave-assisted method. The optimal extraction conditions were microwave power 600 W, water-to-material ratio 40 mL/g, temperature 70 ℃, and microwave time 40 min. The yield of polysaccharide was 12.17%, and it was 12.05% after repeated verification for 3 times. The results showed that microwave power was the main factor affecting the yield of polysaccharide. This study can provide a reference for further processing and utilization of Ficus carica.

28 Changes in the Flavor Components of Peanut Oil Caused by Different Pressing Processes

KAN Qixin , HUANG Yuxing , DU Jie , MA Yingchuan , ZHAO Lichao , CHEN Meng , CAO Yong

2021, 37(12):221-229. DOI: 10.13982/j.mfst.1673-9078.2021.12.0264

[Abstract](196) [HTML](368) [PDF 758.88 K](647)

Abstract:
In this study, headspace solid-phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS) and electronic nose were used to analyze the volatile flavor components and fatty acid compositions of the peanut oils produced by different pressing processes. A total of 10 types of 38 volatile compounds were detected in the peanut oils from 6 different pressing processes, including 19 flavor components. Furans (63.43%~66.48%), aldehydes (10.04%~5.47%) and phenols (8.83%~7.18%) were the main volatile components in the hot-pressed peanut oil, whilst esters (26.43%), aldehydes (23.47%) and acids (22.10%) were the main volatile components in the cold-pressed peanut oil. In addition, small amounts of key flavor components such as pyrazins, pyridines and ketone were detected in the hot-pressed peanut oil, which were not detected in the cold-pressed peanut oil. The results obtained by the electronic nose were essentially in agreement with those of GC-MS, with the sulfides, aromatic compounds, nitrogen oxides and methyl compounds making greater contributions to the overall flavor of peanut oil. The results of principal component analysis and K-mean cluster analysis showed that there were significant differences in the volatile components of 6 peanut oils. Oleic acid, linoleic acid and palmitic acid were the main fatty acids in 6 kinds of peanut oil (whose contents were over 90%). However, the comparisons of the fatty acid compositions of the peanut oil produced at different temperatures revealed that the oxidation of unsaturated fatty acids accelerated with an increase of pressing temperature. In summary, the comparisons of the changes in the flavor and nutrient components of the peanut oils produced by different pressing processes revealed that the contents of the flavor components in peanut oil increased significantly under high-temperature pressing conditions, with its quality decreased slightly. Electronic nose can distinguish rapidly peanut oils produced by different pressing processes.

29 Improving the Flavor Quality of Fermented Pear Juice with Lactobacillus plantarum by Ultra-high Pressure Pretreatment

ZHANG Ping , RUAN Zheng , LI Biansheng

2021, 37(12):230-239. DOI: 10.13982/j.mfst.1673-9078.2021.12.0290

[Abstract](230) [HTML](207) [PDF 1.65 M](497)

Abstract:
This study aimed to explore the effects of ultra-high pressure pretreatment and pasteurization pretreatment on the proliferation and metabolism of Lactobacillus plantarum in pear juice as well as the flavor quality of fermented pear juice. The number of viable bacteria, pH value, total sugar and total acid content of pear juice during the fermentation process were determined. The changes in the volatile flavor compounds of the pear juice before and after fermentation were examined by static-headspace solid-phase microextraction (HS-SPME) and gas chromatography-mass spectrometry (GC-MS), then sensory evaluation on the flavor of pear juice was carried out before and after fermentation. Compared with heat treatment, the ultra-high pressure pretreatment could better preserve the original flavor of pear juice and led to less irritation of sterilized pear juice. The effects of the two pretreatment methods on the volatile flavor compounds in fermented pear juice were significantly different (p<0.05). After the fermentation with Lactobacillus plantarum, the contents of volatile alcohols, esters, and alkanones in the fermented pear juice pretreated by ultra-high pressure increased by 36.47%, 95.43% and 80.00%, respectively, while the contents of volatile olefins and aldehydes decreased by 7.56% and 27.00%, respectively. Pasteurization pretreatment made the fermented pear juice having increased contents of volatile alcohols, esters, and olefins (by 63.83%, 25.67% and 17.82%, respectively), a decreased content of aldehydes (by 4.08%), and an increased content of alkanones (from 0 to 0.90 mg/L). Compared with the fermented pear juice pretreated by pasteurization, the fermented pear juice with an ultra-high pressure pretreatment had higher (p<0.01) contents of volatile alcohols, esters and olefins, and lower (p<0.05) contents of volatile aldehydes and alkanones. The ultra-high pressure pretreatment makes the fermented pear juice pretreated fresher.

30 Changes of Volatile Flavor Substances in the Fermentation of Dahe Black Pig Ham under Standardized Technological Conditions

LI Yufang , SHI Ya’nan , WEI Guangqiang , LI Xiang , HUANG Aixiang

2021, 37(12):240-251. DOI: 10.13982/j.mfst.1673-9078.2021.12.0333

[Abstract](128) [HTML](187) [PDF 722.25 K](464)

Abstract:
Solid-phase microextraction-gas chromatography-mass spectrometry (SPME-GC-MS) technology combined with partial least squares-discriminant analysis (PLS-DA) and relative odor activity value ( ROAV) were used to analyze the volatile flavor compounds of Dahe black pig ham fermented for 90 d, 150 d, 210 d, 270 d, 450 d and 630 d. The results showed that a total of 137 volatile flavor components were identified during the fermentation process, including aldehydes, alcohols, acids, hydrocarbons, ketones, esters, aromatics, and other compounds. Among them, aldehydes (51.63% ~ 68.17%) and alcohols (12.73% ~ 23.64%) were the most abundant in type and content. The types of volatile flavor substances increased (by 23 types) with the extension of the fermentation time, but the compositions of volatile flavor substances in the Dahe black pig ham fermented for different time periods(210 d, 270 d, 450 d, 630 d) resembled. This result indicated that the principal flavor compounds were formed after fermentation for 210 days. The 16 key flavor substances were detected during the fermentation process, including 1-heptanol, 3-methyl-1-butanol, 3-methylbutanal, 2,3-octanedione, phenylacetaldehyde, hexanal, octanal, and other substances. The fermentation time under the standardized process conditions hada certain impact on the formation of volatile flavor compounds in ham, and the processing period of Dahe black pig ham can be set to 10~12 months. The research provides a theoretical basis for standardized processing of Dahe black pig ham.

31 Analysis of Aroma Components of Baimudan Tea from Different Tea Plant Varieties Using HS-SPME-GC-MS

FENG Hua , WANG Feiquan , ZHANG Bo , ZHANG Jianming , CHEN Rongbing , GONG Xiaojing , CHEN Hong , HUANG Yibiao , YE Jianghua

2021, 37(12):252-264. DOI: 10.13982/j.mfst.1673-9078.2021.12.1273

[Abstract](208) [HTML](234) [PDF 1.26 M](560)

Abstract:
We aimed to investigate the aroma quality characteristics of Bai Mu Dan tea from different tea plant varieties and the material basis for quality differences among the varieties. Aroma components of Bai Mu Dan tea samples from the varieties Zhenghe Dabaicha (ZD), Fuding Dahaocha (FD), Fujian Shuixian (SX), and Meizhan (MZ) were measured using headspace solid-phase microextraction (HS-SPME) coupled with gas chromatography–mass spectrometry (GC-MS) (HS-SPME-GC-MS) and comparatively analyzed using principal component analysis (PCA), partial least squares discriminant analysis (PLS-DA), and hierarchical cluster analysis (HCA). The results indicated that all Bai Mu Dan tea varieties had excellent aroma qualities and distinct characteristics. Specifically, ZD had a fresh aroma with a floral note, FD had a delicate aroma with an obvious pekoe scent, SX had an obvious floral aroma, and MZ had a strong and lasting floral aroma. The aroma scores of the different varieties were in the order MZ>SX>FD>ZD>90 points. A total of 101 aroma components were detected in the Bai Mu Dan tea varieties, with 98, 98, 100, and 96 aroma components identified in ZD, FD, MZ, and SX, respectively. The aroma components mainly consisted of alcohols, hydrocarbons, esters, and ketones. PCA and PLS-DA models, which enabled the effective distinguishing of different Bai Mu Dan tea varieties, were constructed based on the relative contents of all aroma components. Thirteen aroma components had significantly different contents (VIP>1, p<0.05) in different Bai Mu Dan tea varieties. In conclusion, the four investigated Bai Mu Dan tea varieties exhibited significant differences in aroma quality characteristics and distinct aroma profiles, and 13 aroma components were identified as key components that contributed to quality differences among varieties.

32 A New Method for Extracting Outer Membrane Vesicles of Campylobacter jejuni

NIE Xiang , WANG Juan , WU Qingping , ZHANG Jumei , MA Guoxiang , WANG Zhi , TANG Shengjun , PAN Qiqi , ZHANG Weipei , XIAO Kaishan

2021, 37(12):265-271. DOI: 10.13982/j.mfst.1673-9078.2021.12.0282

[Abstract](240) [HTML](262) [PDF 1.43 M](510)

Abstract:
Outer membrane vesicles (OMVs) of Campylobacter jejuni are globular vesicles secreted to the outside of cellsduring the growth process, whichmainly contain outer membrane proteins and some periplasmic substances, and play an important role in the survival, colonization, communication between bacteria and host cells, and pathogenic mechanisms. Therefore, the development of an efficient extraction method is the key to studying the biological function of OMVs. This study found that it is most appropriate to extract OMVs after culturing C. jejuni with MH medium for 15 h under microaerobic conditions. Under optimal conditions, the ultrafiltration concentration method was used to extract OMVs from the bacterial liquid, and the extract was further filtered using a 0.22 μm microporous filter to remove flagella and other impurities. In order to characterize the quality of the extracted OMVs, a transmission electron microscope was used. It was found that the extracted OMVs had a typical morphology (with their size ranging from 50 to 300 nm), and contained less impurities. The results of SDS-PAGE showed that OMVs contained a large amount of proteins (whose total content was 40.50 mg/mL). Finally, the outer membrane protein antibody was used to prove successfully that the main components of the extracted material were OMVs. In this study, an extraction system for extracting C. jejuni OMVs from liquid culture medium was successfully established. Various analytical methods have proved that its extraction efficiency is high and its quality is good. It is suitable for subsequent studies on the biological functions of C. jejuni OMVs.

33 Whole-genome Sequencing of A Klebsiella pneumoniae ST37 Strain and Comparative Analysis of Virulence Factors

LIANG Huixian , YAN He

2021, 37(12):272-279. DOI: 10.13982/j.mfst.1673-9078.2021.12.0272

[Abstract](288) [HTML](415) [PDF 7.54 M](588)

Abstract:
In this study, a multi-drug resistant ST37 (Sequence type, ST) Klebsiella pneumoniae KP200 strain was isolated from the liver of sick swine. ST37 type is a common type among clinical isolates resistant to broad-spectrum β-lactam. Based on the whole-genome sequencing data, virulence factors carried by KP200 and all K. pneumoniae ST37 strains (160 strains) from NCBI were investigated, and the relationship between the virulence and genetic evolution of ST37 K. pneumoniae was analyzed by single-copy core gene evolution. The results showed that KP200 carried 7 types of virulence factor-related genes including capsule (cpsACP, galF, gnd, ugd, manB and manC), type 1 fimbriae (fimBEACDFGHK), type 3 fimbriae (mrkABCD), enterobactin (entABCDEF and fepABCDG), salmochelin (iroE and iroN), aerobactin (iutA) and bacterial Type VI secretion system T6SS (tssJFGKIBCDMHL). K. pneumoniae ST37 carrying more than 5 types of virulence factors accounted for 100%. The results of single-copy core gene evolution analysis showed that KP200 and the other 5 K. pneumoniae strains of human origin had a close relationship and similar virulence factors. This study showed that ST37 K. pneumoniae KP200 strains of swine origin carried a wide variety of virulence factors and had potential pathogenicity. There was an evolutionary relationship between to the virulence factors carried by ST37 K. pneumoniae and the evolution of single-copy core genes. The results of this study can provide basic data for the correlation between the virulence factors of ST37 K. pneumoniae and genetic evolution.

34 Rapid Identification of Authentic Donkey Skin Based on Gas Chromatography

LI Lanjie , ZHANG Huachen , SHI Jing , WEI Zixiang , ZHANG Ning , LIU Guiqin

2021, 37(12):280-285. DOI: 10.13982/j.mfst.1673-9078.2021.12.0328

[Abstract](167) [HTML](180) [PDF 439.19 K](424)

Abstract:
In order to achieve more comprehensive control of the quality of E-jiao, a rapid method based on gas chromatography for identifying authentic donkey skin was established. After the animal sebum was extracted and methylated, fingerprints of total fatty acids in donkey skin, sheep skin, and cow skin were preliminarily established. The relative contents of myristic acid and palmitoleic acid in donkey, sheep and cow hides were determined by normalization method, and quantitative analysis of myristic acid and palmitoleic acid in donkey, sheep and cow hides was carried out by the internal standard method (using methyl heptadecanoate as the internal standard). The results showed high differences in myristic acid and palmitoleic acid among donkey, sheep and cow hides. The relative content of myristic acid in sheep skin (8.94%) was about 3 times that of donkey skin (2.98%) and cow skin (3.03%). The relative content of palmitoleic acid in donkey skin and cow skin (9.98% and 13.46%) was about 3.6 times and 4.8 times, respectively, that of sheep skin (2.78%). Similarly, high differences were detected in the absolute contents of myritic acid and palmitoleic acid in donkey skin (2.98%, 9.98%), sheep hide (8.94%, 2.78%) and cow hide (3.03%, 13.46%). In summary, the establishment of the determination of the myristic acid and palmitoleic acid contents in donkey skin would provide a new idea for the rapid identification of authentic donkey skin.

35 Determination of Fatty Acid Content of Camellia Seeds Oil in Different Regions by GC-MS Combined with Acid Methyl Esterification Pretreatment

TANG Xuxiao , ZHANG Yingzhong , WANG Jing , ZHANG Mengyu , XU Baohua

2021, 37(12):286-293. DOI: 10.13982/j.mfst.1673-9078.2021.12.0410

[Abstract](302) [HTML](191) [PDF 914.76 K](504)

Abstract:
Based on the comparison of acid esterification and alkali esterification pretreatments, the main kinds, relative contents and proportions of fatty acids of Camellia oleifera seeds oil from Hunan, Guangdong, Jiangxi, Yunnan, Guangxi and Hainan were analyzed by gas chromatography-mass spectrometry (GC-MS). The results showed that except for oleic acid, pentadecanoic acid, erucic acid, tricosanoic acid and tetracosenoic acid, there were significant differences in other fatty acids compared by esterification and alkali esterification pretreatments (p<0.05). And the acid esterification method was more suitable for the detection of fatty acids in Camellia oil. The highest contents of myristic acid, heptadecanoic acid, linolenic acid, arachidonic acid, erucic acid and tetracosenoic acid in Camellia oil were from Hunan, which were 0.10%, 0.11%, 0.20%, 0.09%, 0.17%, and 0.07%, respectively. The highest content of palmitoleic acid was from Guangdong, which was 0.12%. The highest content of palmitic acid was from Guangxi, which was 12.97%. The highest content of linoleic acid was from Jiangxi, which was 15.58%. The highest contents of stearic acid and oleic acid were both from Hainan, which were 3.74% and 73.70%, respectively. Camellia oleifera seeds oil has different nutritional characteristics in different producing areas. Camellia oils from Guangdong and Jiangxi had the highest polyunsaturated fatty acid contents, which were 15.33 % and 15.67 %, respectively; Camellia oils from Yunnan had the 85.74% total unsaturated fatty acids. Camellia oils from Hunan and Hainan were stable and easy to preserve. This study provides theoretical basis and reference information for understanding the nutritional value difference of Camellia oleifera in the main producing areas of China.

36 Colorimetric Detection of Salmonella typhimurium Based on Hybridization Chain Reactions and Aptamer

SUN Bo , CHEN Ping

2021, 37(12):294-300. DOI: 10.13982/j.mfst.1673-9078.2021.12.0094

[Abstract](264) [HTML](347) [PDF 1.26 M](561)

Abstract:
A label-free, enzyme-free, and sensitive colorimetric detection method of Salmonella typhimurium (S. typhimurium) detection was proposed based on the recognition mechanism of the aptamer and the amplification strategy of hybridization chain reactions (HCRs) using the color variations of gold nanoparticles (AuNPs) as the colorimetric signals. An initiator and two hairpin probes in the HCR system were designed based on the aptamer of S. typhimurium. The aptamer binds to S. typhimurium DNA, thereby triggering the initiator to open the hairpin probes. This way, HCRs are initiated. While achieving the signal amplification for the target bacteria, the differences in the binding of the sticky ends of the hairpin probes before the reaction and the hybrid long chain formed after the reaction with gold nanoparticles was used to obtain the colorimetric signals, which results in rapid detection of S. typhimurium. Experimental parameters, such as the hybridization chain reaction time, binding time of the hairpin probes with gold nanoparticles, and concentrations of hairpin probes, have been optimized to improve the detection sensitivity. Under the optimal conditions, the logarithmic value of the S. typhimurium concentration and UV absorbance ratio (A630/525) exhibited a good linear relationship in the range of 103~107 CFU/mL. The detection limit equals 6.3×101 CFU/mL, and the spike recovery rate for milk samples ranges between 90.05%~109.97%. The proposed colorimetric method is easy and simple, and it does not require any chemical modification and complicated equipment. Furthermore, the experimental results are visible. This research provides a new method for rapid detection of S. typhimurium.

37 Determination of Oxalic Acid in Crustacean Aquatic Products by Ion Chromatography with Solid Phase Extraction

HUANG Jiale , DANG Hua , WU Ziling , CEN Jianbin , HUANG Jiayu , CHEN Weiping

2021, 37(12):301-308. DOI: 10.13982/j.mfst.1673-9078.2021.12.0392

[Abstract](174) [HTML](165) [PDF 1.42 M](383)

Abstract:
A reliable and sensitive ion chromatography method with solid phase extraction for the determination of oxalic acid in crustacean aquatic products was established. The negative impurities in the extraction solution was precipitated with acetonitrile. The large molecules and Cl- in the supernatant were extracted and purified by the OnGuard Ⅱ RP cartridges and the OnGuard Ⅱ Ag/H cartridges, respectively. The complex matrices sample filtrate was resolved by an IonPac AS11-HC column using hydroxide gradient, which was operated in the online suppression external water mode with suppressed conductivity detection. The results showed that the linear correlation of oxalic acid was good in the range of 0.05~10.00 mg/L (the correlation coefficient was 0.9998). The detection limits (LODs) and the quantitation limits (LOQs) of the method ranged in 0.033~0.041 mg/kg and 0.11~0.14 mg/kg, respectively. The mean recoveries of oxalic acid in crustacean aquatic products ranged from 75.71% to 88.85% with the within-day precisions (n=6) in the range of 1.74%~3.61% and inter-day precisions (n=5) less than 5%. The method was suitable for the quantification of oxalic acid in crustacean aquatic products due to its simplicity and accuracy.

38 Research Progress on Inactivation Modeling of Salmonella spp. in Poultry Meat and Its Derived Products

XIONG Xiaohui , LIU Ruoyu , ZHANG Shuai , LIN Lijun , CUI Xiaowen

2021, 37(12):309-318. DOI: 10.13982/j.mfst.1673-9078.2021.12.0287

[Abstract](211) [HTML](244) [PDF 407.43 K](416)

Abstract:
Salmonella spp. is a common food-borne pathogen that can cause diseases in humans such as gastroenteritis and sepsis, and in severe cases, can endanger the life and safety. Poultrymeat and its derived products are indispensable food materials on consumers' tables. However, poultrymeat and its derived products are extremely susceptible to Salmonella spp. contamination during the growth, transportation and slaughter of poultry, as well as the processing, storage and sales of poultrymeat and its derived products, which is a threat to the safety of consumers. The inactivation model in predictive microbiology can reflect the inactivation effect of traditional heat treatment and emerging sterilization technologies on Salmonella spp. in poultrymeat and its derived products. This review firstly discussed the latest research on traditional thermal inactivation and non-thermal inactivation models of Salmonella spp. In poultry meat and its derived products. Secondly, the effects of the occurrence of sublethally injured Salmonella spp. on the establishment of the inactivation models were considered. Thirdly, the probability models of single cell inactivation were discussed. Finally, the research progress on inactivation models of Salmonella spp. in poultrymeat and its derived products is summarized then some suggestions are present, in order to provide a theoretical reference for the development of food quality and safety management methods in the future.

39 Progress on the Detection Methods of Deoxynivalenol in Grain

DAI Huang , WU Xuyue , HUANG Jinfa , BI Jie , WANG Jiahua , SHU Zaixi , XIAO Anhong

2021, 37(12):319-328. DOI: 10.13982/j.mfst.1673-9078.2021.12.0337

[Abstract](215) [HTML](206) [PDF 1.24 M](610)

Abstract:
It is known that deoxynivalenol (DON) has immunotoxicity, organotoxicity, inhibition of protein synthesis and teratogenicity. Grain under improper storage conditions is easily contaminated by mold which produces DON. DON can cause serious health problems after ingested by humans or animals. DON is stable and difficult to be destroyed and removed in the processing process, which is an important and potential safety hazard in the grain production and processing. There is a serious problem that DON exceeds the maximum residue limit in grain in China. Therefore, accurate and efficient DON detection methods are of great importance to ensure grain safety and human health. In this paper, the main methods for the detection of DON in cereals in recent years were summarized, including thin layer chromatography, high performance liquid chromatography-mass spectrometry, enzyme-linked immunoassay, lateral flow immunoassay strips, Raman spectroscopy, electrochemical method, surface plasmon resonance method, etc. The advantages and disadvantages of these detection methods were discussed and compared. At last the development trend of DON detection methods was prospected. It could provide theoretical support for the development of new detection methods, and is conducive to promoting the application of accurate and rapid detection methods in food safety detection.

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Volume 37,Issue 12,2021 Table of Contents