• Volume 40,Issue 3,2022 Table of Contents
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    • >Special Edition
    • Recent Approaches in Probiotics and Their Metabolites Research to Control Foodborne Pathogens

      2022, 40(3):1-12. DOI: 10.12301/spxb202200448

      Abstract (769) HTML (908) PDF 8.76 M (697) Comment (0) Favorites

      Abstract:Foodborne pathogens will not only cause food spoilage and economic losses, but also have threats on human health. It is urgent to develop efficient and safe foodborne pathogen control strategies. In recent years, a great attention has been paid for research of probiotics in microbiology and food field. In addition to their functions of regulating and improving human health, probiotics and their metabolites have strong removal and inactivation effects on certain microorganisms, and have potential applications in the inhibition of foodborne pathogens. In order to elucidate types of probiotics and their metabolites, their underlying microbial inhibitory mechanisms, and their application status in food safety and quality control, it is crucial for the development of relevant control strategies of foodborne pathogen. This review focused on analyzing and summarizing the inhibitory mechanisms of existing probiotics and their metabolites on foodborne pathogens, and single- or multi-mechanisms including damaging cell structure, affecting replication of genetic substances, blocking energy metabolism pathways, interfering with quorum sensing systems, inhibiting biofilm formation and competition for key nutrients. At the same time, based on the current researches of the applications of probiotics and their metabolites in food safety and quality control, their application parameters and conditions, effects on shelf-life extension and qualities of fruits, vegetables and meat were discussed. The trends of their applications in active packaging and combining with other quality control strategies were also critically reviewed and highlighted. This review would provide meaningful references to the development of food safety and quality control based on probiotics and their metabolites.

    • >Expert Forum
    • Progress of Production Technology for Hypoallergenic Foods and Its Industrial Application

      2022, 40(3):13-20. DOI: 10.12301/spxb202200451

      Abstract (288) HTML (617) PDF 4.93 M (710) Comment (0) Favorites

      Abstract:Food allergies are one of the global food safety issues stated by FAO/WHO. It is a great challenges for people with food allergies to completely avoid allergens due to the diversified food processing. The development of hypoallergenic foods plays a very important role in the safety diet for people with food allergies. Technological principles of processing hypoallergenic foods were reviewed. Thermal processing technologies, such as cooking, microwave and baking, could damage allergenic conformational epitopes by heating-induced protein denaturation. Non-thermal processing technologies, such as high pressure, pulsed electric field, pulsed light, cold plasma, irradiation and ultrasound, could directly destroy allergenic epitopes through protein structure modification, polypeptide chain cleavage and generation of new chemical bonds. Other technologies, such as enzymatic hydrolysis, enzymatic cross-linking, glycosylation and microbial fermentation, could disable or hide allergen epitopes by conformational changes of protein or combining proteins and carbohydrates. In addition, the industrialized processing methods and current production status of hypoallergenic protein ingredients were also reviewed in detail. Partially and extensively hydrolyzed milk proteins of plant-based manufacture based on enzymatic hydrolysis had been achieved, and further studies should to carry out for other processes for food allergenicity reduction as well as other ingredients with hypoallergenic protein. This review hopes to provide a quick reference guide for processing hypoallergenic food at industrial scale.

    • Research Progress in Crustacean Allergens and Their Mitigation Technologies

      2022, 40(3):21-33. DOI: 10.12301/spxb202200321

      Abstract (408) HTML (792) PDF 10.21 M (843) Comment (0) Favorites

      Abstract:Despite being delicious, nutritious, and popular among consumers, crustaceans and their derivatives can induce serious allergic reactions and even death, which has become an increasingly serious food safety issue worldwide. The study outlined the structures and immunological properties of the identified crustacean aquatic product allergens, and the principles and research progress of their mitigation abatement techniques. The reported crustacean aquatic product allergens include tropomyosin, arginine kinase, sarcoplasmic calcium-binding protein, myosin light chain, triosephosphate isomerase and hemocyanin, among which tropomyosin is the major allergen of crustacean aquatic products, which can produce specific IgE reactions with 72%-98% of the sera of crustacean food allergy patients. The allergenicity of crustacean aquatic products could be reduced by physical processing, mainly by inducing protein denaturation through traditional heat treatment, microwave, ultra-high pressure, low temperature plasma and irradiation, which can damage the epitopes of proteins. Chemical modification mitigating techniques, such as acid treatment and glycosylation, could mask or directly destroy the allergenic epitopes by changing the structure of allergens and forming new chemical bonds. Enzyme treatment and fermentation treatment could be used to reduce the allergenicity of crustacean aquatic products. Biological modification mitigating techniques such as enzymatic and fermentation treatments could directly degrade allergenic epitopes. Future research will be needed to investigate the mechanism of allergen structure and epitope modification through targeted allergen epitope reduction, synergistic multiple reduction techniques, and animal and human trials to promote the practical application of allergen reduction techniques and provide reference for the development of hypoallergenic and even desensitized crustacean foods.

    • >Special Studies
    • Preparation of Complex of Oats β-glucan and Quercetin and Its Effect on Lifespan of Caenorhabditis elegans

      2022, 40(3):34-42, 55. DOI: 10.12301/spxb202100903

      Abstract (984) HTML (508) PDF 13.77 M (735) Comment (0) Favorites

      Abstract:The covalent and non-covalent complex of β-glucan of oats and quercetin were prepared using radical catalysis and hydrogen bond adsorption methods, named COGQ and NOGQ, respectively. Their molecular structures were characterized using HPSEC (high performance size exclusion chromatography), FT-IR spectrometry and NMR (nuclear magnetic resonance) spectroscopy. The anti-aging activities of the complex were evaluated by Caenorhabditis elegans(C. elegans) model. Results from HPSEC showed that the relative molecular weights of NOGQ and COGQ were 354kDa and 349kDa, respectively, which were not much different. Compared with β-glucan of oats, both complexes demonstrated several new infrared absorption peaks at 1660cm-1, 1243cm-1 and 1562cm-1 and polysaccharide and polyphenols conjugates are amorphous. According to the NMR data, three monosaccharide residues were observed in the anomeric region of 1H spectrum and three new proton signals at 6.5-8.5 were attributed to phenyl groups in the complex. Compared with the control group, COGQ and NOGQ significantly increased the average lifespan of C. elegans (P<0.05), and the activities of SOD and CAT in both groups were significantly increased (P<0.01), suggesting that COGQ and NOGQ composites may prolong the lifespan of C. elegans by improving the antioxidant capacity of the body. The results could provide a reference for the preparation of polysaccharides and polyphenol composites and the development and utilization of them as novel food antioxidants.

    • Study on Preparation of Avenanthramides and Mechanism of Avenanthramides-Induced Apoptosis of Lung Cancer Cells

      2022, 40(3):43-55. DOI: 10.12301/spxb202100862

      Abstract (1019) HTML (534) PDF 13.98 M (709) Comment (0) Favorites

      Abstract:Avenanthramides (Avns), the unique active ingredients in oat, have multiple physiological functions. However, the natural content of Avns is very low. In this work, a germination procedure was used to promote the biotransformation of Avns in oat grains in order to elevate its natural content, optimize the extraction conditions and analyze its benefit to health. The influence of different experimental parameters on extraction of Avns was carried out by a single factor experiment, and the extraction process was optimized using the response surface methodology. Finally, the potential mechanism of Avns-induced apoptosis of lung cancer cells was explored. Avns were extracted after oat germination using an ultrasonic-assisted traditional organic solvent extraction. High performance liquid chromatography (HPLC) was employed for qualitative and quantitative analysis. With Avn C as standard positive control, the Western blot was used to explore the regulating effect on expression of nuclear factor kappa B (NF-κB) related pathway proteins and X-linked inhibitor of apoptosis (XIAP). Flow cytometry analysis was performed to detect the apoptosis of non-small cell lung cancer (NSCLC) H1299 and A549 after Avns treatment. The results showed that the optimal extraction conditions for Avns yield were as follows:the solid-liquid ratio 1∶22.2g/mL, the ultrasonic power 87.6W, the ethanol volume fraction 84.2%. In this condition, the yield of Avns was 849.251μg/g. The data of Western blot and flow cytometry analysis showed that both Avn C and Avns down regulated NF-κB/p65 phosphorylation and XIAP expression, and exerted promoting effect on apoptosis of H1299 and A549 cells in a dose-dependent manner. The results indicated that Avns might induce apoptosis in lung cancer cells by inhibiting the activity of NF-κB/XIAP signal pathway. This study aimed to provide theoretical basis of the application of Avns for lung cancer prevention.

    • Effects of Different Foxtail Millet Intake on Gut Microbiota and Short Chain Fatty Acids in Mice

      2022, 40(3):56-67. DOI: 10.12301/spxb202100871

      Abstract (685) HTML (732) PDF 15.55 M (744) Comment (0) Favorites

      Abstract:Coarse cereals intake can reduce the incidence of some chronic metabolic diseases. However, there is no uniform standard for coarse cereals intake, and unknown whether high coarse cereals intakes have adverse effect on health remains. In this study, 3-week-old C57BL/6J mice were intervened by adding different ratios of foxtail millet in feed, including 20%, 40%, 60%, and 80% additions for 12 weeks. Using the automatic biochemical analyzer, high-throughput sequencing of 16S rRNA gene, gas chromatography mass spectrometry, the effects of different ratios of foxtail millet on lipid blood levels, gut microbiota and short-chain fatty acids in mice were analyzed. The results showed that the feed with 80% supplementation foxtail millet significantly increased the total cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, propionic acid, butyric acid, isobutyric acid and valeric acid. In addition, foxtail millet intake increased the abundance of Bacteroidota and Muribaculaceae, decreased the abundance of Firmicutes, Actinobacteriota, Lactobacillaceae and Bifidobacterium. The gut microbiota composition in mice varied with different levels of foxtail millet. The microbiota of mice fed with the supplementation of 20% were enriched in Alistipes, Parabacteroides, Enterorhabdus. However, the abundances of Faecalibaculum, Blautia and Roseburia were reduced for the mice fed with the supplementation of 80%. The results showed that, 20% intake of foxtail millet was sufficient to regulate gut microbiota, while 80% intake led to abnormally elevated lipid levels in blood, reduced the diversity and evenness of gut microbiota, and decreased the abundance of probiotics. Therefore, coarse cereals' nutritional value should be rational considered and excessive intake patterns for coarse cereals should be avoided.

    • >Foundational Research
    • Diversity Analysis of Bacterial Community During the Sixth Heap Fermentation of Sauce-Flavor Baijiu Produced in Beijing

      2022, 40(3):68-76. DOI: 10.12301/spxb202100089

      Abstract (642) HTML (473) PDF 7.97 M (539) Comment (0) Favorites

      Abstract:In the present study, the bacterial community and dynamic changes during the sixth heap fermentation of sauce-flavor Baijiu produced in Beijing were studied by using the high-throughput sequencing method. The results showed that at the phylum level, the dominant phyla in the sixth heap fermentation process included Firmicutes, Actinobacteria and Proteobacteria. At the genus level, 14 dominant bacterial genera including Lactobacillus, Lentibacillus, and etc.. Among them, the relative abundances of Lentibacillus increased first and then decreased, while the relative abundance of Lactobacillus increased gradually. Lentibacillus, as hubs with positive correlation, was positively correlated with 7 bacterial genera, while Lactobacillus, as hubs with negative correlation, was negatively correlated with 10 bacterial genera. Compared with other sauce-flavor Baijiu producing areas such as Guizhou province, the bacterial community had significant difference in terms of number of species, order of dominant phyla and relative abundance of bacterial genera. This study revealed the change of bacterial community structure during the sixth heap fermentation of sauce-flavor Baijiu produced in Beijing, hoping to provide a basic data for studying the characteristics of sauce-flavor Baijiu produced in Beijing.

    • Reducing Effect of Kafirin on Pit Mud-Like Odor in Strong Flavor Baijiu

      2022, 40(3):77-87. DOI: 10.12301/spxb202200204

      Abstract (547) HTML (594) PDF 10.84 M (715) Comment (0) Favorites

      Abstract:The pit mud-like odor is an unpleasant odor in strong flavor Baijiu, and the addition of kafirin can reduce the pit mud-like odor in strong flavor Baijiu. In this study, the underlying mechanism of the effect of kafirin on reducing the pit mud-like odor was studied. 3-Methylindol and p-cresol were regarded as the key aroma compounds that caused pit mud-like odor in strong flavor Baijiu. The aroma profile analysis showed that the addition of kafirin significantly suppressed the pit mud-like off-odor, while did not significantly affect other flavors. Headspace solid-phase microextraction analysis verified that kafirin had a reduction effect on the volatility of 3-methylindol and p-cresol, and the headspace concentrations were reduced by 38.99% and 46.39%, respectively. Moreover, addition of 200mg/L kafirin could increase the odor thresholds of 3-methylindol and p-cresol to 1.50μg/L and 0.31μg/L, which were 4.59 and 1.74 times as those of the original ones separately. In order to explain the mechanism of the reducing effect of kafirin on the pit mud-like odor, the ultraviolet-visible spectrophotometers analyses at 25℃, 45℃ and 65℃ were conducted. The results showed that kafirin-3-methylindol or kafirin-p-cresol complexes could be spontaneously formed. The formation process of the kafirin-3-methylindol complex was enthalpy driven, while that of the kafirin-p-cresol was Gibbs free energy driven. In addition, molecular docking analysis showed that the hydrophobic cavity wrapped or linked 3-methylindol and p-cresol inside by spatial matching and intermolecular force, and the major forces between kafirin and 3-methylindol/p-cresol were hydrogen bonds and hydrophobic interactions. The results of this study could provide a solution for weakening the pit mud-like odor in strong flavor Baijiu, and could offer a novel method to reduce the off-odors in the food matrix.

    • Construction and Process Optimization of Cell Factory for Allitol Synthesis with Multienzymatic Cascade System

      2022, 40(3):88-97. DOI: 10.12301/spxb202100648

      Abstract (631) HTML (454) PDF 8.44 M (533) Comment (0) Favorites

      Abstract:Allitol is generally used as a novel functional sweetener with great potential applications in food, medical care and other fields. Based on the Izumoring strategy, a multienzymatic cascade system involved glucose isomerase, D-psicose 3-epimerase and ribitol dehydrogenase was established in Escherichia coli for the production of allitol from cheap substrate D-glucose. The cofactor recycling system was constructed using the formate dehydrogenase to improve the regeneration efficiency of intracellular reduced nicotinamide adenine dinucleotide. To balance the individual expression differences in the multienzymatic cascade system, the fermentation and catalytic conditions of the cell factory were optimized using whole-cell catalytic activity as an indicator. According to the results, the recombinant bacteria could obtain better protein expression was obtained when cells were incubated at 20℃ for 24h with 1.00mmol/L isopropyl-β-D-thiogalactoside. Under catalytic conditions of 40℃ and 50mmol/L Tris-HCl (pH 8.0) with 5.0g/L sodium formate, the recombinant cells could produce 19.33g/L allitol from 25.00g/L D-glucose. The residual amounts of substrate and intermediates were significantly reduced and the yield of allitol was further improved to 21.12g/L through expression system optimization. The whole-cell biotransformation method could provide a theoretical basis for the large-scale synthesis of allitol, accompany with producing allitol from pretreated sugarcane molasses, which could have positive significance in extending the sugar industry chain and increasing the added value of sugar products.

    • De Novo Design and Antibacterial Activity of α-Helical Antimicrobial Peptide YHX-1

      2022, 40(3):98-104, 111. DOI: 10.12301/spxb202100795

      Abstract (790) HTML (496) PDF 6.66 M (533) Comment (0) Favorites

      Abstract:Antimicrobial peptides can not only be used as biological preservatives to prevent microbial corruption in food processing and storage, but also be expected to alleviate the problem of drug resistance caused by antibiotic abuse because of its high antibacterial activity and unique antibacterial mechanism. To obtain a novel antimicrobial peptide, the sequence length, charge numbers and amino acid composition of this antimicrobial peptides were determined and optimized based on the existing database of antimicrobial peptides. According to the bioinformatics prediction, analysis tools and rational de novo design, the novel antimicrobial peptide YHX-1 was designed with the sequence of GKLLSKLLKKLLK. The antibacterial activity of YHX-1 against gram-positive and gram-negative bacteria was evaluated by agar diffusion method, minimum inhibitory concentration (MIC), minimum bactericidal concentration and bactericidal kinetic curves. Its stability in salt ion, plasma and slightly acidic environment, secondary structure, hemolytic activity and cytotoxicity were also determined. The results showed that YHX-1 showed good antibacterial activity against six kinds of pathogenic bacteria with 4μg/mL of MIC against Listeria monocytogenes and Salmonella typhimurium, and it could cause a mortality rate of more than 99.99% of Listeria monocytogenes within 2h. YHX-1 showed a certain sensitivity for salt ions (200mmol/L Na+ or 2mmol/L Ca2+) and 10%-25% plasma which the MIC increased by 2 to 8 times. Furthermore, the MIC of YHX-1 was not significantly affected by slightly acidic environment (pH 5.4-7.4). The results of circular dichroism spectrum showed a typical α-helix structure of YHX-1. Hemolytic activity and cytotoxicity test showed that YHX-1 had good cell selectivity. The newly designed antibacterial peptide YHX-1 was efficient broad-spectrum bactericidal, highly bactericidal efficient and safe which could be used as a new antibacterial agent for food preservation. The de novo design strategy could also provide a reference for designing antimicrobial peptides.

    • Effect of Anthocyanin Extract of Lycium ruthenicum Murr. on Rats with Acute Gouty Arthritis

      2022, 40(3):105-111. DOI: 10.12301/spxb202100218

      Abstract (557) HTML (617) PDF 4.94 M (498) Comment (0) Favorites

      Abstract:To investigate the prevention effect of anthocyanin extract of Lycium ruthenicum Murr. (AEL) on rats with acute gouty arthritis (AGA), 60 male SD rats were randomly divided into 5 groups, including normal control group, model control group, positive control group, AEL high dose group (238.0mg/kg) and AEL low dose group (59.5mg/kg). There were 12 rats in each group. Animals in each group were divided into 2 batches with 6 rats in each batch. After gavage for 2 weeks in the first batch of animals and 4 weeks in the second batch of animals, the rat model of AGA induced by injecting 0.2mL of 50mg/mL microcrystalline sodium urate into the right ankle of rats, and the effect of AEL on ankle joint swelling and claudication gait of AGA rats were evaluated. After continued gavage for 5 weeks, hyperuricemia model was induced by feeding 2.5% potassium oxazinate. The serum uric acid level of rats was measured after modeling at 2h and 3h. It was found that compared with the model control group, high dose of AEL after gavage for 2 weeks could significantly alleviate the ankle joint swelling and improve the claudication gait of rats at 6h after modeling. After gavage for 4 weeks, both high and low doses of AEL could significantly alleviate the ankle joint swelling at 6h and 24h and improve the claudication gait of rats at 6h after modeling, and high doses of AEL could also significantly improve the claudication gait at 24h after modeling. After 5 weeks of gavage, both high and low doses of AEL could significantly inhibit the increment of serum uric acid induced by potassium oxazinate. The results showed that AEL could significantly improve AGA in rats through anti-inflammatory effect and reducing uric acid.

    • Comparative Study of Free and Bound Volatile Components in Lichuan Black Tea and Enshi Green Tea

      2022, 40(3):112-123. DOI: 10.12301/spxb202100343

      Abstract (669) HTML (511) PDF 10.00 M (665) Comment (0) Favorites

      Abstract:The kinds and contents of free and bound volatile substances in Lichuan black tea and Enshi green tea, which are unique to Enshi, Hubei province, Wuling area, were studied by headspace solid-phase microextraction technology combined with gas chromatography-mass spectrometry. A total of 52 volatile compounds were detected in Lichuan black tea, including 36 free aroma compounds and 25 bound aroma compounds. Among them, 9 compounds were both detected in free and bound samples. While, a total of 56 volatile compounds was detected in Enshi green tea, including 15 free forms and 45 bound forms. Among them, there were 4 identical compounds. Meanwhile, the odor activity values were analyzed in two different teas. Aldehydes, alcohols and esters were the most valuable components contributed to the flavor profile of Lichuan black tea. Aldehydes, alcohols and olefins were the most valuable components contributed to the flavor profile of Enshi green tea. The results showed that geraniol and caprylic aldehyde were the main aroma substances in free forms of Lichuan black tea. Methyl salicylate, α-citral and linalool were the major aromatic components in bound forms. The octanal and limonene were the major aroma components for free forms in Enshi green tea. And the linalool and naphthalene were the main aroma components in bound forms. Fruity and floral aroma were the main aroma characteristics of Lichuan black tea, fruity and chemical odor were the major characteristics of Enshi green tea. The phenols and carboxylic acids in the free volatile components of Lichuan black tea and Enshi green tea were significantly different, and phenols and ketones in the bound volatile components were quite different. This study hoped to provide a reference for elaborating the composition of tea aroma and the generation of flavor substances, and at the same time, it would provide references for the deep processing and quality control of Lichuan black tea and Enshi green tea.

    • >Applied Technology
    • Effect of Microwave Treatment on Oil Phase Migration of Phenolic Compounds in Germinated Flaxseed

      2022, 40(3):124-136. DOI: 10.12301/spxb202100607

      Abstract (364) HTML (494) PDF 13.13 M (660) Comment (0) Favorites

      Abstract:The increased endogenous synthesis and oil phase migration of main phenolic compounds in flaxseed were particularly important to the improvement of oxidation stability for flaxseed oil and the bioavailability for α-linolenic acid. The effects of appropriate germination (25℃, 24h) coupled with microwave treatment (700W, 1-5min) on the yield, color, lipid profiles, crystallizing and melting properties, antioxidant activity and oxidative stability of pressed flaxseed oil were investigated, and the release and migration of lignans and free phenolic acids into oil phase were studied. The results showed that the yield of pressed flaxseed oil decreased by 7.39% after 24h germination treatment (P<0.05), but consistently increased by 29.31% after microwave treatment for 1-5min (P<0.05), owing to the destruction of structural integrity of oil bodies and subsequent spillover and fusion, as well as extracellular leakage of lipid. When microwave treatment time extended from 1 to 5min, the ratio of C18∶3ω3 in LnLnLn evidently increased, which was accompanied by the ascending content of total phospholipids, as well as the ratios of phosphatidylethanolamine, phosphatidylglyceride and phosphatidylinositol in flaxseed oil (P<0.05). However, the microwave treatment had no obvious effect on the crystallization behavior and melting properties of pressed flaxseed oil. Moreover, compared with the untreated group, microwave treatment of flaxseed for 5min evidently reduced the contents of primary and secondary oxidation products, and simultaneously improved the oxidation stability and antioxidant activity of pressed flaxseed oil (P<0.05). These changes were mainly attributed to the oil phase migration of lignan macromolecules and its depolymerization product secoisolariciresinol diglucoside, as well as the free phenolic acid vanillin, vanillic acid and ferulic acid. This study aimed to elucidate the effect of germinating combined with microwave pretreatment on the quality characteristics of flaxseed oil, and provide a theoretical basis for the upgrading preparation of flaxseed oil and the high-value utilization of flaxseed.

    • Effect of Millet Flour Ratio on Fresh Noodles Quality, Polyphenol Content and Antioxidant Activities

      2022, 40(3):137-144. DOI: 10.12301/spxb202000120

      Abstract (624) HTML (448) PDF 5.74 M (526) Comment (0) Favorites

      Abstract:In order to investigate the effect of millet flour ratios on the quality, polyphenol content and antioxidant activity of fresh millet noodles, rheological properties and starch gelatinization characteristics of millet-wheat flour dough, and cooking properties, quality properties, polyphenol content and antioxidant activities of fresh noodles were investigated with addition ratios of mass fraction 30%, 40%, 50% and 60% millet flour (mass ratio of unextruded millet flour to extruded millet flour 1∶1) . The results showed that the formation time, stabilization time, peak viscosity, minimum viscosity, final viscosity and retrograde value of millet-wheat dough decreased, while the water absorption rate and total weakening degree increased compared to wheat flour dough, and the quality of mixture decreased significantly. The difference in the gluten strength of millet-wheat dough was small, while the differences of gelatinization characteristics were significantly associated with increased additions of millet flour. There were no significant changes in cooking loss rate and breaking rate of millet-wheat flour fresh noodles (millet noodles for short) when the millet flour addition ratio was lower than 50%, but the cooking loss rate and breaking rate of noodles increased significantly by 8.5% and 87% respectively when it was greater than 50%. L* decreased, a* and b* increased for millet noodles with increasing added ratios, as reflected by the worse color properties. Compared with wheat flour noodles, the hardness and elasticity of millet-wheat noodles decreased significantly, however, little difference was found in noodle texture characteristics with different millet flour addition ratios. The peak area of strongly bound water A21 decreased, while that of free water A23 increased in millet noodles, and the structure of gluten network was not tightly. In millet noodles, the contents of total phenols and total flavonoids were higher than that of wheat noodles, which increased in a rate of quadratic polynomial function with the increasing of addition ratios of millet flour, while free radical scavenging capacity of ABTS+ and DPPH and total antioxidant activity increased significantly. The optimal addition ratio of millet flour into noodles was 50% considering cooking characteristics, quality properties, and antioxidant activity, at which it not only improved healthy function of fresh noodles, but also enlarged its application scope without decreasing noodle quality.

    • Effect of Pretreatment with Osmotic Agents on Drying Kinetics and Quality Characteristics of Heat Pump Dried Scallop Adductors

      2022, 40(3):145-156. DOI: 10.12301/spxb202100766

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      Abstract:In order to improve the heat pump drying (HPD) efficiency and improve the quality characteristics of dried scallop adductors, different kinds of osmotic agent (inulin, trehalose, maltodextrin and whey protein isolate) and mass concentrations (50g/L, 100g/L and 150g/L) were used to treated scallop adductors, and subsequently HPD was performed at temperature of 45℃ and air velocity of 2m/s. The effects of pretreatment with different osmotic agents on the drying kinetics and quality characteristics of scallop adductors were evaluated. The water state and distribution during HPD of scallop adductors were also analyzed based on low field nuclear magnetic resonance (LF-NMR) technology. The results showed that suitable osmotic agent pretreatment of inulin, trehalose, maltodextrin, and whey protein isolate could significantly improve the HPD rate, reduce the total color difference (ΔE) and improve the rehydration efficiency. Taking the comprehensive weighted score as the evaluation index, the optimal mass concentrations of inulin, trehalose, maltodextrin, and whey protein isolate were 100g/L, 150g/L, 100g/L and 50g/L, which were increased by 2.98%, 12.76%, 11.91% and 7.13%, respectively, compared with the control group. The trehalose treatment with a mass concentration of 150g/L had the best advantage in improving the drying rate and quality characteristics of dried scallop adductors. Compared with the control group, the drying time was shortened by 2h, ΔE decreased by 40%, the hardness decreased and the rehydration rate increased by 22.79%. The comprehensive weighted score increased by 12.76% compared with the control group. The LF-NMR results showed that the decrease of water content in scallop adductors during HPD mainly depended on the removal of immobilized water. After pretreatment with suitable concentration of osmotic agent, the migration rate of immobilized water in scallop column increased, the proportion of the free water peak area increased slightly, but the overall change was not significant. The proportion of the bound water peak area increased, whereas, the immobilized water peak area decreased. In addition, the transverse relaxation time shifted to the left during drying, signifying the decreased fluidity of water molecules. The optimum osmotic agent pretreatment for scallop adductors during HPD was 150g/L trehalose.

    • Effects of Micro-Environment Gas Regulation on Fruit Softening of Blueberry During Shelf Life After Controlled Freezing-Point Storage

      2022, 40(3):157-166. DOI: 10.12301/spxb202100135

      Abstract (534) HTML (422) PDF 7.48 M (447) Comment (0) Favorites

      Abstract:To explore the regulation effects of micro-environment gas regulation on blueberry fruit softening during shelf life after controlled freezing-point storage, Legacy blueberry was harvested and stored in the micro-environment gas regulation box added 1-methylcyclopropylene preservation bag, shipped to the controlled freezing point room (-0.5℃±0.3℃) for 30d storage by cold chain logistics car and then commercially packed and storage at 7℃±1℃. Fruit firmness, cell wall polysaccharides content, cell wall degradation enzymes activity were determined to investigate the influence of micro-environment gas regulation on blueberry fruit firmness during shelf life and the correlation between blueberry firmness and cell wall metabolism indexes. The results showed that micro-environment gas regulation maintained higher contents of cellulose, hemicellulose and propectin in late stage of shelf life, delayed the increase of soluble pectin content, inhibited the activities of polygalacturonase, pectin methylesterases, α-L-arabinofuranosidase and cellulase, delayed the occurrence of β-galactosidase activity peak, and then delayed the decline of fruit firmness. Clustering and correlation analysis showed that the cellulose, hemicellulose, and pectin was divided into Ⅰ cluster. The correlation coefficient with fruit firmness was 0.580,0.663 and 0.645, respectively, which had very significant positive correlation. And soluble pectin, polygalacturonase, pectin methylesterase, α-L-arabinofuranosidase, cellulase and β-galactosidase were divided into Ⅱ cluster, and negatively correlated with fruit firmness. The combination of micro-environment gas regulation and controlled freezing point storage could delay the softening of blueberry fruit during shelf life, which would provide a theoretical basis for maintaining the blueberry firmness during shelf life.

    • >Safety Supervision
    • Research Progress of Spoilage Bacteria Pollution and Inhibition of Traditional Soy Products

      2022, 40(3):167-178. DOI: 10.12301/spxb202100341

      Abstract (683) HTML (911) PDF 9.64 M (583) Comment (0) Favorites

      Abstract:Traditional soy products are rich in nutrition and contain high water content, but easy to rot. In particular, fresh soy products have short shelf life and must be refrigerated at low temperature for transportation and storage. These seriously affect the product quality of traditional soy products and the edible safety of consumers, which obviously limit the output of production and processing enterprises and the scale of industrial development. It has increasingly become a research hotspot to determine the source and species of spoilage bacteria in traditional soy products, analyze the correlation between different spoilage bacteria and the quality change of soy products, adopt safe and effective methods to inhibit them and effectively extend shelf life. In this paper, the causes and ways of spoilage of traditional soybean products were summarized from the aspects of planting soil, seed coat microorganisms and endogenous microorganisms, pretreatment of raw materials, heating residues, potential safety hazards brought by processing accessories, incomplete cleaning of equipment, and storage environment. During the storage and production of raw materials, high standards and strict hygiene management should be carried out. The sources, spoilage phenomena and polluted soy products of main microorganisms such as bacteria and fungi causing the spoilage of traditional soy products were summarized. During the storage of traditional soy products, based on the dynamic changes of different dominant bacterial communities in the spoilage bacteria system, it was the key to effectively extend the shelf life via systematically separating and identifying spoilage bacteria by traditional methods combined with modern technology and inhibiting them according to specific spoilage bacteria. And the bacteriostatic methods and mechanism of physical sterilization, chemical bacteriostasis and biological preservation used for the spoilage bacteria of traditional soy products were elaborated. According to the characteristics of different traditional soy products and spoilage bacteria, new physical sterilization technology combined with safe, efficient and effective biological methods, especially the application of microbial bacteriostatic agents, provided unique advantages for effectively prolonging the shelf life of traditional soy products, and made a prospect in order to provide reference for the new direction of traditional soy products preservation.

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