Abstract:Soybeans provide a low-cost protein source with good nutrition and physicochemical properties. In the processing of soybeans, soybean protein and peptides are very important products. Due to its non-negligible use value in the prevention and alleviation of certain diseases, it has attracted the attention of domestic and oversea researchers and consumers. As an important source of high-quality protein, it has broad development prospects in the food industry and other fields. This article introduced the production process and physiological activity of soybean protein and peptides, and discussed the edible safety and processing characteristics of soybean protein. The differences between the traditional technology and new technology of soybean protein isolate and soybean peptides were compared respectively, and the advantages of the new technology were proposed, which provided a new idea for the production and processing of soybean protein and peptides. The biological activities of soybean protein and peptides were mainly introduced, including diverse biological activities such as reducing cholesterol, regulating immunity, improving osteoporosis and regulating the balance of intestinal microflora, and summarized the novel bioactivity direction of the current research. Meanwhile, it also introduced the good gelation, emulsification and organization of soybean protein processing characteristics, especially the domestic problems and future research directions of textured soybean protein (artificial meat).

Abstract:Soybean is one of the main food crops planted in the world, and becomes an important food trade variety due to its richness of fat and protein. In 2018, the global soybean production had reached 366 million tons, and 80% of which was concentrated in the United States, Brazil and Argentina. In order to promote the interconnection of food standards of all economies and elevate the facilitation and integration of food trade in the Asia Pacific region, a systematic analysis of 12 economies was conducted on the soybean standards of 10 APEC economies including China, the United States, Australia, Canada, Japan, South Korea, Mexico, the Philippines, Thailand, Chinese Taipei and 2 major soybean producing countries including Brazil and Argentina. The similarities and differences applicability of standard, product classification, grading and quality indicators related to grade parameters were proposed to promote the interconnection of APEC soybean standards, which could provide reference for grain workers engaged in grain standardization, quality testing and soybean import and export trade.

Abstract:Based on the comparative analysis of the quality indexes and some important food safety indexes among the maize standards of some economies in the Asia Pacific region and the international Codex Alimentarius Commission, the report concluded that the tendency quality requirements of maize standards in various economies were the same, and the used quality indicators were similar. The maize quality standards of the economies tended to grade maize by the indexes of test weight, unsound grain, foreign mater, moisture, color, odor, and etc, to classify maize by the color of maize seed. There were differences in terms of definitions, testing instruments, testing methods, sensory testing and quality requirements. And the quality grade and result determination of the same sample tested and judged using the standard of different economies were divergent . Important safety indexes such as mycotoxins and exotic seeds varied greatly, especially the internationally recognized exotic harmful seeds. The suggestions were that we should start the research on the determination methods of test weight, unsound grain, foreign mater, moisture and other important indicators of maize in the Asia-Pacific region, unify the relevant determination methods and equipment, make a visual reference system for sensory detection indicators; and carry out discussions and exchanges among multi-layer testing technicians, collect testing data of maize samples, and further analyze the actual differences of maize standards in different economies; increase international peer communication and promote the coordination on maize quality standards, in order to form a unified or similar technical standard system conducive to realizing regional trade facilitation and integration.

Abstract:As a new type of applied science and technology, photon quantum irradiation has attracted more and more attention in the field of preservation. To explore the role of photon quantum irradiation in the preservation of tomato, the effects of photon quantum irradiation on the main quality indexes of tomato were studied with postharvest tomatoes. The results showed that at 4℃, compared with ordinary low-temperature refrigeration, photon quantum irradiation significantly reduced the decay index of tomato, slowed down the increase of weight loss rate, delayed the decline of tomato hardness and vitamin C content, and could reduced the content of malondialdehyde to a certain extent. Photon quantum irradiation also had an effect on the activity of tomato physiological metabolism related enzymes. It could improve the activity of superoxide dismutase, delay the decrease of peroxidase activity, at the same time, the activity of polyphenol oxidase was inhibited, thereby inhibiting browning of tomato. Simultaneous scanning electron microscopy results showed that photon quantum irradiation could delay the changes in the internal structure of the tomato, maintain the integrity of tomato internal structure. Therefore, photon quantum irradiation had better preservation effect than ordinary low-temperature refrigeration. The research results laid the foundation for the further application of photon quantum irradiation in the preservation of fruits and vegetables such as tomatoes.

Abstract:Using GC-O-MS to compare and analyze the change of volatile flavor components in watermelon juice before and after heat treatment. The results showed that 44 and 50 odor compounds were identified by GC-O-MS in fresh and heated watermelon juice, respectively. The key odor compounds in fresh watermelon juice were nonanal (freshness and herbaceous flavor), (E)-2-nonenal (freshness and cucumber flavor), (E, Z)-2,6-nonadienal (freshness and cucumber flavor), (E, Z)-3,6-nonadienol (freshness and cucumber flavor), (E, Z)-2,6-nonadienol (freshness and cucumber flavor) and geranyl acetone (flower fragrance and sweet taste) identified by combination of sniffing, odor dilution factor and odor activity value. However, the key odor compounds in heated watermelon juice were (E)-2-heptenal (fat flavor and bitterness), decanal (fat flavor and soap flavor), 6-methyl-5-hepten-2-one (mushroom and musty flavor), acetophenone (bitter almonds flavor), diethyl disulfide (garlic flavor) and (Z)-6-nonenal (pungent odor). Among them, the characteristic odor of (Z)-6-nonenal was fresh and cucumber flavor initially. Due to the concentration of (Z)-6-nonenal in heated watermelon juice exceeding the tolerance of the sensory assessor's nose, it showed an irritating smell. The heat treatment produced odorous components, and the change in odor compounds led to the cooking taste of the watermelon juice after heating.

Abstract:In order to investigate the effect of different transportation time on the physiology and quality of mango during the later low-temperature storage, simulated transportation experiments of mango on the analog transport vibration table at 180r/min for 12,24 and 36 h were carried out. The changes in moisture distribution, free moisture content, weight loss rate, titratable acid content, vitamin C content, respiration intensity, pectinmethylesterase (PME) content, and polygalacturonase (PG) content of mango during 20days storage under 13℃ were measured. The results showed that transportation vibration led to different degrees of bruising on mango, accelerated water loss, significantly increased the rate of water loss and respiratory peak, maintained the PME and PG content at a higher level, and lost more titratable acids and vitamin C. At the same time, the impact on the physiological quality of mango was enlarged with the increasing transportation vibration time. Therefore, vibration during transportation process accelerated mango metabolism and the quality declined during the later low-temperature storage. The quality damage of mango in transportation groups of 24h and 12h was acceptable. However, more irreversible damage to mango in transportation group of 36 h was occurred.

Abstract:To explore the changes of quality and the flavor compounds, kiwifruit (Actinidia chinensis) were investigated during storage at room temperature. Hardness of the fruit in different storage periods was measured, and the samples with medium hardness (130-150N after 0day storage, 90-100N after 5 days storage, 40-50N after 10days storage and 20-25N after 15days storage) at different storage times were selected for subsequent research. The results showed that during storage, the fruit hardness and titratable acid content were continuously decreased, and the contents of fructose and glucose were increased, while the soluble solids and sucrose contents were increased first and then decreased. A total of 70 volatile compounds were identified in kiwifruit. Among them, the species of volatile compounds were the most abundant at storage period of 5days, and the least abundant at storage period of 15days. During storage, the species of aldehydes decreased while esters increased. A total of 8 key volatile compounds were identified from kiwifruit through dilution analysis, including 1-hexanol (FD=243), ethyl butyrate (FD=243), (E)-2-hexenal (FD=81), (E)-2-heptenal (FD=81), ethyl benzoate (FD=81), geranyl acetone (FD=81), (Z)-4-decenal (FD=27) and β-damascenone (FD=27). At the same time, combined with sensory evaluation, it was concluded that the kiwifruit was best to eat at the storage period of 5days with the hardness of 98.50N.

Abstract:L-fructose is an important rare sugar, which is widely used in food, medicine and chemical synthesis. To synthesize L-fructose from glycerol, the recombinant Escherichia coli (E. coli) co-expressing E-type horse liver alcohol dehydrogenase (HLADH-EE) and NADH oxidase (NOX) was constructed and coupled with the recombinant E. coli co-expressing aldolase. The induction conditions of the strain with the expressions of HLADH-EE and NOX were optimized, the optimal induction conditions were as follows:temperature at 20℃, induction for 16h, and addition 0.05 mmol/L IPTG. The effects of temperature, pH, wet cell and glycerol concentration on the synthesis of L-fructose by whole-cell from glycerol were investigated by single factor experiment. The conditions of whole-cell transformation were optimized by orthogonal array design. The optimal conditions of temperature, pH, wet cell addition amount, and glycerol concentration were 40℃, 9.0,25g/L, and 500mmol/L, respectively. 2.67g/L of L-fructose was gained under the optimal reaction conditions. In this study, whole-cell strategy was adopted to produce L-fructose from cheap glycerol, which not only eliminated tedious enzyme purification steps and cofactors addition, but also reduced the production cost, and provided theoretical knowledge for the green production of L-fructose and the modification of existing technologies.

Abstract:To study the stability of 2-butenal flavor compounds at different storage conditions, the effects of storage temperature, relative humidity, and the volume content of headspace oxygen on the stability of E-2-methyl-2-butenal, 3-methyl-2-butenal and 2-phenyl-2-butenal were investigated by gas chromatography-mass spectrometry. The results showed that the influence order on the stability of 2-butenals in turn were the volume content of headspace oxygen, the storage temperature, and the relative humidity. After 20 weeks storage at room temperature with air in the headspace of the container, the content of 2-butenals was dropt to 90%. To ensure the quality of 2-butenal, it should be suggested to use within 12 weeks after first opening the container. These three 2-butenals should be less used for formulating the high-temperature-resistant flavorings because they were not resistant to high temperature. Mass spectrum and retention indexes in two different polar chromatographic columns were applied to determine the compounds newly formed during storage. The results showed that E-2-methyl-2-butenal and 3-methyl-2-butenal were easily oxidized to produce E-2-methyl-2-butenoic acid and 3-methyl-2-butenoic acid, respectively. However, 2-methyl-3-phenyl-2-propenoic acid and 1-phenyl-1-propanone were derived from 2-phenyl-2-butenal during storage. The results also indicated that 2-butenal flavor compounds should be preserved at lower temperature and at inert gas atmosphere.

Abstract:The fermentation characteristics of milk protein concentrate (MPC) with different concentration of lactose was studied after fermentation using Lactobacillus bulgaricus and Streptococcus thermophilus. The results showed that lactose concentration affected the time of fermentation entering stable phase and pH value. With the increase of lactose concentration, the final pH value of MPC fermentation was decreased (4.14-4.59). The microrheological parameters indicated that the solid-liquid balance and fluidity index of MPC fermentation product were increased with the increase of lactose concentration, while the macroscopic viscosity index was decreased. The texture characteristics showed that the water retention rate of MPC fermented product increased with the increase of lactose concentration, and the gumminess and elasticity increased first and then decreased, while hardness and viscosity were not affected. The results of GC-MS showed that the acid compounds and ketone compounds were the main volatile substances in the MPC fermentation product. The content of acid compounds were decreased, while the content of lactose metabolites such as 2,3-butanedione and 3-hydroxy-2-butanone were increased accompanied by the lactose increased. The results of this study provided basic data for further study of the fermentation characteristics of MPC and broadened the application of MPC in different fermented dairy products.

Abstract:The endophytic bacterial community diversities of hybrid maize seeds and their parents were explored by traditional isolation and culture methods. The experimental results showed that hybrid corn Jingke 665, Jingke 968, MC738 and Jingnongke 728 had 2,4, 5 and 7 OTUs (operational taxonomic units) respectively, and the parents were Jing 725, Jing 92, Jing 724, Jing 2416 and MC01, which contained 2,1, 3,3 and 4 OTUs, respectively. The same dominant species of the endophytic bacteria were found in both parents and their offspring. Bacillus subtilis subsp. subtilis NCIB 3610T was the first dominant strain of the progeny Jingke 665, and its parents of Jing 725 and Jing 92. Bacillus megaterium NBRC 15308T was the first dominant species of progeny MC738 and was the second dominant species of its parent Jing 2416. Bacillus subtilis subsp. subtilis NCIB 3610T was the third dominant species of the progeny Jingnongke 728 and was the second dominant species of its parent Jing 2416. There was a common dominant genus between the progeny from the common parent. Bacillus were the common dominant genus in hybrid maize Jingke 665 and Jingke 968, which both had the common father of Jing 92. Bacillus and Micrococcus were the common dominant genus in hybrid maize Jingke 968 and MC738, which derived from the common mother Jing 724. Bacillus and Micrococcus were the common dominant genus inhybrid corn MC738 and Jingnongke 728, which were both from the common father of Jing 2416. Therefore, there was a genetic correlation between the parental progeny of maize, and there was also a correlation between endophytic bacteria of hybrid corn with the same parent.

Abstract:In order to evaluate the effect of non-viable Lactobacillus paracasei L9 (L9) in normal temperature yogurt on relaxing constipation and modulating gut microbiota, sixty-one subjects with constipation were recruited and divided into two groups, drinking normal temperature yogurt or yogurt containing non-viable L9 for 28 days, respectively. Constipation-related symptoms, the content of short chain fat acids (SCFAs) and variation of gut microbiota were analyzed. Compared to the group drinking normal temperature yogurt, the results in group drinking yogurt with non-viable L9 were as follows:the defecation frequency was significantly increased (P<0.05), the defecation condition and consistency scores were remarkably reduced (P<0.01), the content of butyric acid was dramatically increased (P<0.01), propionic acid and total acid were significantly increased (P<0.05), and bacterial species producing SCFAs such as Blautia, Ruminococcus_2 and _hallii_group were significantly increased. The results indicated that normal temperature yogurt with non-viable L9 could help to relieve constipation and modulate gut microbiota, which might provide a theoretical basis for developing functional foods containing non-viable L9.

Abstract:In order to solve the problem of single scallop product and low proportion of deep processing, the nutritional composition of adductor muscle from Chlamys farreri was determined, and the effects of cassava starch with different concentration on the gel strength, texture properties, water holding capacity (WHC), whiteness, protein pattern and microstructure of scallop puree were studied in this paper. The results showed that the content of water, crude protein, crude fat and ash in adductor muscle from Chlamys farreri was 82.15%, 16.23%, 2.05% and 1.24%, respectively. The total amount of hydrolyzed amino acids except tryptophan was 13.204%. The gel strength, WHC, hardness and chewiness of Chlamys farreri puree increased and then decreased with the addition of cassava starch increasing, but there was no significant difference in the springiness, cohesiveness and whiteness of the Chlamys farreri puree. The electrophoresis pattern showed that the bond of myosin heavy chain was the narrowest in sample containing 1% cassava starch, suggesting starch promoted the cross-linking of the Chlamys farreri puree protein. Optical microscopy and scanning electron microscopy indicated that a denser network structure with smaller pores was formed when cassava starch was added to 1% or 2%. Therefore, Chlamys farreri is a high-protein aquatic resource, which can be used to produce scallop gel, and 1% cassava starch has a good improvement on the quality of Chlamys farreri gel. This paper can provide a theoretical basis for deep processing of scallops.

Abstract:Different proportions of Rebaudioside M was used to substitute sucrose in yogurt, the results showed that the highest sensory score of yogurt was gained when 60% sucrose was replaced. Rebaudioside M, sucralose and mogroside were separately added to the yogurt. The results showed that the optimal addition amount of each in 100 mL milk was 24mg, 9mg and 40mg, respectively. Based on the single factor experiments, the response surface analysis method was used to optimize the ratio of Rebaudioside M, sucralose and mogroside. The optimal process parameters for the production of sugar-free yogurt was Rebaudioside M 7.91mg, sucralose 3.03mg and mogroside 13.62mg per 100mL of milk after analyzing by Design-Expert software. In the verification experiment under this condition, the sensory score of the sugar-free yogurt was 92.00, and the relative deviation from the theoretical value was 0.53%. The sensory quality of sugar-free yogurt was best, which was closer to the taste of sucrose-added yogurt than that of a single sweetener.

Abstract:In order to ensure the safety of tea drinking for consumers, a rapid method for the determination of six organophosphorus pesticide (parathion, fenthion, terbufos, sulfotep, profenofos and ethoprophos) residues in honeysuckle and tea infusion was established by QuEChERS-GC-MS/MS. Honeysuckle and tea infusion were extracted by acetonitrile and ethyl acetate respectively, centrifugated after salting out, purified by mixed purification agents (10mg MWCNTs, 15mg PSA and 150mg MgSO₄), filtered through 0.22μm membrane and then detected by GC-MS/MS. The results showed that in honeysuckle and tea infusion, six organophosphorus pesticides showed a good linear relationship in the concentration range of 1-1000μg/kg and 1-1000μg/L, respectively. And the correlation coefficients were all above 0.991. Under four addition levels, the recoveries were between 67.2% and 110.3%, and the RSD was less than 19% (n=6). The limit of quantitation of honeysuckle and tea infusion was 1μg/kg and 1μg/L, respectively. On this basis, the migration model of six organophosphorus pesticides was studied during brewing process of honeysuckle. The results showed that the transfer rate (TR) of organophosphorus pesticides was highly correlated with the octanol-water partition coefficient (Kow). The prediction model was lg TR=-0.5362 lg Kow+3.9152(lg Kow>3), and the correlation coefficient was 0.914, which meant a good fitting degree. However, the correlation between pesticide mobility and water solubility (Ws) was not shown. The establishment of the detection method and migration model will be helpful to further understand the migration behavior of chemical pollutants during brewing process of honeysuckle, and provide scientific basis and technical support for establishing the maximum residue limit of organophosphorus pesticides in honeysuckle.