2020, 38(5):1-9. DOI: 10.3969/j.issn.2095-6002.2020.05.001
Abstract:In recent years, the study of the generation mechanism of harmful substances in food processing has become a hot and frontier field of food safety research. Thermal processing is the most common processing method for soy products and wheat products. The protein glycation during food thermal processing will not only cause changes in protein structure, nutritional properties and functional properties, but also produce some harmful products. In heat processing, reducing sugars are mainly reactive carbonyl compounds and its will degrade during heat processing to form α-dicarbonyl compounds (α-DCs). These compounds are important intermediate products of the Maillard reaction that occurs during the heat processing. They have stronger reactivity and can undergo glycation with proteins, thereby changing its structure and nutritional properties. Currently, more and more scholars have conducted researches on the glycation effects of reducing sugars and α-DCs on proteins during food thermal processing. However, there is no literature on the glycation of plant-based proteins during the heat processing. Therefore, the structure and nutritional characteristics of soybean protein and glutenin were introduced, and the active carbonyl compounds involved in glycosylation reactions in food and their production mechanisms were analyzed. Meanwhile, the research progress of glycosylation of plant-based protein during heat processing was emphatically introduced. It will be of great significance to study the mechanism of protein modification and the mechanism of producing harmful substances in food heat processing.
2020, 38(5):10-13, 40. DOI: 10.3969/j.issn.2095-6002.2020.05.002
Abstract:As people's health has become the center of national policies and guidelines, all trades are focusing on improving people's health, conducting in-depth scientific research, and accelerating the transformation and upgrading of enterprises. Baijiu, as a popular drink, has also received extensive attentions for its health functions. Many experimental results have shown that Baijiu contains a lot of health factors that are beneficial to the human body. Meanwhile, civilized drinking is beneficial to human health and can reduce the risk of a variety of diseases. Baijiu-related researchers and Baijiu manufacturing companies should continue to conduct further researches on health benefits of Baijiu, and correctly guide consumers to understand the health attributes of Baijiu. We should take people's health as the core and scientific research as the driving force to improve Baijiu products and tell a good story of Baijiu.
2020, 38(5):14-23. DOI: 10.3969/j.issn.2095-6002.2020.05.003
Abstract:Sugar reduction is a major technical challenge for the food industry, due to effects of sugars in foods on public health. This paper reviews the health effects of dairy products and sugars, with an emphases on the consumption status and dietary recommendation of sugar. The sugar reduction policies in different countries and areas were also illustrated. According to the application and contribution of sugar to the quality of dairy products, the challenges necessity and research progress of sugar reduction in dairy products were discussed. General methods for sugar reduction include gradually decreasing sugar (direct reduction), sugar substitution, food structure modification, and multisensory integration. Decreasing sugar gradually could make the consumers adapt the taste and flavor of low sugar foods, and it might be the most ideal methods to reduce sugar in food. The risk of gradual sugar reduction for food companies in markets makes them prefer to using non-nutritive sweeteners, sugar alcohols, and fibers to substitute sugar in products. Effects of sweeteners on the mouth feel make the sugar reduction be a technical challenge. Advances in food structures could also provide novel ways to reduce sugar in dairy products. The technologies include in the homogeneously distributing sugar, modifying fracture mechanics and modifying tastant release from food matrices. The use of multisensory (aroma, color, and other stimuli) integration principles would be a promising approach.
2020, 38(5):24-30. DOI: 10.3969/j.issn.2095-6002.2020.05.004
Abstract:With the continuous change of people's diet structure, low-fat cheese is gradually attracting the attention of consumers. However, low-fat cheese has the defects of hard texture, difficult to chew, and flavor inferior compared to full-fat cheese. Fat substitutes can replace fat to produce a smooth mouth feel, improve the texture and structure defects of low-fat cheese, so as to improve the quality of low-fat cheese. In order to further understand the role and research progress of fat substitutes in cheese, this review comprehensively discussed the application and improvement of different fat substitutes in low-fat cheese in terms of yield, color, texture, flavor and functional properties. Furthermore, it put forward the possible future development direction of low-fat cheese and provided a reference for promoting the industrial production of low-fat cheese in China.
2020, 38(5):31-40. DOI: 10.3969/j.issn.2095-6002.2020.05.005
Abstract:Chitosan oligosaccharide (COS) and kojic acid (KA) were used as synthetic initiators and the COS-based polymer (COS-O-KA) were synthesized by selective partial alkylation reaction to graft kojic acid onto the COS molecular chain. After characterization of structure by NMR spectroscopy, molecular weight, polydispersity index, water-solubility, hemolysis assay in vitro, biocompatibility in vitro, antioxidant activity, and animal toxicity of COS-O-KA were studied. The results revealed that the three polymers of different substitution degree (COS-O-KA1-3) were synthesized successfully which proved by NMR spectroscopy. In addition, COS-O-KA1-3 exhibited preferable water-solubility, hemolytic activity in vitro, biocompatibility in vitro, and scavenging activity of DPPH free radical and ABTS+ free radical in comparison with that of the free COS and KA. Among them, when the concentration was 15mg/mL, the hemolysis rate of COS-O-KA1-3 was less than 20%, while the hemolysis activity of the same concentration of COS and KA was more than 30%. The DPPH free radical scavenging rates of COS, KA, COS-O-KA1, COS-O-KA2 and COS-O-KA3 were 52.28%, 59.33%, 85.21%, 87.35% and 82.83%, respectively. The scavenging activity of COS-O-KA1-3 on ABTS+ free radical increased slowly and reached a stable level (83.87%, 85.76%, 82.33%, respectively) at 2.0mg/mL, which was much higher than that of COS (39.65%) and KA (46.54%). Meanwhile, owing to its non-cytotoxicity, COS-O-KA might be considered as a promising material for antioxidant applications.
2020, 38(5):41-47, 77. DOI: 10.3969/j.issn.2095-6002.2020.05.006
Abstract:To investigate the effect and potential mechanism of chitooligosaccharides on reducing liver lipid accumulation in vitro, sodium oleate was used to induce HepG2 cells to establish non-alcoholic fatty liver cell model, the lipid profiles including total lipid accumulation, total triglyceride, total cholesterol, high/low density lipoprotein cholesterol and free fatty acids contents were analyzed by oil red O staining and corresponding commercial kits, respectively. The expression of genes and proteins related to intracellular lipid metabolism were detected by real-time PCR and western blot. The results indicated that 4.0mg/mL chitooligosaccharides had a significant inhibitory effect on liver lipid accumulation and reduced the mRNA and protein expression levels of diacylglycerol acyltransferase 2 (DGAT2), liver X receptor alpha (LXRα), peroxisomes proliferator-activated receptor-γ (PPARγ), pregnenolone X receptor (PXR) and differentiation cluster 36 (CD36). These results suggested that chitooligosaccharides could reduce the accumulation of lipids by regulating fatty acid absorption and triglyceride synthesis pathways. This study aims to provid theoretical support for using chitooligosaccharides as dietary supplements in lipid-lowering and liver protection.
2020, 38(5):48-55. DOI: 10.3969/j.issn.2095-6002.2020.05.007
Abstract:In order to study the hypotensive mechanism of combination product of κ-carrageenan and potassium, the effect of low-molecular weight carrageenan potassium (LCP) on intestinal flora regulation was studied using high-throughput sequencing and bioinformatics analysis. Experiments indicated that LCP had a stable and sustained antihypertensive effect on spontaneously hypertensive rats. Compared with that in control group, the final depressurizing amplitude was about 18mmHg (2.3kPa). Through analyzing the types and concentrations of short-chain fatty acids in contents of cecum, it was found that the content of acetic acid, isobutyric acid, and butyric acid in LCP group was significantly higher than that in blank group, and the variation of isobutyric acid production was particularly obvious. The 16S rRNA sequencing results of cecum contents showed that compared with the blank group, the F/B value of the LCP group was reduced, the bacterial abundance was increased, and the number of Ruminococcus which producing butyric acid was dominant. Overall, the results indicated that LCP could be used as a regulator of intestinal microbiota, realized to promote the healthy recovery of intestinal disregulation and therapeutic of hypertension.
2020, 38(5):56-68. DOI: 10.3969/j.issn.2095-6002.2020.05.008
Abstract:Polymethoxy flavonoids (PMFs) are a class natural products, which almost exclusively exist in citrus plants possessing distinguished anti-carcinogenic, anti-inflammatory and antioxidative activities. In order to increase the water solubility and medicinal value of PMFs, tangeretin and nobiletin, the two most abundant source and the highest anticancer activity of natural polymethoxy flavonoids, were oxidated by dimethyldioxirane to polymethoxy flavonoids (3-hydroxytangerine (7) and 3-hydroxynobiletin (8)). The compound 7 or 8 was reacted with ethyl chloroacetate by Williamson synthesis in anhydrous potassium carbonate and N,N-dimethylformamide. Then the reaction solution was controlled under alkaline conditions at room temperature for hydrolysis to obtain two polymethoxy flavonoids carboxylic acid derivatives (tangerine-3-O-acetic acid (1) and nobiletin-3-O-acetic acid (2)) that have not been reported in the literature. Under the conditions of CH2Cl2 as solvent, EDCI and DMAP as the catalytic system, tangerine and nobiletin carboxylic acid derivatives were reacted with glycine methyl ester hydrochloride and phenylalanine methyl ester hydrochloride respectively and four polymethoxy flavonoids amino acid methyl ester derivative were obtained. After the hydrolysis treatment, four new polymethoxy flavonoids amino acid derivatives 3 to 6 were first synthesized. The structure of all synthesized compounds were characterized by 1H NMR,13C NMR, and MS.
2020, 38(5):69-77. DOI: 10.3969/j.issn.2095-6002.2020.05.009
Abstract:The chaperone property of sodium caseinate has not been applied to prevent the thermal aggregation of egg white proteins. The effect of sodium caseinate on thermal aggregation of egg white proteins was analyzed via measuring the turbidity, soluble protein content of supernatant, particle size and molecular weight distribution. When the concentration of sodium caseinate was 2mg/mL,the thermal aggregation (90℃, 30min) of egg white proteins solution (5mg/mL) could be suppressed. And with the increasing of the addition of sodium caseinate (2-3mg/mL), the inhibitory effect was enhanced.Due to the low solubility of sodium caseinate, the inhibitory effect of the aggregation was not significant changed at higher concentration of sodium caseinate (4-5mg/mL). The results of SDS-PAGE illustrated that the inhibitory effect of sodium caseinate on the thermal aggregation of ovalbumin and ovaltransferrin determined its effect on preventing thermal aggregation the egg white proteins.With the increase of the addition of sodium caseinate, the insoluble aggregates of egg white proteins was gradually changed to soluble aggregates, and the large and dense aggregates were transformed to small and loose. The results indicated that sodium caseinate could prevent the thermal aggregation of egg white proteins.
2020, 38(5):78-84. DOI: 10.3969/j.issn.2095-6002.2020.05.010
Abstract:To investigate the effects of anthocyanins from black rice on spatial learning and memory in C57BL/6 mice fed with high fat diet. 48 C57BL/6 mice were randomly divided into 4 groups:normal chow diet (NCD) group, high fat diet (15%) (HFD) group, high fat diet plus 40mg/kg anthocyanins (LBA) group, and high fat diet plus 200mg/kg anthocyanins (HBA)group. After 12 weeks, the cognitive components of behavior were evaluated by Morris water maze test. Serum total cholesterol and triglyceride, oxidative stress index, monoamines content of hippocampus in mice were determined. The expressions of inflammatory cytokines in hippocampus were determined by real-time PCR. The results indicated that spatial learning and memory ability, activity of SOD (superoxide dismutase) and GSH-Px (glutathione peroxidase) in hippocampus of mice in HFD group were significantly reduced. The serum total cholesterol, triglyceride, MDA (malondialdehyde), and inflammatory factors TNF-α, COX-2, and IL-1β mRNA were dramatically increased. However, supplementation of anthocyanins from black rice significantly elevated the spatial learning and memory ability of mice, the oxidative status in hippocampus was dramatically improved, and the mRNA levels of inflammatory factors were significantly reduced. In summary, HFD led to chronic oxidative stress, impaired the cognitive ability such as hippocampus-dependent spatial learning and memory. Anthocyanins from black rice, could improve the oxidative stress, increase the activity of SOD and GSH-Px, reduce the production of MDA and the mRNA levels of inflammation factors, and finally improve the learning and memory ability in mice.
2020, 38(5):85-90. DOI: 10.3969/j.issn.2095-6002.2020.05.011
Abstract:As a novel target of blood glucose regulation, natural active substance cyclic nucleotide phosphodiesterase PDE9A was gradually attracted the attention. The target protein was obtained from E. coli BL21 cells via IPTG-induced expression. Then the protein was gradually purified by nickel column affinity purification system, Q-Sepharose ion exchange purification system and Sephacryl S300 molecular sieve purification system. Finally, the acquired target PDE9A protein with high purity was proved to have high affinity for substrate cGMP digestion, which provided a preliminary basis for the development of novel functional food for reducing blood glucose in the future.
2020, 38(5):91-99. DOI: 10.3969/j.issn.2095-6002.2020.05.012
Abstract:Konjac has gained increasing attention as a high-quality dietary fiber and hydrocolloids resource. In order to further understand the current status, growing trends and developing patterns of konjac research, the research situation in the past 10 years from 2009 to 2018 based on the literature on konjac research in the SCIE database of Web of Science was surnmarized using bibliometric method. Through a multi-dimensional statistical analysis, the development process of konjac research was comprehensively demonstrated and compared with the previously published literatures. The results indicated a rapid development momentum of konjac research in 2009—2018 since the amount of published research paper in this period far exceeded the levels of any previous periods. Among them, research in Asia was very active, which was consistent with the evolution of industrial distribution and development. Besides, the Chinese scholars were in a leading position in konjac research. The directions of chemistry and polymers were continuous hot fields of konjac research, and research in food science and technology was gaining more attention, especially for its compound, thickening and gelation as a hydrocolloid. Moreover, the health properties of konjac became more popular in recent years, but related research was still inadequate. In addition, the konjac research in terms of agriculture and pharmacology still needed more attention to lay the theoretical foundation for the application of konjac in the field of health and biology.
2020, 38(5):100-108, 126. DOI: 10.3969/j.issn.2095-6002.2020.05.013
Abstract:The muscle from the back portion of grass carp was used to investigate the effects of different levels of salt addition (mass fraction 0%, 0.5％, 2.5％, 5.0%) on the quality of grass carp during cold storage (1,6, 13d at 0℃). The results from two-way analysis of variance indicated that both storage time and salt content significantly affected the pH value as well as the amounts of malondialdehyde and total volatile base nitrogen in fish muscle (P<0.05), and these two factors had no significant interaction effect on the pH value and malondialdehyde content. In comparison with the control group without salt, the addition of 2.5% and 5.0% salt led to significant reduction in pH values and increase of malondialdehyde content by 28%-189% and 120%-322%, respectively, which exerted pro-oxidative effects. However, the addition of 0.5% salt resulted in a reduction of malondialdehyde content by 18%-31% in the fish muscle after cold storage for 6 d or 13 d and showed inhibiting effects for lipid oxidation. The salt concentration and storage time had minor effects on the color of fish muscles (L*, a*, b* values). The increase of total volatile base nitrogen levels in the fish muscle during cold storage fitted well with the first order reaction function (R2=0.9701-1), and the reaction rate constant (0.0498-0.0894d-1) was decreased with increasing concentration of salt.
2020, 38(5):109-118. DOI: 10.3969/j.issn.2095-6002.2020.05.014
Abstract:To explore the improvement of biotransformation approach of Rosa roxburghii flavonoid aglycon releasing ability, β-glucosidase from different sources were used to hydrolyze quercetin-3-O-rutinoside, quercetin-3-O-rhamnoside, and quercetin-3-O-glucoside. Quercetin content and glycoside conversion rate as indicators, the conversion rate of quercetin glycosides and content of quercetin hydrolyzed by β-glucosidase from Lactobacillus acidophilus, Trichoderma, and almond were dynamically monitored by HPLC. And the optimized enzymatic hydrolysis time, enzymatic hydrolysis pH, enzymatic hydrolysis temperature, and enzyme dosage (enzyme-substrate mass ratio) were chose as single factors, and the effects of independent change of each factor on the index were examined. Then Box-Behnken method was used to study the influence of each factor and its interaction on the conversion rate, and to optimize the process conditions. Almond β-glucosidase hydrolyzed the three glycosides and converted them to the highest quercetin content. The conversion rates for different substrates were in the order of quercetin-3-O-glucoside(74.10%), quercetin-3-O-rutinoside(64.30%), and quercetin-3-O-rhamnoside (31.80%). The optimal optimized hydrolysis process conditions of almond β-glucosidase were hydrolysis time of 28.90min, hydrolysis pH value of 4.9, hydrolysis temperature of 52℃, and the enzyme dosage of 0.08%. Under these conditions, the conversion rate of quercetin-3-O-rutinoside, quercetin-3-O-rhamnoside, and quercetin-3-O-glucoside were 71.48%, 36.32%, and 77.86%, respectively.
2020, 38(5):119-126. DOI: 10.3969/j.issn.2095-6002.2020.05.015
Abstract:The effects of different storage time on the biochemical components and sensory qualities of Wuyi rock tea Jinsuoshi were studied,which provided the theoretical basis for the scientific drinking, storage, transportation, and nutrition maintenance of Wuyi rock tea.The materials of the experiment were lightly and mediumly baked Jinsuoshi. The results showed that the contents of polyphenols, catechins, caffeine and water extract decreased and the water content increased. However, the amino acid content first increased and then decreased. After 12 months storage, the contents of polyphenols in lightly and mediumly baked Jinsuoshi decreased by 21.03% and 19.48%, catechins decreased by 21.87% and 17.24%, ester catechins decreased by 30.58% and 26.76%, non-ester catechins decreased by 10.25% and 6.45%, and caffeine decreased by 17.60% and 13.36%.The amino acid content of lightly baked Jinsuoshi was the highest (2.32%) in 6 months, and that of medium baked Jinsuoshi was the highest (2.25%) in 8 months. In the early stage of storage, the internal heat of lightly and mediumly baked Jinsuoshi gradually faded and the sensory quality was improved. In the late stage of storage, the taste became more mellow, but the freshness and sharpness of aroma slightly decreased, so the score of sensory quality first increased and then slightly decreased. The highest sensory quality score was obtained in lightly baked Jinsuoshi after 6 months storage, and in mediumly baked Jinsuoshi after 8 months storage. In conclusion, the rational storage is beneficial to improve the sensory qualities of Wuyi rock tea.