Abstract:Large quantities of ground meat are produced during the meat processing, which are used as low-value by-products. Binders and the mechanic effects help change the spatial structure of myofibrillar/myosin, which promote the protein-protein and protein-water cross-linking, to form a uniform and dense 3D gel network structure, and hence enhance the integrity of the product. At present, common binders include hydrophilic colloid, transglutaminase, soybean protein isolate, plasma protein and gluconate-δ-lactone. They play an important role in recombinant meat products according to their characteristics. Their mechanisms are summarized and compared, the effects of temperature, pH and concentration on the bonding properties are briefly analyzed, providing a theoretical basis for the subsequent research of binders.

Abstract:Kombucha biofilm is a cellulose biofilm containing the symbiotic culture of bacteria and yeast, floating on the surface of kombucha beverages. Due to its properties of high water-holding capacity and mechanical strength, good thermal stability, biocompatibility, and degradability, it has a broad application prospect. The authors review the composition and symbiotic relationship of microorganisms in kombucha biofilms, the synthesis mechanism of bacteria cellulose, the structure and properties, and the applications in food technology, medical materials, textile industry, waste water treatment and other fields. The future research and applications of kombucha biofilm are also discussed.

Abstract:To investigate the most suitable lyophilization protection formula for Bifidobacterium adolescentis and improve the efficiency of industrial production, the authors examined the lyophilization protection properties of various saccharide and protein protectants for B. adolescentis, the protection effect of compounding saccharide protectants with different structures and the protective effect of that with protein. Finally, the ratio between the dried mush and the lyophilizing agent was optimized to achieve high-density lyophilization. The results showed that the protective effect of saccharide (alcohol) protectants on B. adolescentis was generally higher than that of protein lyophilization protectants, and the lyophilization protection effect of small molecule saccharide below tetrasaccharides was better, among which sorbitol and raffinose had the best effect, and the lyophilization survival rate increased to about 56% after the combination at the mass ratio of 1∶1. The lyophilization pr

Abstract:As a by-product in wheat processing, wheat bran is high in output and rich in nutrition, lactic acid bacteria treatment can increase its added value. To clarify the effects of lactic acid bacteria fermentation on the components of wheat bran, solid fermentation of wheat bran was performed using Lactobacillus plantarum, Lactobacillus rhamnosus, Pediococcus pentosaceus, and Lactobacillus buchneri , respectively. Wheat bran was sampled at an interval of 8 h, the dynamic changes of soluble dietary fiber, crude protein, starch, total phenol, phytic acid and DPPH free radical scavenging capacity during wheat bran fermentation were studied. The results showed that four lactic acid bacteria grew rapidly in wheat bran substrate within 24 h. The content of soluble dietary fiber in wheat bran increased significantly during the lactic acid bacteria fermentation, the content of soluble dietary fiber increased from 4.72% to 6.58% after 48 h fermentation by L. buchneri. With the increase of fermentation time, the content of starch in wheat bran gradually decreased. While, the content of crude protein increased firstly, then decreased slightly, and finally went to constant. L. plantarum was more efficient in increasing polyphenol content than the other strains; the polyphenol content could be increased from 1.34 mg/g to 3.86 mg/g, and the antioxidant activity of wheat bran increased significantly. Furthermore, the phytic acid content in wheat bran can be significantly reduced. In conclusion, L. plantarum and L. buchneri used in this study are effective in improving the nutritional attributes of wheat bran. As a result, the utilization of wheat bran can be improved.

Abstract:N-acetylneuraminic acid has various biological functions and has important applications in food additives and pharmaceutical synthesis, etc. In order to reduce its production cost, in this study, N-acetylneuraminic acid was produced by recombinant Escherichia coli whole cells using the fermentation broth containing N-acetylglucosamine as the substrate. The catalytic conditions of N-acetylneuraminic acid production were optimized. The optimum result was achieved at 30 ℃ (the reaction temperature), initial pH 6.5, 1.38 mol/L pyruvate, 0.4% Triton X-100 added, and OD₆₀₀ 30, the highest yield of N-acetylneuraminic acid reached 180 mmol/L, and the molar conversion rate was 65.45% in 5 L fermentor. N-acetylneuraminic acid produced was separated and purified using anion resin. It was confirmed by high performance liquid chromatography that the sample was high purity N-acetylneuraminic acid. Its purity reached 98.3%, and the recovery rate of crystallization was 42.5%. A method about N-acetylneuraminic acid produced from fermentation broth with N-acetylglucosamine using recombinant E. coli whole cells biotransformation was built and optimized, which not only saves costs but also has the advantage of sustainable development.

Abstract:To enrich protein nutrition types, reduce cost and enhance flavor of the current milk flavors, soybean protein isolate was used to partially replace cream to build a mixed substrate. Two novel milk flavors were developed based on the mixed substrate by fermentation in combination with two different enzymatic hydrolysis methods. Meanwhile, the organoleptic properties, main metabolites, and volatile compounds were determined for the two milk flavors. The results showed that the flavor prepared by one-step enzymolysis combined with fermentation was more associated with higher levels of free fatty acids and medium-long chain volatile acids, which led to rancid and astringent flavor; while the flavor prepared by two-step enzymolysis combined with fermentation accumulated higher concentrations of polypeptides and amino acids, short-chain volatile acids, 3-hydroxy-2-butanone, benzaldehyde, furfural, and δ-dodecanone, which led to higher sensory evaluation score and regarded as the proper meth

Abstract:In order to prevent the browning of fresh-cut apple, the authors compared the compound components composed of different food additives, and found that honey could be used as coating material to effectively delay the browning of fresh-cut apple slices. The fresh-cut apple slices were soaked in 0.1 g/g basswood honey solution, and the fresh color can be maintained after 8 d; the inhibitory kinetics of honey on apple polyphenol oxidase (polyphenol oxidase, PPO) was studied. It was found that honey had a non-competitive inhibitory kinetics on apple PPO, and the inhibition ability of enzyme activity came from the antioxidant and free radical scavenging ability of honey (correlation coefficient r>0.6); after further analyzation of the relationship between honey components and enzyme activity inhibition rate, it was found that protein and polyphenols in honey (r values were 0.79 and 0.63 respectively) were important for honey anti-browning.

Abstract:Crustacyanin plays an important role in the formation and regulation of the color in crustacean aquatic products. To study the gene structural feature and prokaryotic expression of Procambarus clarkii (P. clarkii) crustacyanin A2 (PcCRA2), the coding sequence of PcCRA2 gene (cra2) was obtained by gene cloning. The expression patterns of cra2 in 9 different tissues of P. clarkii were detected by real-time fluorescence quantitative PCR (RT-qPCR). Escherichia coli BL21 (DE3) was used as the host to conduct the heterologous recombinant expression of PcCRA2. The results showed that the full length of cra2 cDNA was 573 bp, encoding 190 amino acids. Bioinformatics analysis indicated that the relative molecular weight of PcCRA2 was 21 158.9, with a theoretical isoelectric point of 5.59. Amino acid alignment revealed that the protein coding sequence of cra2 had the highest similarity to that of C. quadricarinatus (91.58%). RT-qPCR demonstrated that cra2 was expressed in all tested tissues, with the highest expression in epidermis (P<0.05). The prokaryotic expression vector pET28a-cra2 was constructed and induced in DE3. The optimal expression condition was adding 0.5 mmol/L IPTG at 30 ℃ for 6 h after 4 h of inoculation. Results indicated that the recombinant protein could specifically bind to astaxanthin, with a maximum absorption peak at 505 nm. These results provide a foundation for further studies on the biological function of crustacyanin.

Abstract:The meal substitute powder was modified by different modification methods, and the modified meal substitute powder was dried to study the effects of different modification methods and drying methods on the nutritional/functional components of meal substitute powder, and the best modification and drying methods are determined. The results showed that the enzymatic hydrolysis combined with fermentation modification technology was beneficial to improve the content of bioactive substances and the antioxidant activity of meal substitute powder. Compared with microwave freeze-drying, infrared freeze-drying is conducive to the retention of active substances, and its drying time is short. Therefore, enzymatic hydrolysis combined with fermentation modification technology and infrared freeze-drying are conducive to the retention of bioactive substances in meal substitute powder.

Abstract:CrgA has been identified as a negative regulator of the carotenoid biosynthesis in Blakeslea trispora and some other zygomycetes. The presence of the ring finger domains suggest that CrgA may function as an ubiquitin ligase, a key enzyme in the ubiquitination regulation system. In order to test this hypothesis, one ubiquitin activating enzyme(BtE1) and 18 putative ubiquitin-conjugation enzymes(UBC) from B.trispora were isolated and identified. Bioinformatics analysis indicated that each of the 18 UBC proteins contained a conserved domain of UBC, indicating that all of them belong to ubiquitin binding enzymes. Phylogenetic relationship analysis showed that 18 UBC proteins belong to 7 protein subfamilies, homologous with those of Saccharomyces cerevisiae. 6 candidate UBC proteins were screened based on phylogenetic analysis, and BtE1, 6 BtUBC proteins, BtCrgA and BtWC-1b were obtained by heterologous expression and affinity purification, which were ubiquitinated in vitro. BtCrgA can perf

Abstract:In this study, 5 different concentrations of thermostable α-amylase were applied to quinoa to investigate the effect of physicochemical properties, phenolic compounds and antioxidant capacities during extrusion. The results showed that the water solubility increased, the water absorption and viscosity decreased and the particle size decreased after thermostable α-amylase-extrusion coupling treatment compared with the traditional extrusion. Moreover, the mass concentration of phenolic acid, flavone and the antioxidant activity were significantly increased with the addition of thermostable α-amylase. The thermostable α-amylase significantly increased the mass concentration of rutin, caffeic acid, and gallic acid by exploring the change of phenolic compounds during extruding by HPLC. In conclusion, the addition of thermostable α-amylase can significantly improve the physicochemical properties and phenolics compared with the traditional extrusion, and this study provides data to support th

Abstract:To explore the effects of different levels of compound probiotics on the growth performance, intestinal morphology and intestinal microbial composition of white feather broilers under the condition of Clostridium perfringens infection. Three-day-old healthy white feather broilers which have been infected with Clostridium perfringens were fed a basal diet supplemented with high (500 mg/kg), medium (200 mg/kg) and low (50 mg/kg) doses of compound probiotics composed of Bacillus subtilis and Bacillus licheniformis and 50 Times new romang/g chlortetracycline for 21 days. The intestinal microbial composition in cecum of white feather broilers and its diversity and differences between groups were analyzed based on the second-generation high-throughput sequencing technology. The results showed that feeding high and medium doses of compound probiotics significantly decreased the feed to meat ratio and increased the villus height to crypt depth ratio of white feather broilers (P<0.05), similar to chlortetracyline preparation group. At the same time, the richness and diversity changed after feeding different doses of compound probiotics and chlortetracyline preparation, and the compound probiotics significantly improved the Simpson index (P<0.05). In addition, comparing the changes of dominant flora at phylum level between compound probiotics, chlortetracyline preparation and blank group, it was found that the relative abundance of Tenericutes decreased significantly (P<0.05). At the genus level, it was found that the relative abundance of Fournierella increased significantly. The relative abundance of Lachnospiraceae decreased significantly (P<0.05). The results reveal that compound probiotics can promote the growth performance and intestinal microflora structure of white feather broilers, providing an important theoretical basis for a more comprehensive understanding of the application of compound probiotics as a substitute for antibiotics in white feather broilers breeding.

Abstract:The use of microfluidic chips for polymerase chain reaction (PCR) can improve detection efficiency and automation. However, it is still difficult to integrate the nucleic acid extraction, amplification and detection functions into one chip. In addition, the temperature control of the special PCR instrument for microfluidic chip is not fast and accurate enough. Based on the principle of temperature cycling in space instead of temperature cycling in time, a rotary three-temperature zone microfluidic PCR amplification platform was built by the authors to extract and amplify E. coli nucleic acids. The results show that the rotary three-temperature zone microfluidic PCR amplification platform has good thermal uniformity and stability. The heating and cooling rates of the platform were 3.5 ℃/s and 2.67 ℃/s, respectively. The single cycle time is only 110 s. Compared with the 9700 PCR, the platform has a simpler temperature control scheme, higher heating and cooling rates and shorter cycle ti