Abstract:Food allergy is an adverse immune response that specific to food allergens, while immune tolerance is defined as the absence of such an immunological reaction to the ingested food antigens. The prevalence of cow's milk is increasing in recent years and most children allergic to cow's milk develop immune tolerance after three years old as reported. Based on these facts, the review introduces milk allergy and the related immune cells that trigger immune tolerance including dendritic cells, regulatory B cells and regulatory T cells, and their roles in immune tolerance. Three methods for inducing immune tolerance are also summarized.

Abstract:Zearalenone(ZEN) is a nonsteroidal estrogenic mycotoxin. It significantly endangers the development of human reproductive system, and enters the human body mainly through contaminated cereal crops, meat and dairy products. Rapid, sensitive and accurate detection of ZEN has become an emerging method in recent years. This article reviewed and compared the current detection methods of ZEN in China and abroad, mainly focused on the detection principles and the latest research progress of related methods. The development of ZEN detection technology was also prospected.

Abstract:The yield of geraniol-modified chitosan oligosaccharide (COS-M-Ger) derivatives was increased based on the improvement of experimental scheme described in previous research. COS-M-Ger1，COS-M-Ger2 and COS-M-Ger3 were synthesized through a two-step reaction of geraniol bromination and substitution, and the yield was 4~7 times higher than that of the previous study. The products were characterized by UV-Vis, FT-IR, 1H-NMR and elemental analysis to confirm the successful synthesis, and the substitution degrees of products were in the range from 0.260 to 0.283. Solubility, X-ray diffraction analysis and TGA showed that the products had better solubility than Ger under acidic and neutral conditions. Compared to COS, the crystallinity of product was stronger, however, the thermal stability was worse. The antibacterial results showed that the antibacterial effects of COS-M-Ger1，COS-M-Ger2 and COS-M-Ger3 were better than those of COS and two commercially available antibacterial agents. This paper provides a theoretical basis for the mass production of COS derivatives with good solubility and high antibacterial effect.

Abstract:To study the effect of signal transmission between residues and water on protein thermo stability, the Residue-Residue and Residue-Water interaction networks were constructed based on the trajectories obtained by molecular dynamics simulation of wild-type lipase (WTL) and its mutant (6B) at different temperatures,with residues and water as nodes and residue-residue and residue-water interactions as edges. The Dijkstra algorithm was used to calculate the shortest path between nodes in the network. The results showed that at 300 K, the residues on loop between αB and β4 and αB in WTL and 6B frequently communicated with water, which reduced the flexibility of this region. At 400 K, WTL only strengthened the internal connection of αC, while in 6B, the loop between β7 and β8, αA and the longest loop were connected to each other and maintained stable communication with water, thus stabilizing the thermal stability of lipase. In addition, the mutation point A20E in 6B was more likely to form stable hydrogen bond with water after the mutation, and the mutation increased the thermal stability of lipase. Thus, this study can provide a theoretical basis for rational design to improve the heat resistance of protein.

Abstract:Penicillium oxalicum is an important biocontrol microbe in plants. A linear pentapeptide was isolated from P. oxalicum distributed in the Three Gorges river bank, and it had an extremely strong inhibitory effect on P. Digitatum, a pathogen causing citrus rot. In order to explore the biosynthesis mechanism of linear pentapeptide, the cDNA libraries of three P. oxalicum strains (114-2, SG-4, SJ-3) with different pentapeptide contents were sequenced by the BGISEQ-500 platform, and the results were compared with the reference transcriptome. High-throughput sequencing produced 6.55 GB of data averagely, and the alignment rate with the reference transcriptome reached 91.65%. Compared with 114-2 without pentapeptide production, comparative analysis of differentially expressed genes showed that a total of 1 648 genes were up-regulated and 1 251 genes were down-regulated in SG-4 and SJ-3 that could produce pentapeptide. AntiSMASH analysis suggested that there might be 33 non-ribosomal peptide synthetases (NRPS) genes in P. oxalicum genome, among which the expression of 15 NRPS was consistent with that of pentapeptide. Further RT-PCR expression analysis showed that the gene cluster PDE_01071 might be responsible for pentapeptide synthesis.

Abstract:To investigate starch fine structure changes during rice storage, five rice cultivars collected from different regions were stored at 35℃ under relative humidity 75% for accelerated storage observation. After rice starch extraction, microstructure, particle size distribution, crystal structure, short-range ordered structure and amylopectin chain length distributions of starch were measured. The results showed that the starch fine structure of five rice cultivars changed with storage time (30, 60 and 90 d). Relative crystallinity of rice starch presented an increasing tendency to different degrees, and rice starch displayed typical A-type crystallization without transformation during storage. The short-ranged ordered structure of rice starch became tighter and more ordered. The percentage of short amylopectin chains (DP 6~12) increased, while the medium and long amylopectin chains (DP 25~36 and DP ≥37) decreased over time. The particle size and size distribution of rice starch insignificantly changed during storage.

Abstract:β-glucosidase may stimulate hydrolysis of stevioside to produce rubusoside. However,there are three β-1,2-glucose residues in stevioside molecule, which may produce rubusoside, steviolbioside, steviol glucosyl ester, steviolmonoside and steviol during the hydrolysis. To date, the structures of by-products remain unclear, and the analysis of reaction route is even more limited. The reported production throughput is not high enough for industry production. β-glucosidase from Aspergillus niger was applied to catalyze the hydrolysis of stevioside for rubusoside production in high-throughput. This reaction route was analyzed through substrate specificity test, structural characterization of products and by-products, and analysis of real-time composition. The results indicate that the enzyme is specific to stevioside. The main hydrolysis product is rubusoside, and it is demonstrated for the first time that the by-product, steviol glucosyl ester, is directly produced by hydrolyzing sophorosyl group of stevioside instead of the hydrolysate of rubusoside.

Abstract:This study mainly analyzed the components of sea cucumber ovum and studied their effects on the cognitive discrimination in mice. 70 SPF (Specific Pathogen Free) male ICR (Institute of Cancer Research) mice were randomly divided into the control group, scopolamine group, piracetam positive group (400 mg/kg), sea cucumber ovum low, medium and high dose groups (75, 150 and 450 mg/kg). Mice were intragastrically administered 30 minutes before intraperitoneal injection of 1 mg/kg scopolamine daily. After 30 days, mice were subjected to different behavioral experiments including open field test, new object recognition test, Y maze, Morris water maze, and step-through task. During the behavioral experimental training period, oral administration and scopolamine injection were continued to establish the model. The results showed that compared with the scopolamine group, the sea cucumber ovum group significantly increased the active time of mice in the central area of open field (P <0.05), and significantly improved their discrimination index in the object recognition test (P <0.05). Spontaneous alternation was significantly increased in the Y maze P <0.01), and the escape latency was significantly reduced in the Morris water maze space exploration test(P <0.01). At the same time, it significantly increased the crossing times (P< 0.05) and cumulative time(P < 0.05) of mice in the platform area. During the dark avoidance experiment, the latency of mice entering the dark roP om was significantly increased(P < 0.05) and the number of errors was significantly decreased (P < 0.05).

Abstract:To alleviate the scarcity of natural blue pigment resources, anthocyanin-Fe²⁺ chelates were prepared using anthocyanin and Fe²⁺ salt in this study. Their feasibility as natural blue pigments and the color stability in a simulated beverage system (pH 3.0) during storage and under thermal treatment were evaluated. The results showed that the anthocyanin-Fe²⁺ chelate prepared with an anthocyanin:Fe²⁺ molar ratio of 1:350 was bluish violet, and its degradation followed the first-order reaction kinetics (R² >0.80). Under dark storage for 14 days, the color stability of anthocyanin-Fe²⁺ chelate at 4 ℃ was better than that at 20 ℃. The half-life and activation energy values of anthocyanin-Fe²⁺ chelate were improved by adding xanthan gum, which slowed down the degradation and blue color loss. However, the thermal stability of anthocyanin-Fe²⁺ chelate was poor during thermal treatment, and its degradation was accelerated at high temperature. In conclusion, anthocyanin-Fe²⁺ chelates, as natural edible blue pigments, have good application potentials and exhibit good stability in low-temperature food processing and storage.

Abstract:In order to produce zinc supplements easily digested and absorbed by the human body and to increase the added value of dark meat of mackerel, the oligopeptide of dark meat mackerel was chelated with zinc. The mackerel dark-colored meat peptide chelated zinc was prepared by the ultrasonic method using the peptide (<3 000) of dark meat mackerel as raw material. The chelation process was optimized by single factor combined with response surface methodology based on the chelation yield and chelation rate, and the amino acid compositions and energy spectrum of the chelate were further analyzed. The results showed that the optimal chelating process conditions were set as chelating time of 51 min, chelating temperature of 72 ℃, peptide zinc mass ratio of 1:2, peptide concentration of 5.35%, and chelating pH value of 7.9. Under this condition, the zinc chelation yield and chelation rate were 55.86% and 65.12%, respectively, consistent with the predicted values. This study could provide a theoretical basis for the preparation of zinc chelates and the high-value utilization of mackerel dark meat.

Abstract:The inhibition mechanism of cinnamic aldehyde semicarbazone on xanthine oxidase activity was examined. The experiment examined the IC₅₀ values, inhibitory type, and the inhibitory constant value of cinnamic aldehyde semicarbazone on xanthine oxidase to analyze the oxidation of xanthine. The inhibition type was determined by Lineweaver - Burk double reciprocal plot and the corresponding inhibition constants (K_Ｉ and K_ＩＳ) were calculated. The experiment also examined the effects of cinnamic aldehyde semicarbazone on the concentration of serum uric acid，the activity of serum xanthine oxidase and liver xanthine oxidase in mice. Cinnamic aldehyde semicarbazone showed significant inhibitory effects on the activity of xanthine oxidase with IC₅₀ of 55.48 μmol/L，and it was the reversible inhibitor and competitive-uncompetitive mixed type inhibitor with K_Ｉ of 27.25 μmol/L and K_ＩＳ of 50.30 μmol/L. Compared with the model group, cinnamic aldehyde semicarbazone could significantly reduce the concentration of serum uric acid，the activity of serum xanthine oxidase and liver xanthine oxidase in mice (P <0.05，n =10). The active sequence was allopurinol>cinnamic aldehyde semicarbazone>cinnamyl aldehyde. Cinnamic aldehyde semicarbazone had significant inhibitory effects on the activity of xanthine oxidase. It could also significantly reduce the concentration of serum uric acid, the activity of serum xanthine oxidase and liver xanthine oxidase in mice. These results suggest the utilization of cinnamic aldehyde semicarbazone as a new drug candidate for reducing uric acid and treating gout.

Abstract:The compositions and possible mechanism of industrial hemp (Cannabis sativa L.) leaves against Staphylococcus aureus (S. aureus) were evaluated to provide a theoretical basis for the development of promising alternatives for natural preservatives based on the components of industrial hemp leaves. The main active components were extracted by ethanol and ethyl acetate sequentially, and then separated through silica gel column. The minimum inhibitory concentration (MIC) was determined using micro-dilution method to obtain components with high activity, and the antimicrobial components were analyzed by GC-MS. Furthermore, changes in cell wall integrity, cell membrane permeability, energy metabolism as well as oxidative damage before and after the treatment were measured to explore the antibacterial mechanism. Results showed that Fr5 (petroleum ether : ethyl acetate=1:1) exhibited a better effect on S. aureus with the MIC of 31.25 μg/mL, and 24 compounds were totally identified. After bacteria are treated with Fr5, apparent deformation was observed on the surface of bacteria, extracellular alkaline phosphatase (AKP) content increased, while the electric conductivity, nucleic acid content, and soluble protein content rose. Meanwhile, the concentration of adenosine triphosphate (ATP) and the activity of superoxide dismutase (SOD) in bacteria were firstly increased and then decreased. Therefore, Fr5 fractions could damage the structure of cell wall and cell membrane of S. aureus, leading to the increase of membrane permeability and thus releasing cell contents, which affected bacterial metabolism and caused oxidative damage to plasma membrane, and finally inhibited the cell growth and metabolism.

Abstract:Infant Formula Food for Special Medical Purpose (IFFSMP), a special food designed according to the nutritional requirements of infants suffering from special disorders, diseases or medical conditions, is the main food source for those infants. However, in recent years, some solid beverages should have been illegally sold as IFFSMP frequently by some unscrupulous enterprises, harming the health and growth of infants. In order to deepen the social understanding of IFFSMP, promote the healthy development of industry, and guarantee the life and health of those special infants, this paper summarizes and compares the regulations and standards for the supervision of IFFSMP in domestic and abroad, and analyzes the current status on the approval of IFFSMP in China. The differences of IFFSMP, solid beverages, and common infant formula milk powder are also introduced. This review also dissects the reasons why the sales of solid beverages pretending to be IFFSMP have been repeatedly banned. The suggestion of further strengthening the supervision of IFFSMP is put forward.