柠檬醛对副溶血性弧菌的抑制作用

有效预防和控制副溶血性弧菌对食品的污染对于保障公众健康具有重要意义。本研究首先利用琼脂稀释法测定7?种植物源活性物质（丁香酸、阿魏酸、绿原酸、硫辛酸、原儿茶酸、原儿茶醛和柠檬醛）对副溶血性弧菌的最小抑菌浓度,在此基础上选择柠檬醛进行后续实验;通过检测经柠檬醛处理后的副溶血性弧菌生长曲线、细胞膜电位、胞内ATP浓度、细胞膜完整性以及细胞形态的变化,探究柠檬醛对副溶血性弧菌的抑制作用及可能的作用机理。结果表明：柠檬醛相比于其他6?种植物源活性物质对副溶血性弧菌有更好的抑菌效果,其对两株标准菌株和8?株分离菌株的最小抑菌浓度在0.10～0.60?mg/mL范围内;柠檬醛能够引起副溶血性弧菌细胞膜电位去极化、胞内ATP浓度降低及细胞膜完整性下降,同时可使细胞皱缩变形。本研究结果表明柠檬醛具有良好的抑菌功效,并有潜力作为天然的抗菌物质应用于食品工业。     

动物源性食品产地溯源技术研究进展

随着消费者膳食结构的改变和安全意识的增强,动物源性食品的产地来源已成为人们关注的焦点问题之一。食品的产地溯源是食品追溯体系中重要的组成部分,它既有利于保护消费者的利益,保护地区品牌和特色产品,确保公平竞争,又能有效地实施产品召回,防止食源性病原菌的扩散。稳定性同位素分析、矿物元素含量分析以及化学成分分析法被认为是进行食品产地溯源的有效技术手段,具有很好的发展前景。本文主要综述几种溯源技术的基本原理,介绍其在动物源性食品产地溯源中的应用现状及存在的问题,并对今后的发展提出相关建议。     

Cloning,sequencing and structural analysis of membrane-bound polyphenol oxidase from Granny Smith apples (Malus × domestica Borkh)

The gene sequence coding for the membrane-bound polyphenol oxidase (mPPO) with a length of 1761 bp was cloned by PCR method and shown to contain one highly conserved sequence encoding a di-copper-binding region. The predicted three-dimensional structure of mPPO indicated that the active site was located near two copper ions and composed of a typical bundle of four α-helices. Each of the two catalytic copper ions was coordinated with three histidine residues in the hydrophobic pocket, yielding His 180, His 201, His 210, His 332, His 336 and His 366. Docking studies showed that 4-methylcatechol and chlorogenic acid have different binding models due to different ligand sizes and binding sites in the active centre, and it was found that the smaller compound exhibited a higher affinity for mPPO. Molecular dynamic simulation results indicated that Phe 353 is important in controlling enzymatic activity through influencing substrate coordination in the active site.     

Performance of UV-LED and UV-C treatments for the inactivation of Escherichia coli ATCC 25922 in food model solutions: Influence of optical and physical sample characteristics

Shortwave ultraviolet light (UV-C) and ultraviolet light-emitting diodes (UV-LEDs) are emergent technologies to inactivate pathogenic and spoilage microorganisms in food. However, the effectiveness of these technologies is influenced by the optical properties of the treated food. This work aimed to evaluate the effect of the optical properties of nine model food solutions on the efficacy of UV-C (at 255 nm) and UV-LEDs (at 255, 265 or 280 nm) to inactivate E. coli ATCC 25922. Model solutions were formulated with saccharose (SC), tartrazine (TT) and xanthan gum (XG), exposed from 0 to 50 min. The microbial population was reduced after 15 min of UV-C and UV-LED treatment by >6 log CFU/mL for water and TT, and by UV-C for SC, XG, TT + SC, and (XG + TT + SC) _m solutions. The inactivation data were correlated using three different models. Colored compound (TT) showed 60% degradation by UV-C compared to 3% by UV-LED at 50 min.Industrial relevanceNon-thermal treatments such as those based on ultraviolet light, UV-C, and UV-LEDs could have high industrial relevance because of their simplicity of operation and reduced by-product formation, being a friendly alternative for food processing. Understanding the effect of different optical and physicochemical properties of liquid food to be treated by UV-based technologies is mandatory for the equipment's efficient design and operation. Furthermore, the proper selection of processing conditions, such as delivered dose and processing time, allows for obtaining safe and high-quality products.     

Digestion of meat proteins in a human-stomach: A CFD simulation study

Understanding gastric digestion mechanisms is important for the design of functional foods. In this study, we have investigated the meat-protein digestion in human-stomach by using a CFD method. The gastric motility is modeled with a dynamic mesh. The disintegration of large food particles in an acidic environment is simulated using a reaction-diffusion-convection model. A food matrix is used to model the large food-particles. The numerical results show that the digestion and emptying become faster when the meat is treated at a higher temperature. The digestion rate is reduced considerably when the gastric motility or the H⁺ secretion is weakened due to a stomach disorder. TACs stimulate backflows which enhance the transport of enzymes and H⁺, thereby accelerating the digestion process. Due to the flow resistance by the food matrix made of large food particles, liquid gastric contents are emptied in a pathway close to the stomach inner-surface. Large food-particles are mainly disintegrated in the region next to the stomach inner-surface. Therefore, the characteristic length scale of species transport (for enzymes or H⁺) should be the size of food matrix, instead of the size of large food-particles.     

Changes in the structural and physicochemical characterization of pea starch modified by Bacillus-produced α-amylase

In this study, changes in structural and physicochemical properties of pea starch treated with Bacillus-produced α-amylase were determined. The results showed that enzymatically modified pea starch had lower amylose content and granule size but higher branching degree and relative crystallinity. After enzyme hydrolysis, the distribution of A and B1 chains slightly decreased, while the distribution of B2 and B3 chains increased lightly. Enzymatic hydrolysis preferentially occurred in the amorphous region and cannot change the crystalline structure of pea starch. Moreover, pea starch showed lower light transmittance, peak viscosity, breakdown viscosity, pasting temperature, shear viscosity, storage modulus and loss modulus, while the oil adsorption capacity and gelatinization enthalpy significantly increased with increasing α-amylase hydrolysis time. Correlation analysis indicated that α-amylase hydrolysis had different effects on different pea varieties. This research could provide ideas for exploring new applications for enzymatically modified pea starch in food industry.Industrial relevanceThis study found that Bacillus-produced α-amylase significantly changed the amylose content, granule size and viscosity of pea starch, which was helpful to further investigate the modified starch. This technology is expected to widen the applications of pea starch modified by Bacillus-produced α-amylase in food industry, for example as thickener, stabilizer and beverage, to improve the texture, stability and shelf-life of various food products.     

Intake of Pro- and/or Prebiotics as a Promising Approach for Prevention and Treatment of Colorectal Cancer

Colorectal cancer (CRC) is the third most common type of cancer, posing a serious threat to human life. It is widely believed that dietary factors may be crucial modifiers of CRC risk, with pro-and/or prebiotics being especially promising. In this review, a synthesis of CRC prevention and treatment of strategies relying on usage of pro- and/or prebiotics supplements is given, as well as discuss mechanisms underlying the contribution of pro-and/or prebiotics to the suppression of colonic carcinogenesis. Furthermore, a framework for personalizing such supplements according to the composition of an individual's gut microbiome is suggested. Various factors including diversity of one's intestinal microflora, integrity of their intestinal barrier, and the presence of mutagenic/carcinogenic/genotoxic and beneficial compounds are known to have a prominent influence on the development of CRC; thus, clarifying the role of pro- and/or prebiotics will yield valuable insight toward optimizing interventions for enhanced patient outcomes in the future.     

Afterglow of atmospheric non-thermal plasma for disinfection of lentil seeds from Botrytis Grey Mould

Seed-borne fungal diseases of grains are a serious threat to grain crops' yield due to lack of either resistant crop varieties or dependence on fungicides. Therefore, there is a growing demand to develop sustainable technologies for crop protection. In the present study, an atmospheric microwave plasma was employed to eradicate Botrytis cinerea from lentil seeds. Argon, air and a combination of them were applied to create the plasma. There was a 41% reduction in the percentage of artificially contaminated seeds (with an initial contaminated seed percentage of 95.8%) after 100 s treatment of 2.5 g of lentil seeds with the afterglow of air plasma followed by 24-h holding time. A 32.3% reduction occurred when a 30% air/70% Argon was applied for 10 s and 60 min of holding time. The holding time of 24 h increased catalase activity from 0.8 to 1.1 mM H₂O₂ mg⁻¹ min⁻¹ that was an indicator of early plant immune system fortification. This also changed seeds' colour toward redness and yellowness. Conclusively, the afterglow of microwave plasma could be considered as a part of integrated disease management in lentil crops.     

Protein quality and antioxidant properties of soymilk derived from black soybean after in vitro simulated gastrointestinal digestion

Protein quality and antioxidant properties of soymilk derived from black soybean (eight varieties) in China were analysed following in vitro simulated gastrointestinal digestion (including dialysis). Soymilk from black soybean possessed high okara weight but low yield, protein content and sensory scores. The in vitro digestibility of protein in all black soymilk samples was higher than 60%, and the Shenmu black soybean exhibited the highest digestibility. Non-digested milk from the black soybean exhibited significantly high total phenolic content (TPC) (127.15–173.04 mg/100 mL), ferric-reducing antioxidant power (FRAP) (272.18–366.27 μmol L⁻¹) and DPPH free radical-scavenging activity (61.20–83.81%). These parameters were significantly lower in the non-digested soymilk than those in soymilk after gastric digestion but higher than those of soymilk in the dialysed fraction. Gastric digestion significantly increased bioactive compound levels released from black soymilk, and the bioaccessibility of phenolic compounds was 24.37–36.05%. Hence, black soymilk was sufficiently available for human absorption.     

Comparison of biochemical properties and thermal inactivation of membrane‐bound polyphenol oxidase from three apple cultivars (Malus domestica Borkh)

A comparative study of the properties of membrane‐bound polyphenol oxidase (mPPO) from three apple cultivars, namely Red Fuji (FJ), Granny Smith (GS) and Golden Delicious (GD), was carried out for the first time. Data indicate that mPPOs from three cultivars exhibit significantly different properties. GS mPPO had the strongest affinity to catechol, but FJ mPPO had the highest maximum velocity. Red Fuji (FJ) mPPO had the significantly higher activity than those of GD and GS mPPOs. Red Fuji (FJ) mPPO had the highest activity at pH 8.00, while GD and GS mPPOs at 4.50 and 7.50–8.00, respectively. Red Fuji (FJ) mPPO was more stable than GD and GS mPPOs over the pH range of 5.0–8.5. The optimal temperature for GS mPPO was within 70–75 °C, which is higher than those for mPPOs from FJ and GD. Thermal inactivation of the three mPPOs followed a first‐order kinetic model with different inactivation kinetic parameters.