QuEChERS结合超高效液相色谱-串联质谱法测定砂仁中4种黄曲霉毒素

该研究建立了利用QuEChERS-超高效液相色谱串联质谱（UPLC-MS/MS）法同时测定砂仁中4种黄曲霉毒素（Aflatoxin B1、B2、G1、G2）的分析方法。通过对QuEChERS前处理技术、色谱和质谱条件的优化，确定了最佳的实验条件。研磨后的样品经φ=1%甲酸酸化的乙腈提取，无水硫酸镁及氯化钠脱水盐析，上清液经十八烷基键合硅胶（C18）、乙二胺-Ｎ-丙基硅烷（PSA）、无水硫酸镁混合吸附剂净化。经ACQUITY UPLC HSS T3色谱柱（1.8 µm，2.1 mm×100 mm）进行分离，以乙腈和φ=0.1%甲酸-5 mmol/L乙酸铵溶液进行梯度洗脱。在正离子模式下，进行多反应监测（MRM），进一步通过空白基质标准溶液外标法定量。结果表明，4种黄曲霉毒素在0.20~10.00 μg/L范围内线性关系良好，相关系数均大于0.998 9。实际样品的加标回收试验结果显示，回收率范围为89.50%~113.12%，日内精密度为1.31%~6.71%，日间精密度为1.29%~6.20%，4种黄曲霉毒素的方法检出限为0.30~0.60 μg/kg、定量限为1.00~2.00 μg/kg。该方法操作简单，快速，灵敏，适用于砂仁中4种黄曲霉毒素的定性、定量筛查。     

Lactococcus lactis phages from the perspective of their diversity,thermal and biocidal resistance

Lactic acid bacteria (LAB), particularly Lactococcus lactis, are of great significance in dairy fermentations. Many LAB strains are susceptible to attack by phages that affect their technological, biochemical and physiological functions. Phages of L. lactis are a serious concern because of the economic importance of this bacterium in the dairy industry. Members of L. lactis phages belonging to the P335, 936 and c2 groups are more problematic for the dairy industry. Many phages of the 936 group are resistant to various thermal and biocidal treatments commonly used in the dairy industry. This article reviews the diversity of L. lactis bacteriophages of the P335, 936 and c2 groups and discusses their interaction with their bacterial hosts. In addition, this review provides an overview of the resistance of L. lactis phages to thermal treatments and chemical biocides, and highlights some novel strategies to destroy these phages.     

肉桂提取物清除自由基及抑菌能力作用研究

主要研究了用响应面法(RSM)优化肉桂提取工艺,同时对肉桂提取物进行了自由基实验及抑菌实验,结果表明:最佳工艺参数为浸泡时间10.8h、固液比1∶14、超声波处理时间60min;肉桂提取物对DPPH·清除率有较好的效果。     

戊糖乳杆菌DF9对副溶血弧菌群体感应的淬灭作用

以副溶血弧菌的群体感应(quorum sensing,QS)为靶标,研究戊糖乳杆菌DF9的乙酸乙酯提取物作为群体感应抑制剂(QS inhibitor,QSI)对其的淬灭效果.在确定DF9-QSI对副溶血弧菌和哈维氏弧菌BB170生长影响的基础上,探讨亚抑菌浓度的DF9-QSI对副溶血弧菌QS信号分子AI-2的活性、动力...     

果蔬发酵制品的功效及应用研究进展

近年来以新鲜果蔬、食用真菌等为原料,经过酵母菌、乳酸菌等多种有益菌发酵而成的功能性发酵制品在我国发展迅速,其营养价值高,富含多酚类、黄酮类、有机酸类、益生菌、益生元、维生素、矿物质、生物酶等功效成分,具有抗氧化、消炎抑菌、改善肠道功能、提高免疫力、解酒护肝等功效。随着人们生活水平的提升,绿色健康保健型产品越来越受到消费者的青睐,因此,研究和开发功能性果蔬类发酵产品意义重大。本文综述了果蔬发酵制品的功效及其在食品行业、种植业、畜牧业和水产养殖业中的应用,展望了我国果蔬发酵产品应用的广阔前景,以期促进果蔬的综合加工利用及其发酵产业的发展,为高效开发功能性果蔬发酵产品,并实现其工业化生产提供参考资料。     

Influence of incongruent dissolution-precipitation on 8YSZ ceramics during cold sintering process

The incongruent dissolution-precipitation behaviors of 8YSZ (8 mol% yttria-stabilized zirconia) ceramics during cold sintering process is studied in this paper by changing the pH of liquid media. The different solubility of Y³⁺ and Zr⁴⁺ at the same lattice position causes the disparate dissolution behaviors, and results in incongruent precipitation. Compared with acidic or alkaline solution, neutral solution is more conducive to the incongruent dissolution-precipitation process, and the concentration ratio of dissolved Y³⁺ and Zr⁴⁺ can reach ～6385. The incongruent dissolution-precipitation process facilitates the formation of neck structure and promotes the ionic migration and diffusion at the subsequent high-temperature sintering process, which improves the mechanical properties and electrochemical properties of 8YSZ ceramics. This work reveals the principle of incongruent dissolution-precipitation process of zirconia-based ceramics, and it is of significance for selecting suitable liquid media to control the incongruent dissolution-precipitation behaviors in cold sintering process to prepare high-performance zirconia-based ceramics.     

抗氧化剂从聚丙烯向食品模拟液中迁移的深层影响因素研究

目的研究影响有害物质向食品中迁移的因素,以有效预测包装材料对食品的污染风险。方法研究温度、模拟液的溶解度参数和抗氧化剂的相对分子质量分别对抗氧化剂BHA,BHT,1076和168从聚丙烯向乙醇模拟液中迁移焓变、分配系数和扩散系数的影响,并把Scatchard-Hilderbrand热力学理论模型预测的平衡分配系数(D_(r0))与实验值(D_r)进行比较分析。结果 4种抗氧化剂从PP向无水乙醇中迁移的平衡分配系数对数(ln D_r)、扩散系数对数(ln D_f)与温度倒数(1/T)成直线关系,符合吉布斯-亥姆霍兹方程和阿累尼乌斯方程,迁移为吸热反应,焓变随抗氧化剂相对分子质量的增大而减小,扩散系数随着相对分子质量和模拟液溶解度参数的减小而增大。同时,抗氧化剂从聚丙烯中迁移到不同溶解度参数模拟液中的平衡分配系数(模拟液质量浓度/塑料质量浓度)实验值,与Scatchard-Hilderbrand热力学理论模型计算值随模拟液溶解度参数的变化趋势基本一致。结论模拟液与PP的溶解度参数越接近,抗氧化剂初始迁移扩散系数越大,抗氧化剂相对分子质量对迁移扩散系数的影响越小,4种抗氧化剂从PP中迁移平衡分配系数变化符合Scatchard-Hilderbrand热力学理论模型。