生物传感器在食品安全领域的研究进展

文章综述了生物传感器在食品安全领域的研究进展,对各种识别元素、纳米材料及传感技术在食品生物传感器中的应用进行了介绍.对传感器未来的发展方向和面临的挑战进行了探讨.     

Yak-milk-derived exosomes promote proliferation of intestinal epithelial cells in an hypoxic environment

Intestinal epithelial cells (IEC) are an important part of the intestinal barrier. Barrier function was disrupted under hypoxia, but milk-derived exosomes can regulate the intestinal barrier function. However, the mechanisms underlying the association between yak milk exosomes and hypoxia in IEC remain poorly understood. In this follow-up study, we proposed an effective optimization method for purifying yak-milk-derived exosomes. The Western blot analyses indicated that the expression of the proteins of the endosomal sorting complexes required for transport (TSG101), proteins of the tetraspanin family (CD63), and heat shock protein 70 (Hsp-70) proteins from yak-milk-derived exosomes were significantly higher than those in cow-milk-derived exosomes. Flow cytometry analysis showed that yak milk had 3.7 times the number of exosomes compared with cow milk. Moreover, we explored whether yak milk exosomes could facilitate intestinal cell survival under hypoxic conditions in vitro. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide results showed that yak-milk-derived exosomes significantly increased survival of IEC-6 cells with rates of up to 29% for cells incubated in hypoxic conditions for 12 h, compared with those of cow-milk-derived exosomes posttreatment (rates of up to 22% for cells incubated in hypoxic conditions for 12 h). Confocal microscopy revealed that the IEC-6 cells uptake more yak-milk-derived exosomes than cow milk in hypoxic conditions. Furthermore, the Western blot analyses indicated that yak-milk-derived exosomes significantly promote oxygen-sensitive prolyl hydroxylase (PHD)-1 expression and decrease the expression of hypoxia-inducible factor-α and its downstream target vascular endothelial growth factor (VEGF) in the IEC-6 cells. Further, yak-milk-derived exosomes significantly inhibited p53 levels. In conclusion, our findings demonstrate that yak-milk-derived exosomes more effectively activate the hypoxia-inducible factor signaling pathway, thus promoting IEC-6 cell survival, which may result in higher hypoxia tolerance than cow-milk-derived exosomes.     

猕猴桃感官评定与质地剖面分析的相关性

为确定猕猴桃质地的仪器测试方法是否反映人的真实感官,本研究以3种猕猴桃(海沃德、秦美、徐香)为对象,进行感官评定与质地剖面分析指标间的相关性分析。结果表明:3个品种猕猴桃的感官评定与质地剖面分析指标间广泛存在相关性,但相关系数不高(|r|=0.002~0.807)。采用逐步回归分析建立各感官指标的多参数预测模型,发现感官指标预测值与实际值的相关系数均有不同程度提高。预测模型中海沃德、秦美、徐香猕猴桃感官指标预测值与实际值间的相关系数分别为0.377~0.782、0.370~0.895和0.490~0.764。在预测模型的检验中,以总体可接受度为评定标准,其平均相对误差分别为10.04%(海沃德)、9.78%(秦美)和11.09%(徐香)。本研究结果证明利用多质构指标融合可以建立与感官评定更好地相关性。     

不同种类脂肪替代物对软冰淇淋浆料流变特性及产品品质和口感的影响

分别利用浓缩牛乳蛋白（milk protein concentrate,MPC）、菊粉、葡聚糖及其复合物（浓缩牛乳蛋白-菊粉（MPC-inulin,M-I）、浓缩牛乳蛋白-葡聚糖（MPC-dextran,M-D））作为脂肪替代物制作无脂软质冰淇淋。通过仪器分析和感官评价综合分析其替代脂肪效果。结果表明,不同实验组冰淇淋在pH值、滴定酸度和膨胀率方面无明显差异,葡聚糖及菊粉的添加增加了体系稳定性,MPC可以增加体系黏度并延缓融化速率。葡聚糖组冰淇淋具有与对照组冰淇淋相似的粒径分布,而MPC组、菊粉组和M-D组的粒径更小且分布更为集中。M-I组和M-D组的频率扫描和温度扫描的动态流变学参数与对照组更为接近。感官评价分析表明,M-I和M-D组具有较好脂肪类似的口感。回归分析进一步得到整体口感与温度依赖的动态流变学参数的回归模型,为模拟低脂软冰淇淋顺滑细腻的口感提供可行的评价方法。     

高压脉冲电场技术在杨梅保鲜中的应用研究

高压脉冲电场灭菌技术是国际上研究较为热门的非热灭菌技术之一。实验目的是探讨高压脉冲电场技术用于杨梅保鲜的可行性。工作电压100kV的高压脉冲电场由本实验室研制,将新鲜杨梅置于高压脉冲电场产品处理室中,设置不同电场参数(脉宽、频率、电场作用时间)对杨梅进行处理,通过分析对照组和处理组杨梅的pH变化以及气味、色泽等感官指标的变化来验证高压脉冲电场对杨梅的保鲜效果。结果显示影响杨梅保鲜的最主要因素是电场脉冲宽度,最佳的参数组合是脉宽10μs,频率80Hz,作用时间10s。结论:高压脉冲电场对杨梅保鲜有一定的效果。     

两种兔耳草提取物的体外抑菌作用

短管兔耳草(Lagotis brevituba Maxim)和短穗兔耳草(Lagotis brachystachy Maxim)在传统藏药中具有抑菌消炎的功效。采用琼脂孔扩散法和96孔培养板对倍稀释法测定了这两种植物不同极性溶剂逐级提取物对4种采后真菌和4种腐败细菌的体外抑菌率和最低抑制浓度。结果表明:在供试真菌中,短管兔耳草提取物对F.semitectum和P.expansum具有抑菌活性,短穗兔耳草提取物对P.expansum和A.alternate具有抑菌活性。两种植物的提取物对供试细菌的抑菌活性整体上较强,短管兔耳草提取物对S.aureus和P.fluorescence有抑菌活性,而短穗兔耳草提取物对S.aureus,E.coli,B.subtilis和P.fluorescence都有抑菌活性。提取物对细菌的最低抑菌浓度最低可达0.05g/mL。结论:这两种植物的提取物具有较广的体外抑菌谱和较强的抑菌活性。     

武陵青花椒壳挥发油成分及脂肪酸分析

分别采用水蒸气蒸馏法和同时蒸馏萃取法提取武陵青花椒壳中的挥发油成分,提取率分别为6.4%和8.5%。再用气相色谱-质谱法（GC-MS）对挥发油成分进行分析,用峰面积归一化法确定各组分的相对含量。两种方法均鉴定出43种化合物,其中水蒸气蒸馏法以β-芳樟醇（66.91%）、反式-橙花叔醇（6.28%）、D-柠檬烯（5.24%）、4-萜烯醇（2.6%）为主,同时蒸馏萃取法以β-芳樟醇（64.32%）、D-柠檬烯（5.97%）、反式-橙花叔醇（4.17%）、反式-9-十八烯酸（3.09%）为主。同时对挥发油进行甲酯化,然后用GC-MS对挥发油中含有的脂肪酸进行了分析,共分离鉴定出6种脂肪酸。结果表明:两种方法提取的挥发油的组成及含量存在差异,挥发油中主要为不饱和脂肪酸。水蒸气蒸馏法对无极性和弱极性的萜烯和萜醇类化合物提取效果较好,而同时蒸馏萃取法适于各种极性化合物,对极性稍强的脂肪酸和酯类有较好的提取效果。      

复合生防菌群对连作大豆根际土壤可培养微生物区系的影响

采用盆栽试验,研究了复合生防菌群对大豆根际土壤可培养微生物区系的调节作用。结果表明,复合生防菌群可以明显改变大豆根际微生物区系组成。在大豆不同时期,复合生防菌群处理的大豆根际细菌、真菌和放线菌在数量上发生了较大改变。在大豆真叶期和复叶期,复合生防菌群接种处理大豆根际细菌较对照增幅分别达到71.8%和114.3%,而根际真菌较对照减少12.9%和22.3%。在大豆真叶期,复合生防菌群接种处理大豆根际放线菌数量较对照减少9.9%,而在复叶期,根际放线菌数量较对照增加27.4%。此外,施用复合生防菌群可有效降低土传病原菌镰孢菌属（Fusarium）和丝核菌属（Rhizoctonia）的比例,并且提高根瘤菌（Rhizobium）、固氮菌（Azoto-bacter）、木霉属（Trichoderma）、假单胞菌属（Pseudomonas）和芽孢杆菌属（Bacillus）等有益菌的比例。     

角叉菜胶致血栓动物模型制备及在功能食品评价中的应用

对角叉菜胶诱导鼠尾部血栓模型的造模机制、造模方法及其影响因素进行综述,并对该模型在功能食品抗血栓功效评价中的应用进行了简要介绍,旨在为我国抗血栓功能食品的功能评价方法研究提供参考。     

Comparison of aromatic and phenolic compounds in cherry wines with different cherry cultivars by HS‐SPME‐GC‐MS and HPLC

To compare the influence of cultivars on the production of aroma compounds and polyphenols, eight cherry varieties (six sweet and two sour) were fermented into cherry wines, and their compositions were analysed. Results showed that by headspace solid microextraction coupled to gas chromatography–mass spectrometry (HS‐SPME‐GC‐MS), a total of twenty‐first aromatic compounds, mostly consisting of esters, acids, terpenoids and C₁₃‐norisoprenoids, were identified, and eleven polyphenols including five anthocyanins and six phenolic acids were quantified using HPLC. May Duck and Early Richmond wines contained significantly higher levels of phenolic acids (>42 mg L^?1) that were associated with high contents of chlorogenic and neochlorogenic acids and also relatively high amounts of octanoic acid and β‐damascenone (odour activity values ≥1000). Hongdeng, Zhifuhong and Bing wines were characterised by higher concentrations of anthocyanins (>41 mg L^?1) and also relatively higher levels of isopentyl acetate. Lapins and Governer Wcod wines were distinguished by lower concentrations of polyphenols and relatively higher contents of ethyl 3‐methylbutanoate.