普洱茶发酵过程中真菌群落结构的变化分析

该文通过变性剂法提取普洱茶样品中微生物的基因组DNA作为模板,以真菌的通用引物扩增18S rDNA的NS31/Glol区,再将PCR产物用变性梯度凝胶电泳进行分析,通过对DGGE图谱的统计分析和18S rDNA序列分析研究普洱茶发酵过程中真菌群落结构的组成和演变规律。研究结果表明:普洱茶不同发酵阶段的真菌多样性呈现出一定差异和变化趋势,黑曲霉(Aspergillus niger)在整个发酵过程中占有优势地位,此外还包括酿酒酵母(Saccharomyces cerevisiae)和光孢青霉(Penicillium glabrum)。     

食用玫瑰鲜花处理工艺技术的研究

通过研究低温速冻、热风烘箱干燥、真空冷冻干燥以及糖渍4种不同处理方式对玫瑰鲜花香气成分、黄酮以及颜色的影响,确定热风烘箱干燥是最适宜的原料处理方式,最佳的工艺参数为:干燥温度60℃,干燥时间8.5h。在该条件下,玫瑰花的风味、颜色变化最小,黄酮含量最高。     

Emulsification enhances the retention of esters and aldehydes to a greater extent than changes in the droplet size distribution of the emulsion

The physicochemical and organoleptic properties of an emulsion depend on the way the constituents interact with one another to form emulsion droplets, interfacial region and continuous phase. The objective of this work was to evaluate the respective impact of both the emulsification and the modification of the properties of an emulsion, such as the droplet size distribution, on the partition of aroma compounds. The emulsions were prepared with sodium caseinate and the low melting point fraction of anhydrous milk fat (Φ = 0.3). Their volume-surface mean droplet size ranged from 1.8 to 0.3 μm. Results showed that the measured partition coefficients of ethyl pentanoate, isoamyl acetate, hexanal and t-2-hexenal were lower than the calculated ones from values measured separately over continuous and dispersed phases. The droplet size distribution had no significant impact on the partition coefficient of the three esters whereas, for a volume-surface mean diameter below 0.5 μm, the partition coefficients of the two aldehydes were drastically reduced. The greater retention is not related to the sodium caseinate remaining in the continuous phase of the emulsion. The formation of an interfacial area seems to govern the partition of aroma compounds in emulsions.     

硫酸软骨素提取用酶的现状及前景

硫酸软骨素(chondroitin sulfate,CS)在医药、化妆品和食品工业上有广泛的用途,市场前景广阔。对硫酸软骨素提取用酶做了简要的介绍,提出了目前硫酸软骨素行业存在的问题,并阐述了硫酸软骨素生产工艺及行业的发展状况及未来趋势。     

不同饲养模式对青海藏羊肉食用品质和营养成分的影响

为了提高青海藏羊养殖效益,取3 种不同饲养模式（放牧组、放牧＋补饲组、全舍饲组）的藏羊肉,采用色差仪、酸度计、嫩度仪测定羊肉的色度、pH值和嫩度等食用品质指标,参照国家标准规定方法测定羊肉脂肪、蛋白质、水分等营养成分含量以及重金属、抗生素、农兽药等有害物质残留量。结果表明：3 种饲养模式的羊肉在蒸煮损失方面存在显著差异（P＜0.05）,全舍饲组羊肉的蒸煮损失率显著低于其他两组,3 种饲养模式的羊肉失水率和剪切力不存在显著差异;全舍饲组羊肉的脂肪含量显著高于其他两组（P＜0.05）,而水分含量则差异不显著,3 组羊肉的蛋白质含量不存在显著差异;3 种饲养模式羊肉的饱和脂肪酸含量存在显著差异（P＜0.05）,不饱和脂肪酸含量无显著差异;只有放牧＋补饲组的羊肉检出铅含量为0.022 mg/kg,3 种饲养模式下的羊肉均未检出其他有害物质。全舍饲组藏羊肉的加工性能较好,而放牧组藏羊肉的蛋白质含量更高,在生产中应考虑其不同用途从而选择不同饲养模式。     

不同类型酵母对精酿啤酒化学和感官特性的影响

为研究不同类型的酵母对精酿啤酒的化学和感官特性的影响,选取5株酿酒酵母（4株上面发酵酵母、1株下面发酵酵母）进行酿造发酵实验,采用顶空固相微萃取（HS-SPME）法以及离子色谱（IC）法提取并鉴定分析啤酒中的香气成分和有机酸成分,采用偏最小二乘法-判别分析（PLS-DA）进行挥发性化合物的定量与鉴别,并用电子舌对成品酒进行滋味评价。结果表明,4株上面啤酒酵母（A1-A4）与下面啤酒酵母L5相比,上面啤酒酵母的起发速度更快,发酵度更高,发酵液风味物质含量较高,酯香醇厚。综合发酵性能指标可以看出,菌株A2的发酵速度较快,最早达到发酵峰值,发酵液感官风味协调,是一株发酵性能优良的精酿啤酒酵母;菌株A3具有较高的发酵度为80.87%,乙酸乙酯的产量高达45.64 mg/L,是一株具有高发酵度的啤酒酵母。     

Detection of antibiotics in sheep milk by receptor-binding assays

Receptor-binding assays to detect antibiotics in sheep milk were evaluated. Specificity of the Betastar Combo, SNAP and Twinsensor^BT tests was optimal using inhibitor-free bulk sheep milk (99–100%), and no differences between the visual or instrumental classification were found. For individual sheep milk free of antibiotics, specificity was elevated by the Betastar Combo and SNAP tests. However, lower specificity was obtained by the Twinsensor^BT test, especially in the last weeks of the lactation period. Regarding cross-reactions, interferences related to drugs other than β-lactams and tetracyclines were not detected. Furthermore, the use of azidiol, as a preservative of milk, had no effect on the test. In all cases, the detection capability was able to detect most β-lactams and tetracyclines at or below maximum residues limits. The receptor-binding tests evaluated showed a very good performance in the detection of antibiotics in sheep milk, thus being suitable for milk quality control programmes.     

酱香型白酒的研究现状

酱香型白酒因其独特的风味、口感和相对较好的饮后舒适度,深受广大消费者的喜爱。近年来有关酱香型白酒的研究成为了科研人员的热点课题,该文从酱香型白酒的生产工艺、酿酒微生物、特征性风味物质研究进展和酿造环境四个方面概述了酱香型白酒的研究现状,并对酱香型白酒发展前景进行了展望,以期为酱香型白酒工作者提供借鉴与参考。     

应用PCR-DGGE技术分析不同性状窖泥的细菌群落结构

基于聚合酶链式反应-变性梯度凝胶（PCR-DGGE）技术分析了不同性状窖泥的细菌群落DGGE指纹图谱,结果表明,通过DGGE指纹图谱能够区分新窖泥、窖壁泥和窖底泥,其中以窖壁泥退化前后图谱变化最明显。PCR-DGGE图谱优势条带测序结果显示,窖泥中细菌微生物包括拟杆菌门、放线菌门、厚壁菌门、变形菌门4类,其中新窖泥微生物种类最丰富,涵盖以上门类,特有优势微生物为Enterobacterale科、双歧杆菌属（Bifidobacterium）、假单胞菌属（Pseudomonas）及里氏杆菌属（Riemerella）。紫单孢菌科（Porphyromonadaceae）仅存在于窖底泥中,Tumebacillus属微生物只存在于窑壁泥中。通过窖泥的DGGE图谱对比分析,能够对窖泥类型做出初步判定,并能及时发现窖泥退化现象,为工厂窖泥培养、检测和窖泥优化提供了理论支持。