具有良好风味嗜热链球菌的筛选及其产香特性分析

嗜热链球菌作为酸奶发酵剂的常用菌株之一，在牛乳发酵和贮藏过程中可以赋予产品优良的质地、丰富的营养价值和独特的风味。本实验在前期研究的基础上，以商业发酵剂为对照组，以分离自不同地区传统发酵乳中的具有良好发酵特性的7株嗜热链球菌为实验菌株，采用固相微萃取结合气相色谱-质谱联用技术对发酵终点，即pH4.5时发酵乳中的挥发性风味物质进行检测分析。结果表明，在所有实验菌株中，G80-2发酵乳中的挥发性风味化合物的组成及含量最接近对照组。在此基础上，对G80-2菌株在牛乳发酵和贮藏过程中所产生的挥发性风味物质进行动态分析，发现该菌株在发酵和贮藏期间检测出酸类（4种）、醇类（10种）、酮类（12种）、醛类（6种）、酯类（1种）等多种化合物，且一些主要特征风味物质如乙酸、乙醛、双乙酰、乙偶姻、2-庚酮、1-庚醇等相对含量较高，说明该菌株可作为发酵剂应用于乳制品生产中。

Screening of Streptococcus thermophilus with Good Flavor and Analysis of Its Aroma Production Characteristics

As one of the main strains of fermented milk, Streptococcus thermophilus can impart excellent texture, rich nutritional value and unique flavor to fermented milk during the fermentation and storage process of fermented milk. On the basis of the previous research, 7 strains of S. thermophilus with good fermentation characteristics isolated from traditional fermented milk in different regions were used as the experimental strains this experiment, and commercial starters were used as the control group, solid phase microextraction was used combined with gas chromatography-mass spectrometry technology to detect and analyze the volatile flavor substances in the fermented milk at the end of the fermentation, which was pH4.5. The results showed that among all the experimental strains, the composition and content of volatile flavor compounds in G80-2 fermented milk were closest to the control group. On this basis, the dynamic analysis of the volatile flavor substances produced by the G80-2 strain during the fermentation and storage of milk was carried out. It was found that the strain was detected acids (4 types), alcohols (10 types), ketones (12 types), aldehydes (6 types), esters (1 type) and other compounds during fermentation and storage. Some main characteristic flavor substances such as acetic acid, acetaldehyde, diacetyl, acetoin, 2-heptanone, 1-heptanol, etc. were relatively high in content. It was concluded that the strain could be used as a starter in the production of dairy products.