保加利亚乳杆菌的筛选及其发酵乳中的风味物质

Screening of Lactobacillus delbrueckii subsp.bulgaricus and Its Flavor Substances in Fermented Milk

以分离自传统发酵乳中的7株保加利亚乳杆菌为试验菌株,测定发酵乳制作和贮藏(12 h)期间pH值、滴定酸度、活菌数、黏度的变化,并结合固相微萃取与气相色谱-质谱联用技术(SPME-GC-MS)检测贮藏12 h时发酵乳中的挥发性风味物质。结果表明,7株保加利亚乳杆菌中,IMAU62115在牛乳中的发酵时间最短(7 h),活菌数最高为4.95×108 CFU/mL,滴定酸度为95°T,黏度为820 mPa·s。贮藏12 h时,7株保加利亚乳杆菌发酵乳的风味成分差异显著,从IMAU20403、IMAU20396、IMAU62121、IMAU62115、IMAU20220、IMAU20227、IMAU20234中分别检出29,28,26,26,32,31种和26种风味物质,主要有酸类、醛类、酮类、醇类及酯类化合物等。其中,IMAU62115发酵乳中的主要特征性风味物质有双乙酰、乙偶姻、3-甲基丁醛、2-壬酮等,这些风味化合物在IMAU62115发酵乳中的浓度较高,OAV值大于1,对发酵乳的风味贡献较大。本研究筛选的保加利亚乳杆菌IMAU62115菌株是一株具有优良发酵特性的菌株。

In the study,7 strains of Lactobacillus delbrueckii subsp.bulgaricus isolated from traditional fermented dairy products are used to determine the changes of pH,titratable acidity,viable counts and viscosity during the production and storage(12 h)of fermented milk.In addition we detected for the flavor substances produced during storage(12 h)of fermented milk by solid phase microextraction combined with gas chromatography-mass spectrometry(SPME-GC-MS)methods.The results indicate that the IMAU62115 displayed the shortest fermentation time of 7.0 h and the number of viable cell counts of fermented milk gave the highest value of 4.95×108 CFU/mL,the TA reached 95°T and the viscosity was 820 mPa·s.Among the 7 strains storage for 12 h,the flavor components of these strains in fermented milk had a significant difference and 29,28,26,26,32,31 and 26 kinds of flavor substances were detected in IMAU20403,IMAU20396,IMAU62121,IMAU62115,IMAU20220,IMAU20227 and IMAU20234 respectively,mainly including acids,aldehydes,ketones,alcohols and esters,etc.Among them,the main characteristic flavor substances in IMAU62115 fermented milk are diacetyl,acetoin,3-methylbutyraldehyde,2-nonanone and so on.It has a high concentration of these flavor compounds in fermented milk,and the OAV value is greater than 1.Thus it has a great contribution to the flavor of the fermented milk.Therefore,the strain of Lactobacillus delbrueckii subsp.bulgaricus IMAU62115 screened in this study is a strain with excellent fermentation characteristics.