SPME-GC-MS结合ROAV分析单菌及复配发酵牛乳中关键性风味物质

采用固相微萃取-气相色谱-质谱联用技术检测分析Streptococcus thermophilus与Lactobacillus delbrueckii subsp.bulgaricus单菌及复配发酵牛乳中的挥发性风味物质,结合相对气味活度值(relative odor activity value,ROAV)探讨发酵牛乳中关键性风味物质。结果表明:本实验共鉴定出100种挥发性风味物质,包括酸类、酮类、醛类、醇类、酯类、烷烃类和芳香族类化合物等。主成分分析表明,表征S.thermophilus单菌发酵乳的关键性风味物质是双乙酰、正壬醛和甲苯;表征L.bulgaricus单菌发酵乳的关键性风味物质是正庚醛、丁酸-2-甲基丙酯和1-庚醇;表征S.thermophilus与L.bulgaricus复配发酵乳的关键性风味物质是乙醛、3-甲基正丁醛、乙偶姻、2-壬酮、2-庚酮、醋酸乙烯酯、碳酸庚基苯基酯、甲酸乙烯酯和2-壬醇。相较于单菌发酵,复配发酵的风味物质组成、各组分相对含量及关键性风味物质均发生改变。

Analysis of Key Volatile Compounds in Fermented Cow Milk Produced by Pure and Mixed Cultures by SPME-GC-MS Combined with ROAV

Solid phase microextraction coupled with gas chromatography-mass spectrometry (SPME-GC-MS) and relative odor activity value were used to study the key volatile compounds of fermented cow milk produced by pure and mixed cultures of Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus. The results showed that 100 volatile compounds, including acids, ketones, aldehydes, alcohols, estersds, hydrocarbons and aromatic compounds were detected. Principal component analysis (PCA) indicated that 2,3-butanedione, nonanal and toluene were the characteristic aroma compounds of fermented cow milk produced by a pure culture of S. thermophiles while hexanal, butanoic acid-2- methylpropyl ester and 1-heptanol were the characteristic aroma compounds of fermented cow milk produced by a pure culture of L. bulgaricus. Acetaldehyde, 3-methyl-butanal, acetoin, 2-nonanone, 2-heptanone, acetic acid ethenyl ester, carbonic acid-heptyl phenyl ester, formic acid-ethenyl ester, and 2-nonanol were the characteristic aroma compounds of fermented cow milk produced by mixed cultures. Compare to fermented cow milk produced by pure cultures, the compositions of volatile compounds and their relative contents and the key volatile compounds were all changed in fermented cow milk produced by mixed cultures.