固相微萃取-气相色谱-质谱结合电子鼻技术分析发酵乳中挥发性风味物质

Analysis of volatile flavor compounds in fermented milk by solid phase microextraction-gas chromatography-mass spectrometry and electronic nose

摘要:

【背景】德氏乳杆菌保加利亚亚种(Lactobacillus delbrueckii subsp. bulgaricus)和嗜热链球菌(Streptococcus thermophilus)作为酸奶的常用发酵剂，在乳制品生产中的应用十分广泛。【目的】在前期研究基础上，以筛选出的具有良好风味的复配发酵剂(复配比为1:100) L. delbrueckii subsp. bulgaricus IMAU20312与S. thermophilus IMAU80809为实验对象，分析牛乳在发酵及贮藏期间风味物质的动态变化规律，为发酵剂的开发与应用提供依据。【方法】采用固相微萃取-气相色谱-质谱联用(solid-phase microextraction-gas chromatography-mass spectrometry,SPME-GC-MS)结合电子鼻技术检测并解析新鲜牛乳在发酵及贮藏阶段所产生的挥发性风味物质。【结果】该发酵剂在牛乳发酵及贮藏期间产生酸类物质23种，醛类物质13种，醇类物质15种，酮类物质18种，酯类物质11种，烷烃类物质22种。香气活度值(odor activity value,OAV)结果表明发酵乳中关键性风味物质(OAV≥1)有2种，而其他化合物如1-辛烯-3-醇、3-羟基丁醛、3-甲基-正丁醛、2,3-丁二酮、2-壬酮及己酸乙酯等对发酵乳的整体风味起修饰作用(0.1≤OAV<1)。热图聚类分析的结果表明牛乳在发酵与贮藏期间产生的风味物质有显著差异，类似的分析结果在电子鼻系统检测分析中也有发现。【结论】该复配发酵剂在牛乳发酵和贮藏期间能产生的多种风味物质，这些化合物能赋予产品良好的风味。

关键词:德氏乳杆菌保加利亚亚种;嗜热链球菌;固相微萃取-气相色谱-质谱;挥发性风味物质;电子鼻

Abstract:

[Background] Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus thermophilus are commonly used as yogurt starters, which are widely used in dairy production. [Objective] Based on the previous study, the compound starter with good flavor was screened out (1:100). L. delbrueckii subsp. bulgaricus IMAU20312 and S. thermophilus IMAU80809, and the dynamic variation of flavor compounds in cow milk during the fermentation and storage was analyzed. The result is expected to lay a basis for the development and application of related starters. [Methods] We employed solid-phase microextraction-gas chromatography-mass spectrometry (SPME-GC-MS) and electronic nose to detect and analyze the dynamic changes of the volatile flavor compounds in milk during fermentation and storage. [Results] A total of 23 acids, 13 aldehydes, 15 alcohols, 18 ketones, 11 esters, and 22 alkanes were produced in the fermentation and storage of milk. According to odor activity values (OAV), there were two key flavor compounds (OAV≥1) in the fermented milk. Moreover, other compounds such as 1-octene-3-ol, 3-hydroxybutyraldehyde, 3-methyl-n-butyraldehyde, 2,3-butanedione, 2-nonanone, and ethyl ester modified the overall flavor of the fermented milk (0.1≤OAV<1). According to the cluster heatmap, the flavor substances produced during fermentation and storage were significantly different. Similar results were also found by electronic nose detection. [Conclusion] The flavor compounds produced by the compound starter in milk during fermentation and storage endow fermented milk a good flavor.

Key words:Lactobacillus delbrueckii subsp. bulgaricus;Streptococcus thermophilus;solid-phase microextraction-gas chromatography-mass spectrometry (SPME-GC-MS);volatile flavor compounds;electronic nose