Ott A, Germond J E, Baumgartner M, Chaintreau A
Nestlé Research Center, NESTEC Ltd., Vers-chez-les-Blanc, Lausanne, Switzerland.
J Agric Food Chem. 1999 Jun;47(6):2379-85. doi: 10.1021/jf980650a.
A quick headspace GC method for quantification of volatiles was developed, involving only minor sample preparation. Yogurt flavor compounds could be quantified in the micrograms per kilogram to milligrams per kilogram range without any difficulty, despite the complex matrix. Volatiles of traditional acidic and mild, less acidic yogurts were compared, and important differences were found for acetaldehyde, 2,3-butanedione, and 2,3-pentanedione. Concentrations of 2,3-butanedione and 2,3-pentanedione increased 2-3-fold in mild, less acidic yogurts compared to traditional acidic ones. This is due to accumulation of the precursors of the diketones, 2-acetolactate and 2-acetohydroxybutyrate, during fermentation in mild, less acidic yogurt. These precursors are subsequently converted to the corresponding diketones during storage. On the contrary, acetaldehyde formation was reduced in the mild yogurt, due to growth differences between the lactic acid bacteria used for fermentation of the milk. The quantitative results presented in this study validate previous GC sniffing conclusions (Ott et al. J. Agric. Food Chem. 1997, 45, 850-858), showing that yogurt aroma is the superposition of impact flavor compounds generated by fermentation on milk compounds.
开发了一种快速顶空气相色谱法用于挥发性成分的定量分析，该方法仅涉及少量样品制备。尽管酸奶基质复杂，但酸奶风味化合物可在每千克微克至每千克毫克的范围内轻松定量。比较了传统酸性酸奶和温和的、酸性较弱的酸奶中的挥发性成分，发现乙醛、2,3 - 丁二酮和2,3 - 戊二酮存在重要差异。与传统酸性酸奶相比，温和的、酸性较弱的酸奶中2,3 - 丁二酮和2,3 - 戊二酮的浓度增加了2至3倍。这是由于在温和的、酸性较弱的酸奶发酵过程中，二酮的前体2 - 乙酰乳酸和2 - 乙酰羟基丁酸积累所致。这些前体在储存过程中随后转化为相应的二酮。相反，由于用于牛奶发酵的乳酸菌生长差异，温和酸奶中的乙醛生成减少。本研究给出的定量结果验证了先前气相色谱嗅觉分析的结论（Ott等人，《农业与食品化学杂志》，1997年，45卷，850 - 858页），表明酸奶香气是发酵产生的影响风味化合物与牛奶化合物叠加的结果。
