UMR SPO: INRA, Université Montpellier, Montpellier SupAgro, 34060 Montpellier, France; Moët & Chandon, F-51200 Epernay, France.
UMR SPO: INRA, Université Montpellier, Montpellier SupAgro, 34060 Montpellier, France.
Food Res Int. 2018 Jan;103:192-199. doi: 10.1016/j.foodres.2017.10.040. Epub 2017 Oct 21.
Vicinal diketones produced during wine fermentation influence the organoleptic qualities of wine. Diacetyl and 2,3-pentanedione are well known for their contribution to butter or butterscotch-like flavours. We developed an analysis method to quantify vicinal diketones and their precursors, α-acetolactate and α-acetohydroxybutyrate, under oenological conditions. Five-fold dilution of the sample in a phosphate-citrate buffer (pH7.0) strongly attenuated matrix effects between the beginning and end of alcoholic fermentation and protected the sample from spontaneous precursor decarboxylation. The use of diacetyl-d as an internal reference improved precision by eliminating differences in the derivatization and extraction yields between the internal standard and the analytes. We obtained unexpected results for alcoholic fermentation by Saccharomyces cerevisiae using this approach. Indeed, the level of diacetyl and 2,3-pentanedione throughout fermentation were very low. However, we observed a large quantity of both precursors. The production dynamics of α-acetolactate were unconventional and there were two distinct phases of accumulation. The first corresponded to the growth phase, and the second to glucose depletion. There was a rapid decrease of precursor levels at the end of fermentation, but there was still a significant amount of α-acetolactate. The amount of precursor remaining at the end of fermentation constitutes a potential source of diacetyl during wine maturation. α-Acetohydroxybutyrate accumulated during the growth phase followed by a continuous decrease of its concentration during the stationary phase. Residual quantities of α-acetohydroxybutyrate found in wine at the end of fermentation does not constitute a sufficient source of 2,3-pentanedione to affect the aromatic profile.
在葡萄酒发酵过程中产生的邻二酮会影响葡萄酒的感官质量。二乙酰和 2,3-戊二酮以其对黄油或奶油糖果样风味的贡献而闻名。我们开发了一种分析方法，可在酿造条件下定量测定邻二酮及其前体α-乙酰乳酸和α-乙酰羟丁酸。在磷酸盐-柠檬酸盐缓冲液（pH7.0）中对样品进行五倍稀释，可强烈减弱酒精发酵开始和结束之间的基质效应，并防止样品自发进行前体脱羧。使用二乙酰-d 作为内标可通过消除内标和分析物之间的衍生化和提取产率差异来提高精密度。使用这种方法，我们对酿酒酵母的酒精发酵获得了意想不到的结果。实际上，在整个发酵过程中二乙酰和 2,3-戊二酮的水平都非常低。但是，我们观察到了大量的前体。α-乙酰乳酸的生产动力学是非传统的，有两个明显的积累阶段。第一个阶段对应于生长阶段，第二个阶段对应于葡萄糖耗尽。发酵结束时前体水平迅速下降，但仍有大量的α-乙酰乳酸。发酵结束时残留的前体数量是葡萄酒成熟过程中二乙酰的潜在来源。α-乙酰羟丁酸在生长阶段积累，随后在静止阶段其浓度连续下降。发酵结束时葡萄酒中残留的α-乙酰羟丁酸数量不足以成为 2,3-戊二酮的充足来源，不会影响其香气特征。
