Department of Life Sciences and Chemistry, Jacobs University Bremen, Campus Ring 1, 28759 Bremen, Germany.
Department of Life Sciences and Chemistry, Jacobs University Bremen, Campus Ring 1, 28759 Bremen, Germany.
Food Res Int. 2018 Jul;109:506-516. doi: 10.1016/j.foodres.2018.04.068. Epub 2018 May 1.
Degradation products of proteins produced during fermentation are believed to be the key precursors of a range of Maillard reactions that deliver the characteristic flavor and aroma of cocoa and chocolate. We have utilized UPLC-ESI-Q-q-TOF to identify and relatively quantify the largest collection of cocoa oligopeptides during a spontaneous fermentation time series using Ivory Coast cocoa beans. Peptides were identified, sequenced by tandem mass spectrometry and annotated based on their characteristic fragmentation pattern in the positive-ion mode. This enabled us to quantitatively trace the sequential degradation of the two main cocoa storage proteins, namely, albumin and vicilin. We observed sequential proteolytic degradation forming longer peptides in the early stages of fermentation and an increasing number of shorter peptides at the latter stages of fermentation. Protein degradation is mediated by both endo- and exopeptidases degrading at either peptide termini. In excess of 800 fermentation peptides could be unambiguously identified, providing unprecedented mechanistic details of cocoa fermentation.
发酵过程中产生的蛋白质降解产物被认为是一系列美拉德反应的关键前体，这些反应赋予了可可和巧克力的独特风味和香气。我们利用 UPLC-ESI-Q-q-TOF 技术，在使用象牙海岸可可豆的自发发酵时间序列中，鉴定和相对定量了最大的可可低聚肽集合。通过串联质谱对肽进行了鉴定和测序，并根据其在正离子模式下的特征碎裂模式进行了注释。这使我们能够定量追踪两种主要可可贮藏蛋白（白蛋白和伴白蛋白）的顺序降解。我们观察到在发酵的早期阶段，通过连续的蛋白水解作用形成了更长的肽，而在发酵的后期阶段，形成了越来越多的短肽。蛋白降解是由内切肽酶和外切肽酶介导的，它们分别在肽的两端进行降解。可以明确鉴定出超过 800 种发酵肽，为可可发酵提供了前所未有的机制细节。
