Nitrogen metabolism of branched‐chain alcohols acetates in jujube wine assessed by 13 C‐labeling

Abstract

Branched-chain alcohols acetates (BCAA) are important aroma components of jujube wine. However, their presence is somewhat difficult to control during fermentation. In this regard, 13C-labeling and Gas Chromatography-Mass Spectrometer (GC-MS) were used to explore the Ehrlich pathway for the formation of BCAA. Initially, branched-chain (BC) amino acids, known to be involved in the production of BCAA, were investigated. BC amino acids, aldehydes, and alcohols were observed to gradually transform, while a small amount of alcohols was esterified to BCAA. Following the addition of 13C-BC amino acids into the jujube pulp, 13C-aldehydes, 13C-alcohols and 13C-BCAA were detected in the wine at 2, 24, and 72 hr, respectively, by mass spectrometric analysis. BC amino acids were observed to be transaminated, decarboxylated to aldehydes and then reduced to alcohols. The alcohols were subsequently esterified with acetyl CoA to form BCAA confirming a potential pathway for flavor regulation and quality improvement of jujube wine. Practical applications Jujube wine, produced by jujube fermentation with Saccharomyces cerevisiae, is a famous alcoholic beverage in Taihang Mountain districts in Hebei with Chinese characteristics. But the development of jujube wine was restricted because its flavor and quality were very unstable. Branched-chain alcohols acetates (BCAA) are the key aroma compounds of jujube wine. Understanding the formation mechanism of BCAA could provide the guide of process optimization and flavor regulation, making it become a unique brandy with Chinese characteristics, recognized, and accepting by the world.