The mechanism of low temperature enhances dough aromas during fermentation by Pichia kudriavzevii: Sugar and amino acid metabolism, acid utilization and alcohol production

Abstract

In order to investigate the impact of low temperature on enhancing aromas in fermented dough by Pichia kudriavzevii CGMCC 17607 (EP), the study initially utilized gas chromatography to detect volatile organic compounds (VOCs), followed by analyzing basal metabolites derived from these VOCs. Metabolomics was employed to monitor metabolic changes during fermentation, while proteomics was used to examine protein expression related to these changes. Results indicated notable increases in VOCs such as 3-methyl-1-butanol and 2-phenylethanol. Essential metabolites exhibited decreases in sugars (e.g., sucrose, maltose), organic acids (e.g., lactic acid, acetic acid), and amino acids (e.g., leucine, histidine). Particularly, low temperature fermentation led to raised levels of NAD+, NADH, acyltransferases, and ATP, excluding pyruvic acid and glucose-6-phosphate dehydrogenase. These outcomes suggested that low temperature fermentation boosted acid utilization and alcohol production. Metabolomics and proteomics highlighted decreased glycolysis influencing energy metabolism. Moreover, metabolomics revealed elevated levels of flavor substances like octanoic acid and its derivatives with aromatic properties, as well as geranic acid with terpenoid aroma. Furthermore, key intermediates like chorismite and phenylpyruvic acid, along with the pivotal enzyme chorismate synthase, illustrated the biosynthesis pathway of shikimic acid instead of phenylalanine. In summary, at low temperature, EP showed weakened glycolysis, with sugars and amino acids metabolizing into desirable flavor substances like alcohols, which promoted acidity reduction and aroma enhancement of dough.