Analysis of the Formation of Characteristic Aroma Compounds by Amino Acid Metabolic Pathways during Fermentation with Saccharomyces cerevisiae

Amino acid metabolic pathways can have profound impacts on the activities of key enzymes in the biosynthesis of specific aroma compounds during yeast fermentation. Aroma compounds, pyruvic acid and glucose were monitored in relation to the key enzymes of leucine aminotransferase (LTR), phenylalanine aminotransferase (PAL), pyruvate kinase (PK) and acetyl-CoA in the amino acid metabolic pathways during the fermentation of simulated juice systems with added amino acids in order to explore the formation of characteristic aroma compounds. The addition of L-phenylalanine or L-leucine to the simulated juice systems significantly improved the activities of PK, PAL and LTR, and the content of acetyl-CoA, and significantly increased the concentrations of phenylethyl alcohol, octanoic acid, isoamyl acetate, phenylethyl acetate, ethyl hexanoate and ethyl caprylate during fermentation. Correlation analysis showed that there was a significant positive correlation between PAL, LTR, PK and acetyl-CoA and pyruvic acid formation. Path analysis revealed that the addition of amino acids affected the metabolism of pyruvate to alcohols, acids and esters to some extent.