Evaluation of Physicochemical Properties, Bioactivities, Flavor Profiles and Key Metabolites during Tamarind Pulp Fermentation by Kluyveromyces marxianus

To improve the flavor of tamarind and enhance its market prospects, Kluyveromyces marxianus was used to ferment tamarind pulp. The physicochemical properties, bioactive components, and flavor compounds of the tamarind pulp were determined. The mechanism underlying flavor formation in the fermented tamarind pulp was further explored from the perspectives of metabolomics and transcriptomics. During fermentation, the malic acid content increased significantly from 85.92 mg/100 mL to 546.76 mg/100 mL. Electronic nose analyses indicated a time-dependent enhancement of aroma complexity in fermented tamarind pulp. 3-Methyl-1-butanol, phenethyl alcohol, isoamyl acetate and phenethyl acetate were the dominated volatile compounds. The emergence of these flavor compounds markedly altered and enriched the aroma profile of tamarind pulp. However, the levels of flavor-contributing amino acids in the tamarind pulp decreased, though they were likely utilized by the yeast to generate new flavor compounds and support its growth. Transcriptome profiling revealed significant enrichment of pyruvate metabolism, amino acid degradation, and redox-related processes, providing molecular evidence for metabolic reprogramming in the yeast strain.