A review on aroma-active compounds derived from branched-chain amino acid in fermented meat products: Flavor contribution, formation pathways, and enhancement strategies

Fermented meat products have been favored by consumers due to their characteristic qualities, especially their unique flavors. The aroma-active compounds originating from catabolism of branched-chain amino acids (BCAA) are perceived as malt, nuts, and cheese aromas, remarkably contributing to the overall aroma characteristics of fermented meat products. Research on formation pathways and enhanced production for branched-chain flavor compounds has garnered attention. This review summarized the presence, level, and contribution of branched-chain flavor compounds in fermented meat products, as well as the sources of amino acid precursors and the synthetic pathways. Furthermore, strategies for enhancing the levels of branched-chain flavor compounds are emphatically discussed in aspect of starter culture of lactic acid bacteria (LAB). The findings revealed that aroma-active flavor compounds, such as branched-chain aldehydes, alcohols, and acids, are present in various fermented meat products, significantly demonstrating high odor activity values. BCAA, generated through the combined action of endogenous muscle enzymes and microbial proteases, are crucial precursors for developing corresponding flavor compounds. Branched-chain flavor compounds can be formed through either Strecker degradation or biosynthesis via the α-keto acid decarboxylase pathway and α-keto acid dehydrogenase pathway by LAB. The targeted enhancement strategies for branched-chain volatiles include increasing precursor supply, optimizing fermentation conditions, and genetically modifying strain genes. Future research endeavors should prioritize the screening of more efficient production strains and the optimization of metabolic engineering techniques to enhance the production of branched-chain flavor compounds.