Flavour formation by lactic acid bacteria and biochemical flavour profiling of cheese products

TLDR

Flavour development in cheese arises from enzymatic degradation of caseins into peptides and amino acids, which are precursors for volatile aroma compounds, and recent research has identified enzymes involved in amino acid conversion. The paper aims to highlight enzymes and pathways involved in flavour formation and discuss their impact on developing industrial starter cultures. The authors review the enzymes and pathways that contribute to flavour formation in cheese.

Abstract

Flavour development in dairy fermentations, most notably cheeses, results from a series of (bio)chemical processes in which the starter cultures provide the enzymes. Particularly the enzymatic degradation of proteins (caseins) leads to the formation of key-flavour components, which contribute to the sensory perception of dairy products. More specifically, caseins are degraded into peptides and amino acids and the latter are major precursors for volatile aroma compounds. In particular, the conversion of methionine, the aromatic and the branched-chain amino acids are crucial. A lot of research has focused on the degradation of caseins into peptides and free amino acids, and more recently, enzymes involved in the conversion of amino acids were identified. Most data are generated on Lactococcus lactis, which is the predominant organism in starter cultures used for cheese-making, but also Lactobacillus, Streptococcus, Propionibacterium and species used for surface ripening of cheeses are characterised in their flavour-forming capacity. In this paper, various enzymes and pathways involved in flavour formation will be highlighted and the impact of these findings for the development of industrial starter cultures will be discussed.