Lipolysis and Metabolism of Fatty Acids in Cheese
Résumé
Enzymatic hydrolysis (lipolysis) of milk glycerides to free fatty acids is essential for flavor development in cheese. The principal lipolytic agents in cheese include lipoprotein lipase from raw milk, pregastric esterase in cheeses made using rennet paste, and enzymes from the starter and nonstarter microbiota. Lactic acid bacteria are weakly lipolytic and mainly possess nonlipolytic esterases located intracellularly. Lipolysis level is, thus, low in many internal bacterially ripened cheeses. It is higher in certain varieties, such as Swiss cheese, smear-ripened, and particularly mold-ripened cheeses, in which specific lipolytic secondary microbiota develops. Exogenous lipases are occasionally used to develop flavor. Short-chain fatty acids directly contribute to flavor, but fatty acids can also act as precursors for the production of a wide range of other flavor compounds, such as esters, lactones, and methylketones that are associated with diverse flavors. Methods for determining levels of fatty acids are also discussed.