The formation mechanism of lactones in Gouda cheese

Lactones are fat-derived aroma compounds, but the formation mechanism of these compounds during ripening of Gouda cheese is unknown. Both enzymatic and chemical formation pathways were investigated in this study. Lactone formation from milk triglycerides or free fatty acids by lactic acid bacteria enzymatic activity was not observed. Instead, the mechanism of the lactone formation in cheese was a one-step, non-enzymatic reaction, where a hydroxy fatty acid, esterified in a triglyceride undergoes trans-esterification to release the lactone directly. The lactone reaction potential was determined for all major gamma- and delta-lactones by controlled heating of the fat. The chemical formation of lactones was temperature-dependent and the Arrhenius parameters of the formation reaction were estimated for each of the lactones. The kinetics of the reaction were first-order, and could be used to explain the formation of lactones in ripening Gouda cheese up to about 40 weeks. (c) 2006 Elsevier Ltd. All rights reserved.