Cheese making: new perspective in lipolysis and influence of exogenous enzymes in fatty acids and volatile compound profile of semi hard cheeses

The flavour of mature cheese is the result of a complex series of biochemical reaction, involving, especially hydrolytic enzymes, and occurring in the curd, during ripening. More than 500 varieties of cheese are produced all over the World, and each of them possesses its typical sensory characteristics. Flavour depends on milk variety as well as on starter bacteria used in cheese-making and ripening. The latter is the essential step for the development of typical flavours, during cheese ripening procedures, and it requires the hydrolytic activities of proteases and lipases. Usually, these activities come from Lactic Acid Bacteria (LAB), rennet or fungi. In industrial cheese production, the milk pasteurization process leads to the removal of the endogenous bacteria. A way to increase cheese flavour and/or to reduce the time of ripening is to use exogenous enzymes, during cheese making, by adding some commercial lipases. He we will highlight the use of a thermophilic esterase in cheese production (EST2 from Alicyclobacillus acidocaldarius), and more in detail its action in the cheese ripening step as well as in the improvement of cheese flavour. Considering that thermophilic esterases have different mechanism of action respect to lipases and being more stable respect to all the commercial lipases, it could be an interesting technological tool to improve the sensory quality or to accelerate cheese ripening.