HYNES Erica Rut
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Enhanced lipolysis and proteolysis in hard cooked cheese by changes in cheesemaking
MARÍA AYELÉN VÉLEZ; CARINA BERGAMINI; CARLOS ALBERTO MEINARDI; MARIO CANDIOTI; SILVINA REBECHI; MARÍA CRISTINA PEROTTI; ERICA HYNES
Simposio; 6th IDF Cheese Ripening & Technology Symposium; 2012
International Dairy Federation
Proteolysis and lipolysis during hard cooked cheeses are main biochemical changes that lead to the appreciated characteristics of the product. The aim of this work was to increase the activity of native milk enzymes (plasmin and lipoprotein lipase) and coagulant enzyme by modifications in hard cooked cheese technology, in order to enhance lipolysis and proteolysis and accelerate ripening. Changes in cheesemaking were first assayed in preliminary experiments in minicurds and miniature cheeses. The effect of pH at whey drainage (4.6, 5.4 and 6.4), cooking temperature (50 and 56ºC), curd washing and type of coagulant enzyme (bovine and camel quimosin) on activities of plasmin and coagulant on specific substrates was assessed, as well as its influence on proteolysis, described by peptide profiles, electrophoresis and nitrogen fractions. As for lipolysis, different pre-treatments of cheesemilk were tested: mechanical treatments (homogeneization and agitation) and sanitation methods (natural creaming and thermal treatment). Miniature cheeses were made with pretreated milk and lipolysis was analyzed by GC. Changes in pH were discarded as high pH values increased plasmin activity and beta casein hydrolysis but diminished coagulant activity and production of peptides derived from alpha s1 casein. A similar trend was observed for cooking temperature: at 56 °C coagulant activity decreased, and even if it reactivated later, proteolysis was slowed down. On the contrary, including a step of curd washing was favorable because it increased plasmin activity and did not affected coagulant enzyme, with resultant increased global proteolysis. Total lipolysis was significantly higher only for homogeneized, non-thermally treated milk. Most favorable treatments were combined and applied in cheese making trials at pilot plant. Experimental cheeses were made with homogenized milk; curd was washed and cooked at 50 ºC. Standard cheesemaking was applied for control cheeses. Experimental cheeses had increased levels of enzyme activities, proteolysis and lipolysis, and their genuine aroma and piquant taste was intensified.