Changes of Texture, Microstructure and Free Fatty Acid Contents of Lighvan Cheese during Accelerated Ripening with Lipase

In this study, the effect of addition of three different levels of microbial lipase (۰, ۴, and ۸.۰ g lipase in ۱۰۰ kg milk) was investigated on the physiochemical properties, free fatty acids, textural properties, and microstructure of Lighvan cheese during ripening. The addition of lipase did not significantly affect pH, acidity, moisture, and salt content of Lighvan cheese, but increased its free fatty acid content considerably. It also increased hardness and decreased the brittleness of Lighvan cheese in all stages of ripening. The number and the mean diameter of fat globules, which were entrapped in casein network, were affected by all levels of the added lipase. Following the addition of lipase to Lighvan cheese and after ۹۰ days of ripening, individual fat globules or their aggregates totally disappeared and some fingerprints of fat were observed. Disappearance of fat globules along with increase in protein matrix junctions leads to uniform structure of casein consisting voids which are produced from fermentation.