Animal lipase (EC 220.127.116.11) has been designated with many names: animal lipase; triglyceride lipase; tributyrase; butyrinase; glycerol ester hydrolase; tributyrinase; tributyrin esterase; triglyceride hydrolase; esterase; triglyceridase; triacylglycerol ester hydrolase; pregastric lipase; pregastric esterase.
It is a hydrolase acting on triacylglycerol esters, freeing fatty acids and partial glycerides. It works on mono-, di- and tri-glycerides. Its physiological role is linked to the digestion of milk fats. The lipase from pregastric tissue is secreted from the tongue region and washed into the stomach with the saliva (see Figure 18.104.22.168). The area richest in lipase is commonly referred to as gullet. The gullet is the region that is bordered anteriorly by the vallatae papillae of the tongue and posteriorly by the pharyngeal
Figure 22.214.171.124 Dorsal view of the tongue, pharnyx, and esophagus of the bovine in which the soft palate, pharynx, and origin of the esophagus are cut dorsally and reflected.
end of the esophagus. The gullets include the soft palate, the root of the tongue, the glosso-epiglottic regio, the epiglottis, the larynx, and the apex of the arytenoids cartilage.
It is a major component of rennet paste. As such, lipase has been used for a thousand years in unconscious way to produce piquant cheeses. During the twentieth century, research has determined the source of pregastric lipase, allowing the extraction and production of this enzyme from its specific tissue.
Industrially, the enzyme is obtained from kid goat, lamb, and calf gullets, which are collected in approved slaughterhouses and immediately frozen. Liquid preparations and dry preparations are available on the market. For long storage, it is best to keep the dry preparations frozen.
Animal lipase is generally used in dairy processing to enhance or accelerate flavor development in cheese production or in the production of enzyme modified dairy ingredients such as enzyme modified cheese (EMC) that are used to create a cheese taste to several foods like soups, snacks, and sauces. In cheese production, the enzyme is used particularly in the production of traditional Italian piquant cheeses or other similar cheese varieties. The free fatty acid released, especially short-chain free fatty acids, are responsible for the flavor profiles typical of Italian piquant cheeses. Each type of triacylglycerol lipase gives rise to its own characteristic flavor profile in cheese, partly due to free-fatty acid selectivity (see Figures 126.96.36.199 and 188.8.131.52). Calf triacylglycerol lipase generates a buttery and slightly peppery flavor, kid goat triacylglycerol lipase sharp peppery profile, often called piccante, and lamb triacylglycerol lipase generates a strong “pecorino” flavor (FIL— IDF Bulletin N° 294/1994).
In cheese manufacturing, triacylglycerol lipase is added after the starter culture and before the coagulant. It performs its technological function during cheese ripening. Lipolysis belongs to the primary events of cheese ripening. Further flavor development and ripening is caused by secondary events, including the metabolism of fatty acids and amino acids. The ripening process of cheese is therefore complex, and is not only due to primary enzymatic activity, but is also involves many microbiological and chemical changes resulting in flavor changes of the cheese (McSweeney et al., 2004).
Figure 184.108.40.206 Effect of pH on triacylglycerol lipase.
Figure 220.127.116.11 Effect of temperature on triacylglycerol lipase.
The determination of the activity of pregastric lipase is described in the International Standard ISO 13082:2011 (E)—IDF 218:2011 (E): Milk and milk products: Determination of the lipase activity of pregastric lipase preparations.