Enzymes pregastric esterase

Cheese/hutter flavor. Pregastric lipases, have, been used for years to intensify flavor in Menzyme-modified cheese , and for an intensified butter flavor in lipolyzed butter. Generally the fatty acid residues that need to be split off (to generate the right flavor) are the short chain fatty acids, especially the C to C-jq acids typical of Italian cheeses. The butyric acids are produced from butterfat more specifically by newly developed lipases (really esterases) from Mucor meihei and a very new one, from Aspergillus oryzae, especially for cheddar cheese flavor development. The latter enzyme is marketed under the name Flavor Age (4). Flavors produced in this manner are used widely in cheese-flavored snack foods the value of the intensified cheese flavors is on the order of 50 million, but the. value of the enzymes employed is only about 2-3 million. 

Let us now assume that the pregastric enzyme has characteristics of both an esterase and a lipase. When it acts as an esterase, the catalyzed hydrolysis of tributyrin will depend largely on the concentration of the tributyrin-surfactant complex, XS, which, in turn, is dependent upon [S] below the cmc but remains constant as the micelle starts to form. The actual effective concentration of the substrate will be equal to that of the tributyrin-surfac-tant complex, [XS], which will, in turn, be dependent on the type of surfactant used. 

In conclusion, the behavior of the pregastric lipase reflects its dual functions, those of a lipase and an esterase, and which fimction is dominant is more likely to depend upon the substrate imder attack and the environment of the reaction medium than upon the enzyme itself. 

The presence of an efficient smfactant is essential for the pregastric lipase-catalyzed hydrolysis reaction of a lipid substrate. When the concentration of the substrate is greater than its solubility limit, the addition of surfactant to the solution, at a concentration either close to or above its cmc, will give rise to the formation of larger aggregates between substrate and surfactant. Under these conditions, the enzyme is behaving as a lipase. However, when the substrate is partially water soluble, the enzyme will behave as an esterase, and the purpose of the surfactant, even at low concentrations, is as a solubilizer that dissolves and increases the concentrations of the solubilized form. 

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