THE SUNFLOWER SEEDS LIPASE ACTIVITY ON VARIOUS SUBSTRATA UNDER THE INFLUENCE OF SOME OUTER AND INNER FACTORS

Abstract

In this work the sunflower seeds lipase activity on its own substratum (sunflower oil), as well as on other substrata, of 7 plant species (pumpkin, soy bean, sesame, almond, maize, walnut and peanut), at various temperatures and pH values, has been analyzed. The experiment materials consist of dried sunflower seeds degreased (with petroleum ether), used as enzyme (lipase) source, and refined oils from 7 plant seeds above mentioned – as substratum for enzyme. The lipase activity was determined at 20ºC and 40ºC as well as at 3 pH values (5.5; 7.4 and 9.5). The method principle consists in titrating fatty acids (released from oils by enzyme, in a certain time interval) with a solution of KOH 0.01n. The determination of the lipase activity from sunflower seeds, at 20°C, 40°C and various pH, has shown distinct values of the enzyme activity depending on substratum nature, temperature and pH values. The enzyme activity on various substrata has registered: - at 20°C the highest values in oils of: soy and walnut (pH 5.5), walnut and peanut (pH 7.4), sunflower and walnut (pH 9.5); - at 40°C the highest values in oils of: peanut, soy and sunflower (pH 5.5), walnut and maize (pH 7.4), maize and walnut (pH 9.5). The comparative analysis of the sunflower seeds lipase activity on various substrata has shown, both at 20°C and at 40ºC, the highest values at pH 5.5, and the lowest ones at pH 9.5.