EFFECT OF DIFFERENT SOURCES OF LUTEIN IN LAYER DIETS ON EGG QUALITY
The aim of this paper was to search the lipase coming from four plant sources, to see to what extent pH, temperature or/and substrate influence the activity of this enzyme, and which of these sources shows a higher enzyme activity. The lipase sources were represented by seeds (fruits) of: peanut, walnut, almond, and sesame, and as substrates were used refined oils of: sunflower, pumpkin, soy bean, corn, peanut, walnut, almond and sesame. The activity of lipase was determined at 20°C and 40°C, at three pH values (5.4, 7.4 and 8.2) for each temperature, and has consisted in titrating of fatty acids released from oils by lipase, in a certain time interval. The lipases coming from peanut, walnut, almond and sesame have registered, on the eight refined oils, the highest values of activity at pH 5.4 (at 40°C). Compared to the other three sources, the activity of walnut lipase was significantly higher on the oils of: sunflower, pumpkin, soy bean and walnut, the highest activity being recorded on walnut oil, at 40°C. Both the temperature, but especially pH and chemical composition of substrate (oil) have influenced the activity of lipases derived from the four plant sources.
Key words: lipase, oil, source, pH, temperature, substrate