COMPARISON OF LIPOLYTIC ENZYME-ACTIVITY ASSAYS OF OATS

Assaying lipolytic enzyme activities is recommended in order to avoid storage deterioration of oat products. Three enzyme activity assays are presented: lipolytic esterase activities were measured in solution either with p-nitrophenyl or with 4-methylumbelliferyl palmitate photometrically or fluorometrically, respectively. True lipase activity was determined in dry oat meal with triolein as the substrate by measuring the released fatty acids colorimetrically as copper soaps. The assays were optimized for pH value, temperature and substrate concentration. Linear initial rates and linear relationships between activities and extract volumes were found. The standard deviations were less than 5%. In samples from a rolled oat flake production the results were in good agreement. Lipolytic esterases seemed to be more stable towards heat treatment than true lipase; they are more sensitive, easier and faster to measure than trioleinase.