S. Miller, R. Fulcher, I. Altosaar
Jul 1, 1989
Citations
0
Influential Citations
7
Citations
Journal
Journal of Cereal Science
Abstract
The fluorogenic substrate 4-methylumbelliferyl heptanoate (MUH) has been reported to be suitable for measurement of lipase activity in cereal grains. In the present study, MUH hydrolysis was compared with a conventional lipase assay which measured the release of free fatty acids (FFA) from endogenous substrates in oats. Correlations of r = 0·83 and r = 0·94 were demonstrated between the two assays during heat treatment to inactivate hydrolases. A correlation of r = 0·71 was observed between the two assays in a survey of 21 domestic cultivars of mature, ungerminated oats. However, the range of activities for the two assays was different. A fivefold variation in lipase activity, and a twofold variation in MUH hydrolysis were noted. Incorporation of the esterase inhibitor di-isopropylfluorophosphate (DFP) into the reaction mixtures indicated that the MUH assay was measuring primarily esterase activity. It was concluded that the MUH assay is not a valid measure of lipase activity in oats.