Cereal Chem 69:379-381   |  VIEW ARTICLE

Lipase Activity in Oats---Distribution, pH Dependence, and Heat Inactivation.

B. Ekstrand, I. Gangby, and G. Akesson. Copyright 1992 by the American Association of Cereal Chemists, Inc. 

The lipase activity in oat kernels at different pHs, at different stages of development, and in different parts of the oat kernel was studied. The measurement of lipase activity was performed by means of fluorescence spectrophotometry. Lipase activity was higher in the aleurone layer and embryonic tissues than it was in the starchy endosperm. This also was shown in flour samples from fractionated milling. In accordance with the lipase distribution found in the oat kernel, the lipase activity was highest in flour fractions close to the superficial bran layer and was lowest in the internal endosperm fractions. The development of lipase activity during germination of the seeds caused an increase in the activity at neutral and alkaline pH, whereas the activity at acid pH remained relatively constant. This indicated that the lipase activity at alkaline pH was more related to the metabolic processes initiated by the growth of the embryo. Three different Swedish cultivars were analyzed. Lipase activity varied only slighly and was not correlated to fat content. Lipase inactivation was studied in model laboratory studies. These showed the importance of good heat transport into the sample, not only high temperature, in inactivating the enzyme.