Possible Roles of Lipase, Lipoxygenase and Peroxidase in Buckwheat Flour and Noodles

The freshness of buckwheat flour and its unique flavor is important for the quality of buckwheat products. Several reports have shown that lipid degradation and oxidation in buckwheat flour are the main causes of measurable quality deterioration during storage. On the other hand, some flavor compounds are produced by lipid degradation and oxidation pathway. Therefore, understanding lipid degradation and oxidation pathways is important in the quality control of buckwheat flour and products. In some crops, lipoxygenase pathway is important for lipid degradation and oxidation. The pathway includes some enzymes such as lipase (triacylglycerol lipase EC 3.1.1.3) (LIP), lipoxygenase (EC 1.13.11.12) (LOX) and peroxidase (EC 1.11.1.7) (POX). This review, mainly based on our recent results, summarizes the main aspects of the possible relation between these enzymes, their substrates and flour deterioration/flavor generation as well as purification and characterization of related enzymes. LIP and POX activity in buckwheat flour apparently plays a role in the lipid degradation and quality deterioration whereas LOX does not have significant influences. LIP and POX activity in buckwheat flour also plays an important role for flavor generation of boiled buckwheat noodles whereas LOX does not have. This indicates that the mechanism of quality deterioration and flavor generation in buckwheat flour is different from that of rice and soybean. _____________________________________________________________________________________________________________