Effect of lipoxygenase activity and red seed coat on rice bran deterioration

BACKGROUND: Many studies have suggested that the main reason for rice bran deterioration is the effect of lipase, but there have been fewer reports about the effect of lipoxygenase (LOX) activity and red seed coat on rice bran deterioration. In this study, several rice bran materials with white or red coat and different LOX isozyme activities and near isogenic lines about the colour of coat and LOX isozymes were subjected to accelerated aging experiments, during which their fatty acid values were monitored. RESULTS: Rice bran materials with different LOX isozyme activities and colour of coat showed different changes in fatty acid value during aging. Red coat with high LOX‐1,2 and low LOX‐3 activity caused the fatty acid value to increase at a lower rate than white coat with low LOX‐1,2 and high LOX‐3 activity, while the latter caused the fatty acid value to increase at a lower rate than white coat with low LOX‐1,2,3 activity. The results for the near isogenic line further confirmed the role of LOX isozyme activity and the colour of coat in rice bran deterioration. CONCLUSION: It can be inferred that high LOX isozyme activity is beneficial to delay rice bran deterioration; for example, high LOX‐1,2 activity is essential for red rice bran storage, while high LOX‐3 activity is essential for white rice bran storage. The results of this investigation may be helpful in further studies of the mechanism of rice bran deterioration. Copyright © 2009 Society of Chemical Industry