Abstract:The lipoxygenase (LOX) activities and the compositions of fatty acids and volatiles as well as their changes in sweet corn (var. Jingtian 5) and waxy corn (var. Jingtianzihuanuo 2), harvested before, at, and after the favorable harvest time, were investigated. The LOX activities of the samples were in a range of 2.63~4.28 U/gFW, and the fatty acids in the highest and lowest amounts were linoleic acid (32.40%~46.68%) and linolenic acid (0.97%~2.40%), respectively. The volatiles in the highest amount were hexanol and hexanal. Jingtian 5 samples harvested before and at the favorable harvest time showed the highest hexanol content, whereas Jingtian 5 harvested after the favorable harvest time and Jingtianzihuanuo 2 harvested in all three periods had the highest hexanal content. With prolonging of the harvest time, the LOX activities and crude fat content in both cultivars increased, but the contents of linoleic acid and hexanal exhibited a downward trend. Correlation analysis indicated that the substrates linoleic acid and linolenic acid in the LOX pathway had significant positive correlation with the hexanal contents but no significant correlation with LOX activity. These findings indicate that the volatiles from the LOX pathway in these fresh corns may depend on the level of linoleic acid or linolenic acid, rather than the level of LOX activity. In addition, the differences in the volatile contents between the two cultivars, especially of hexanol and hexanal, might reflect the differences in the LOX pathway between the two samples.
