Studies on oil quality in maize and Oriental genera of Maydeae

Very few systematic studies have been done on the Asiatic relatives of maize (MNL 57:96-104, 1983). Practically no work has been done on oil quality aspects. The quality of oil is important from the viewpoint of human nutrition as well as the stability of oil during storage. It has been shown that linoleic acid, an essential fatty acid, is hypocholesteremic and palmitic acid is hypercholesteremic, while oleic acid and stearic acids appear to have little effect on blood cholesterol level.

Both the cultivated and wild forms of Coix have traditionally been used by tribal people for human consumption and medicinal purposes. Considering these facts, oil content and fatty acid composition have been studied in maize and Oriental genera of Maydeae, namely, Coix lacryma-jobi L. (wild Coix), Coix lacryma-jobi var. 'ma yuen' Stapf (cultivated Coix), Trilobachne cookei (Stapf), and Chionachne koenigii (Thwaites).

Maize is found to have more oil content than the other genera of Oriental Maydeae studied. But oil content in cultivated Coix and wild Coix is considerably more than in Chionachne and Trilobachne.

Fatty acid composition of maize and its Asiatic relatives revealed that palmitic acid is higher in Trilobachne and lower in both cultivated and wild Coix than in maize. Stearic acid was considerably lower in all the Oriental genera of Maydeae than maize, and oleic acid was the lowest in normal maize. Cultivated Coix has more than two-fold and Trilobachne had 1.7 times the oleic acid content of maize. Maize had the highest linoleic acid of the genera of Maydeae. Wild Coix and Chionachne had about 0.8 fold the linoleic acid content of maize.

Table.

The oleic to linoleic acid ratio, which gives an idea of storage quality of oil, is higher in all the Oriental genera of Maydeae. Maize has the least oleic to linoleic acid ratio, showing its lower stability. Wild Coix, which has a considerably higher amount of oil as well as higher linoleic acid, can be explored for extracting a nutritionally better quality of oil.

N. D. Sharma and J. K. S. Sachan
 
 


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