Some Properties of Oil and Toxic Substances in Thai Cottonseed Oil

Abstract

Cottonseed oil content, fatty acid composition, physico-chemical properties and gossypol content were determined for six cotton varieties obtained from 11 locations in Thailand. Testing procedures were those of the American Oil Chemists's Society (methods Aa 3-38 and 4-38).
Oil content varied between 18.8 and 21.9% and depended on variety, location and environmental factors. Highest oil content (21.9%) was recorded in the variety L-142-9m-358-11. properties of the oil included a dark brown colouration; specific gravity and efractive index of 0.9191 and 1.480 respectively, at 25 C; free fatty acid level of 1.50; an iodine number of 104.32 and saponification value of 197.84. Cottonseed oil was found to have a high level of unsaturated fatty acids (70%) of which linoleic acid was the major component (50%). Free gossypol content of unsaturated fatty acids (70%) of which linoleic acid was the major component (50%). free gossypol content averaged 0.70% but ranged from 0.33% to 1.09%, the variety BD 1016-13 having the lowest level and RD 1017-7 the highest.
In an independent study using cottonseed oil extracted commercially from a number of varieties, an initial gossypol content of 0.72% was able to be reduced to below th 0.03% safety level as result of heat treatment under vacuum during the refinery process which consisted of neutralization, bleaching and deodorization.