Two-step process for gossypol reduction and protein enhancement in cottonseed kernel powder

Cottonseed is the major by-product of cotton and it contains about 33% protein which shows its potential to be utilized for food applications. However, the presence of gossypol restricts its use for edible purpose. The previous attempts made for gossypol reduction in cottonseed meal resulted in poor extraction efficiency and loss in protein quality. The present study aimed at efficient removal of gossypol from the cottonseed kernel powder to produce the high-protein flour with an excellent amino acid profile. The process was divided into two stages; in the first part, gossypol was extracted from the kernel powder at optimized conditions (acetone-to-water ratio 90:10, sample-to-solution ratio (1:10), 30-min shaken time, and number of extractions 4). Further, the oil was removed from the acetone-treated sample that yielded 15.7% oil. In the second-stage processing, the de-oiled sample was treated at optimized conditions (ethanol-to-water ratio 50:50, citric acid 0.2 M, sample-to-solvent ratio 1:15, and incubation time 30 min) in a water bath at 100 degree celsius temperature. The cottonseed flour produced in the present study had 64% protein, 23% carbohydrates, 0.24% total gossypol, and all essential amino acids except tryptophan.