Study of Separation of Cottonseed Protein and Gossypol From Cottonseed

Abstract

Cottonseed protein has a vast potential for itself to be utilized as protein rich diet for human and animal rations but it is ironically underutilized due to the presence of a polyphenolic toxic pigment gossypol present in the cottonseed. The total worldly produce of cottonseed in 2018-19 was around 43.45 million metric tons and the available protein from this cottonseed was estimated to be around 11 million metric tons. The obtained cottonseed protein can effectively provide the protein supply for around half a billion people around the world. Cottonseed meal contains about 30-44% good quality protein which can be utilized for animal and aquaculture feeds. However due to the presence of this toxin gossypol in cottonseed, the use of cottonseed meal as rich protein source diet is limited in monogastric animals and not suitable for human use. Gossypol acts as a toxic material in cottonseed meal as it binds with the lysine of the protein during processing and gets converted from free form (toxic) to bound gossypol. The aim of the present research work was to extract gossypol from cottonseed using solvent extraction technique utilizing different environment friendly solvents like methanol, ethanol, propanol, butanol and their combinations (mixed solvents) in acidic medium to minimize the binding of gossypol with protein. The acidic conditions were produced using mild acids like oxalic acid, citric acid and phosphoric acid. The extraction in acidic medium favored the hydrolysis of bound gossypol and the binary solvents like 2-propanol-water and ternary solvents like butanol-ethanol-water and butanol-propanol-water are able to dissolve gossypol better under such conditions, which resulted in higher extraction of gossypol. It was found from the experimental results that gossypol which is non-polar in nature, was comparatively more soluble in less polar binary solvents like 2-propanol water (95:5 v/v) and less soluble in more polar binary solvents like methanol-water (95:5 v/v) and ethanol-water (95:5 v/v). The......