Characterization of the solubility of proteins from glandless cottonseeds

Authors: Cao, Heping; Sethumadhavan, Kandan; Pelitire, Scott

Submitted to: Meeting Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 3/1/2023
Publication Date: 5/31/2023
Citation: Cao H., Sethumadhavan, K., and Pelitire. S.M., 2023. Characterization of protein solubility from glandless cottonseed. In: Proceedings of Beltwide Cotton Conferences, January 10-12, 2023, New Orleans, Louisiana. p. 47-52.

Interpretive Summary: Cottonseed is classified as either glanded or glandless depending on the presence or absence of pigment glands which contain toxic gossypol. Cottonseed is composed of approximately 10% linters, 40% hulls and 50% kernels. The kernels contain about 35% oil and 40% protein. The presence of gossypol in glanded seed limits its use primarily to feed ruminants. Glandless seed does not contain gossypol glands and has only trace levels of gossypol which may be useful as a food ingredient or as a feed for non-ruminant animals. The objective of this study was to develop acidic juices and drinks fortified with glandless cottonseed protein. Protein isolate was purified from glandless cottonseed by NaOH solubilization and HCl neutralization. Protein isolate was added to 4 types of beverages: 1) apple juice (fruit juice), 2) grape juice (formulated fruit drink), 3) orange juice (pulpy fruit juice), and 4) Pepsi soda (soda product). Soluble protein was determined after incubation and mixing overnight at 37°C and room temperature. The results showed that only about 10% of the protein was recovered in the soluble phase, indicating low solubility of cottonseed protein in the beverages. Therefore, cottonseed protein solubility was investigated further under different temperatures, buffer pH, and detergent. The proteins were evaluated with several protein assays as well as gel electrophoresis. The results provided useful information for increasing the solubility of glandless cottonseed protein for developing acidic juices and drinks.

Technical Abstract: Cottonseed is classified as either glanded or glandless depending on the presence or absence of pigment glands which contain toxic gossypol. Cottonseed is composed of approximately 10% linters, 40% hulls and 50% kernels. The kernels contain about 35% oil and 40% protein. The presence of gossypol in glanded seed limits its use primarily to feed ruminants. Glandless seed does not contain gossypol glands and has only trace levels of gossypol which may be useful as a food ingredient or as a feed for non-ruminant animals. The objective of this study was to develop acidic juices and drinks fortified with glandless cottonseed protein. Protein isolate was purified from glandless cottonseed by NaOH solubilization and HCl neutralization. Protein isolate was added to 4 types of beverages: 1) apple juice (fruit juice), 2) grape juice (formulated fruit drink), 3) orange juice (pulpy fruit juice), and 4) Pepsi soda (soda product). Soluble protein was determined after incubation and mixing overnight at 37°C and room temperature. The results showed that only about 10% of the protein was recovered in the soluble phase, indicating low solubility of cottonseed protein in the beverages. Therefore, cottonseed protein solubility was investigated further under different temperatures, buffer pH, and detergent. The proteins were evaluated with several protein assays as well as gel electrophoresis. The results provided useful information for increasing the solubility of glandless cottonseed protein for developing acidic juices and drinks.