Location: Commodity Utilization ResearchTitle: Antioxidant activities of the water-soluble fractions of glandless and glanded cottonseed protein
Submitted to: Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/23/2020
Publication Date: 5/6/2020
Citation: He, Z., Zhang, D., Olanya, O.M. 2020. Antioxidant activities of the water-soluble fractions of glandless and glanded cottonseed protein. Food Chemistry. 325:126907. https://doi.org/10.1016/j.foodchem.2020.126907.
Interpretive Summary: There are numerous studies in antioxidant peptides from plant proteins. However, most of the studies tested the hydrolyzed peptides. Thus, in this work, we directly evaluated four types of antioxidant activity of the water soluble fractions of cottonseed protein without enzymatic hydrolysis or other treatments. We found considerably high activities of three antioxidant functions. While the water soluble protein fractions may not be used as food additives, these data could be helpful in understanding the antioxidation mechanism in plant seed food products themselves, such as plant seed-based butters, thus better developing and preserving these food products for long shelf lifetimes. It would be of great interest in further research on the protein fraction or peptide fragments in food products and processes (such as roasting) involved in the protective effects of food spoilage.
Technical Abstract: The studies of bioactive components of cottonseed proteins for food additives are very limited due to the presence of toxic gossypol in the common glanded (Gd) cottonseed. Recent progress in genetically-improved (glandless, Gl) and genetically-modified (GMO) cotton plants revived the research of cottonseed protein as valuable animal feed and human food for consumption. In this research, we tested four types of antioxidant activity of two water soluble protein samples (Gl-L and Gd-L) isolated in a lab scale from glandless and glanded cottonseed meal, respectively, and one soluble protein samples (Gd-P) in a pilot scale from glanded cottonseed meal. SDS-gel electrophoresis showed that the distribution patterns of the peptide fragments in Gl-L and Gd-L were similar, but more fragments and higher molecular mass bands were observed in the Gd-P gel image. Both DPPH (1,1-diphenyl-2-picrylhydrazyl) radical-scavenging activity and hydroxyl radical-scavenging activity were observed in all three samples. There were non-linear increases in the scavenging activities with increase in protein concentration. While Gd-P showed the highest activity (up to 71%), Gl-L and Gd-L exhibited comparable activities in most cases. Under the test conditions, the superoxide radical-scavenging activity was very low (3.4-8.9%) in Gl-L and Gd-L, and Gd-P seemed to speed up the relevant oxidation. All three samples showed effective and comparable inhibition of linoleic acid oxidation. However, in contrast to the DPPH and hydroxyl radial-scavenging behaviors, Gd-P showed lower capability of inhibition of linoleic acid autoxidation than other two lab-prepared products. While the water soluble protein fraction may not be used as the food additives, these data could be helpful in understanding the antioxidant mechanism in plant seed food products themselves, thus better developing and preserving these food products since the studies of the antioxidant potentials of protein/peptides in plant seed food products and processes are rare.