Effect of germination on composition profiling and antioxidant activity of the polysaccharide-protein conjugate in black soybean [Glycinemax (L.) Merr.]

• Published in: International journal of biological macromolecules Vol. 113; pp. 601 - 606
• Main Authors: Lee, Ai-Lien, Yu, Yi-Ping, Hsieh, Jung-Feng, Kuo, Meng-I, Ma, Yung-Shun, Lu, Chun-Ping
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01-07-2018
• Subjects: Antioxidant activity; Antioxidants - chemistry; Antioxidants - metabolism; Black soybean; Germination; Glycine max - growth & development; Glycine max - metabolism; Monosaccharides - analysis; Plant Proteins - chemistry; Plant Proteins - metabolism; Polysaccharide; Polysaccharides - chemistry; Polysaccharides - metabolism; Sprout; Black soybean; Sprout; Polysaccharide; Germination; Antioxidant activity
• ISSN: 0141-8130; 1879-0003
• DOI: 10.1016/j.ijbiomac.2018.02.145

Black soybeans are commonly consumed as health foods and used in traditional Chinese medicine, but they are rarely cultivated as edible sprouts. During germination, the composition of seeds undergoes distinct changes that cause variations in bioactivities. In this study, the water-soluble black soybean polysaccharide (BSPS) was isolated from sprouts harvested at two-day intervals during the first week of seedling growth. The chromatographic profiles of the BSPS in ungerminated seeds showed fraction 1 (F1, about 64kDa) and fraction 2 (F2, <1kDa) that degraded during germination. The polysaccharide in F1 fraction of ungerminated seeds was covalently associated with the protein and mainly contained arabinose, galactose, glucose, and galacturonic acid at various levels during germination. The 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2′-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid) (ABTS) scavenging activities and the reducing power of F1 were highest on the seventh day of germination. The phenolic and flavonoid content significantly increased after the fifth day of germination, suggesting that these ingredients also contributed to the antioxidant activities. During long-term germination, the polysaccharide-protein conjugate in the F1 fraction with enhanced antioxidant activities is regarded as a potential natural antioxidant for the development of functional foods.
•The acidic polysaccharides (BSPS) were isolated from black soybean seeds and their sprouts.•The high molecular weight fraction, F1 (64 kDa), was a polysaccharide-protein conjugate and degraded during germination.•The best antioxidant activities of F1 were found in germinated sprouts on day 7.•The phenolic, protein and polysaccharide were all important contributors to overall antioxidant activity.