Antioxidant activity and rheological properties of the polysaccharides isolated from Ribes stenocarpum maxim with different extraction methods

The purpose of the present study is to illustrate the effects of extraction methods on the antioxidant activity and rheological properties of polysaccharides isolated from Ribes stenocarpum Maxim (RPs). RPs were extracted by ultrasonic-assisted extraction (RPs-1), alkaline extraction (RPs-2), acid extraction (RPs-3), microwave-assisted extraction (RPs-4), and three-phase separation (RPs-5). The results showed that RPs-1, RPs-2, RPs-3, RPs-4, and RPs-5 are acidic heteropolysaccharides with glucose, arabinose, and galacturonic acid as the main chain units and absence of triple-helix structure. Of them, RPs-3 possess the highest uronic acid content, best thermal stability, and strongest DPPH, ABTS, and hydroxyl radical scavenging abilities. Rheological properties showed that the above-mentioned polysaccharides are non-Newtonian fluids and own the similar shear thinning properties. RPs-3 represent the highest apparent viscosity and better stability in the over-acid or over-alkali environment. The above results indicated that the acid extraction could serve as the most favorable extraction method for RPs. Novelty impact statement A novel polysaccharide was isolated from Ribes stenocarpum Maxim by acid extraction, showing a stronger antioxidant activity and excellent rheological properties, which has a good application prospect in food processing.