Anti-oxidant and anti-fatigue properties of apple pomace polysaccharides by acid or alkali extraction

Summary The anti-fatigue effects and structure-activity relationship of apple polysaccharides (APPs), the active components in apple pomace, remain unknown. We examined the effects of different extraction methods on polysaccharide structures and anti-fatigue activities. Additionally, the structural and biochemical properties of APPs prepared under acidic (ACAPP) or alkaline (ALAPP) conditions, were characterised. ACAPP and ALAPP were acidic heteropolysaccharides primarily comprising arabinose, rhamnose, galactose, glucose, xylose and galacturonic acid. The molecular weights of ACAPP and ALAPP were 110 kDa and 89.6 kDa, respectively. ALAPP had more branched chains than ACAPP and showed stronger free radical-scavenging and anti-fatigue properties. The anti-fatigue properties of APPs correlated with their anti-oxidant activities and were exerted through eliminating free radicals and mediating an oxidative balance. The stronger anti-fatigue activity of ALAPP is probably related to its structural characteristics. Collectively, our study provides a fundamental basis for the development and use of APPs in medicine and functional foods.