Effects of extraction methods on the rheological properties of polysaccharides from onion (Allium cepa L.).

In this work we described the rheological properties of polysaccharides (HBSS, CHSS, DASS, CASS) sequentially extracted from onion (Allium cepa L.). Four onion polysaccharides (ACLPs) solutions resulted into significant differences on their rheological properties. ACLPs solutions showed non-Newtonian shear-thinning behavior over the range of 0.5-2.5%. At concentration of 1%, the apparent viscosity of CHSS was observed to be the highest. The apparent viscosity of ACLPs solutions decreased with the acidic pH (4.0) or alkaline pH (10.0) which was further declined at higher temperature (90 °C). After the addition of various salts, ACLPs had apparent differences on apparent viscosity. The G' (storage modulus) and G″ (loss modulus) of ACLP solutions were increased with increasing oscillation frequency. Moreover, the crossover value of oscillation frequency gradually decreased with increasing concentration of ACLPs. Our results exhibited that among the ACLPs, CHSS can be used as supplements in the food industry as thickening agent, gelling agent and stabilizer.