Effect of extraction pH on the yield and physicochemical properties of polysaccharides extracts from peanut sediment of aqueous extraction process

Abstract

Aqueous extraction process (AEP) was an environmentally friendly process method. Gradient pH was applied to obtain polysaccharides extracts (PSEs) from sediment phase of AEP of peanut oil. PSE4.0, PSE6.0, PSE8.0, PSE10.0 and PSE12.0 were named according to the extraction pH. The yields of PSE4.0 and PSE12.0 were 39.57% and 38.68% respectively, being higher than those of other PSEs. The protein and total sugar content of PSEs were closely associated with extracting pH. The particles size of PSEs increased, as the extraction pH increased. Meanwhile, solubility decreased and viscosity increased. The protein and polysaccharide conjugates may be a contributing factor to the enlargement of particle size. The interfacial tension (γ) of PSEs was highly correlated with protein content. Additionally, the extraction pH also had influence on emulsifying stability, oil-holding capacity and viscoelastic property. Results indicated that the physicochemical properties of PSEs were significantly affected by extraction pH, with protein component playing a vital role. Thus, in term of industry application, it was not necessary that the residual protein in PSEs was removed. Moreover, the method for avoiding removal of protein during polysaccharide extraction provided a new insight into the improvement of physicochemical properties.