The Rheological Behavior of Polysaccharides from Mulberry Leaves (Morus alba L.)

Abstract

In this study, mulberry leaves polysaccharides (MLPs) namely HBSS (extracted with hot buffer soluble solids), CHSS (extracted with chelating agent soluble solids), DASS (extracted with diluted alkali soluble solids), and CASS (extracted with concentrated alkali soluble solids) were obtained using four different solvents and examined for their rheological potential. Different MLPs solutions harbored obvious disparity for viscosity and displayed a shear-thinning behavior at the tested range. Among all the fractions, DASS possessed the highest apparent viscosity at 0.5–2.5%. The apparent viscosity of MLPs solutions declined at acidic pH, alkaline pH, and higher temperature (90 °C). The HBSS fraction showed the best heat stability of all the fractions. All the fractions displayed noticeable differences in apparent viscosity in response to Na+ and Ca2+ at 20 °C. Both the modules such as G′ (storage modulus) and G” (loss modulus) showed augmentation with oscillation frequency. Initially, the value of G” was higher than G′ of MLPs at lower frequency and lower concentration, and the MLPS displayed stronger viscous nature; whereas, G′ was consistently higher at higher frequency and higher concentration, and the MLPS displayed stronger elastic characteristic. From our data, it was indicated that these MLPs can be used as promising natural materials (thickeners, gelling agents, binding agents, stabilizers) for their direct application to the food industry.