Water resistance, weight loss and enzymatic degradation of blends starch/polyvinyl alcohol containing SiO2 nanoparticle

Abstract

The aims of the study were to investigate the effect of polyvinyl alcohol (PVA) and nano-SiO2 within the thermoplastic starch (TPS) blends on the rate and extent of starch enzymatic hydrolysis using enzymes α-amylase and amyloglucosidase. The results of this study have revealed that blends with a nano-SiO2 content at 5wt.% exhibited a significantly reduced rate and extent of starch hydrolysis. The results suggest that this may have been attributed to interactions between starch and nano-SiO2 that further prevented enzymatic attack on the remaining starch phases within the blend. The total solids that remained after 6000min were 54wt.% (TPS:PVA); 61wt.% (TPS:PVA:1% nano-SiO2); 64wt.% (TPS:PVA:3% nano-SiO2); 68wt.% (TPS:PVA:5% nano-SiO2). The rate of glucose production from each nanocomposite substrates was most rapid for the substrate without nano-SiO2 and decreased with the addition of nano-SiO2, for TPS:PVA blend (226μg/mlh), 166μg/mlh (TPS:PVA:1% nano-SiO2), 122μg/mlh (TPS:PVA:3% nano-SiO2) and 94μg/mlh for (TPS:PVA:5% nano-SiO2). Enzymatic degradation behaviour of TPS:PVA:nano-SiO2 was based on the determinations of water resistance, weight loss and the reducing sugars. It has been established that the nanoparticles hinder degradation, while the susceptibility to enzymatic degradation varies in the order: TPS:PVA>TPS:PVA:nano-SiO2.