DisplayTitle

Gums and hydrocolloids are commonly used as texturizing agents in food applications. Currently, research on starch nanotechnology is gaining momentum within the starch industry. Therefore, understanding the fundamental rheological behaviors of starch nanoparticles (SNPs) and their blends with commercial gums is of significant industrial importance. In this study we investigated how the SNP source, molecular structure, morphology and concentration influence the rheological properties of common food gums such as barley beta-glucan (BG), carrageenan (CAR) and xanthan (XAN). SNPs from waxy and high amylose maize starches were isolated by acid hydrolysis and binary blends consisting of 0.5% (w/v) gum and different concentrations of SNP were prepared. Static and dynamic rheological properties were determined using continuous shear tests, frequency and temperature sweep modes. All blends demonstrated pseudoplastic behavior at shear rates between 0.1-100 s-1. The effect of SNP concentration on viscosity and thixotropy varied with gum type, and was more pronounced in BG and CAR than XAN. The viscoelastic behavior was comparable for BG-SNP and CAR-SNP blends. At room temperature they behaved like a viscoelastic liquid which transitioned to an elastic gel with increasing temperatures. The addition of SNP resulted in a crossover (G? = G?) at lower temperatures in BG and CAR, while the effect on XAN was not significant. SNPs are insoluble in water, however during heating they undergo swelling and solubilization due to disruption of intermolecular bonds. The thermal stability of SNPs differs with source and positively correlates to the amylose content of the native starches. The SNP morphology, surface charge, thermal stability and intermolecular interactions with the gum play an important role in the network formation and thus the rheological properties of gum-SNP blends.