Rheological properties of corn, potato and tapioca starch hydrolysates

Corn, potato and tapioca starches were treated with bacterial alpha-amylase to obtain the respective hydrolysates (SH) of dextrose equivalent (DE) 2, 4, 6, 8 and 10 and those without enzyme treatment were treated as control. Amylose equivalent decreased and reducing sugar content in SH increased with progressive hydrolysis. HPLC profile of SH revealed the formation of malto-oligosaccharides of different degrees of polymerization (DP) depending upon the starch source. The hydrolysis of starch led to a decrease in the viscosity. The increase in viscosity caused due to higher concentrations was lower in hydrolysates compared to the respective control starch. The control starches and their hydrolysates exhibited pseudoplastic behaviour although some hydrolysates did not show good fit. The gels obtained from hydrolysates with DE 6 exhibited thermo-reversible properties. Firmness, brittleness, chewiness and gumminess of gels generally decreased with increasing degree of hydrolysis.