RAPID VISCO-ANALYZER (RVA) PASTING PROFILES OF WHEAT, CORN, WAXY CORN, TAPIOCA AND AMARANTH STARCHES (A-HYPOCHONDRIACUS AND A-CRUENTUS) IN THE PRESENCE OF KONJAC FLOUR, GELLAN, GUAR, XANTHAN AND LOCUST-BEAN GUMS

The Rapid Visco-Analyzer (RVA) 20 min test was used to study the effects of different levels of konjac flour, guar, gellan, xanthan and locust bean gums on starch cooking properties. Wheat, corn, waxy corn, tapioca and A. hypochondriacus and A. cruentus starches were affected to different degrees by different levels of the gums. Peak viscosity increased at the higher gum concentrations, especially with locust bean gum at the 0.4 g level. The increase in viscosity was more pronounced with wheat and com starches than with waxy corn and tapioca starches which consist mostly of highly branched amylopectin thus preventing close physical association between molecules. Amaranth starches showed much lower viscosity with all the gums than the other starches. Peak viscosity, time to reach the peak and maximum setback viscosity were affected by the gums. The increase in viscosity of starch/hydrocolloid systems is due to the release of amylose and low molecular weight amylopectin which promotes the formation of polymer complexes and significantly adds to the viscosity of the system.