Pyrodextrin from waxy and normal tapioca starches: Physicochemical properties

Waxy and normal tapioca starches, after mixing in water with hydrochloric acid at pH 3.0 and drying at 40 degrees C to approximately 10% moisture content, were dextrinized at 3 temperatures (130, 150, and 170 degrees C) and times (1, 2, and 4 h). Color, morphology, crystallinity, solubility, turbidity, gelatinization, and retrogradation were evaluated for the pyrodextrins and unmodified starches. Compared to normal tapioca starch, waxy tapioca starch had a greater degree of solubility change at 130 degrees C, higher clarity and lower retrogradation. The 170 degrees C/4 h pyrodextrin from waxy tapioca starch had a slightly yellow color; 100% aqueous solubility at 10.0% solids and room-temperature (RT); high clarity and stability of its 2.0% paste stored 10 days at 4 degrees C; granule morphology with birefringence in 100% glycerol; loss of granule morphology and birefringence in 50% glycerol at RT; Type A crystallinity at 5% and 15% moisture content (MC); no crystallinity at 50% MC; and no gelatinization or retrogradation enthalpy at 75% and 50% water content. These properties point to potential applications of waxy tapioca starch as a food carbohydrate with excellent solubility, high clarity, and low retrogradation.