[Physicochemical and functional evaluation of pregelatinized and microwaved cassava (Manihot esculenta Cranz) starches].

Abstract

The aim of this study was to evaluate the effect of two physical modification methods, drum-drying pregelatinization and microwave heating (at 25% moisture), on some characteristics of cassava starch. The water absorption, solubility and swelling power of pregelatinized starch increased considerably between 65 and 90 degrees C (56 to 86 g water/g starch, 89 to 99% and 63 to 87, respectively), while in microwaved starch these indices dropped, in general terms, from 75 degrees C (5 to 37 g water/g starch, 1 to 37% and 12 to 38 respectively) compared to native starch values (10 to 40 g water/g starch, 2 to 40% and 13 to 41, respectively). All samples showed a marked breakdown during heating, while the pregelatinized starch has the lowest setback values. The morphology of microwaved starch was slightly affected, while in the pregelatinized starch all vestige of granular integrity disappeared. Of the two methods used, pregelatinization caused the most remarkable changes of cassava starch characteristics.