Effect of pretreatments and drying methods in the quality attributes of fortified yam flour (Dioscorea rotundata)

Abstract

Yam is consumed in tropical regions because it is a good source of carbohydrates, proteins, fiber, and micronutrients, together with several alternatives of consumption such as cooked, boiled, roasted or fried. Its use for the development of flours and subsequent fortification has been considered as an alternative to address micronutrient deficiencies that have irreversible physical and cognitive consequences to child population. The aim of this study was to evaluate the effect of pretreatments (precooking and dipping) and drying methods (convection and vacuum) on the quality attributes of pretreated yam flour as well as the stability during storage after fortification with iron, calcium, and vitamin A. The results show that gelatinization temperature ranged from 79.2 to 86.0 °C and precooking led to changes on pasting properties where values of maximum viscosity and retrogradation diminished. The drying methods favored the protein concentration on the surface of the granules, reducing the solubility and hydration of the samples. With the fortification, the lightness decreased from 72.29 to 66.64 due to the addition of iron. The presence of molecular oxygen conditioned the oxidative degradation of vitamin A. Precooking caused greater colloidal stability and convection drying preserved on the nutritional quality of the flour.

Keywords:
Dioscorea rotundata; flour; micronutrients; viscosity; stability