Total polyphenol extraction from red sorghum grain and effects on the morphological structure of starch granules

Abstract

The aim of this study was to propose a treatment to reduce the content of total polyphenols (TPP) and to obtain flour without significant morphological changes in the starch granules. The response surface methodology (RSM) was used to predict the influence of temperature and time on TPP extraction. Research work was conducted using the central composite design methodology. Results showed that the effect of temperature was more significant than that of time. A quadratic fit of data regarding temperature and linear data adjustment as to time was obtained. A scanning electron microscopy analysis of starch showed no morphological change in the granules at the temperature studied. Starch granules presented a size distribution ranging from 6 to 25 lm being 35% of granules <15 lm, and 65% of granules >15 lm in size, respectively.