Investigation on Functional, Thermo-Mechanical and Bread-Making Properties of Some White and Black Rice Flours

Abstract

The flour from white rice, Arborio (ARF) and Basmati (BRF) varieties, and the black rice Negro (NRF) variety, were investigated in this study in terms of proximate composition, solvent retention capacity (SRC), and thermo-mechanical properties of dough and bread quality. The flours fell into the classes with very low (NRF) and low amylose content (ARF and BRF); NRF flour had the highest contents of protein (11.16%), crude fiber (4.75%), ash (1.30%), and fats (3.42%). Correlations were obtained between CaCl2-SRC and fiber content, and between NaCl-SRC and lactic acid-SRC and protein content. The dough prepared from BRF had a lower value of the thermo-mechanical weakening, which suggests a higher resistance of the proteins to kneading. On the other hand, NRF exhibited a higher value of thermo-mechanical weakening, suggesting a lower protein resistance. Increasing the amount of water used to prepare the dough resulted in the decrease of the rate of starch retrogradation, while the breakdown decreased for BRF and remained constant for ARF and NRF. The specific volume and texture of the bread have been improved by using a larger amount of water in the preparation of the dough. The texture was negatively correlated (p < 0.05) with the specific volume of the bread. The best quality bread was obtained when the NRF was used.