Functional and micro-structural properties of starch and flour produced from one indigenous and three improved local rice (Oryza sativa) varieties

Abstract

Study on the functional and micro-structural quality of starch and flour obtained from four (4) varieties of rice was assessed. The quality aspect of the rice varieties was compared between local and improved variety (Faro 44, 52, 61 and Kwandala). The samples were processed to obtain flours and starches. The Proximate composition, micro-structure and functional attributes of the samples were analyzed. The percentage moisture contents in rice flours ranged from (8.39-8.68 %) while those of starches ranged from (8.68-9.98%). The percentage ash content of the flour samples analyzed ranged from (0.71-0.91%) while those of starches ranged from (0.49-0.64%). The percentage fat content of rice flour samples ranged from (1.55-2.15%) while those of starch ranged from (1.47-2.62%). The percentage protein content of rice flour ranged within (6.64-7.66%) while those of starches ranged between (6.99-7.88 %). The results of the CHO content of rice flour samples fell within (80.99-82.36%) while those of starches ranged from (80.50-81.51%). Starch yield content varied between (52.64-56.40%). The results of loose density and packed Bulk Density of rice flour ranged between (1.14-1.18g/mL) and (1.13-1.21g/mL), while loose bulk density and packed density of the rice starch ranged within (0.65-0.73g/ml) and (0.71-0.73g/mL). The results of Water Absorption Capacity of rice flour ranged within (1.58-1.86 g/g) while those of starch ranged between (1.90-1.99g/g). The results of Oil Absorption Capacity of rice flour ranged between (1.83-2.17g/g). While, those of starch ranged from (2.02-2.33g/g). The Gelling consistency of rice flour ranged between (16.32-35.54mm), meanwhile those of starch ranged from (17.05-60.35mm). Amylose content for rice flour ranged from (21.11-26.10 %) while those of starches ranged from (21.11-26.10%) and (21.35-25.14%). Amylopectin content of rice flours ranged from (20.09-23.67) while those of starches ranged from (19.94-23.70%). The granulated starch samples were polyhedral in shape with an average length - width of (4.96-6.56mm), while those of starch ranged from 5.55-5.77mm respectively. The rice starch to aid highest and lowest swelling power and solubility ranged between 24.43-33.02 °C and 11.50-18.23°C at 95°C, respectively.