GRAIN QUALITY EVALUATION OF IMPROVED BLACK RICE (Oryza sativa L.) GENOTYPES AND ASSESSMENT OF THEIR SUITABILITY FOR PREPARATION OF SOUTH INDIAN FOODS

VIJAYA SHAMA, PULLAGURA

GRAIN QUALITY EVALUATION OF IMPROVED BLACK RICE (Oryza sativa L.) GENOTYPES AND ASSESSMENT OF THEIR SUITABILITY FOR PREPARATION OF SOUTH INDIAN FOODS

Date

2023-07-12

Authors

VIJAYA SHAMA, PULLAGURA

Publisher

ACHARYA NG RANGA AGRICULTURAL UNIVERSITY

Abstract

Black rice is a speciality rice variety with black bran covering the endosperm. Despite being nutrient-dense, it is not widely consumed by people because of a lack of awareness among public and no preference for its colour. In the present study, six improved black rice varieties including Burma black (control), BPT 2841, BPT 2848, BPT 3136, BPT 3137 and BPT 3145 grown in Kharif- 2021 were obtained from the Agricultural Research Station (ARS), Bapatla. These genotypes were investigated for physicochemical, cooking quality, nutraceutical properties, biochemical profile, proximate composition, micronutrients (iron and zinc), glycemic index and correlation among these parameters to identify black rice variety possessing desirable quality and nutritional traits suitable for consumption. Except for the proximate composition of rice genotypes, ANOVA revealed significant differences among all the attributes studied. All the black rice genotypes along with control had desired parameters such as high hulling, milling and high head rice recovery percentage; medium and long kernel length, medium and long slender grain type; long kernel length after cooking; medium kernel elongation ratio; high volume expansion ratio and good water absorption index. In terms of chemical quality, all the rice varieties differed from control by having intermediate amylose content (20-25) and intermediate alkali spreading value (4-5), which give a soft and flaky texture to the cooked rice, which are the important traits to determine the rice quality. The proximate composition does not differ significantly among the rice genotypes. The mean values of moisture, protein, fat, ash, fiber, carbohydrates and energy per 100g of the black rice were noted as 10.78g, 10.08g, 1.95g, 0.91g, 1.16g, 75.14g and 358 kcal. Burma black had the highest total anthocyanin content (30.57 xviii mgC3G/100g), followed by BPT 2841 (26.76 mgC3G/100g). The BPT 2841 recorded the highest total phenol content and total antioxidant activity (238.17 mgGAE/100g and 99.52 mgAAE/100g), followed by control (218.89 mgGAE/100g and 97.52 mgGAE/100g). The phytates and oxalates ranged from 351.38 to 410.36 mg/100g and 2.24 to 5.38 mg/100g; the highest values were recorded in Burma black. The Burma black had the highest values for moisture, protein, fat, ash and fiber, followed by BPT 2841, BPT 2848, BPT 3137, BPT 3136 and BPT 3145. Burma black had medium iron and zinc (1.55 mg/100g and 2.05 mg/100g). The black rice genotypes such as BPT 2841, BPT 2848 and BPT 3136 were categorized as medium iron rice varieties. BPT 2848 was categorized under low glycemic index variety; the remaining rice genotypes and control were classified under medium glycemic index varieties (56-69). Correlation studies revealed a significant positive association among the parameters such as hulling with head rice recovery; thousand grain weight with kernel length and kernel breadth; kernel length after cooking with kernel breadth after cooking, alkali spreading value with gel consistency, water uptake and Iron; kernel elongation ratio with L/B ratio; total phenol content with total anthocyanin content, total antioxidant activity and protein; carbohydrate with volume expansion ratio, bulk density, water solubility index and energy; iron with zinc and ash; fat with energy. Glycemic index showed a non-significant negative correlation with amylose, carbohydrates and energy. Selection of these significantly correlated characters will improve the overall quality of the genotypes. The suitability of black rice for product development was evaluated for traditional foods like payasam and vadiyalu; baked products like cake; extruded products like vermicelli using the nine point hedonic rating scale. The highest overall acceptability was scored in payasam and cake by BPT 2848 (8.80 and 8.92), in vadiyalu by BPT 3137 (8.72) and in vermicelli by BPT 3136 (8.76). The payasam and cakes of all black rice genotypes were displayed similar values compared to the control. However the vadiyalu and vermicelli made from Burma black (control) scored the lowest in terms of sensory score since the cooked foods became mushy and sticky due to its low amylose content. So, Burma black is not suitable for products like vadiyalu and vermicelli. The highly accepted samples of vermicelli and vadiyalu were assessed with control and white rice products for shelf-life study (30 days), which revealed that all samples were suitable for consumption, since the sensory and nutritional parameters remain unchanged. On comparison with control, the black rice genotypes had varied traits such as intermediate amylose and alkali spreading values, whereas all the biochemical quality profile, nutritional parameters and glycemic index showed similar trends. So, the black rice genotypes would be preferred over the control for desired eating quality and value added products. In addition to the desired quality characteristics, it had a low and medium glycemic index, antioxidant properties, a high protein content, and a high and medium iron and zinc content. The daily consumption of black rice could reduce several non communicable diseases like diabetes and cancer due to the presence of phytochemicals. Hence, it may be possible to achieve nationwide sustainable nutritional security by including black rice in people's regular meals.