Effect of Variety and Polishing on Cooked Red Rice Colour Change after Blending with Iron and Folic Acid Fortified Kernels

Abstract

Micronutrient malnutrition is a global issue and iron deficiency is a major public health concern, particularly, in young children and pregnant women in Sri Lanka. Rice fortification with micronutrients has been recognized as a key approach to alleviate micronutrient deficiency in rice eating populations. Sri Lankans consume both parboiled (55%) and raw rice (45%) in red (23%) and white (77%) forms. Therefore, this study was conducted to investigate the issue of iron and folic acid fortified kernel blending with red pericarp rice. The objective was to investigate the influence of the variety and degree of polishing on the intensity of blue colour spot development in cooked rice around kernels during cooking. Nine red rice varieties; Bw 361, Attakari, Bg 252, Ld 365, Ld 356, Bg 406, At 303, At 362 and Bw 364 were polished to 2 and 8 %. Rice blending was done at 1: 99 ratio (kernel: red rice) with kernels having 8 mg/100 g of ferric pyrophosphate and folic acid (13.5 mg/100 g). Fifty grams of blended and normal rice (control) in raw and parboiled forms were cooked under same conditions and blue color spot development was visually observed. Results revealed that no colour change in controls and blended parboiled red rice after cooking. However, Attakari and Bg 252 raw rice developed high and slightly greenish blue color spots, respectively under both polishing levels. The blue color intensity decreased with the increasing degree of polishing for both varieties. Therefore, it is assumed that the phenolic compounds (antioxidants) in the bran reduce Fe3+ to Fe2+ during cooking and the variety and polishing influences the intensity of colour change.