Effect of Storage Duration and Processing Parameters on Some Cooking Properties of Ofada Rice

Abstract

Effects of storage duration, soaking time and parboiling temperature on cooking properties (cooking time, water uptake ratio, solid loss, cooked kernel length, and amylose) of Ofada rice was determined and optimised using response surface methodology. Storage duration, soaking time and parboiling temperature were 1, 5, and 9 months; 1, 3, and 5 days; and 80, 100, and 120°C. Data were analysed by ANOVA and regression analysis. The cooking time ranged between 14-38 min, water uptake ratio (WUR) 2.51-4.61, solid loss 1.47-4.78%, cooked kernel length 6.32-11.90 and amylose 17.34-26.28%. There exist significant differences in the cooking properties. The coefficient R2 ranged between 0.97-0.75 which is a positive indicator of the model fitness. Storage duration and parboiling temperature influenced cooking except in solid loss and cooked kernel length respectively. Effect of soaking time was found prominent in WUR and solid loss. Optimum treatment for quality cooking properties are storage of paddy for 5 months, soaking for 18h and parboiling at 80°C to yield 20 min cooking time, 4.22 water uptake ratio, 4.11% solid loss, 10.58 mm cooked kernel length and 25.08% amylose. The validated experiment yielded 21.41 min, 3.99, 2.73%, 8.20 mm and 26.39% for cooking time, water uptake ratio, solid loss, cooked kernel length and amylose respectively.

Keywords

• Ofada
• cooking properties
• response surface methodology
• optimisation
• modelling