Optimization of milling degree for maximizing nutrient retention and yield in milled rice: A study on six common Bangladeshi rice cultivars

Abstract

Awareness of the nutritional value and health benefits of milled rice is crucial for its role as a staple food. This study explores the impact of different degrees of milling (DOM)—5%, 7%, and 9%—on head rice yield, proximate composition (protein, fat, fiber, and carbohydrates), and mineral content (sodium, magnesium, potassium, iron, calcium) in six rice cultivars: BRRI Dhan 28, 29, 36, 90, 51, and Bogura Katari. Our findings reveal that head rice yield decreases significantly, by 3% to 8%, when DOM is increased from 5% to 7% or 9%. Increasing the DOM also led to pronounced losses of protein (15% to 25%), fat (40% to 70%), and fiber (15% to 40%), while carbohydrate content increased. Additionally, substantial reductions in mineral content were observed at 9% DOM. Notably, consuming rice milled at 5% DOM can meet significant portions of daily nutrient requirements: 50% of protein, 10% of fiber, 20% of fat, 10% of sodium, 80% of magnesium, 35% of potassium, 100% of iron, and 30% of calcium, based on a per capita consumption of 400 g per day. This research highlights the importance of optimizing DOM between 5% and 7% to enhance head rice yield and maximize nutrient retention.