Optimization of Air-Jet Impingement Drying for Reducing the Glycemic Index of Pre-Cooked Brown Rice

Abstract

Processing methods that modify starch structure can significantly influence the glycemic response of cereal-based foods, offering opportunities to develop healthier value-added products. This study investigates the optimization of air-jet impingement drying for reducing the glycemic index (GI) of pre-cooked brown rice. Experimental trials were conducted using varying drying temperatures, air velocities, and treatment durations to evaluate their effects on starch retrogradation, moisture removal, and final product quality. Key parameters assessed included in vitro starch digestibility, estimated glycemic index, resistant starch content, texture, color, and rehydration properties. Results indicated that optimized air-jet impingement drying enhanced the formation of resistant starch through controlled retrogradation, leading to a significant reduction in estimated GI compared to conventionally processed rice. Moderate drying temperatures and air velocities provided the most favorable balance between structural modification and product quality, while excessive drying intensity resulted in undesirable textural changes and reduced rehydration capacity. The treated rice maintained acceptable sensory characteristics and improved nutritional profile, indicating its suitability as a functional food product. The study highlights the potential of advanced drying techniques to improve the health benefits of staple foods while maintaining processing efficiency. While analytical methods were used to assess starch transformations and quality attributes, the primary emphasis remains on food processing outcomes and nutritional enhancement. These findings provide practical insights for the rice processing industry to develop low-GI products, add value to brown rice, and support healthier dietary options through optimized post-harvest processing technologies.