Multi-Dimensional Quality Attributes of Cooked Rice as Influenced by Nitrogen Supply and Milling Intensity

Nitrogen fertilization and milling degree are important determinants of the eating quality of rice, yet their combined effects on the multi-dimensional quality of cooked rice remain insufficiently understood. In this study, rice from the japonica cultivar Yanjing 939 was produced under five nitrogen application rates (0, 150, 210, 270, and 330 kg/hm²) and processed to three milling degrees (0%, 5%, and 10%). Nitrogen application increased grain protein content and affected the pasting properties, texture, cooking behavior, sensory quality, and volatile characteristics of cooked rice. Moderate nitrogen application generally increased hardness, palatability, and overall sensory performance, whereas excessive nitrogen was associated with lower water absorption, swelling, and several sensory scores. Milling removed outer grain layers rich in protein, lipids, and crude fiber, thereby increasing water absorption and swelling and improving sensory quality, while reducing the number and abundance of volatile compounds. Significant interactions between nitrogen application and milling degree were observed for protein content and some pasting, textural, and sensory characteristics. Overall, moderate nitrogen application (210-270 kg/hm²) was generally favorable for Yanjing 939 in this study. DOM5 provided a more balanced combination of nutrient retention, sensory quality, and volatile composition, whereas DOM10 produced the highest overall sensory score at 270 kg/hm² but was accompanied by a broader reduction in volatile compounds.