Rice grain and starch properties: Effects of nitrogen fertilizer application

The effects of nitrogen application at different levels (0, 20, 40 and 60 kg/ha) on the characteristics of milled rice and starch from three paddy cultivars were studied. Milled rice was evaluated for physicochemical, cooking and textural properties while starch was evaluated for granule size distribution, structure, thermal and rheological properties. Milled rice from paddy grown with nitrogen application showed lower gruel solids loss and water up take ratio during cooking and higher cooked grain hardness, cohesiveness, and chewiness. Starch from rice grown with application of nitrogen showed lower amylose content and higher pasting temperature, gelatinization transition-temperatures and enthalpy of gelatinization. Principal component analysis indicated that cooked grain hardness and cooking time were closely associated with amylose content and protein content, respectively.