Effect of steam curing on pasting and textural properties, starch structure and the quality of a local aromatic rice variety

Abstract

Steam curing is a process that is used to improve the quality of freshly harvested rice in the shortest time. The purpose of this study was to evaluate the effects of initial moisture content (IMC) and steaming time on the marketability of rice. The results indicate positive and more impressive effects of prolonged steaming (30 min) on head rice percentage (HRP), grain hardness, and elongation in the sample with IMC of 20% (w.b) compared with the sample with IMC of 17% (w.b). The results also showed a decreased peak (PV) and breakdown (BD) viscosity in both IMC. The highest decrease was observed in the samples that were steamed for 30 min. The results of scanning electron microscopy (SEM) revealed that the steaming of paddy for 30 min could not create a completely smooth surface in the grain. These observations indicate the inadequacy and uneven distribution of moisture for complete gelatinization even in grains with higher IMC. Practical applications Steam curing at atmospheric pressure is an applicable and effective method to reduce losses during milling process even for short time due to the structural changes. For high quality aromatic rice, short time steaming has positive effect on cooking quality with no significant changes in aroma. In order to produce good quality and marketable product by this method, it is necessary to process paddy with minimal or no chalky kernels.