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Komal chawal, meaning soft rice, produced by brown rice parboiling of a low amylose rice variety chokuwa, was studied for its physical, physico-chemical, morphological and structural characteristics. The product was produced by soaking the brown rice at 60 °C for 90 min, followed by steaming and air drying to 12.0% (wb). The two steaming conditions used were: (1) opensteaming at atmospheric pressure for 20 min and (2) pressure-steaming at 1 atm (gauge) for 10 min. The three different drying temperatures used were 40, 50 and 60 °C. When soaked in water at 60 °C for 20 min the product attained a hardness value of cooked rice. The extent of changes in the kernel and flour properties as compared to the raw form were affected by the severity of the steaming condition and drying air temperature. The pressure steamed samples exhibited virtually persistent growth in paste viscosity in the profiles obtained from the rapid viscosity analyzer. X-ray diffraction analysis of flours revealed a loss of A-type pattern and formation of feeble peaks of A ? Vtype mixed patterns in steam-treated samples. Scanning electron photomicrographs showed the loss of the polygonal shape by starch granules during processing. The values of rehydration ratio, equilibrium moisture content for rehydration, sediment volume, extent of color change as denoted by total color difference, and the percent head rice yield were higher in pressure steamed komal chawal samples.

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Hot air drying kinetics of paddy grains during instant controlled pressure drop (ICPD) assisted parboiling process and its impact on the quality and micro-structural properties of milled rice were investigated. Among five mathematical models, Midilli model showed best fitted outcomes for prediction of adequate drying behavior. For the mapping of moisture ratio (MR) as a function of treatment pressure (TP), decompressed state duration (DD) and drying time (DT), artificial neural network (ANN) and adaptive neuro-fuzzy interface system (ANFIS) were applied. ANFIS model (5-5-5) with Gaussian membership function demonstrated best performance when contrasted with 3-5-1 ANN architecture. Effective diffusivity of the drying process varied from 2.8 × 10−09 to 7.0 × 10−09 m2/s with the increase of TP and DD. In comparison of quality parameters with the variation of TP and DD, positive impacts on head rice yield (HRY), redness (a*) and yellowness (b*) values and negative consequences on cooking time (CT) and brightness (L*) value were observed. The outcomes additionally uncovered that parboiled rice obtained at 0.6 MPa TP, indicated best quality in terms of improved process performance, HRY, CT, color and micro-structural properties.

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