Effect of Drying Methods and Parboiling Conditions on Amylose Content and Parboiled Rice Quality

Abstract

<b>Abstract.</b> In the present study, Japonica and Indica varieties were selected for parboiling and drying experiment. The effect of parboiling conditions (soaking temperature= 65 ˚C for 6 h, steaming pressures = 0.5-1.5 kg/cm²for 5 min respectively) and comparison of three different drying methods on rice quality were taken under evaluation. The parboiled rice was dried using laboratory drier at first stage temperature (FST) = 90˚C and second stage temperature (SST) = 50˚C during two-stage drying (TSD) with 120 min tempering, 50 ˚C was used in single stage drying (SSD) with an air velocity of 3.0 m/s respectively. Samples were dried at room temperature (25-30 ˚C, 60±5 % RH) for 2-3 days in case of shade drying (SD). The results revealed that Rong Youhua Zhan (RYZ) at P₃ and huaidao5 (H₅) at P₂ had given maximum head rice yield (HRY) for all drying methods than other parboiling conditions, but SD was found more effective in HRY enhancement. The severity of parboiling condition increased the hardness and observed maximum at P₃ (44.65 N) in RYZ and P₂ (37.08 N) in H₅ during SSD. The darkest color 20.79 and 22.63 found at P₃for both RYZ and H₅ varieties during SSD respectively. The maximum cooking time (31.50 and 30.00) min at P₃ and P₂ recorded for cooking of parboiled RYZ and H₅ rice varieties during SSD respectively. The maximum amylose content concentration was observed at P₃ during TSD method, and other drying methods have less influence on amylose concentration.