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

Published by the American Society of Agricultural and Biological Engineers, St. Joseph, Michigan

Citation:  2022 ASABE Annual International Meeting  2200217.(doi:10.13031/aim.202200217)
Authors:   Khurram Yousaf, Kunjie Chen, Zhenwei Yu
Keywords:   Amylose, drying temperature, rice, parboiling, soaking, steaming.


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/cm2 for 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 P3 for 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.

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