Abstract

Since germination creates chalky grain around the entire surface of the kernel, it is commonly eliminated by steaming germinated paddy before drying. In this work, a continuous fluidized bed with a capacity of 100 kg/h was therefore used to treat the chalkiness with high-temperature hot air. The performance of this dryer in terms of water evaporation capacity and energy consumption along with the quality attributes was determined quantitatively. Two crops of Khao Dawk Mali 105 stored for 1 month and 8 and 9 months were used as the raw material. Hot air at temperatures of 130–150 °C with full recycling of the exhaust air was able to eliminate the chalkiness perfectly. The best performance, as indicated by higher water evaporation capacity and lower energy consumption, was obtained at a higher feed rate, higher bed depth and higher drying temperature. The higher bed depth and drying temperature provided a higher degree of starch gelatinization and the correspondingly higher head brown rice yield and hardness of the cooked germinated brown rice except for stickiness. Within the studied drying temperature range, the amount of accumulated gamma-aminobutyric acid after drying the rice which had been stored for 1 month decreased slightly compared to that of the sun-dried product, in a range of 11.4–12.6 mg per 100 g, and decreased significantly for the rice which had been stored for 8 and 9 months. The storage period also influenced the texture after cooking. It is recommended that to obtain the premium quality from the germinated product, the paddy should be stored for 1 month, and a drying temperature of approximately 130˚C should be applied. Under the recommended conditions, the energy consumption was about 1.13 MJ/kg of paddy, and the operating cost of the continuous fluidized bed was 0.17 USD/kg, which was more economical than that of the conventional method.

摘要

由于发芽会在整个谷粒表面产生白垩颗粒，因此通常通过在干燥前将发芽的稻谷蒸熟来消除它。因此，在这项工作中，使用容量为 100 kg/h 的连续流化床用高温热空气处理白垩质。该干燥机在水分蒸发能力和能耗以及质量属性方面的性能被定量确定。以存放 1 个月和 8 个月和 9 个月的两批 Khao Dawk Mali 105 为原料。温度为 130–150 °C 的热空气与废气的完全循环能够完美地消除白垩。在较高的进料速率下获得了最佳性能，如较高的水蒸发能力和较低的能耗所示，更高的床层深度和更高的干燥温度。较高的床层深度和干燥温度提供了更高的淀粉糊化程度，相应地，煮熟的发芽糙米的整粒糙米产量和硬度更高，但粘性除外。在所研究的干燥温度范围内，储存1个月的大米干燥后γ-氨基丁酸的积累量与晒干相比略有下降，在11.4-12.6毫克/100克的范围内，储存 8 个月和 9 个月的大米显着下降。储存期也影响烹饪后的质地。建议为了从发芽产品中获得优质品质，稻谷应存放 1 个月，干燥温度应在 130˚C 左右。