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    Item type:Publication,
    Effect of high-temperature fluidized bed drying on quality of 'Kum Doi Saket' variety of purple rice
    (2015-01-01)
    Junka, N.
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    Wongs-Aree, C.
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    Kanlayanarat, S.
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    Boonyaritthongchai, P.
    The objective of this study was to investigate the effects of high-temperature drying in a range of 100-150 °C using fluidization technique on quality changes of 'Kum Doi Saket' indigenous purple rice variety in Thailand. Experimental results revealed that using high temperature process reduced free fatty acid content (FFA) in kernel without any effects on kernel colour, anthocyanins and antioxidant content. A higher process temperature resulted in a better quality of brown rice in terms of FFA. Moreover, it was found that the antioxidant activity of purple rice subjected to various drying conditions and tested by 2,2-diphenyl-1-picrylhydrazyl radical assay (DPPH) technique showed no significant difference with the reference purple rice. As for FFA level, it significantly decreased when the samples were dried at temperatures of 130 and 150 °C. The present study found that within the range of parameters studied, the purple rice harvested at 28.3% (d.b.) moisture content of dried at 150 °C for 1.5 minutes was of the best quality. This drying temperature did not affect the anthocyanin content nor the antioxidant activity of purple rice and had the highest drying rate.
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    Item type:Publication,
    Performance comparison between gradient orifice and uniform orifice distributors in rotating fluidization for coated jasmine rice
    (2026-04-01)
    Prakotmak, Preeda
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    Phothong, Watchama
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    Junka, Nittaya
    A rotating fluidized bed coater offers an alternative technology in which particles are fluidized by balancing centrifugal, buoyant, and gravitational forces, thereby improving coating homogeneity and mass transfer. The coating performance between the gradient orifice distributor (GOD) and the uniform orifice distributor (UOD) was compared at rotational speeds of 20, 70, or 120 rpm. The experiment was set up to coat a turmeric-extract solution onto the surface of jasmine rice. The coating substance was sprayed from the nozzle at 35 or 40 mL/min at an air-atomization pressure of 1.5 bar for 6 or 8 min. Hot air (55 or 60 °C) flows were passed at an inlet velocity of 2.9 m/s, with 85 % by volume of the air recycled. The quality of the sample was evaluated based on its final moisture content, percentage of fissure kernels, head-coated rice yield, color, coating efficiency, total phenolic content, and antioxidant activity. Based on the results, GOD was a suitable distributor plate for producing turmeric-extract-coated rice. For optimal coating conditions, the jasmine rice should be coated at a drying temperature of 55 °C, using a coating solution spray rate of 35 mL/min, a rotational speed of 70 rpm, a spraying coating time of 6 min, and a drying time of 10 s after the spraying stage. Using these conditions, the coating efficiency was 84.2 % and the antioxidant activity of the coated rice was 30.53 % higher than that of the referent white rice.