Effect of high-temperature fluidized bed drying on quality of ‘Kum Doi Saket’ variety of purple rice
2015
Rattanamechaiskul, C. | Wongs-Aree, C. | Kanlayanarat, S. | Boonyaritthongchai, P. | Junka, N. | Prom-u-thai, C.T.
The objective of this study was to investigate the effects of high-temperature drying in a range of 100-150 oC 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 oC. 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 oC 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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