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Author: search.filters.author.Junka, N.Subject: search.filters.subject.Anthocyanins

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    Comparative study of organic solvents and extraction conditions on colour and antioxidant capacity in red cabbage
    (2017-01-01)
    Junka, N.
    ;
    Rattanamechaiskul, C.
    ;
    Wongs-Aree, C.
    ;
    Kanlayanarat, S.
    In industrially natural-dye production, there are many organic solvent with different efficiencies for extracting colour and antioxidants of red cabbage. The objective of this study was to investigate appropriate organic solvent and extract condition on colour and antioxidant activity. Two organic solvents were used for extraction: ethanol for hydrophilic antioxidants and hexane for lipophilic antioxidants. Experimental results showed that red cabbage extracted by ethanol was significantly higher in purple colour, anthocyanin content, total phenolic content, antioxidant activity by 2,2-diphenyl-1-picrylhydrazyl radical assay (DPPH), and ferric reducing/antioxidant power assay (FRAP) than extraction by hexane due to anthocyanins being the main phenolic compound in extract. To find the appropriate concentration and extraction time, the results revealed that the red cabbage extracted by 70% ethanol for 18 h was suitable for extracting bioactive polar compounds, such as hydrophilic antioxidants.
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    Effect of high-temperature fluidized bed drying on quality of 'Kum Doi Saket' variety of purple rice
    (2015-01-01)
    Junka, N.
    ;
    Wongs-Aree, C.
    ;
    Rattanamechaiskul, C.
    ;
    Kanlayanarat, S.
    ;
    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.