Radio Frequency Heating for Biological Decontamination in Kariyat Herb (Andrographis paniculata (Burm.f.) Wall.ex Nees)
Nattasak Krittigamas1, Suchada Vearasilp2, Dumnern Karladee1, Sangtiwa Suriyong1, Tongpaan Tiamraj3, Dieter von Hörsten4
1Chiang Mai University, Dept. of Plant Science and Natural Resources, Thailand
Kariyat (Andrographis paniculata (Burm.f.) Wall.ex Nees) is a herbaceous plant which is used in traditional medicine. The main active ingredients of this plant are androprapholides and dehydroandroprapholide. The aim of this study was to investigate the efficiency of radio frequency RF treatment in controlling biological contaminates such as total bacterial count, total yeast and mold, enterobacteria; (Eshericia coli, Salmonella spp., Staphylococcus aureus, Clostridium spp.) and its effect on androprapholides and dehydroandroprapholide contents. Milled herb with initial moisture content (mc) of 5% was conditioned to 20% mc. Then, the herb samples were exposed to RF at an operating frequency of 27.12 MHz with temperatures of 80, 85, 90 and 95°C for 3 and 5 minutes of application time. The percentage of biological contamination was detected by the use of the Potato Dextrose Agar (PDA) and blotter methods. After that the amount of androprapholide(hRf) and dehydroandroprapholide were determined by ethanol extract methods. The result showed that total bacteria count from RF 90°C 5 min reduced from 3.5×105 CFU/g to 6.8×104 CFU/g lower than acceptance criteria (2×105 CFU/g), total yeast and mold from every treatment treatments were 1.5×104 CFU/g which less than acceptance criteria (2×104 CFU/g). The enterobacteria number was 8×102 CFU/g which lower than acceptance criteria (1×103 CFU/g). Escherica coli, Salmonella spp., Staphylococcus aureus, Clostridium spp. were not detected in most RF treatments. The amount of active ingredients as androprapholide was detected from 62-65 hRf which were treated with RF from 80 and 85°C and it was not detected from 90 and 95°C treatments, and dehydroandroprapholide was not detected from RF-treatment temperatures of 80-85°C, but the RF treatment 90 and 95°C they were found at the number of 65 hRf. The experiment has shown that RF treatment at 90°C for 5 minute showed the best performance in biological decontamination with remaining their active ingredient. A high temperature (90°C) resulted to androprapholide to dehydroandroprapholide by dehydration process.
Keywords: Androprapholide, decontamination, dehydroandroprapholide, Kariyat herb, radio frequency (RF) technique
Contact Address: Nattasak Krittigamas, Chiang Mai University, Dept. of Plant Science and Natural Resources, Chiang Mai, Thailand, e-mail: nattasak.kcmu.ac.th