Curry ingredients such as turmeric, coriander, cumin, fennel, fenugreek often contain microbial contaminants. Our preliminary analysis showed that microbial contamination in fenugreek was relatively higher than other ingredients, and therefore the decontamination using a non-thermal plasma was performed to enhance its microbial quality. Corona discharge plasma jet (CDPJ) was used for the decontamination of fenugreek seeds. The results showed that aerobic bacteria were decreased by 0.88 - 2.51 log units, and yeast and mold exhibited the reduction of 0.58-1.95 log units with the treatment for 20 min. For the microbial inactivation pattern, the Weibull model gave the best distribution fit among the models tried. The decontamination effect of the CDPJ was enhanced with the decrease of the distance from the plasma electrode, and with the increase of the current intensity. The effect of the plasma treatment on antioxidant capacity of fenugreek seed was also investigated, and the obtained results indicated that total phenolic content and DPPH radical scavenging ability were unaffected by the treatment at a current intensity of 1.00 A regardless the treatment distance from the electrode, whereas significant increases were observed with the treatment at 1.25 A and 1.50 A currents.

In the present study, the effects of non-thermal plasma, corona discharge plasma jet (CDPJ) against foodborne disease bacteria (Escherichia coli O157:H7 ATCC 43894, Salmonella typhimurium ATCC 13311, Staphylococcus aureus ATCC 25923) were determined, and the inactivation patterns were modeled using GinaFiT software in Microsoft Excel. Among inactivation models studied, Weibull-tail model was chosen as the best fit model based on SSE, RMSE, and r 2 values. The initial decimal reduction times (δ) of E. coli O157:H7, S. aureus, and Sal. typhimurium were 6.36, 8.31, and 12.11 s respectively. The inactivation effect increased with the current strength and was highest at span length of 25 mm. After 120 s treatment of the CDPJ at 1.50 A with span length of 25 mm, E. coli O157:H7 was reduced by 5.26 log, S. aureus by 4.21 log, Sal. typhimurium by 2.89 log.