Combined Effect of Ultraviolet (UVC) and Far Infrared (FIR) Radiation on Quality and Microbial Decontamination of Cumin Seeds

Cumin seeds may have been exposed to a high level of bacterial contamination and presence of pathogenic organisms could potentially create a public health risk. Apart from the public health, heavy microbial contamination is also a crucial problem in exportation. Most microorganisms contaminating the cumin seeds reside on the surface, and generally inner parts of the seeds are free from the microorganisms. Due to that, inner parts may not require to be exposed to heat or radiation in a possible decontamination process. Adequacy of the surface pasteurization might then help keeping original quality of seeds. UVC and FIR have low penetration power, and there might be no any detrimental defects to the ingredients during a decontamination process. Therefore the objective of this study was to determine the effect of UVC and FIR treatments on the quality and microbial decontamination of cumin seeds. FIR treatment at different exposure times and temperatures were applied followed by a constant UVC treatment with an intensity of 10.5 mW/cm for 2 h. After treatments, total mesophilic aerobic bacteria (TMAB) and yeast and mold content of the seeds were determined, and changes on quality were evaluated in terms of moisture, volatile oil, color changes and weight losses. TMAB of the cumin seeds were decreased to the target level of 10 CFU/g after 1.57, 2.8 and 4.8 min FIR treatment times at 300, 250 and 200 °C, respectively plus 2 h UVC treatment. Under the given conditions, a complete elimination for total yeast and mold contents were obtained while there were no significant changes in volatile oil content and color of the cumin seeds. Consequently, the combined UVC and FIR treatment was determined to be a promising innovative method for decontamination of the cumin seeds.