EFFECT OF ULTRAVIOLET (UV-C) LIGHT AND GASEOUS OZONE ON MICROBIAL AND COLOR QUALITIES OF WHOLE BLACK PEPPER SEEDS (PIPER NIGRUM L.)

Abstract

Microbial contamination of spices, especially black pepper, may sometimes reach as high as 8 log cfu/g, which can cause a major problem in the quality and safety of foods they are added. This study aimed to explore the potential of ultraviolet C (UV-C) light and ozone for decontamination of black pepper seeds. Ozone (15 ppm for 1 h) and UV-C (28.8 J/cm(2)) treatments were applied alone, in succession, or simultaneously to whole black pepper seed with a laboratory scale fluidized bed UV-C system. Total aerobic mesophilic bacteria (TAMB) count (in uninoculated seeds), Escherichia coli (E. coli) count (in inoculated seeds) and color (L*, a* and b*) of black pepper were evaluated. Ozone and UV-C treatments alone caused 0.41- and 0.77-log reduction in the initial TAMB count (6.97 log cfu/g), respectively. TAMB decreased by 0.74- and 0.66-log upon successive and simultaneous treatments, respectively. Thus, the combined treatments did not have any additive or synergistic effects on TAMB. Both ozone and UV-C treatments alone resulted a 0.8-log reduction in the initial E. coli count of 6.3-log. The combined treatments caused an additive effect on inactivation of E. coli in black pepper seeds. The successive and simultaneous treatments caused 1.7- and 1.4-log reductions in the E. coli, respectively. None of the treatments affected the color (L*, a* and b* values) significantly. In conclusion, the individual treatment has potential for reducing the natural contamination level on the seeds, and the combined treatments may have further potential towards reducing specific microbial contaminations.