Inhibitory effects of ultraviolet-C light and thermal treatment on four fungi isolated from pig slaughterhouses in Korea

Pig slaughterhouses harbor high humidity because of the necessary cleaning that takes place simultaneously with slaughter, which facilitates the existence of mold. Due to the enclosed space, there are several limitations to the control of mold growth with respect to cleaning, ventilation, and drying. In this study, the prevalence of fungi was investigated in four pig slaughterhouses in Korea. Four fungi (Aspergillus niger, Penicillium commune, Penicillium oxalicum, and Cladosporium cladosporioides) were detected with the highest frequency. These four strains were subjected to various treatments to reduce their growth. The fungi were inoculated onto stainless steel (SS) chips and treated with ultraviolet (UV)-C irradiation and hot water. Individual treatments with UV-C (15, 30, 90, 150, 300, and 600 mJ/cm(2)), and hot water (60, 65, 70, and 83°C) were performed to sanitize the SS chips. Simultaneous cleaning with 60°C hot water and more than 150 mJ/cm(2) of UV-C reduced the fungal incidence by > 6.5 Log from 6.6–7.0 Log CFU/cm(2) (initial count). Our results demonstrate that a combined treatment of UV-C and hot water is the most economical and convenient way to prevent microbiological contamination of small tools (such as knives and sharpeners) and steel surfaces in slaughterhouses.