Bacterial Counts on Ceramic Tableware Following Different UV-C Exposure Durations: A Post-Test Control Group Study

Abstract

Microbial contamination of food-contact surfaces is an important food-safety concern. UV-C irradiation may provide a supplementary non-chemical approach for reducing bacterial contamination on tableware; however, the effect of different exposure durations under standardized conditions requires further evaluation. Objective: This study aimed to determine the effect of different UV-C exposure durations on bacterial counts on ceramic tableware at a fixed irradiation distance. Methods: A true experimental post-test control group design was conducted using the STERUVAM UV-C sterilization cabinet. Twenty-four ceramic plates were allocated into four groups (n = 6 per group): control (0 minutes) and UV-C exposure for 5, 10, and 15 minutes. The distance between the UV-C lamp and the tableware surface was maintained at 5 cm. Bacterial contamination was assessed using surface swabbing, serial dilution, culture on Plate Count Agar, and enumeration after incubation at 37°C for 48 hours. Differences among groups were analyzed using the Kruskal-Wallis H test, followed by Mann-Whitney U pairwise comparison. Results: The mean bacterial count decreased progressively with increasing UV-C exposure duration, from 58.0 in the control group to 30.7, 5.5, and 1.2 after 5, 10, and 15 minutes of exposure, respectively. This corresponded to bacterial-count reductions of 46.7%, 90.4%, and 97.9%, respectively. The difference among the four groups was statistically significant (H = 21.184, df = 3, p < 0.001). Conclusion: Longer UV-C exposure was associated with greater reductions in bacterial counts on ceramic tableware under the tested conditions. The 15-minute exposure produced the greatest observed reduction (97.9%), indicating its potential as a supplementary approach for tableware sanitation.