Effects of ultraviolet light on aerobic plate counts, Salmonella typhimurium, and Escherichia coli levels on eggshell surface

Abstract

The effects of 254nm ultraviolet light (UV) radiation on aerobic plate counts (APC), and populations of Salmonella typhimurium, and Escherichia coli on eggshells surfaces were investigated. In the first experiment, eggs were exposed to UV treatment of (7.35mW/cm²) for 0, 15, 30, and 60s on a hand operated egg roller. Three eggs were collected from each exposure treatment for evaluation of treatment effects on APC. In the second experiment, the UV lights were placed in a chamber equipped with a commercial style egg conveyor. UV treatment of 7.5mW/cm² and time intervals of 0, 12, 36, and 48s were used. Three eggs were placed consecutively on the conveyor and passed through the chamber, the center egg was selected for APC evaluation and three sets of eggs were evaluated per treatment. In all remaining experiments, eggs were exposed to UV treatment of a minimum of 18mW/cm² for 4 min in a UV sanitation machine. The machine contained a chamber equipped with UV lights and conveyor system to carry a commercial style eggflat. In the third experiment, 42 eggs were placed on an egg flat (6 rows, 7 columns) and passed through UV sanitation machine. Seven eggs were collected, one from each column. In the fourth experiment, Salmonella typhimurium was inoculated on 14 unwashed clean eggs. Seven eggs inoculated with Salmonella typhimurium were placed on the egg flat, surrounded with other unwashed clean eggs, and passed through the UV sanitation machine. In the fifth experiment, Escherichia coli was inoculated on 14 unwashed clean eggs. Seven eggs inoculated with Escherichia coli were placed on the egg flat, surrounded with other unwashed clean eggs, and passed through the UV sanitation machine.