Bacteriology of washed and unwashed eggs. I. Bacterial counts of egg contents after storage

The influence of egg washing on the bacterial counts of egg contents after subsequent storage was studied. Unwashed eggs were compared to eggs subjected to industrial large-scale machine washing. The washing procedure consisted of sprinkling under pressure with a 43 °G water solution of detergent, rinsing with 47°G tap water, and drying in a stream of hot air (60–65°G). The eggs were stored at 4°C for eight weeks and at 30 °G for 12 days. At the end of the storage periods, the total bacterial count, the number of hemolytic bacteria, and the number of coli-aerogenes in the egg contents were examined. A total of slightly more than 400 eggs were used in the investigation.No coli-aerogenes bacteria were detected in any washed or unwashed eggs. For eggs, stored at 4°C, the logarithmic total bacterial counts were for washed eggs 2.07; 2.42, and for washed 2.08; 1.95 (mean and median values, respectively). The corresponding values for eggs stored at 30 °G were for unwashed eggs 1.40; 1.30, and for washed eggs, 1.62; 1.48. These differences between unwashed and washed eggs are not significant.Hemolytic bacteria were detected in 35.2 % of unwashed and in 33.0 % of washed eggs after cold storage and no significant difference was seen between the number of bacteria in these eggs (logarithmic mean values 2.43 and 2.47, respectively). Nor was any significant difference seen between the counts of the hemolytic bacteria in eggs stored at 30 °G, where these bacteria were detected in 19.6 % of unwashed and in 23.9 % of washed eggs (logarithmic mean values of number of bacteria 2.10 and 2.46, respectively). The importance of obtained results is discussed from the point of view of food hygiene with references to the relevant literature.