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Bacteriology of Washed and Unwashed Eggs
Bakteriologiska förhållanden hos tvättade och otvättade ägg: I. Bakteriehalten hos ägg efter lagring
I. Bacterial Counts of Egg Contents after Storage
Acta Veterinaria Scandinavica volume 12, pages 467–478 (1971)
Summary
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.
Sammanfattning
Inverkan av ett äggtvättningsförfarande på äggens bakterieinnehåll efter lagring studerades. Otvättade ägg jämfördes med ägg, som maskin-tvättats enligt ett förfarande för industriell tvätt i stor skala. Tvättningen omfattade duschning under tryck med en 43° G vattendetergentlösning, skölj ning i 47-gradigt vatten och torkning i varmluftström (60–65°C). Lagring skedde vid 4°G i 8 veckor och vid 30°G i 12 dygn. Vid respektive lagringsperiods slut undersöktes ägginnehållet med avseende på totalantal bakterier, antal hämolyserande bakterier samt antalet koli-aerogenes. Undersökningen omfattade något mer än 400 ägg.
Icke i något fall kunde koli-aerogenes-bakterier påvisas i tvättade eller otvättade ägg. För ägg lagrade vid 4°G var log-värdet för totalantalet bakterier hos otvättade ägg 2,07; 2,42, och för tvättade ägg 2,08; 1,95 (medelvärde respektive medianvärde). Motsvarande värden för ägg lagrade vid 30° G var för otvättade ägg 1,40; 1,30, och för tvättade 1,62; 1,48. Skillnaderna mellan tvättade och otvättade ägg med avseende på dessa värden var icke signifikanta. Hämolyserande bakterier kunde påvisas i 35,2 % av de otvättade och 33,0 % av de tvättade äggen efter kyllagring och skillnaden i antal bakterier hos dessa ägg var icke signifikant (logaritmiska medelvärden 2,43 respektive 2,47). Icke heller förelåg någon signifikant skillnad beträffande antalet hämolyserande bakterier hos ägg, lagrade vid 30° G, där dessa bakterier kunde påvisas i 19,6 % av de otvättade och i 23,9 % av de tvättade äggen (logaritmiska medelvärden för antalet bakterier 2,10 respektive 2,46). Betydelsen av funna resultat diskuteras ur livsmedelshygienisk synpunkt i anslutning till relevant litteratur.
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Acknowledgements
The interest and cooperation of Dr. Sven Rydberg, Mr. Carl Scott and Mr. Göran Erixon is gratefully acknowledged.
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Ostlund, K. Bacteriology of Washed and Unwashed Eggs. Acta Vet Scand 12, 467–478 (1971). https://doi.org/10.1186/BF03547715
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DOI: https://doi.org/10.1186/BF03547715