Preservability of Unpasteurized Liquid Whole Eggs by Chilling

Studies on the Bacterial Contamination of Liquid (Frozen) Whole Eggs. III

Abstract

Unpasteurized liquid whole eggs were stored at 10°C and 5°C to investigate their preservability from bacteriological and chemical viewpoints. After 4-5 days at 10°C or 8 days at 5°C, little deterioration of quality was observed. However after 6 days at 10°C or 10 days at 5°C, we observed the formation of off-odor (fishy or fruity), an increase in bacterial counts, a decrease in pH, a decrease in glucose content, an increase in volatile basic nitrogen (VB-N), formation of trimethylamine nitrogen (TMA-N), and an increase in the acidity of the ether extract. In these storage tests, it was found that psychrotrophic bacteria such as Aeromonas, Pseudomonas, Flavobacterium, and Micrococcus became predominant and that coliform bacteria and enterococci grew only slowly. On the other hand, on storage at 25°C, Enterobacteriaceae, Micrococcus, and Streptococcus dominated, and fairly rapid growth of coliform bacteria and enterococci was observed. The strong putrid odor formed after 2 days at 25°C was different from the fishy or fruity odor that developed at 5°C or 10°C. In liquid whole eggs stored at 5°C or 10°C, most of the isolates forming red colonies on desoxycholate agar were not coliform.