Heat‐resistant Bacteria in Pasteurized Whole Egg

Abstract

Samples of egg melange taken from an egg packing station contained an average of 7·3 x 104 organisms/ml which survived laboratory pasteurization at 65°C for 3 min. Many of the organisms surviving pasteurization were found to be coryneform bacteria related to Microbacterium lacticum which could be differentiated into several groups. The remainder were a miscellaneous collection of unidentified cocci and coccobacilli and some Bacillus spp. The coryneform bacteria were shown to be the most heat‐resistant isolates with negligible loss of viability after 60 min at 65°C, At least two of the representative strains were very heat‐resistant, 0·01% surviving 20 and 38 min at 80°C in phosphate buffer at pH 7·1. Growth tests showed that none of the isolates grew at 5°C after 10 d incubation but those capable of growing most rapidly at 10° and 15°C were also the most heat‐resistant. Such strains had a doubling time at 15°C of between 6 and 8 h in whole egg. Freezing the coryneform bacteria in liquid whole egg at –18°C had negligible effect on viability or heat‐resistance at 65°C.

Survival of faecal streptococci in raw and pasteurised egg products

“…The observed decline in viability that precedes growth on transfer to whole egg of cells of Strep, faecium grown in heart infusion broth is not peculiar to this organism and a similar result has been reported with Microbacterium lacticum NGDO 747 (Payne et al, 1979). The alternative explanation, that the increase in viable count was due to the growth of a low level of contaminants, is unlikely because the cultures appeared identical to the inoculum.…”

“…Barnes et al, 1978Barnes et al, 1978 Preparation of sterile egg Liquid whole egg and egg albumen were prepared as previously described (Corry and Barnes, 1968;Payne et al, 1979). Eggs were stored for 3 d at 1 °C prior to breaking out the contents.…”

“…There is no statutory requirement for the pasteurisation of egg albumen although at least 2-5 min at 57-2 °C is recommended. Several types of organisms, including faecal streptococci, have been shown to survive pasteurisation (Barnes and Corry, 1969;Shan et al, 1970;Payne et al, 1979).…”

Storage Stability of Liquid Egg Products Below 0 C

“…Gram negative bacteria were predominant in the unpasteurized whites. Seviour and Board (1972), , and Suzuki et al (1979) reported that Gram negative bacteria such as Aeromonas, Enterobacteriaceae, Flavobacterium, and Pseudomonas were predominant in unpasteurized liquid egg products and in spoiled shell eggs, and Shafi et al (1970), Payne et al (1979), and Payne and Gooch (1980) stated that gram positive bacteria such as Bacillus, coryneform, Micrococcus, and Staphylococcus were predominant in pasteurized liquid egg products. The microbiological findings obtained in this study agreed generally with the results obtained by these researchers.…”

Pasteurization Design Criteria for Production of Extended Shelf-Life Refrigerated Liquid Whole Egg

“…at 6O"C)to assure a 9 log cycle (9D) reduction in the number of Salmonella (USDA 1969). Heat resistant spoilage microorganisms, however, survive pasteurization and spoil the product if it is not held frozen (York and Dawson 1973;Shafi et al 1970 andPyne et al 1979). Increased thermal treatment followed by aseptic packaging h a s been suggested to produce a long shelf-life pasteurized LWE (PLWE) (Essary et al 1983;Hamid-Samimi et al 1984).…”