Impact of commercial processing on the microbiology of shell eggs

• Published in: Journal of food protection 2005, Vol.68 (11), p.2367-2375
• Main Authors: Musgrove, M.T, Jones, D.R, Northcutt, J.K, Harrison, M.A, Cox, N.A
• Format: Article
• Language: English
• Subjects: Animals; Bacteria, Aerobic - growth & development; Bacteria, Aerobic - isolation & purification; Biological and medical sciences; Chickens; Colony Count, Microbial; Consumer Product Safety; critical control points; Disinfection - methods; Egg and egg product industries; Egg Shell - microbiology; eggs; Enterobacteriaceae; Enterobacteriaceae - growth & development; Enterobacteriaceae - isolation & purification; Escherichia coli; Escherichia coli - growth & development; Escherichia coli - isolation & purification; food contact surfaces; Food Contamination - analysis; Food Contamination - prevention & control; Food Handling - methods; Food industries; Food Microbiology; food processing; food sanitation; Food-Processing Industry - methods; Food-Processing Industry - standards; Fundamental and applied biological sciences. Psychology; HACCP; Hygiene; microbial detection; plate count; Salmonella; Salmonella - growth & development; Salmonella - isolation & purification
• ISSN: 0362-028X; 1944-9097
• DOI: 10.4315/0362-028X-68.11.2367

Shell egg microbiology has been studied extensively, but little information is available on how modern U.S. processing conditions impact microbial populations. As regulations are being drafted for the industry, such information can be important for determining processing steps critical to product safety. Five different shell egg surface microbial populations (aerobic bacteria, yeasts and molds, Enterobacteriaceae, Escherichia coli, and Salmonella) were monitored at 12 points along the processing line (accumulator, prewash rinse, washer 1, washer 2, sanitizer, dryer, oiler, scales, two packer head lanes, rewash entrance, and rewash exit). Three commercial facilities were each visited three times, a total of 990 eggs were sampled, and 5,220 microbiological samples were subsequently analyzed. Although variations existed in concentrations of microorganisms recovered from each plant, the patterns of fluctuation for each population were similar at each plant. On average, aerobes, yeasts and molds, Enterobacteriaceae, and E. coli prevalence were reduced by 30, 20, 50, and 30%, respectively, by the end of processing. The microbial concentrations (log CFU per milliliter) in the egg rinse collected from packer head lanes were decreased by 3.3, 1.3, 1.3, and 0.5, respectively, when compared with those of rinses collected from eggs at the accumulator. Salmonella was recovered from 0 to 48% of pooled samples in the three repetitions. Higher concentrations of Salmonella were recovered from preprocessed than from in-process or ready-to-pack eggs. These data indicate that current commercial practices decrease microbial contamination of egg shell surfaces.