Impact of intervention strategies on Listeria contamination patterns in crawfish processing plants: a longitudinal study

• Published in: Journal of food protection 2004-06, Vol.67 (6), p.1163-1169
• Main Authors: Lappi, V.R, Thimothe, J, Walker, J, Bell, J, Gall, K, Moody, M.W, Wiedmann, M
• Format: Article
• Language: English
• Subjects: Animals; Astacoidea - microbiology; Biological and medical sciences; cooked foods; crayfish; cross contamination; employee training; environment; Fish and seafood industries; fish products; Fish Products - microbiology; food contact surfaces; food contamination; Food Contamination - analysis; Food Contamination - prevention & control; Food Handling - methods; Food industries; Food Microbiology; food pathogens; food processing plant specific listeria control strategies; food processing plants; food safety education; food sanitation; Food-Processing Industry - standards; Fundamental and applied biological sciences. Psychology; HACCP; Listeria; Listeria - growth & development; Listeria monocytogenes; Listeria monocytogenes - growth & development; longitudinal studies; Prevalence; process control; raw materials; ready-to-eat foods; risk management process; risk reduction; sampling; sanitation procedures; Seasons; Shellfish - microbiology
• ISSN: 0362-028X; 1944-9097
• DOI: 10.4315/0362-028X-67.6.1163

Two ready-to-eat crawfish processing plants were monitored for 2 years to study the impact of Listeria control strategies, including employee training and targeted sanitation procedures, on Listeria contamination. Environmental, raw material, and finished product samples were collected weekly during the main processing months (April to June) and tested for Listeria spp. and Listeria monocytogenes. Before implementation of control strategies (year 1), the two processing plants showed Listeria spp. prevalences of 29.5% (n = 78) in raw, whole crawfish, 5.2% (n = 155) in the processing plant environment, and 0% (n = 78) in finished products. In year 2, after plant-specific Listeria control strategies were implemented, Listeria spp. prevalence increased in raw crawfish (57.5%, n = 101), in the processing plant environment (10.8%, n = 204), and in the finished product (1.0%, n = 102). Statistical analysis showed a significant increase in Listeria spp. prevalence (P < 0.0001) and a borderline nonsignificant increase in L. monocytogenes prevalence (P = 0.097) on raw material in year 2. Borderline nonsignificant increases were also observed for Listeria spp. prevalence in environmental samples (P = 0.082). Our data showed that Listeria spp. prevalence in raw crawfish can vary significantly among seasons. However, the increased contamination prevalence for raw materials only resulted in a limited Listeria prevalence increase for the processing plant environment with extremely low levels of finished product contamination. Heat treatment of raw materials combined with Listeria control strategies to prevent cross-contamination thus appears to be effective in achieving low levels of finished product contamination, even with Listeria spp. prevalences for raw crawfish of more than 50%.