Assessment of microbial risk during Australian industrial practices for Escherichia coli O157:H7 in fresh cut-cos lettuce: A stochastic quantitative approach. (May 2021)

• Record Type: Journal Article
• Authors: Bozkurt, Hayriye; Bell, Tina; van Ogtrop, Floris; Phan-Thien, Kim-Yen; McConchie, Robyn
• Is Part Of: Food microbiology. Volume 95(2021)
• Publication Date: 2021-05
• Subjects: Leafy greens -- Season -- Irrigation water -- Irrigation type -- Manure amended soil -- QMRA; Food Microbiology -- Periodicals; Aliments -- Microbiologie -- Périodiques; Food -- Microbiology; Periodicals; Food -- Microbiology -- Periodicals; Food contamination -- Periodicals; 664.001579
• DOI: 10.1016/j.fm.2020.103691
• Languages: English
• ISSNs: 0740-0020

Abstract

Abstract: Escherichia coli O157:H7 risk associated with the consumption of fresh cut-cos lettuce during Australian industrial practices was assessed. A probabilistic risk assessment model was developed and implemented in the @Risk software by using the Monte Carlo simulation technique with 1, 000, 000 iterations. Australian preharvest practices yielded predicted annual mean E. coli O157:H7 levels from 0.2 to −3.4 log CFU/g and prevalence values ranged from 2 to 6.4%. While exclusion of solar radiation from the baseline model yielded a significant increase in concentration of E. coli O157:H7 (−5.2 -log fold), drip irrigation usage, exclusion of manure amended soil and rainfall reduced E. coli O157:H7 levels by 7.4, 6.5, and 4.3-log fold, respectively. The microbial quality of irrigation water and irrigation type both had a significant effect on E. coli O157:H7 concentrations at harvest (p < 0.05). The probability of illness due to consumption of E. coli O157:H7 contaminated fresh cut-cos lettuce when water washing interventions were introduced into the processing module, was reduced by 1.4–2.7-log fold (p < 0.05). This study provides a robust basis for assessment of risk associated with E. coli O157:H7 contamination on fresh cut-cos lettuce for industrial practices and will assist the leafy green industry and food safety authorities in Australia to identify potential risk management strategies. Highlights: The usage of manure and quality of irrigation water were found to be very relevant on pathogen level. E. coli O157:H7 levels over seasons influenced primarily by solar radiation and rainfall. The implementation of GAP is an important mitigation strategy within growers' control. Postharvest washing, and temperature control were identified as important risk control steps. Risk management strategies should be based on local data for reliable risk characterization.