Risk-based assessment and criteria specification of the microbial safety of wastewater reuse in food processing: Managing Listeria monocytogenes contamination in pasteurized fluid milk

Onay B Dogan; Yulie E Meneses; Rolando A Flores; Bing Wang

doi:10.1016/j.watres.2020.115466

Risk-based assessment and criteria specification of the microbial safety of wastewater reuse in food processing: Managing Listeria monocytogenes contamination in pasteurized fluid milk

Water Res. 2020 Mar 15:171:115466. doi: 10.1016/j.watres.2020.115466. Epub 2020 Jan 3.

Authors

Onay B Dogan¹, Yulie E Meneses², Rolando A Flores³, Bing Wang⁴

Affiliations

¹ Department of Food Science and Technology, University of Nebraska-Lincoln, USA.
² Department of Food Science and Technology, University of Nebraska-Lincoln, USA; Daugherty Water for Food Institute, University of Nebraska-Lincoln, USA; The Food Processing Center, University of Nebraska-Lincoln, USA.
³ Department of Food Science and Technology, University of Nebraska-Lincoln, USA; Daugherty Water for Food Institute, University of Nebraska-Lincoln, USA; College of Agricultural, Consumer & Environmental Sciences, New Mexico State University, USA.
⁴ Department of Food Science and Technology, University of Nebraska-Lincoln, USA. Electronic address: bing.wang@unl.edu.

PMID: 31927094
DOI: 10.1016/j.watres.2020.115466

Abstract

Intense pressure on water resources has led to efforts to reuse reclaimed processing wastewater for cleaning purposes in food processing plants. The milk industry produces considerable amounts of wastewater, which can be used for cleaning of equipment after appropriate treatment. However, due to naturally occurring microbiological contamination in raw milk, the wastewater is often contaminated, and therefore the reuse of reclaimed wastewater is perceived as risky. This study aims to quantify the risks of Listeria monocytogenes infection and associated disease burden when wastewater reclaimed from milk processing operations is used in cleaning-in-place (CIP) systems for pasteurized fluid milk production following a quantitative microbial risk assessment (QMRA) approach. Furthermore, this study aims to inform risk-based tolerable limits for levels of contamination in CIP water based on a public health target of 10^-6 DALY per person annually. The suggested model investigates the passage of L. monocytogenes throughout the fluid milk chain, from receipt of raw milk at the plant to the point of consumption and covering storage in receiving and storage tanks, pasteurization, and storage at retail and at home. Risk and disease burden estimates are simulated for general (younger than 65 years), elderly (65 years and older) and pregnant population subgroups. Additional scenarios covering the effect of using clean water, using water with different levels of contamination and using reclaimed wastewater modeled as recovered from cheese whey after membrane filtration (reclaimed water scenario) are considered to estimate a risk-based limit of contamination and simulate a real-life example. The tolerable limit of contamination in CIP water was estimated as -2 log₁₀ CFU/mL to ensure the protection of the most vulnerable subgroup, pregnant women, while higher limits were estimated for the elderly and general subgroups. Under the reclaimed water scenario, the annual number of listeriosis cases was estimated as 3.36, 5.67, and 0.15 for the general, elderly and pregnant population subgroups, respectively, while in the clean water scenario, the estimates were 3.33, 5.56 and 0.15, respectively. In both scenarios, the DALY estimates were lower than the tolerable limit. The results indicate that reclaimed water can be an alternative to potable water for CIP applications.

Keywords: Cleaning-in-place; DALY; Microbiological limits; Quantitative microbial risk assessment; Wastewater reuse.

MeSH terms

Animals
Female
Food Contamination
Food Handling
Humans
Listeria monocytogenes*
Milk
Pregnancy
Risk Assessment
Wastewater

Substances

Waste Water