title: Consumers' behavior in quantitative microbial risk assessment for pathogens in raw milk: Incorporation of the likelihood of consumption as a function of storage time and temperature.
abstract: Foodborne disease as a result of raw milk consumption is an increasing concern in Western countries. Quantitative microbial risk assessment models have been used to estimate the risk of illness due to different pathogens in raw milk. In these models, the duration and temperature of storage before consumption have a critical influence in the final outcome of the simulations and are usually described and modeled as independent distributions in the consumer phase module. We hypothesize that this assumption can result in the computation, during simulations, of extreme scenarios that ultimately lead to an overestimation of the risk. In this study, a sensorial analysis was conducted to replicate consumers' behavior. The results of the analysis were used to establish, by means of a logistic model, the relationship between time-temperature combinations and the probability that a serving of raw milk is actually consumed. To assess our hypothesis, 2 recently published quantitative microbial risk assessment models quantifying the risks of listeriosis and salmonellosis related to the consumption of raw milk were implemented. First, the default settings described in the publications were kept; second, the likelihood of consumption as a function of the length and temperature of storage was included. When results were compared, the density of computed extreme scenarios decreased significantly in the modified model; consequently, the probability of illness and the expected number of cases per year also decreased. Reductions of 11.6 and 12.7% in the proportion of computed scenarios in which a contaminated milk serving was consumed were observed for the first and the second study, respectively. Our results confirm that overlooking the time-temperature dependency may yield to an important overestimation of the risk. Furthermore, we provide estimates of this dependency that could easily be implemented in future quantitative microbial risk assessment models of raw milk pathogens.
authors.affiliation: Department of Veterinary Science and Public Health, Università degli Studi di Milano, Via Celoria 10, 20133 Milan, Italy. Electronic address: matteo.crotta@unimi.it.
authors.forename: Matteo
authors.initials: M
authors.lastname: Crotta
authors.affiliation: Lombardy and Emilia Romagna Experimental Zooprophylactic Institute, Via Rovelli 53, 24100 Bergamo, Italy.
authors.forename: Franco
authors.initials: F
authors.lastname: Paterlini
authors.affiliation: Department of Veterinary Science and Public Health, Università degli Studi di Milano, Via Celoria 10, 20133 Milan, Italy.
authors.forename: Rita
authors.initials: R
authors.lastname: Rizzi
authors.affiliation: Veterinary Epidemiology, Economics and Pubic Health Group, The Royal Veterinary College, Hawkshead Lane, North Mymms, AL9 7TA, Hatfield, United Kingdom.
authors.forename: Javier
authors.initials: J
authors.lastname: Guitian
mesh_terms: D000818:Animals; D003258:Consumer Behavior; D005511:Food Handling; D005516:Food Microbiology; D061353:Food Storage; D008892:Milk / Q000382:microbiology*; D018570:Risk Assessment; D013696:Temperature; D013997:Time Factors
keywords: consumer behavior; milk spoilage; quantitative microbial risk assessment; raw milk