title: Microbiological and Modeling Approach to Derive Performance Objectives for Bacillus cereus Group in Ready-to-Eat Salads.
abstract: In this article, the performance objectives (POs) for Bacillus cereus group (BC) in celery, cheese, and spelt added as ingredients in a ready-to-eat mixed spelt salad, packaged under modified atmosphere, were calculated using a Bayesian approach. In order to derive the POs, BC detection and enumeration were performed in nine lots of naturally contaminated ingredients and final product. Moreover, the impact of specific production steps on the BC contamination was quantified. Finally, a sampling plan to verify the ingredient lots' compliance with each PO value at a 95% confidence level (CL) was defined. To calculate the POs, detection results as well as results above the limit of detection but below the limit of quantification (i.e., censored data) were analyzed. The most probable distribution of the censored data was determined and two-dimensional (2D) Monte Carlo simulations were performed. The PO values were calculated to meet a food safety objective of 4 log10cfu of BC for g of spelt salad at the time of consumption. When BC grows during storage between 0.90 and 1.90 log10cfu/g, the POs for BC in celery, cheese, and spelt ranged between 1.21 log10cfu/g for celery and 2.45 log10cfu/g for spelt. This article represents the first attempt to manage the concept of PO and 2D Monte Carlo simulation in the flow chart of a complex food matrix, including raw and cooked ingredients.
authors.affiliation: Department of Agricultural and Food Sciences, Alma Mater Studiorum-University of Bologna, Ozzano dell'Emilia, (BO), Italy.
authors.forename: Alessandra
authors.initials: A
authors.lastname: De Cesare
authors.affiliation: Department of Physics and Astronomy, Alma Mater Studiorum-University of Bologna, Bologna, Italy.
authors.forename: Silvia
authors.initials: S
authors.lastname: Vitali
authors.affiliation: Department of Veterinary Medical Science, Alma Mater Studiorum-University of Bologna, Ozzano dell'Emilia, (BO), Italy.
authors.forename: Marcello
authors.initials: M
authors.lastname: Trevisani
authors.affiliation: Department of Agricultural and Food Sciences, Alma Mater Studiorum-University of Bologna, Ozzano dell'Emilia, (BO), Italy.
authors.forename: Federica
authors.initials: F
authors.lastname: Bovo
authors.affiliation: Department of Agricultural and Food Sciences, Alma Mater Studiorum-University of Bologna, Ozzano dell'Emilia, (BO), Italy.
authors.forename: Gerardo
authors.initials: G
authors.lastname: Manfreda
mesh_terms: D000077102:Apium / Q000382:microbiology; D001409:Bacillus cereus; D001499:Bayes Theorem; D002611:Cheese / Q000382:microbiology; D015169:Colony Count, Microbial; D005506:Food Contamination / Q000032:analysis; D005511:Food Handling / Q000379:methods*; D005516:Food Microbiology; D059022:Food Safety; D008089:Listeria monocytogenes; D015233:Models, Statistical; D009010:Monte Carlo Method; D012308:Risk Management / Q000379:methods*; D013696:Temperature; D014908:Triticum / Q000382:microbiology; D014675:Vegetables / Q000382:microbiology*
keywords: Bacillus cereus; censored data; performance objective; sampling plan; spelt salad; two-dimensional Monte Carlo simulation