UNCERTAINTY OF MICROBIAL SHELF-LIFE ESTIMATIONS FOR REFRIGERATED FOODS DUE TO THE EXPERIMENTAL VARIABILITY OF THE MODEL PARAMETERS SERGIO F. ALMONACID 1 and J. ANTONIO TORRES 2,3 1 Departamento de Procesos Químicos Biotecnológicos y Ambientales Universidad Técnica Federico Santa Maria Valparaíso, Chile 2 Food Process Engineering Group Department of Food Science and Technology Oregon State University Corvallis, OR Accepted for Publication February 29, 2008 ABSTRACT The uncertainty of shelf-life estimations for refrigerated foods exposed to changing temperature was quantified by considering the contribution of the experimental variability of the model parameters. Assuming the real distribu- tion of the parameters can be replaced by an unknown empirical distribution, this uncertainty was analyzed by a bootstrap methodology. Independent sets of heat transfer and microbial growth parameters were chosen randomly from experimental values. Shelf-life values were estimated for each set, with the variability evaluated using an SD value. The procedure was repeated 10 times to obtain 10 shelf-life SDs. The variation coefficient of these SDs is an absolute measurement of shelf-life variability. At the recommended variation coefficient of 0.1, a sample size of 25 was found acceptable. The shelf-life variability estimated was similar (1 day) for surimi in cardboard and expanded poly- styrene containers with different shelf life and temperature profiles. The method is applicable to other predictions of food stability. PRACTICAL APPLICATIONS The effect of the experimental variability of model parameters on shelf-life estimations confirmed the need to assess the uncertainty of model 3 Corresponding author. TEL: +1-541-737-4757; FAX: +1-541-737-6174; EMAIL: J_Antonio. Torres@OregonState.edu Journal of Food Process Engineering 33 (2010) 66–84. All Rights Reserved. © Copyright the Authors Journal Compilation © 2009 Wiley Periodicals, Inc. DOI: 10.1111/j.1745-4530.2008.00298.x 66