Estimating the efficacy of mild heating processes taking into account microbial non-linearities: a case study on the thermisation of a food simulant

Vasilis Valdramidis, Dublin Institute of Technology
Brijesh Tiwari, Manchester Metropolitan University
P J. Cullen, Dublin Institute of Technology
Alain Kondjoyan, INRA, UR370 Qualité des Produits Animaux
Jan Van Impe, Katholieke Universiteit Leuven

Food Control, Vol.22, 1, 2010 Available from the publisher here


Traditional and novel approaches for the calculation of the heat treatment efficiency are compared in this work. The Mild Heat value (MH-value), an alternative approach to the commonly used sterilisation, pasteurisation and cook value (F, P, C–value), is calculated to estimate the efficiency of a mild heat process. MH-value is the time needed to achieve a predefined microbial reduction at a reference temperature and a known thermal resistant constant, z, for log-linear or specific types of non log-linear microbial inactivation kinetics. An illustrative example is given in which microbial inactivation data of Listeria innocua CLIP 20-595 are used for estimating the inactivation parameters under isothermal conditions of 58, 60, 63 and 66oC by the use of the log-linear and the Geeraerd et al., (2000) model. Thereafter, dynamic temperature profiles (targeting at 54 and 57 C) representing milk thermisation are exploited for illustrating the application of MH-value. Finally, the equivalent holding times of different temperatures are calculated taking into account the observed non-linearity.