Journal of Food Engineering vol:78 issue:3 pages:1010-1021
In this research the combined mild heat and high pressure (HP) treatment of two food processing targets is under study: one microbiological safety target (Escherichia coli K12) and one quality related target (carrot Pectin Methylesterase, PME). A polynomial non-monotonous model structure fulfilling a number of constraints was identified for describing the log-linear inactivation kinetics of E. coli (at T = 5-45 degrees C and P = 200-500 MPa). Similarly, a polynomial non-monotonous model structure is used in order to describe the evolution of the carrot PME inactivation kinetics at T = 10-65 degrees C and P = 0.1-825 MPa. Iso-rate contour plots are constructed integrating the microbial and enzymatic kinetics for the combined T and P treatments. Additionally, the effect of the pressure build-up time (specific to the experimental set-up at hand) on the processing targets was quantified based on the microbial and enzymatic activity load before the initiation of the experiment and after the stabilisation of the treatment conditions. When T-P kinetic diagrams were constructed with combinations of treatments (also at extrapolation regions) resulting in the same log reductions, i.e., iso-reduction contour plots, it was evident that carrot PME was more resistant than E. coli. According to the analysis of the T-P diagrams (incorporating the pressure build-up processing effects), a thermal process in a range of 55-80 degrees C, and a combined low temperature (30-50 degrees C)-high pressure (700-800 MPa) process revealed to be equivalent. (c) 2006 Elsevier Ltd. All rights reserved.