Kinetic modelling in food science: a case study on chlorophyll degradationin olives

This paper critically reviews the use of kinetics in modelling (bio)chemica l changes in foods. Multiresponse modelling (taking more reactants and prod ucts of the reaction under study into consideration in the modelling proces s) is advocated as opposed to uniresponse modelling tin which only one resp onse, a reactant or a product, is considered). Multiresponse modelling requ ires slightly more sophisticated software but is rewarding in that models c an be tested much more rigorously and that estimation of parameter values i s much more precise than can be achieved with uniresponse modelling. The ap proach was applied to an example taken from the literature, degradation of chlorophyll in olives during fermentation. The two models proposed in the l iterature for this degradation were found to be incorrect using the multire sponse approach. An alternative model was proposed which gave a much better fit. In addition, ways were indicated how the model could be further refin ed. It was also shown with this example that transformation of data (such a s taking the logarithm to apply a first-order model) can lead to false conc lusions concerning the kinetic model and consequently to serious errors in the resulting parameter estimates. In almost all cases, non-linear regressi on with untransformed data is to be preferred. (C) 2000 Society of Chemical Industry.