A prototype model structure for mixed microbial populations in homogeneousfood products

An important factor which has not been included in many models in the field of predictive microbiology is the influence of a background of microflora in a food product. It is however generally known that the growth of a micro organism as a pure culture can be substantially different from its growth i n a mixed culture, due to microbial interactions. Because of the importance of these interactions and the lack of suitable modeling techniques in the field of predictive microbiology to describe them, the potential of models in other research fields-namely ecology-to deal with interactions is explor ed in previous work of the authors. However, a model structure for microbia l growth in food products cannot simply be copied from those elaborated in ecology. The structure of a predictive growth model is indeed typical, prim arily due to the explicit modeling of a lag phase. The current paper propos es a prototype model structure for growth of mixed microbial populations in homogeneous food products. The model is able to describe a lag phase and r educes to a classical predictive growth model in the special case of single -species growth. (C) 1999 Academic Press.