DEGRADATION OF PECTIC COMPOUNDS DURING PASTEURIZED VEGETABLE JUICE SPOILAGE BY CHRYSEOMONAS-LUTEOLA - A PREDICTIVE MICROBIOLOGY APPROACH

Predictive modelling consists in describing effects of environmental f actors on microbial growth parameters. With food spoilage bacteria, th is approach must be extended to both growth and food damage characteri sation. In order to study the incidence of storage temperature on vege table damage, using predictive microbiology tools, kinetics of pectic compound degradation were studied. Chryseomonas luteola has been chose n because of its ability to grow on post-harvested vegetables. Experim ents were performed at refrigerated temperatures (0-10 degrees C) with low initial bacterial charges (10(1)-10(3.5) cfu/ml). Microbial speci fic growth rate (mu), stability phase before pectic degradation (S-p) and alteration percentage (A(p)) were chosen as reference parameters. Then, sub-optimal temperature effects on these three parameters were e stimated using modified Ratkowsky model. Results obtained in synthetic medium were compared with data observed in endive juice to appreciate the alteration of vegetable during post-harvest storage. (C) 1998 Els evier Science B.V.