PREDICTIVE MODELING APPLIED TO GROWTH OF SPOILAGE VIRGIBACILLUS PANTOTHENTICUS ON INDUSTRIAL CRÈME CARAMEL

Abstract

The aim of this work was to identify the spoilage microorganisms in commercially produced crème caramel and to study their growth kinetic in different conservation conditions. Fifty-four randomly selected strains were isolated from altered crème caramel samples with typical "medicine smell." In order to detect the strains that cause the smell alterations, an experimental medium (PM) was prepared with crème caramel. Nineteen out of 28 isolated strains of gram-positive spore-former bacteria developed "medicine smell" in PM medium. Of the 19 isolated strains, five were identified as Virgibacillus pantothenticus. One was studied in a fermenter in aerobiosis at 4, 12 and 30C and in anaerobiosis at 30C. The modified Gompertz model was applied. In aerobic conditions, the maximum growth rate decreased with the temperature: m = 1.68 at 30C and m = 0.28 at 12C; at 4C, there was neither growth nor alteration. In anaerobic conditions, at 30C the maximum growth rate was lower than in aerobiosis (m = 0.90), and there was no smell alteration. The appearance of these alterations was independent of the maximum growth rate. "Medicine smell" was a result of piperonal alterations. Microbiological spoilage risk could be reduced with tight control of the temperature in the production chain.3 Corresponding