MATHEMATICAL MODELING OF MICROBIAL GROWTH IN FRESH FILLED PASTA STORED AT DIFFERENT TEMPERATURES

Growth curves for a selection of pertinent microorganisms in ricotta and ricotta-filled ravioli were analyzed in terms of Gompertz's model. The growth of Enterobacteriaceae, molds and yeasts and psychrotrophic microorganisms during storage at 0, 4, 8 and 10C was determined. Lag phase duration and specific growth rate were inversely related. The activation energies from an Arrhenius-type equation were calculated for the microorganisms under study. For ricotta samples, molds and yeasts were the most sensitive organisms showing E_μ values of 74.60 KJoule/mol while Enterobacteriaceae and psychrotrophic microorganisms had E_μ values of 24.30 and 25.70 KJoule/mol, respectively. For ricotta-filled ravioli samples, the three microorganisms showed activation energies in the range of 31.47–32.99 KJoule/mol; hence the temperature dependence of their growth rates was comparable. Results allow to predict microbial growth of different microorganisms in ricotta and ricotta-filled ravioli when exposed to different storage temperatures.