Sonication treatment of pomegranate juice containing Saccharomyces cerevisiae and Byssochlamys fulva: Thermodynamic and predictive modeling after treatment and during shelf life

摘要

The effect of ultrasound treatment (100 W, 30 kHz; 50 and 100% amplitudes) on inactivation of Saccharomyces cerevisiae and Byssochlamys fulva in pomegranate juice and shelf life of the juice during storage at different temperatures (5, 15 and 30 degrees C) for 30 days was modeled using predictive and thermodynamics models. The Baranyi and square root type models were implemented to determine the growth rate of microorganisms. It was predicted that the minimum growth temperature (T-min) of B. fulva increased by increasing sonication amplitude, however, the T-min of S. cerevisiae was not function of sonication amplitude. The predicted shelf life was shown to be in good agreement with the measured sensorial shelf life. Increasing the temperature from 5 to 35 degrees C, reduced the shelf life from 17.5 to 3.5 days for B. fulva and from 15 to 5 days for S. cerevisiae. Moreover, for B. fulva, the activation energy (E-a) decreased from 43.4 to 27.5 kJ/mol by increasing the amplitude, while no significant change was observed for S. cerevisiae. Besides, thermodynamics properties of the shelf life such as enthalpy (Delta H++), entropy (Delta S++) and Gibbs free energy (Delta G(++)) were proven to be suitable measures to determine the microbial spoilage reaction.