HEAT RESISTANCES OF CANDIDA APICOLA AND ASPERGILLUS NIGER SPORES ISOLATED FROM DATE FRUIT SURFACE

Candida apicola and Aspergillus niger strains were isolated and identified from Deglet-Nour dates, and their loads were determined on the fruit surface. The thermal inactivation of their spores was evaluated between 42 and 70C. The estimated D values for C. apicola and A. niger were D-50 = 2.3 +/- 0.4 min and D-50 = 22.1 +/- 2.1 min, respectively. The z(T) values obtained were 9.4 +/- 2.6 and 9.6 +/- 1.0C for C. apicola and A. niger, respectively. The experimental survival spores obtained on the date surface during non-isothermal treatment were compared with the simulated data based on the Bigelow method and on pasteurization value calculations. C. apicola and A. niger spores can be inactivated by relatively low temperatures. Validation shows that this model and its parameters can be used to optimize pasteurization of these fungal spores on the surface of fruits using the temperature-time profile data. These thermal treatments can pasteurized date surface while minimizing the color date degradation.