Mathematical modeling of microbial growth in packaged refrigerated orange juice treated with chemical preservatives

Microbial flora of refrigerated orange juice was analyzed during storage at 10 degreesC and the effects of the following factors were discussed: 1) th e previous washing process of the orange peel, 2) the different levels of t he added preservatives (citric acid, ascorbic acid, potassium sorbate, sodi um benzoate), 3) the gaseous permeabilities of the packaging film. Gompertz equation was applied to model molds and yeasts growth for the different tr eatments and packaging conditions. The washing procedure with sodium hypoch lorite extend 2 - 3 d the storage life of the juice (time to reach microbia l counts of 10(6) CFU/ml) in both packaging films. The use of organic acids and potassium sorbate or sodium benzoate (1.66 - 6.94 mM) led to storage l ife values > 11 d in polyethylene and > 20 d in the low gaseous permeabilit y film, maintaining good sanitary conditions.