Microbial aspects on short-time osmotic treatment of kiwifruit Original Research Article

In order to study the influence of solution concentration on the microbiological quality of fruit after osmotic dehydration, Kiwifruit slices have been immersed for three hours into osmotic solutions, inoculated with Metschnikowia pulcherrima, at different concentrations (from 40° to 65° Brix) to obtain high moisture fruit products. Microbial adhesion kinetic to the fruit surface was studied: the number of adhering cells was affected by the sucrose concentration of the osmotic solution and the microbial adhesion was strongly reduced at high sugar concentration (65° Brix). Samples were packed in LDPE bags under air atmosphere and preserved at refrigeration temperature. Microbial load of inoculated and osmotically treated kiwifruit slices was determined during eighteen days of storage time. A mathematical model based on the Zwietering modified Gompertz equation, was used to obtain growth parameters of the yeast and to outline the microbial evolution of osmodehydrated Kiwifruit slices during storage. Storage data showed that, the microbial load was the lower, when higher the solution concentration used for the osmotic dehydration.