Results and Discussion
IGURE 1 SHOWS THE TEMPERATURE EVOLUTION OVER THE TIME
at the fruit surface and at the fruit center in 3 different ex- periments, 1 for each freezing method.
Table 1 shows the obtained freezing rates and characteristic
freezing times of the assayed freezing methods for peach and mango. Data are mean values obtained from all the experi- ments.
It is well known that the lower the freezing rate, the greater
the structural damage. Air-blast freezing had the lowest freez- ing rate of the 3 processes studied. This was consistent with the major damage found in the fruit tissues due to the formation of large ice crystals. There was also damage in the surface zone of the samples, where there were broken cells (Fig. 2). Damage in- creased from the surface towards the center of the product. This effect is attributed to the observed thermal gradients manifested in bigger characteristic times in the center than in the surface of the fruits ( Table 1). Similar results were reported by Otero and others (1998) in eggplant.