Respiration Rates of Fresh-Cut Peach Slices as Affected by Storage Period of Intact Fruit

To design modified atmosphere packaging (MAP) suitable for minimally processed fruits it is necessary to know the respiration rate of the product. The respiration kinetics of fruits and vegetables are complex because of the large number of variables involved. Some variables such as the type of cultivar, degree of ripeness, storage temperature, and O-2 and CO2 concentrations inside the package have been extensively studied. However, the effect of the length of time between harvest and processing remains poorly understood. The aim of this study was to determine the influence of storage time prior to processing on the respiratory kinetics of fresh-cut peach slices and its application in modelling and designing packages with microperforated films. Peaches ('Calante') were harvested at commercial maturity stage and stored at 1 degrees C and 95% RH for 21 days. Afterwards, whole fruit were washed, drained, peeled, stoned and cut into slices. The slices were dipped in a preserving solution at 2 degrees C and then stored at 4 degrees C in a humidified air flow. The respiration rate was determined at 0, 6, and 12 days in a closed system. Immediately after harvest, the respiratory rate of peach slices was also determined for use as a reference. The O-2 consumption and CO2 production were measured by GC. The slices obtained from peaches processed immediately after harvest showed a higher respiratory rate than those from fruit stored for 21 days. The respiratory rate for the samples kept in airflow diminished during the first 6 days. However, after 12 days the respiratory rate showed a sharp increase. A mathematical model was used to predict the evolution of the gaseous composition inside microperforated packages. The results show that for a proper MAP design, the changes in respiratory activity produced by storage time should be taken into account.