Effect of a cold quarantine treatment on physiological disorders and quality of cactus pear fruit

Despite Italy is second only to Mexico for fresh production of cactus pears worldwide, postharvest handling and treatments are quite simply, being fruit immediately marketed after harvest. However, as the demand for fresh fruit beyond the harvesting period is constantly growing, in the next future the cactus pear industry likely will have to adopt postharvest treatments and technologies that can widen the marketable window. Yet, the potential exploitation of new markets in countries where the introduction of pests like Mediterranean fruit fly are considered risky, can be achieved only if fruit are subjected to approved quarantine protocols. Of the three main cultivated varieties ('Bianca', 'Gialla' and 'Rossa') limited studies concerning cold storage have been done mainly on fruit of cv 'Gialla', while knowledge on response to cold quarantine treatments lacks for all cultivars. Thus this study was undertaken to get knowledge on postharvest behavior of the three main Italian cultivated cactus pears varieties, i.e. 'Bianca', 'Gialla' and 'Rossa' subjected to a cold quarantine treatment followed by either a week of simulated marketing conditions at 20 degrees C or by two additional weeks of storage at 8 degrees C before transfer to simulated marketing conditions at 20 degrees C for three days. These storage conditions so far are not practiced by packing houses as fruit are directly marketed after harvest, but could be a typical protocol in case fruit should be sold in countries that require approved cold quarantine treatments. Results showed an abnormal increase in respiratory activity and ethylene production rates following transfer from cold storage to 20 degrees C, especially after the two additional weeks of storage at 8 degrees C. Peel disorders and decay incidence were slight at the end of storage at 2 degrees C or 8 degrees C, but severe peel disorders developed when fruit were moved to 20 degrees C. Peel injury, decay incidence, the loss of overall appearance upon transfer to 20 degrees C were more severe in fruit stored for two additional weeks at 8 degrees C. Among the three cultivars, susceptibility to chilling injury and decay was higher in cv 'Bianca'. Nevertheless, cold storage seems not to affect the chemical and sensory quality of fruit, whose changes were similar in all cultivars.