POSTHARVEST LIFE AND QUALITY MAINTENANCE  OF CACTUS PEAR RUIT

Mulas Maurizio

Department of Economics and Tree Systems

of the University of Sassari - Italy

CACTUS PEAR FRUIT:

- fresh food source;

-          non-climateric fruit;

-          low respiration rate and low ethylene production;

-          short market period;

-          perishable commodity;

POSTHARVEST LOSSES:

    -          mechanical injuries;

    -          moisture loss;

    -          physiological disorders;

    -          pathological breakdown;

    -          insect damage;

 STORAGE STRATEGIES:

        - temperature management: 5 – 8 °C (4 weeks);

-          high relative humidity:  90 – 95%;

-          ventilation;

-          plastic film application;

MANIPULATION OF THE ENVIRONMENT:

-         controlled/modified atmophere: -         2% O2 + 5% CO2  or  2% O2 + 2% CO2;

-          low pressure storage;

-          ethylene exclusion/removal;

-          sanitation procedures;

POSTHARVEST TREATMENTS:

    - fungicides;

        -          insecticides;

       -          growth regulators;

        -          antioxidants;

PROBLEMS:

    - resistant strains;

-          government regulations;

    -          environmental concerns;

-          consumer demand;

    -          economic aspects (costs);

NON CONVENTIONAL METHODS:

-         intermittent warming: 2 °C + 8 °C (10 + 4 days)  or (21 + 7 days);

-          fruit irradiation;

-          biological control;

-          heat therapy;

HEAT TREATMENTS:

    - vapour;

            -      hot air;

    -         hot water;

OBJECTIVES:

- fruit disinfestation;

-          decay control;

-          reducing chilling injury;

-          delay of senescence;

MATERIALS (1):

* cactus pear cv ‘Gialla’ bastardoni (late fruits);

-          water, 5 min dip at 25 °C (control);

-          water, 5 min dip at 55 °C (HWT);

-          1000 ppm TBZ, 5 min dip at °C;

-          hot air treatment, 24h at 38 °C, RH > 95% (HAT);

-          HWT + HAT;

-          TBZ + HAT;

* storage, 4 weeks at 6 °C + 1 week at 20 °C;

MATERIALS (3):

* cactus pear cv ‘Gialla’ bastardoni (late fruits);

-          untreated fruit (control);

-          2% calcium chloride preharvest spray (CaCl2), 10 weeks after the 2nd induced flush of flowering;

-          hot air treatment, 24h at 38 °C, RH > 95% (HAT);

-          CaCl2 + HAT;

• storage, 6 weeks at 6 °C + 1 week at 20 °C;

MATERIALS (4):

*cactus pear cv ‘Gialla’ bastardoni (late fruits);

-          untreated fruit (control);

-          1000 ppm TBZ 20 °C;

-          150 ppm TBZ 52 °C;

* storage, 6 weeks at 6 °C + 1 week at 20 °C;

DECAY CONTROL: MODE OF ACTION

-          direct action:

            spore removal from inoculated site;

            pathogen inactivation;

-          indirect action:

            heat induced resistance;

ADVANTAGES OF THERMOTHERAPY:

-          synergistic actions;

-          safe;

-          economic;

FUTURE PROSPECTS: COMBINED TREATMENTS

-          controlled atmosphere;

-          plastic film;

-          intermittent warming;

-          biological control;

-          low fungicide doses;