Effect of gamma irradiation on the postharvest physiology of five banana varieties grown in India

Gamma irradiation to 20-40 krad inhibits the ripening changes in preclimacteric bananas without affecting the fruit quality. Both fruit maturity at harvest and post-irradiation storage temperature markedly influence the response to irradiation. The optimum dose and the maximum tolerable dose varied among the five varieties screened. Ability of the banana fruit to withstand higher doses of gamma irradiation depends on the physiological status of the fruit at time of irradiation. Irrespective of varietal differences, irradiation of preclimacteric bananas to doses above 50 krad resulted in severe skin discoloration and fruit splitting. Irradiation under anoxia did not markedly reduce the radiation injury, suggesting that factors other than ozone formed during irradiation in air may contribute the radiation damage. Fruits on the climacteric could tolerate up to 200 krad but no effect on ripening rate was observed. Ethylene or 2,4-D could reverse irradiation-induced inhibition of ripening in bananas. Irradiation seems to decrease the sensitivity of banana fruit to the ripening action of exogenously added ethylene

Development of a radiation process for some Indian fruits: mangoes and sapodillas

A combination heat-radiation process has been evolved for sterilizing mango and sapodilla slices in cans. The fruit, after peeling and slicing, is packed in sanitary cans with sucrose syrup, and the respiratory enzymes are inactivated by heating for 10 min at 70°C. The cans are next evacuated for 6 min at a vacuum of 28 inches Hg, vacuum doubled-seamed, and irradiated with a total dose of 4 × 105 rads at room temperature. Organoleptic evaluation, vitamin retention, and sterility tests show that these processing conditions are optimum and give an acceptable product. Canned mangoes showed progressively lower acceptability with radiation doses above 4 × 105 rads, compared with the thermally processed product. Sapodillas, on the other hand, did not show appreeiable deterioration up to 1.2 × 106 rads

Irradiation of mangoes. I. Radiation-induced delay in ripening of Alphonso mangoes

Extension of storage life of unripe and mature Alphonse mangoes could he achieved at an optimum dose of 25 krads when irradiated under air, nitrogen, or carbon dioxide. Nitrogen atmosphere during irradiation is of some advantage in minimizing changes in organoleptic quality, ascorbic acid, and carotenoids, and at the same time allowing the least spoilage of fruit. Judging from skin color and fruit firmness, a six-day delay in ripening could be expected in fruits irradiated with 25 krads under nitrogen or air. Radiation effect on fruit skin is more prominent in terms of inhibition in chlorophyll disappearance and earotenoid formation than in ripening changes in the meat of the fruit

Irradiation of mangoes. II. Radiation effects on skin-coated Alphonso mangoes

The respiratory patterns of skin-coated and uncoated Alphonso mangoes, either unirradiated or irradiated under gaseous atmospheres like air, nitrogen, or carbon dioxide, were studied. The skins were coated with an emulsion made of an acetylated monoglyceride preparation. Skin-coated fruits show physiological damage presumably due to too much inhibition of respiration. This defect is rectified by a spurt in respiratory activity when fruits are irradiated in air or nitrogen. Irradiation in carbon dioxide, which also retards respiration, shows physiological damage which is reversible, the recovery of organoleptic qualities being possible to some extent. Suppression of respiration beyond an optimum level seems to be responsible for irreversible damage to the fruit. Organoleptic evaluation, analysis for fruit constituents, skin color, and pressure tests showed that storage life of the fruit can be increased by combining skin-coating with irradiation under either air or nitrogen