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The current status of research on the use of ionizing radiation for shelf life improvement and disinfestation of fresh tropical fruits like bananas, mangoes, and papayas are reviewed. The aspects covered are influence of maturity and physiological state of the fruits on delayed ripening and tolerance to radiation; varietal responses; changes in chemical constituents, volatiles, respiration, and ethylene evolution; biochemical mechanisms of delayed ripening and browning of irradiated fruits; and organoleptic quality. The efficacy of the combination of hot water dip and radiation treatments for control of postharvest fungal diseases are considered. The immediate potential of radiation as a quarantine treatment, in place of the currently used chemical fumigants, for disinfestation of fruit flies and mango seed weevil are discussed. Future prospects for irradiation of tropical fruits are discussed in the light of experience gained from studies conducted in different countries.

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The activity of a crude enzyme preparation.extracted from hepatopancreas of the freshwater prawn, Macrobrachium-rosenbergii, was assayed for collagenolytic, trypsinolytic, orchymotrypsinolytic, and pepsinolytic activities against collagen, lyophilized prawn tissue, and artificial substrates. At optimum pH for each activity, the enzyme preparation had collagenolytic activitiy, slight trypsinolytic and ol-chymotrypsinolytic activities; and no pepsinolytic activity. Of the commercial enzymes tested, only collagenase significantly degraded lyoph@zed prawn tissue. These results suggest that the -. prawn enzyme preparation may contain a collagenolytic portion which might affect the texture of the prawn.

A determination of the relationship of acidity and sucrose concentrations to rate of osmotic dehydration of papaya and mango was made. Dehydration by the osmotic step was found to increase with increasing sucrose concentration and contact time. Mango weight loss was directly proportional to sucrose concentration while it was non‐linear for papaya, apparently due to reversal of pectin gelation. Acidification of concentrated sucrose syrups with organic acids increased the osmotic rate for dehydration of papaya but not mango. Combining acid and sucrose was found to increase moisture removal from papaya by inhibiting gelation.