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Lengthening the storage-life of tropical and subtropical fruits

Objective

- To prolong the storage life of tangerines and other citrus fruit as well as mangoes and tomatoes by the use of individual-seal packaging;
- To combine this technique with curing and the application of elicitors;
- Optimisation of these techniques in order to prolong storage and improve other properties of the fruit, including fruit firmness and resistance to storage pathogens;
- To study the occurrence of putative defence reactions such as the accumulation of antifungal compounds and lignification;
- Examination of textural changes of peel and juice vesicles of citrus fruit during storage.
- Application of modified atmosphere packaging improved the keeping quality of mango. Use of perforated polyolefin films enabled the combination of normal ripening of the fruit together with reduced weight loss. This was successfully tested in an experimental shipment of mangoes from Thailand to Japan.
- Physical treatments of mango fruit (heated forced air, hot water dips, UV illumination) markedly reduced the decay incidence. Heat treatment improved colour of 'Tommy Atkins' mango and enhanced ripening in most of the Thai varieties.
- Seal packaging of tangerines markedly extended their storage life and improved the fruit quality as compared to commercially used waxing treatment.
- Heat treatments (curing and hot water dips) reduced decay and chilling injury of various citrus fruits. Compared to curing, hot water dip was found to be easier to implement.
- Several antifungal compounds were detected in citrus, mango and tomato fruits. Citral was found to be one of the major preformed antifungal compounds in lemon. The identification of other antifungal materials is in progress.
- It was suggested that citral plays a role in the resistance of lemon fruit against postharvest pathogens. The effect of postharvest heat treatment and plant growth regulators on citrus decay might be related to the changes of preformed antifungal materials.
- Ultraviolet illumination elicited intensive production of phytoalexins scoparone and scopoletin in the flavedo of kumquat, orange and lemon, and reduced susceptibility of these fruits to Penicillium digitatum. Phytoalexin accumulation correlated with an increase in antifungal activity of flavedo extracts.
- Pulp weakening during pomelo storage was found to be a result of the following combined factors:
- the increase in the amount of soluble pectin;
- the increase in pectinmethylesterase activity;
- the degradation of cell wall material;
- the cultivar with the highest number of subepidermal layers was the most stable during storage.
- An optimised Modified Atmosphere Package for mango fruit was designed using a mathematical model. Numerous seal packaging experiments were carried out including a commercial mango shipment to Japan;
- The effect of hot water dips on chilling injury and decay of various citrus fruits was determined in comparison to the effect of heat curing;
- Storage experiments were conducted on tangerines in Thailand and Israel using seal packaging with different films in comparison with waxing;
- Investigations were conducted in search of preformed and induced antifungal materials in the fruit of citrus, tomato and various mangoes cultivars in relation to the enhancement of decay resistance by heat and UV treatments;
- Changes in cell wall components and the activities of related enzymes were examined during the weakening of pomelo pulp in storage.

Funding Scheme

CSC - Cost-sharing contracts

Coordinator

THE AGRICULTURAL RESEARCH ORGANISATION OF ISRAEL - THE VOLCANI CENTRE
Address
Derech Hamqabim
50250 Bet Dagan
Israel

Participants (3)

Chiang Mai University
Thailand
Address

50002 Chiang Mai
Kasetsart University
Thailand
Address
Kampangsaen Campus
73140 Nakorn Pathom
UNIVERSITY COLLEGE LONDON
United Kingdom
Address
Gower Street
London