Being indigenous to South-east Asia and Papua New Guinea, the banana is an important local food crop, and in some countries is also an export crop. Nevertheless, the fruit faces a number of problems there, including losses due to disease, to premature ripening or to mechanical damage such as bruising, poor quality due to inappropriate ripening environments and loss of distant markets due to limited shelf life.
To tackle these problems, this project will study: causes and control of post-harvest losses, especially those due to diseases; ethylene physiology and ripe-fruit quality, temperature management during handling; and modified-atmosphere storage and physiology.
In Malaysia, scientists at MARDI will investigate storage and transport, physiology and pathology. Using the many Malaysian banana cultivars, they will measure green life of the fruit, test ethylene evolution and determine response to storage atmospheres. Assessments of the cultivars for desirable ripe-fruit quality will include taste panel tests. Following integration of the various aspects of the entire project, this team will conduct semi-commercial and commercial-scal storage and handling trials.
Complementary studies in the Malaysian university system will include: a post-harvest disease survey and screening of possible control measures; measurement of biochemical indices of fruit quality, using fruit material from the MARDI trials; and evaluation of the role of ethylene physiology in determining quality.
In the Philippines, research will emphasise handling of bananas and the physiology of modified-atmosphere storage. Major banana companies there already use the ‘vacuum’ packing method developed by CSIRO, and the scientists will investigate whether ethylene removal, the application of intermittent evacuation or the addition of other gases such as carbon dioxide can confer additional benefits. They will determine the effects of different parameters such as temperature, the application of fungicides and timing of treatment on shelf life, fruit quality, wastage from disease and the green-ripe disorder. They will also characterise the physiological and biochemical status of the stored fruit in terms of respiration, specify effects on the ethylene biosynthetic pathway and various enzyme activities associated with quality changes during and after modified-atmosphere storage.
Scientists in Australia will conduct a substantial laboratory-based program-with field trails, mainly on controlled ripening, in northern New South Wales. In pathology studies with pathogenic isolates, both local and from the work in Malaysia, they will test heat sensitivity of the fungi to assess the usefulness of low-cost hot water dips for fruit, with instant added fungicides. They will measure the heat-transfer properties of bananas, packed in various ways in flowing air streams, and apply the results to the practical problems of cooling and ripening these and other fruits. This will involve construction of apparatus to measure the surface heat-transfer coefficient.
A third aspect of the Australian studies concerns fruit quality and controlled ripening. In close association with the team in Malaysia, the scientists will note biochemical changes in fruit ripened under varying conditions of temperature and humidity, and will study, in particular, the role of the ethylene biosynthetic system in development of fruit quality.
Ethylene studies will cover both South-east Asian and Australian cultivars, to determine the correct environment conditions for ripening different kinds of bananas. Investigations into the mechanism of action of ethylene absorbents are expected to identify reliable absorbents manufactured from cheap local materials. This team will also assess the needs of Malaysia and the Philippines for low-cost ripening rooms and tents, and the possible need for more elaborate rooms.
Integration of all these approaches should lead to the development of improved handling systems for bananas, and all promising handling technologies will be tested on other fruits, especially pineapples.