Use of calcium to inhibit ripening and senescence of fruit and vegetables

• Food Crop Research Institute, Indonesia

Indonesia produces large and diverse fruit and vegetable crops. However, such tropical produce suffers from considerable wastage due to the lack of rapid transport to markets and of low-temperature storage facilities. In laboratory studies at the University of New South Wales, post-harvest application of calcium by vacuum infiltration has produced delays of several days in the ripening of avocados, mangoes, pears apples and tomatoes, although not of bananas, during storage at a ambient temperature of 20C.
The present project (one of four ACIAR projects on tropical fruit and vegetables) will investigate whether this safe and relatively simple process can be used in Indonesia to extend storage life there. Laboratory studies will determine the range of range of produce that will respond to calcium, and investigate the element's movement in plant tissue and its mode of action inhibiting metabolism.
Initial studies, mainly conducted in Australia, will examine produce such as mango and avocado in more detail to determine the relations between amount of calcium, method of vacuum infiltration, storage temperature (at 2530C) and retardation of ripening. The team will extend these studies to other produce, including papaya, guava and melons and the more exotic fruits rambutan, mangosteen, salak, logans and litchi, and to vegetables such as cabbage, root and tuber crops, various types of beans and onions.
For produce that show some response, studies on calcium movement in the plant tissue will locate any specific responsive regions, which may serve as control sites, particularly for ripening of fruit. The scientists will determine the mode of action of calcium at these sites to establish the optimum levels needed there for maximum retardation of metabolism. Consequent modification to the method of applying calcium could then ensure the most efficient infiltration of calcium into these areas.
Subsequent studies, mainly in Indonesia, will test the value of the laboratory calcium treatments on a semi-commercial scale. Assessment of final produce quality will involve appearance as well as sensory and nutritional attributes. Later work will evaluate the more promising materialthis time on a commercial scale in the Indonesian marketing systemwith some attention to the design of appropriate commercial methods of applying calcium.
Concurrently with the laboratory program, the Indonesian team will evaluate present production and utilisation of horticultural produce in selected areas of the country. Any recommendations on commercial usage for any produce will await the outcome of a study to assess the likely impact of such usage.
Results should have application in all countries of South-east Asia the currently experience similar problems with post-harvest loss of fruit and vegetables.