RESOLVING LONG DISTANCE SHIPPING DISORDERS IN 'HASS' AVOCADOS

A number of disorders are prevalent in avocados when shipped long distances. There may be external chilling injury, but usually more seriously, is internal collapse manifested as some form of mesocarp discoloration, and pathological decay. In order to decrease postharvest stress, and extend shelf life, the concept of minimizing water loss and decreasing the rate of carbohydrate reserve usage, was studied. The use of wax fruit coatings was compared to untreated controls and packaging fruits in micro-perforated polypropylene bags. Storage temperatures of 2ºC, 5.5ºC and 8ºC were investigated. It was found that low (2ºC) storage for 30 days resulted in internally sound fruit, and that by minimizing fruit mass loss during storage, the potential for chilling injury could be decreased. A threshold value of mass loss relating to external damage at 2ºC is suggested. The lower temperature resulted in lower CO2 exchange after discharge of fruit, and such fruit also took longer to soften, extending the shelf life. The most successful treatment was packing the fruit in micro-perforated polypropylene bags. It is suggested that this technology could be extended to cartons and even pallets. The type of fruit cooling also appeared to be important, and it is suggested that hydrocooling be considered. Further work is being conducted to investigate the effects of fruit origin and maturity on quality, using the suggested technologies which minimizes fruit water loss and allows for lower shipping temperatures and consequently improved quality. Key words: Avocado, ‘Hass’, water loss control, long distance low temperature shipping, disorders.