The effects of short heat-treatments on the induction of chilling injury in avocado fruit (Persea americana Mill)

The ripening of avocado fruit and the development of chilling injury in relation to short heat-treatments has been studied in the cv. 'Hass'. The minimal conditions needed to induce maximal production of heat shock proteins (HSP) in samples of mesocarp tissue were an exposure to 38 degrees C for 4 h. Short heat-treatments applied during the ripening process reduced the maximum rate of ethylene production during the climacteric period, but this was not correlated with lower levels of 1-aminocyclopropane-1-carboxylic acid (ACC). Heat-treatment also hastened the occurrence of the climacteric in fruit treated in the early pre-climacteric period. A similar regime applied to fruit immediately prior to this event delayed the onset of the climacteric. The use of short heat-treatments to overcome the effects of chilling injury was investigated by subjecting the fruit to 38 degrees C for 0, 6, 12, 24? 36 or 48 h prior to transferring them to 0 degrees C for 7, 14 or 21 days. Heating for 6-12 h provided a significant degree of protection from chilling injury and therefore may have potential for extending the period of cold storage.