Effect of fruit maturity on the response of 'Kensington' mango fruit to heat treatment

Abstract

The effects of conditioning and hot water treatments on immature and mature ‘Kensington’ mangoes were examined. A hot water treatment of 47°C fruit core temperature held for 15 min increased weight loss (50%), fruit softness (15%), disrupted starch hydrolysis and interacted with maturity to reduce the skin yellowness (40–51%) of early harvested fruit. Immature fruit were more susceptible to hot water treatment-induced skin scalding, starch layer and starch spot injuries and disease. Conditioning fruit at 40°C for up to 16 h before hot water treatment accelerated fruit ripening, as reflected in higher total soluble solids and lower titratable acidity levels. As fruit maturity increased, the tolerance to hot water treatment-induced skin scalding and the retention of starch layers and starch spots increased and susceptibility to lenticel spotting decreased. A conditioning treatment of either 22° or 40°C before hot water treatment could prevent the appearance of cavities at all maturity levels. The 40°C conditioning temperature was found to be more effective in increasing fruit heat tolerance than the 22°C treatment; the longer the time of conditioning at 40°C, the more effective the treatment (16 v. 4 h). For maximum fruit quality, particularly for export markets, it is recommended that mature fruit are selected and conditioned before hot water treatment to reduce the risk of heat damage.