Ethylene production in freshly harvested fruit peaked before full ripeness, and showed transient increases in the after-harvest period. At later times ACC became depleted, and both ACC and ethylene production declined to low levels. ‘Reka’ had lower levels at harvest than the other cultivars. In vented storage, little or no new ACC was formed after harvest, and the total ethylene production was determined by the ACC content at harvest. The ratio of ACC content to ethylene production (a measure of the half life of ACC) varied from 50 ˜ 100 h in unripe fruit to 7 ˜ 20 h in ripe or stored fruit. MACC formed a low proportion of total ACC, and fluctuations in storage suggested that the two forms were interconvertible. MACC levels were higher in fruit exposed to ethylene. Exogenous ethylene up to 2 μll/l stimulated ACC content and ethylene production, but had only minor effects on soluble solids and acid content. Ethylene production was suppressed by low temperatures or in high CO₂ - N₂ atmospheres.

The high internal concentrations of ethylene in the flesh, ca. 2 ˜ 8 μlg, is consistent with the relatively minor effects of the exogenous ethylene, and suggest that suppression of respiration by rapid cooling in the early postharvest period is more important than ventilation for maintaining freshness in this crop.

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