|When and how to harvest cherimoya
Cherimoya are a climacteric fruit that, when maturing, will show signs of softening and colour change and have an increase in their respiration rate, continuing to mature after picking and developing increased sweetness and aroma. Climacteric fruits normally have a single rise in respiration after being picked, but cherimoya show two rises. Softening comes in the first respiratory rise, while the full development of aroma, flavour and optimum flesh texture for eating come at the start of the second respiratory rise.
Despite this, it hasnt been possible to clearly determine exactly when to pick cherimoya. They need to be harvested firm, after complete development, but before any sign of softening. A maturity indicator is needed for harvesting that could allow for longer storage to accommodate the seasonality of production. This would allow exports to more easily reach international markets at their peak rather than having to be air freighted which is currently the only method possible for New Zealand exporters.
If fruit is left on the tree to ripen, the flesh can become gritty and mealy or discoloured. If fruit is picked too soon it wont ripen.
One maturing indicator is a change in skin colour (such as in the variety Bronceada, which changes from yellowish-green to a bronzed yellowish-green), although colour change may not be so apparent in cool weather.
Other maturity indicators used, which are too late in maturity for commercial use, are aroma release, seeds rattling when the fruit is shaken (although its difficult to check this while the fruit is still on the tree), a cream colour appearing between segments on the skin, and increased surface smoothness. Fruit harvested at these stages is no good for long-term storage.
When harvesting the fruit they should be cut, not pulled, from the tree, with the stem cut close to the fruit so other fruit isnt damaged during storage. Any fruit left on the tree too long will usually split or crack and begin to decay.
A range of harvested cherimoya
Only small-scale growers who pick and pack fruit by hand will be able to successfully handle tuberculate fruit (which has raised protuberances covering the skin surface), as large-scale operators will find their machinery will damage the fruit too much.
Next how cherimoya should be stored