RIPENING AND STORAGE
Unique ripening behaviour
- The fruit does not soften on the tree, although it is physiologically mature.
- Maturity tests are carried out regularly at pack-houses.
- For good eating quality, avocados should contain more than 10% oil. (Remember that the oils in the avocado are mainly polyunsaturated oils, and contain no cholesterol).
- Avocados with a high oil content, i.e. picked towards the end of a cultivar’s season will soften faster than early fruit with low oil content.
- Softening begins at the round end of the fruit then continues up to the stem end.
Storage of avocado
- All avocado cultivars can be kept under refrigeration for a few days in order to maintain fruit firmness.
- The recommended temperature is 6 – 7°C and the optimal relative humidity 85 – 95% (7.5°C for early season fruit).
- The general rule is that the earlier the season, the more sensitive the fruit will be to chilling injury.
- Moving avocados in and out of cold storage repeatedly is very detrimental to fruit quality.
- When avocados are ripe, they can be stored at 4°C without damage occurring.
Ripening of avocado
- In order to trigger fruit-softening, avocados can be kept at 20 – 25°C at 95% relative humidity for one or two days.
- When an avocado is approaching eating ripeness, the short fruit stalk comes off easily when touched gently.
- Hass fruits are usually picked without stems, as they are hardy.
- In a hard, unripe avocado, which will still take days to soften, the fruit stalk is still firmly attached.
- In the Hass variety, the fruit skin changes its colour from green to purple/black during the ripening process.
- In any box of avocados the fruits will vary in the time they take to ripen. This is because the fruits on the tree ‘set’ over a long period.
- However, by triggering the fruit as described above, ripening can be synchronised.
- Commercial stores and ripening rooms where fruit is kept should have adequate ventilation to prevent the build-up of carbon dioxide and ethylene,
which can be detrimental to fruit quality. - Avocados should not be stored for any length of time with bananas, apples or cabbages, as the ethylene gas given off by these crops can have a negative effect on fruit quality, causing internal discolouration.
- Fruit that starts turning grey internally, particularly Fuerte, in general has either been picked too late in the season, or has been stored for too long.
- If avocados are stored for too long at low temperatures (below 5°C) they will show typical signs of chilling injury. (Blacking of the skin and internal grey or brown discolouration).
Ripening tip
- To ripen avocados at home, keep them at room temperature until they are ripe.
- To accelerate the ripening process, place avocados in the fruit bowl with other fruit (especially bananas), or better still, pop them into a brown paper bag with the bananas.