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).
- 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.