Depending on cultivars and environmental conditons it takes 90 to 160 days after flowering for Kenya mangos to reach maturity stage of final fruit development (ripeness). Not all fruits on one tree will ripen at the same time. A great problem is to determine precisely the stage at which the fruit is ripe for picking. Fruits harvested too early will be of inferior quality after storage; however, fruits picked when too ripe cannot be stored for any length of time and may give rise to problems such as jelly seed. The fruit will have its best flavour if allowed to ripen on the tree. None of the tests (acid, sugar content or specific gravity) used to determine ripeness, however, are fully reliable.
The fruits are generally picked when they begin to change colour. This may occur first in a small area or the change will cover most of the fruit’s surface. However, one destructive maturity test that can be applied even before the external colour break starts is to examine the colour of the flesh around the seed. When this begins to change from green-white to yellow or orange, it indicates that the fruit is beginning to ripen and may therefore be picked. Also the greater the swelling of the shoulders above the stalk also called peduncle attachment, the riper the fruit is likely to be (see diagram of a mature mango fruit).
During and after harvesting the highly perishable fruit must be handled with the greatest care. The fruit is removed from the tree by cutting the fruit stalk about 2 cm from fruit. This will prevent the latex milky plant juice (exuded from the cut stalk) adhering to the skin of the fruit, staining it and rendering it unattractive. Ladders or long picking poles with a cutter blade and an attached canvas bag, held open by a ring, are also in use. To avoid physical damage, the picked mangos should be carefully placed into clean wooden or plastic containers and never into gunny bags. If there is a delay in the transfer of the fruits to a store or packing shed they should be kept in a sheltered place to minimize sunburn, loss of moisture and accumulation of dust.
After any sorting, grading, washing, fungicidal treatment and perhaps waxing, the fruits are ready for packing, preferably into shallow single-layered trays of 4–5 kg each. Because mangos are harvested during the summer months, the fruit temperature may be as high as 35°C and more. This has a detrimental effect on the shelf life of the fruit. It is therefore advisable to move the packed fruits into cold storage as quickly as possible to help them lose this inherent heat. The recommended storage temperature must, however, not drop below 7°C (range: 7–10°C) as otherwise cold injury may occur.