During-harvest handling of mangoes

Mango fruits should be harvested at the ideal stage in order to develop the most adequate organoleptic quality and the longest postharvest life. Less mature fruit is usually more sensitive to chilling injury during after-harvest storage and often develop an inferior aroma and flavor. The immature fruit may not ripen adequately after harvest, and in some cases it may never ripen. On the other hand, fruits harvested when over-ripe are very sensitive to bruising, decay and to water loss and quality deterioration, and will have a short shelf life. The right stage of maturity at harvest will depend on whether the fruits are intended for immediate consumption, sale in nearby markets or processing (late harvest) or fruits harvested at physiological maturity and intended for transport to distant export markets (‘mature green mangoes’).

NB: It is recommended that fruit for drying is also picked as soon as visible signs of ripening appear (¼ to ½ ripe), to minimize damages during handling and to regulate the ripening process viz-a-viz the processing quantity requirements.

Generally, physiological maturity in mango is reached about 12 to 16 weeks after fruit set, with variations depending on the variety, geographical region and environmental conditions. Commonly farmers use physical characteristics of the fruit to determine maturity, for example; skin / flesh colour, fruit size, or softness to touch;

At the time of maturity, the mango stone becomes hard and pulp colour changes from white to yellow starting at the endocarp and progressing outward to the skin during maturation.

Floating fruits in water (fruit density test) – as mango fruits mature they accumulate dry matter and thus become denser. Using a 1.0 % salt solution (100 gm salt in 10 litres water), pick 12 fruits at random per tree, if 9 out of 12 fruits sink to the bottom, these are ready for harvest. More floaters mean fruits are immature hence, additional days are needed.

At commercial scale, total soluble solids, total acidity, and the sugar / acid ratio are good criteria for determining the maturity stage. During maturation soluble solids increase and titratable acidity decreases. Most markets require mangoes to be harvested with about 9 to 11 % total soluble solids (°Brix), pH (3.5 to 4) and °Brix / acid ratio 32.

In practice many methods are employed by farmers for harvesting mangoes. Sometimes trees are shaken and fruits drop to the ground causing serious damages to the fruit and the tree. Some farmers use long sticks with a hook to pull the fruit and drop it resulting in the same fruit damages as with shaking the trees. In few farms, a pole with a net at the end is used to pick fruits from the upper part of the tree. However, most of these nets are not constructed in a way that enables the fruit to be cut, but rather to pull it. Therefore, although the net receives the fruit and prevents it from dropping on the ground, it does not allow cutting it with a stalk.

With all these methods, the fruit is harvested without a stalk. Harvesting fruits without the stem increases latex flow, water loss, and decay. Latex causes burning of fruit skin, deterioration of fruit color, and even health problems for allergic pickers and packers. To avoid these problems, fruits should either be picked individually by hand using appropriate instruments like clippers / shears or by carefully pulling the fruit from the tree into a basket or net, or by two people, one on a ladder picking the fruit and the other person catching the falling fruit. Either way, ensure that the fruit has a 10 cm stalk which after harvest can be cut to 2–3 cm and laid stalk down on a wooden grid to let latex flow out without spoiling the fruit-skin. When fruits are harvested after 08:00 hours, the turgor pressure in the fruit will be lower and hence less latex will be exuded from the cut stems.

In Mali, some farmers leave the harvesting of mango to buying agents (– known in French as ‘pisteurs’) who upon payment of the agreed amount to the farmer, will harvest themselves. Commonly they maximize the harvest by taking all of the fruit they can, regardless of its quality and ripeness. However, alternatively farmers are organizing themselves in ‘harvesting teams’ (‘Coupeurs’). It is therefore necessary that, as long as such teams are used, training intended to improve organic mango fruit quality should also be provided to these teams.