Only fully grown mangoes should be picked for harvesting; this will ensure that they have an excellent flavour when fully ripe. "mature" is defined as the stage of development that ensures the correct completion of the ripening process in the United States Standards for Grades of Mangos. These standards were last updated in 2007. At the time of harvest, a mango should have already begun to mature from the inside (stage 2) to live up to this anticipation. If mango is picked when it is still immature (stage 1), it will not ripen properly and will never have a good flavour or aroma.
Numerous indicators of maturity, such as;
- The number of days since full bloom,
- The shape of the fruit,
- Its specific gravity,
- The colour of the skin and the pulp,
- The starch content,
- The total solids (dry matter content),
- The total soluble solids, and
- The titratable acidity has all been evaluated.
The most common types of maturity indices are the change in fruit shape (fullness of the shoulders; shoulders rising over the stem attachment point) and the change in skin colour from dark green to light green to yellow (in some varieties). The development of red blush on the skin of some mango cultivars is not a reliable indicator of ripeness. This blush may become more noticeable as the ground colour transforms from green to yellow during the ripening process. The degree to which the flesh develops a golden tint throughout maturation is a dependable maturity index in all cultivars.
Even though it is difficult to assess when a crop is ready to be harvested, it might be advantageous to instruct individuals to look for certain qualities when picking mangos to be selected. These characteristics are as follows. These criteria can also be used to sort harvested mangoes by maturity and ripeness stage at the shipping point (packinghouse) or the receiving point (importer's facility or distribution centre) to reduce variability in ripening and deterioration rates during subsequent handling. This can be done to reduce how long it takes for mangoes to go wrong after being handled. It is commercially available online sorting technology based on firmness (deformation force), soluble solids content (near-infrared light), and/or the severity of faults.
Fruit shape
When mangoes reach full maturity, they will swell and acquire what is commonly referred to as "shoulders." Shoulders are the expansion development that occurs around the fruit stem. Additionally, the fruit of cultivars gradually changes shape from flat to round, developing what is known as "cheeks" along the way. For many cultivars, a fruit's shape and whether or not it has full cheeks or outgrown shoulders are considered reliable indicators of when it is ready to be harvested.
Irrigation affects the shape of mango fruit, such that mangos picked from trees that have not been irrigated have fruit that is thin and gives the appearance of being immature even when the maturity level may be appropriate. Mangoes grown on farms that receive adequate irrigation have wider cheeks and a rounder form as a result.
External appearance
The variations in colour on the outside of the fruit do not necessarily match the maturation of the fruit on the inside. Some cultivars keep their green colour even when they are fully ripe, whilst others turn from green to yellow as they mature. In addition to the actual physiological development of the fruit, the position of the fruit on the tree and the amount of sunshine it receives when the fruit is growing and developing significantly impact the amount of red blush that appears on its cultivars. In cultivars with the red blush characteristic, the red blush on the fruit should not be considered the only indicator of when the fruit is ready to be harvested.
The mango peel contains a number of natural openings known as lenticels. The primary function of these apertures is to promote the exchange of gases. As the fruit matures, the lenticels found in mangoes become more prominent. A common measure of harvest quality in South American countries is the size or prominence of the lenticel. However, Haden mangoes are fully mature when the red blush begins to lessen, and the green lenticel spots become yellow. This is because lenticel expansion does not appear as prominent in other commercial varieties.
A discernible shift in
glossiness appears in mature mangoes, most likely as a result of shifts in the
chemical components of the peel waxes. Mangoes get more glossy as they mature.
As a consequence, mangoes develop off-white shades of green on the peel
(similar to how grapes "bloom"), which harvesters quickly detect as a
sign that the fruit is ready to be picked.
Latex level
As the mango fruit matures and begins to ripen, the milky, sticky latex or sap that begins to exude from the stem (pedicel) as soon as the mango fruit is detached from the tree transforms into a clear, watery fluid. The mango tree most likely stores water inside the fruit. As a result, the amount of latex in the mango's vascular tissues fluctuates. Extremely tough fruits contain flesh that is so hard that it can limit the growth of vascular veins when they fill with latex. When the mangoes are harvested, the pressure is visible due to latex leaking from the plant's stem. Some commercial mango operations use the quantity or force of the latex squirt as an indicator of the fruit's maturity and/or its susceptibility to harm during hot water treatment.
This can be accomplished in two ways. When measured at the same turgidity level (the pressure level affected by the amount of water retained within the fruit), a mango that has reached a more advanced stage of maturity will have less latex ejection. The force with which the latex sprays differs widely. This is because the quantity of turgidity in the fruit and the maturity of the fruit both affect the force with which the latex squirts out. As a result, it is impossible to quantify a relationship between the amount of latex squirted and the freshness of the fruit. A ripe mango, on the other hand, will not spray any latex at all. When more than thirty per cent of the fruits in a typical sample have a strong latex squirt, it is common to practise in the food industry to wait for an extra twenty-four (24) to forty-eight (48) hours before subjecting the fruit to heat treatment.
Total soluble solids (TSS)
Due to the fact that sugars make up the majority of the soluble solids in fruit juice, total soluble solids (TSS) can serve as a proxy for an estimate of the amount of sugar contained. However, soluble pectins, phenolic compounds, organic acids, and organic acids all contribute to total soluble solids (TSS). The measurement of total soluble solids (TSS) can be impacted by starch suspended in the juice of unripe or immature mangoes, which can lead to inaccurately high values. Additionally, irrigation schedules and the amount of rainfall significantly impact the total soluble solids content of mangoes that are present at harvest time. Compared to mangoes of similar maturities collected from farms where irrigation was stopped before harvest, mangoes picked from fields where irrigation is ongoing or under rainy conditions are likely to have lower TSS levels. The total solids content (TSS) is a better indicator of ripe mango quality than a measure of harvest ripeness because of these potential concerns.
Using a refractometer,
which analyses the refractive index of a small sample of fruit juice to determine
how much a light beam is slowed down when it passes through the fruit juice, it
is possible to calculate the total soluble solids content (TSS) of the fruit
juice. The refractometer has two scales: one for the refractive index, which
may be read directly, and another for the corresponding °Brix or per cent total
soluble solids. The possibility of operator error in reading values is minimised
by digital refractometers. The levels of total soluble solids, or TSS, in
mature green mangos (a minimum of 7 to 9% at harvest) rise steadily during the
ripening process, eventually reaching 14 to 20% in ripe fruit. The minimum
levels of total soluble solids (TSS) considered acceptable for mangoes
destined for export may vary from one transportation distance to the next.
Therefore, the minimal TSS for mangos coming from South America to the United
States may be lower than the minimum TSS for fruit coming from Central America
and Mexico. Still, the total solids (dry matter) content needs to be similar.
The most frequent method for extracting juice consists of pressing one half of a fruit straight onto the prism of a portable refractometer. However, the outcomes that can be obtained through manually squeezing mature fruit during harvest can differ from person to person. Because juice runs off the ripest part of the fruit first when it is squeezed by hand, the TSS content may be overestimated as a result. Another technique for obtaining juice from very firm fruit is to cut off the cheek portion of the fruit and then scrape the edge of a knife along the exposed flesh. This causes a small amount of juice to gather on the knife blade, which is then dripped onto the refractometer prism. The most accurate method is to measure the total sugar content after first extracting juice from the entire fruit using a manual juicer. On the other hand, the mango industry finds that the procedure of extracting juice from entire fruits takes too much time and is too labour-intensive. The total soluble solids (TSS) content can be determined by taking a small sample of flesh tissue from both cheeks. This will make the process simple and expedient. Using a potato peeler, remove two to three plugs of flesh tissue from the equatorial region of each side of a mango. Then, using a lemon squeezer, extract the juice from the flesh tissue. Finally, use the extracted juice to determine the TSS content using a digital refractometer.
Colour of flesh
The level of maturity can be determined by the colour of the flesh (for example, if approximately 75% of the area shows a yellow colour, this corresponds to stage 3 on the 5-point scale shown in the accompanying photographs). This level of maturity can be related to external factors for each cultivar grown in each production area. These are all external features, such as the size of the fruit, its shape (how full the shoulders are), and the colour of the skin around it (change from dark green to light green to yellowish green). Only the mangos that correspond to the maturity indices should be picked by the harvest teams, and they should be instructed to do so.
The firmness of mango fruit gradually diminishes as it matures and ripens on the tree, and this trend continues through harvesting, postharvest handling, and storage of the fruit. It is not recommended to utilise firmness as the only criterion for harvesting, although it can be used as an index of the ripeness stage. At the time of reception at packinghouses, the minimum flesh firmness for mangoes destined for export from South America should be between 15 and 20 lbf. If the TSS and colour ratings of the flesh are satisfactory, lower values for the hardness of the flesh might be acceptable. The initial hardness of mangoes that are carried shorter distances, such as those from Mexico and Central America, maybe lower (10 to 15 lbf), but the colour of the flesh is a better indicator of whether the fruit has reached the correct stage of maturity. The idea of maximal firmness can serve as a valuable signal of immaturity for mangoes that are harvested early in the season. Mangos with high flesh firmness (22 lbf or more) will most likely have a greater frequency of immature fruit and damage caused by heat treatment. There are a variety of destructive and non-destructive methods that have been used to measure the hardness of mango fruit. The flesh penetration force on both cheeks, with the skin peeled off, is measured with a penetrometer with an 8 mm (5/16 inch) tip, which is the method used most frequently to determine hardness. Because mangoes mature (and the flesh softens) from the inside out, the depth at which the peel is removed before measuring should be consistent from fruit to fruit to obtain accurate readings. A more proper procedure would be to cut the fruit in half along its length and then take the measures on either side of the seed, in the middle of the gap between the seed and the skin.
The percentage of dry matter (total solids)
Dry matter (DM) content indicates harvest maturity more strongly than total solids content (TSS). It is strongly related to TSS and ripe mangos' eating quality. In Australia, the DM content of the flesh tissue is regarded as a significantly more accurate indicator of harvest maturity than the flesh's colour and the first TSS. For instance, 18 to 20% dry matter accumulation can be utilised as an accurate harvest maturity index for mangos. Mango cultivars can be evaluated using a comparable range of DM content in conjunction with additional harvest indices, such as the colour of the flesh and its hardness. In a microwave oven, the water can be evaporated from pre-weighed fruit tissue to determine the DM content relatively quickly.
Peel tissue should not be included when calculating the amount of dry matter (DM). Because peel tissue contains a higher concentration of DM than flesh tissue, the results of DM content measurements may be overestimated if peel tissue is included. The tough, green flesh of mangoes can be granted by hand or thinly cut using a potato peeler. Both methods produce a similar texture. Put a sample of about 5 grammes of tissue, weighed to the nearest hundredth of a gramme, into a Petri dish or other container that can be heated in the microwave. Then, adjust the power of the microwave so that the tissue can dry without being burned, and reweigh the sample immediately after it has finished drying. Repeat the microwave treatments at one-minute intervals until there is no change in the weight (minimum drying time is about 4 to 7 minutes).
Written By: Techno Journey