· If flower induction is done early season (October, November and December), allow fruits to mature longer. This requires from 120 to 130 days after flower induction before harvest.
· If induction is done in season (January, February and March) fruits mature fast and these requires only 105 to 115 days before harvest.
· If trees are not induced (natural flowering), fruits are usually harvested 82 to 88 days after full bloom.
· Other distinguishing features of matured fruits are:
o Flattened shoulders at the stem end compared with sloping shape in immature fruits
o Fullness of cheeks
o “bloom” or the presence of white powdery deposit on the peel
o Yellow-green pedicel-end in some fruits
o Yellowing of the pulp
Lately, flotation method using 1.0% salt solution is used to determine maturity:
o 1.0% salt solution (100 gm salt in 10 liters water)
o Pick 12 fruits at random per tree
o If 9 out of 12 fruits sink to bottom, these are ready for harvest
o More floaters mean fruits are immature hence, additional days are needed
Methods of harvesting
· Handpicking for small trees
· For large and tall trees, picking pole is required. Oftentimes, harvesters climb the tree, collect fruits with picking pole, place in bamboo basket and lowered down
· It is advisable to leave 2 to 5 cm pedicel on the fruit to minimize latex flow
· Invert mango with pedicel down, over newspaper or jute sack to avoid latex stain
· Harvesting of mango is recommended after 8:00 a.m. to lessen turgor pressure, the stronger the latex flow.
Sorting and Grading
· Sort mango fruits based on marketable quality (no defects) and non-marketable (with defects)
· Classify marketable to sizes (small, medium and large) using a balance.
· Sorting tables padded with foam are recommended
· For export, fruits should be cleaned from blemishes and other dirt by water
· Non-marketable fruits (small or with defects) can be used for processing
Ripening
If accelerated ripening with carbide is done to minimize problems due to disease, it would be much better to simply subject the fruits to HWT (52° to 55° C for ten minutes), followed by hydro cooling and air drying before packing. Place liners, such as newsprint, inside the container to help conserve some of the heat which can accelerate ripening.
Carbide at the rate of 5-6/kg fruit is used by many retailers to hasten ripening. The carbide is first wrapped in newsprint and enclosed with the fruits in a kaing. Since there are some questions on the safety of the use of carbide and its effect on fruit quality, it would be best to let the mangoes ripen naturally to a little more than half-ripe before treating with 1.25g/kg fruit. With Carbide, fruits ripen four to five days from application.
However, carbide must never be used to force immature fruits to ripen. Although yellowing is improved by carbide, the quality of pulp is inferior.
There is no substitute for natural ripening. The aroma as well as the fruit quality is enhanced.
Control of post-harvest diseases
Hot water treatment (HWT)
To minimize problems with anthracnose and stem-end rot, mangoes should be subjected to hot-water treatment (HWT). This consists of dipping newly harvested fruits in water at 52° to 55° C for ten minutes, followed by hydro cooling with tap water, then air drying.
To attain maximum results, treat the fruits immediately after harvest. HWT removes fresh latex and minimizes latex burns. However, latex, which have already coagulated and dried on the fruit surface, cannot be removed by HWT.
Although a kerosene-fueled dipping tank has been designed for field use, a wood-fired 100-liter half-drum may be used for smaller volumes of fruits. This method of applying HWT requires monitoring of the temperature with a thermometer. The temperature may be lowered or rose using a cool tap water or water heated in a separate tank.
Dipping is done by immersing fruits inside a container, which may be made of plastic, bamboo, or other materials which do not conduct heat. Use of such containers prevents fruit scalding due to direct contact with the heated tank.
For commercial packinghouses, a thermostatically controlled dipping tank may be constructed.
While HWT minimizes post harvest disease in mango, under field condition using large volume of fruits, the treatment is cumbersome and time-consuming. Innovation of HWT is High Temperature Short Time Dip (HTSD). This consists of dipping newly harvested fruits in heated water to 59° to 60° C for 30 seconds to 1 minute, followed by air cooling and drying prior to packing. Disease reduction ranges from 60 to 100% depending on disease prevalence in the field.
Storage
Low temperature storage effectively extends the green life of mango. However chilling injury (CI) is a problem which can be encountered at temperature below 12.5° C. Table 1 shows the expected storage life of ‘Carabao’ mango at different temperatures. Post harvest heat treatment usually increases the sensitivity of mangoes to chilling injury at low temperature.
TABLE 1: Expected storage life of ‘Carabao’ mango at different temperatures
Source: The Philippine Recommends for Mango, PCARRD, 1994
Disinfestations treatment
Mangoes exerted to Japan, Australia, USA, Korea and New Zealand have to undergo disinfestations treatments against fruit fly to meet the quarantine standards of importing countries.
Japan subjects Philippine mangoes to vapor heat treatment (VHT). The treatment consists of heating the fruits in a chamber with vapor-saturated air until the fruit pulp reaches a temperature of 46° C. this temperature is maintained for 10 minutes, after which the chamber is ventilated. The whole process usually takes 4 hours. The extended heat treatment is another disinfestations method that can cause internal breakdown, where portions of the pulp assume a tough leathery texture and a spongy appearance. Early season fruits are susceptible to this disorder, particularly the immature ones.
Internal breakdown can be reduced by culling immature fruits, delaying VHT until fruits show the faintest yellow peel and cooling fruits immediately after treatment. The HWT at 52° to 55° C for disease control makes fruits more tolerant to VHT, if applied four to eight hours before treatment.
Packaging for domestic market
1. Kaing
This is a local basket made out of bamboo with a capacity of 30-36 kg. it is usually used because it is cheaper and readily available. To prevent bruising of fruits, it is lined with newsprint, perforated polyethylene or polypropylene sheets. Avoid using leaves because it could cause the rotting of fruits.
Since kaings could not be piled or stacked during transport, wooden planks or a similar structure be placed on the floor to bear the weight of the basket and to avoid compression damage.
Overfilling should be avoided to minimize compression damage.
2. Wooden crates
Wooden crates have been designed for mangoes but these are more expensive and less readily available than kaings. Wooden crates are rigid and provide adequate protections against injury, particularly during stacking. However, the inner surface of the crates is easily contaminated and hard to clean, thus limiting the use of the crates. Use of newspapers to line crates is important.
3. Fiberboard cartons
These have a capacity of 12 kg and are used to transport mango fruits from Guimaras to packinghouses in Metro Manila. These are designed to serve as cell packs with horizontal divider between two layers of fruits.
4. Plastic crates
Some exporters provide their supplier with returnable plastic crates. This is the best container for local handling of mangoes. These provide adequate ventilation, are durable, stackable, easy to handle, clean and do not require the use of liners. The high initial cost will eventually be compensated since the containers are durable (long lasting). These also reduce injury transportation.
Packaging for export
· Fruits are export are properly labeled and stored in fiberboard carton.
· Fruits are wrapped with tissue-like paper, exposing only about a quarter of the fruit at the apical-end.
· The fruits are packed pedicel-end down in a cell type, 5-kg capacity fiberboard carton which contains single layers of fruits
Disinfestations treatment
Mangoes exerted to Japan, Australia, USA, Korea and New Zealand have to undergo disinfestations treatments against fruit fly to meet the quarantine standards of importing countries.
Japan subjects Philippine mangoes to vapor heat treatment (VHT). The treatment consists of heating the fruits in a chamber with vapor-saturated air until the fruit pulp reaches a temperature of 46° C. this temperature is maintained for 10 minutes, after which the chamber is ventilated. The whole process usually takes 4 hours. The extended heat treatment is another disinfestations method that can cause internal breakdown, where portions of the pulp assume a tough leathery texture and a spongy appearance. Early season fruits are susceptible to this disorder, particularly the immature ones.
Internal breakdown can be reduced by culling immature fruits, delaying VHT until fruits show the faintest yellow peel and cooling fruits immediately after treatment. The HWT at 52° to 55° C for disease control makes fruits more tolerant to VHT, if applied four to eight hours before treatment.
Packaging for domestic market
1. Kaing
This is a local basket made out of bamboo with a capacity of 30-36 kg. it is usually used because it is cheaper and readily available. To prevent bruising of fruits, it is lined with newsprint, perforated polyethylene or polypropylene sheets. Avoid using leaves because it could cause the rotting of fruits.
Since kaings could not be piled or stacked during transport, wooden planks or a similar structure be placed on the floor to bear the weight of the basket and to avoid compression damage.
Overfilling should be avoided to minimize compression damage.
2. Wooden crates
Wooden crates have been designed for mangoes but these are more expensive and less readily available than kaings. Wooden crates are rigid and provide adequate protections against injury, particularly during stacking. However, the inner surface of the crates is easily contaminated and hard to clean, thus limiting the use of the crates. Use of newspapers to line crates is important.
3. Fiberboard cartons
These have a capacity of 12 kg and are used to transport mango fruits from Guimaras to packinghouses in Metro Manila. These are designed to serve as cell packs with horizontal divider between two layers of fruits.
4. Plastic crates
Some exporters provide their supplier with returnable plastic crates. This is the best container for local handling of mangoes. These provide adequate ventilation, are durable, stackable, easy to handle, clean and do not require the use of liners. The high initial cost will eventually be compensated since the containers are durable (long lasting). These also reduce injury transportation.
Packaging for export
· Fruits are export are properly labeled and stored in fiberboard carton.
· Fruits are wrapped with tissue-like paper, exposing only about a quarter of the fruit at the apical-end.
· The fruits are packed pedicel-end down in a cell type, 5-kg capacity fiberboard carton which contains single layers of fruits