VALUE CHAIN #
Keeping Quality and Storage
Washing the fruits immediately after harvest is essential, as the sap which leaks from the stem bums the skin of the fruit making black lesions which lead to rotting.
Some cultivars, especially ‘Bangalora’, ‘Alphonso’, and ‘Neelum’ in India, have much better keeping quality than others. In Bombay, ‘Alphonso’ has kept well for 4 weeks at 52° F (11.11° C); 6 to 7 weeks at 45° F (7.22° C). Storage at lower temperatures is detrimental inasmuch as mangos are very susceptible to chilling injury. Any temperature below 55.4° F (13° C) is damaging to ‘Kent’. In Florida, this is regarded as the optimum for 2 to 3 weeks’ storage. The best ripening temperatures are 70° to 75° F (21.11°-23.89° C).
Experiments in Florida have demonstrated that ‘Irwin’, ‘Tommy Atkins’ and ‘Kent’ mangos, held for 3 weeks at storage temperature of 55.4° F (13° C), 98% to 100% relative humidity and atmospheric pressure of 76 or 152 mmHg, ripened thereafter with less decay at 69.8° F (21° C) under normal atmospheric pressure, as compared with fruits stored at the same temperature with normal atmospheric pressure. Those stored at 152 mmHg took 3 to 5 days longer to ripen than those stored at 76 mmHg. Decay rates were 20% for ‘Tommy Atkins’ and 40% for ‘Irwin’. Spoilage from anthracnose has been reduced by immersion for 15 min in water at 125° F (51.67° C) or for 5 min at 132° F (55.56° C). Dipping in 500 ppm maleic hydrazide for 1 min and storing at 89.6° F (32° C) also retards decay but not loss of moisture. In South Africa, mangos are submerged immediately after picking in a suspension of benomyl for 5 min at 131° F (55° C) to control soft brown rot.
In Australia, mature-green ‘Kensington Pride’ mangos have been dipped in a 4% solution of calcium chloride under reduced pressure (250 mm Hg) and then stored in containers at 77° F (25° C) in ethylene-free atmosphere. Ripening was retarded by a week; that is, the treated fruits ripened in 20 to 22 days whereas controls ripened in 12 to 14 days. Eating quality was equal except that the calcium-treated fruits were found slightly higher in ascorbic acid.
Wrapping fruits individually in heat-shrinkable plastic film has not retarded decay in storage. The only benefit has been 3% less weight loss. Coating with paraffin wax or fungicidal wax and storing at 68° to 89.6° F (20° -32° C) delays ripening 1 to 2 weeks and prevents shrivelling but interferes with full development of colour.
Gamma irradiation (30 Krad) causes ripening delay of 7 days in mangos stored at room temperature. The irradiated fruits ripen normally and show no adverse effect on quality. Irradiation has not yet been approved for this purpose.
In India, large quantities of mangos are transported to distant markets by rail. To avoid excessive heat, build up and consequent spoilage, the fruits, padded with paper shavings, are packed in ventilated wooden crates and loaded into ventilated wooden boxcars. Relative humidity varies from 24% to 85% and temperature from 88° to 115° F (31.6°-46.6° C). These improved conditions have proved superior to the conventional packing of the fruits in Phoenix-palm-midrib or bamboo, or the newer pigeon pea-stem, baskets padded with rice straw and mango leaves and transported in steel boxcars, which has resulted in 20% to 30% losses from shrivelling, unshapeliness and spoilage.
Green seedling mangos, harvested in India for commercial preparation of chutneys and pickles as well as for table use, are stored for as long as 40 days at 42° to 45° F (5.56°-7.22° C) with relative humidity of 85% to 99%. Some of these may be diverted for table use after a 2-week ripening period at 62° to 65° F (16.67° -18.13° C).
https://www.themangofactory.com/nutrition/keeping-quality-and-storage/
Expected yield for each variety (data from Kununurra)
| Year 3 (kg) | Year 4 (kg) | Year 5 (kg) | Year 6 (kg) | Year 7 (kg) | Year 8 (kg) | Average mature tree | |
| Kensington | 6 | 19 | 32 | 45 | 57 | 70 | 70 |
| Irwin | 8 | 27 | 47 | 66 | 85 | 105 | 110 |
| R2E2 | 0 | 11 | 22 | 33 | 44 | 55 | 71 |
| Haden | 3 | 12 | 21 | 30 | 39 | 48 | 104 |
| Keitt | 0 | 14 | 28 | 42 | 56 | 70 | 107 |
| Kent | 2 | 6 | 10 | 15 | 19 | 23 | 69 |
Maturity
Colour change from green to yellow, and the development of “shoulders” on the stem end of the fruit are the best indicators of maturity. Also, the fruit flesh turns from white to yellow starting at the endocarp and progressing outward to the skin during maturation. When the flesh is yellow to half that distance, the fruit can be harvested and will ripen normally off-tree. Fruit are not ripe at this stage, but picked firm to withstand shipment. If picked before this stage, flavour never develops and fruit are more susceptible to chilling injury and hot water damage during post-harvest fruit fly control. If fruit are left on tree until ripe, they often develop physiological breakdown termed “soft nose”, “jelly seed”, or “spongy tissue”. Fruit removal force may also be assessed by individual pickers to determine ripeness.
Harvest Method
Mangoes are hand-harvested, simply by snapping-off fruits from peduncles in less-developed plantings, or by clipping peduncles 4 inches above the fruit when intended for export. This allows the milky, toxic latex to ooze from the stem without touching the fruit surface. Pickers use poles with cloth bags at the end to reach fruit high in the tree, or ladders and hydraulic lifts in developed countries. Mango is harvested 120 days after flower induction.
Post-Harvest Handling and Packaging
Grading
Fruits are graded according to their size, weight, colour and maturity. It has been observed that bigger size fruits take 2-4 days more time in ripening than smaller ones. Hence, packaging of smaller fruits with larger ones should be avoided to achieve uniform ripening. Immature, overripe, damaged and diseased fruits should be discarded.
Packaging
Wooden boxes are commonly used for packaging and transportation of mango fruits. Under dynamic transport conditions vibration results in bruising, decay and low price of fruits. Further, too much ventilation affects the quality of fruits due to shrinkage, loss in weight, colour, etc. To overcome these problems CFB Boxes of 5 kg and 10 kg capacity for packing and shipping of mango fruits have been used successfully and extensively for export purposes.
Paper scraps, newspapers, etc., are commonly used as cushioning material for the packaging of fruits which prevent them from getting bruised and spoiled during storage and transportation. Polythene (LDPE) lining has also been found beneficial as it maintains humidity which results in lesser shrinkage during storage. Wrapping of fruits individually (Unipack) with newspaper or tissue paper and packing in honey comb structure helps in getting optimum ripening with reduced spoilage.
Storage
Storage is essential for extending the consumption period of fruits, regulating their supply to the market and also for transportation to long distances. The mature green fruits can be kept at room temperature for about 4-10 days depending upon the variety. Shelf life of fruits could be extended by precooling, chemical treatments, low temperature, etc.
The harvested fruits are precooled to 10-12oC and then stored at an appropriate temperature. The fruits could be stored for 3-4 weeks in good condition at low temperature. Preventing chilling injury at low temperature can be overcome by keeping the fruits in 0.5 per cent ventilated polythene bags.
Calcium infiltration is an improved technique of extending the storage life of fruits. The fruits are kept in calcium chloride solution (4%) at sub- atmospheric pressure of 500 mm Hg for 5 minutes. The treated fruits can be stored at low temperature (12oC) for 27 days.
It is a general practice to harvest fruits early in the season (premature stage) to capture early market. These fruits do not ripe uniformly without any ripening aid. Such fruits could be ripened uniformly by dipping in 750 ppm ethrel (1.8 ml / litre) in hot water at 52+2oC for 5 minutes within 4-8 days under ambient conditions. Mature fruits can similarly be ripened with lower doses of ethrel for uniform colour development.
Transportation
The truck has been adopted as the most convenient mode of transport due to its easy approach from the orchards, but they were unsuitable for transporting live material as they exert lot of pressure on the fruits. Therefore, refrigerated vans/ containers may be useful for long distance transport and export purposes as they would help in reducing the postharvest losses.
Ripening and Storage
Removal of field heat is critical in maintaining fruit quality and for achieving maximum storage life by forced air cooling. For maximum storage life the fruit should be stored at 13o Celsius. This is the most suitable temperature for transportation without the risk of causing chill damage to the skin.
Fruit is generally put into ripening rooms at the market and gas ripened. This gives more uniformed ripening throughout the tray. Optimum temperatures for ripening mangoes range from 20 to 23 o C. If temperatures are high, fruit will not develop yellow background colour. Rather it will tend to ripen in a less attractive dull yellow/green colour. If temperatures are too low then sometimes fruit flavour can suffer.
Commercially, mangoes (e.g., Kensington Pride) may be stored for three weeks by dipping in a prochloraz solution for controlling anthracnose and other postharvest rots then maintained at 13o Celsius. Both in storage and transport, the temperature must not fall below this level, unless under strictly controlled conditions where the temperature is gradually reduced. The critical minimum storage temperature for most other varieties has not yet been determined. Processed mangoes or mango pulp can be stored at 0o to 1o Celsius for up to six weeks. In the home, sliced mango can be stored in a freezer at minus 18o Celsius for up to 18 months. Stems are trimmed to 0.6 cm prior to packing in 12 kg. boxes containing 8-20 fruits, depending on size. Fruit are culled by hand, removing diseased and off-grade fruit. In countries where fruit flies are endemic, fruit are dipped in hot water for fruit fly and anthracnose control. Hot air treatments can be used to meet export requirements as well. Resins left on fruits cause black lesions which may lead to rot. Fruits are stored for 15 days at 24 ºC and RH of 85-90%. Ethylene is often supplied in more sophisticated operations to accelerate color development (by 3-8 days) and allow more uniform ripening. Refrigerated van used by big companies in transporting the fruits. Controlled atmosphere technologies to preserve quality or prolong shelf-life.
Mangoes are subject to chilling injury, therefore, they must not be stored at <13 ° C. Storage life is only 2-3 weeks under optimal conditions.
http://www.itfnet.org/v1/2016/05/mango-post-harvest-processing/
Top Mango Exporting Countries in the World
| Country
Mexico Philippines Pakistan Brazil India Netherlands Peru Guatemala France Haiti |
Share in Global Exports (%)
10.30 7.80 7.60 6.00 5.20 3.30 2.00 1.90 1.70 1.30 |
* Source: CIA World Factbook (2011 estimates)
https://www.mapsofworld.com/world-top-ten/mango-exporting-countries.html
Mango processing technologies
Mangoes are processed at two stages of maturity. Green fruit is used to make chutney, pickles, curries and dehydrated products. The green fruit should be freshly picked from the tree. Fruit that is bruised, damaged, or that has prematurely fallen to the ground should not be used. Ripe mangoes are processed as canned and frozen slices, purée, juices, nectar and various dried products. Mangoes are processed into many other products for home use and by cottage industry.
The mango processing presents many problems as far as industrialization and market expansion is concerned. The trees are alternate bearing and the fruit has a short storage life; these factors make it difficult to process the crop in a continuous and regular way. The large number of varieties with their various attributes and deficiencies affects the quality and uniformity of processed products.
The lack of simple, reliable methods for determining the stage of maturity of varieties for processing also affects the quality of the finished products. Many of the processed products require peeled or peeled and sliced fruit. The lack of mechanised equipment for the peeling of ripe mangoes is a serious bottleneck for increasing the production of these products.
A significant problem in developing mechanised equipment is the large number of varieties available and their different sizes and shapes. The cost of processed mango products is also too expensive for the general population in the areas where most mangoes are grown. There is, however, a considerable export potential to developed countries but in these countries the processed mango products must compete with established processed fruits of high quality and relatively low cost.
Green mango processing
- Pickles
The optimum stage of maturity should be determined for each variety used to make pickles.
There are two classifications of pickles – salt pickles and oil pickles. They are processed from whole and sliced fruit with and without stones. Salt is used in most pickles.
The many kinds of pickles vary mainly in the proportions and kinds of spices used in their preparation. One basic recipe for the study of the preparation and storage of pickles in oil is as follows:
| Mango pieces | 250 g | Tumeric powder | 2 to 4 g |
| Salt | 60 g | Fenugreek seeds | 2 to 4 g |
| Mustard powder | 30 g | Bengal gram seeds | 2 to 4 g |
| Chili powder | 20 g | Gingelly oil | 20 to 30 g |
The ingredients are mixed together and filled into wide-mouthed bottles of 0.5 kg capacity. Three days later the contents are thoroughly mixed and refilled into the bottles. Extra oil is added to form a 1-2 cm layer over the pickles.
- Chutney
The product is prepared from peeled, sliced or grated unripe or semi-ripe fruit by cooking the shredded fruit with salt over medium heat for 5 to 7 minutes, mixed and then sugar, spices and vinegar are added. Cook over moderate heat until the product resembles a thick purée, add remaining ingredients and simmer another 5 min. Cool and preserve in sterilised jars.
Spices usually include cumin seeds, ground cloves, cinnamon, chili powder, ginger and nutmeg. Other ingredients such as dried fruits, onions, garlic and nuts may be added.
- Drying/dehydration
immature fruit is peeled and sliced for sun-drying. The dried mango slices can be powdered to make a product called amchoo. The use of blanching, sulphuring and mechanical dehydration gives a product with better colour, nutrition, storability and fewer microbiological problems.
Ripe mango processing
- Purée.
Mangoes are processed into purée for re-manufacturing into products such as nectar, juice, squash, jam, jelly and dehydrated products. The purée can be preserved by chemical means, or frozen, or canned and stored in barrels. This allows a supply of raw materials during the remainder of the year when fresh mangoes are not available.
It also provides a more economical means of storage compared with the cost of storing the finished products, except for those which are dehydrated, and provides for more orderly processing during peak availability of fresh mangoes.
Mangoes can be processed into purée from whole or peeled fruit. Because of the time and cost of peeling, this step is best avoided but with some varieties it may be necessary to avoid off-flavours which may be present in the skin. The most common way of removing the skin is hand-peeling with knives but this is time-consuming and expensive. Steam and lye peeling have been accomplished for some varieties.
Several methods have been devised to remove the pulp from the fresh ripe mangoes without hand-peeling. A simplified method is as follows: the whole mangoes were exposed to atmospheric steam for 2 to 2 1/2 min in a loosely covered chamber, then transferred to a stainless steel tank.
The steam-softened skins allowed the fruit to be pulped by a power stirrer fitted with a saw-toothed propeller blade mounted 12.7 to 15.2 cm below a regular propeller blade. The pulp is removed from the seeds by a continuous centrifuge designed for use in passion fruit extraction. The pulp material is then passed through a paddle pulper fitted with a 0.084 cm screen to remove fibre and small pieces of pulp.
Mango purée can be frozen, canned or stored in barrels for later processing. In all these cases, heating is necessary to preserve the quality of the mango purée. In one process, purée is pumped through a plate heat exchanger and heated to 90°C for 1 min and cooled to 35° C before being filled into 30 lb tins with polyethylene liners and frozen at -23.50 C.
In another process, pulp is acidified to pH 3.5, pasteurized at 90°C, and hot-filled into 6 kg high-density bulk polyethylene containers that have been previously sterilised with boiling water. The containers are then sealed and cooled in water. This makes it possible to avoid the high cost of cans.
Wooden barrels may be used to store mango pulp in the manufacture of jams and squashes. The pulp is acidified with 0.5 to 1.0% citric acid, heated to boiling, cooled, and SO2 is added at a level of 1000 to 1500 ppm in the pulp. The pulp is then filled into barrels for future use.
- Slices
Mango slices can be preserved by canning or freezing, and recent studies have shown the feasibility of pasteurized-refrigerated and dehydro-canned slices. The quality of the processed product in all of these procedures will be dependent upon selection of a suitable variety along with good processing procedures. Thermal process canning of mango slices in syrup is the most widely used preservation method.
- Beverages
The commercial beverages are juice, nectar and squash. Mango nectar and juice contain mango purée, sugar, water and citric acid in various proportions depending on local taste, government standards of identity, pH control, and fruit composition of the variety used. Mango squash in addition to the above may contain SO2 or sodium benzoate as a preservative. Other food grade additives such as ascorbic acid, food colouring, or thickeners may be used in mango beverages.
A short description of finished products found in literature is as follows:
Mango juice
prepared by mixing equal quantities of pulp (purée) and water together and adjusting the total soluble solids (TSS) and acidity to taste (12 to 15% TSS and 0.4 to 0.5% acidity as citric acid);
mango nectar containing 25% purée can be prepared using the following procedure.
| Brix of purée | |||
| Nectar components | 15° | 17° | 20° |
| Purée | 100 | 100 | 100 |
| Sugar | 45 | 43 | 40 |
| Water | 255 | 257 | 260 |
Commercial processing conditions may require the use of a preservative.
The pH is adjusted to approximately 3.5 by adding citric acid as a 50% solution.
The time of heat processing will vary with filling temperature, can size and viscosity of the juice or nectar.
Mango squash may be prepared according to flow-sheet described below; the finished product may contain 25% juice, 45% TSS and 1.2 to 1.5% acidity and may be preserved with sulphur dioxide (350ppm) or sodium benzoate (1000 ppm) in glass bottles.
Mango squash simplified flow-sheet.
Ingredients
| Mango pulp | 900 | 900 |
| Sugar | 900 | 1100 |
| Citric acid | 18 | 15 |
| Water | 900 | 900 |
Mangoes are washed, stored, peeled with stainless steel knives. The pulp is prepared by using a pulper with fine sieve (0.025-in); Sugar is mixed with water and citric acid = syrup; The pulp is added to the syrup and mixed well; The mixture is strained trough cloth; The squash is heated at 85° C and bottles are filled and closed.
For additional heat treatment bottles may need to be maintained at a product temperature of 80°C for 30 minutes if the product is to be processed without preservatives. The bottles are then left to cool in water and stored at room temperature.
Two negative points must be avoided: presence of air bubbles (which is a source of quick deterioration) and separation of squash solids (giving an undesirable appearance). The means to avoid these two phenomena are described in the fruit juices section.
A type of “squash type” beverage may also be manufactured with ‘/a pulp + ‘/a water + i/a sugar and pH adjusted to 3.7 by addition of citric acid. Using different sieve sizes affects the quality and reduces air bubbles to a certain extent but homogenisation and de-aeration of purée or squash seem to be important in order to avoid separation and air bubbles.
The squash quality is evaluated on the basis of the following characteristics: pH, titrable acidity, soluble solids, ascorbic acid (by 2,6 dichlorophenol indophenol method), specific gravity.
- Dried/dehydrated.
Ripe mangoes are dried in the form of pieces, powders, and flakes. Drying procedures such as sun-drying, tunnel dehydration, vacuum-drying, osmotic dehydration may be used. Packaged and stored properly, dried mango products are stable and nutritious.
One described process involves as pre-treatment dipping mango slices for 18 hr (ratio 1:1) in a solution containing 40° Brix sugar, 3000 ppm SO2, 0.2% ascorbic acid and 1% citric acid; this method is described as producing the best dehydrated product. Drying is described using an electric cabinet through flow dryer operated at 60° C. The product showed no browning after 1 year of storage.
Drum-drying of mango purée is described as an efficient, economical process for producing dried mango powder and flakes. Its major drawback is that the severity of heat pre-processing can produce undesirable cooked flavours and aromas in the dried product. The drum-dried products are also extremely hydroscopic and the use of in-package desiccant is recommended during storage. http://www.fao.org/docrep/V5030e/V5030E0p.htm
