Mangoes are generally harvested at physiological mature stage and ripened for optimum quality. Fruits are hand-picked or plucked with a harvester. During harvesting, the latex trickles down the fruit surface from the point of detachment imparting a shabby appearance to it upon storage . After harvest the fruits are usually heaped under a tree on the ground. Bruised and injured fruits develop brown to black spots during storage making the fruits unattractive. Moreover, injuries to the peel or to the stalk end serve as avenues for invasion of microorganism and lead to rotting of the fruits. The postharvest losses in mangoes have been estimated in the range of 25-40 per cent from harvesting to consumption stage. If proper methods of harvesting, handling, transportation and storage are adopted, such losses could be minimized.
a) Maturity : The mango fruits should be harvested at green mature stage. The harvest maturity in Dashehari and Langra cultivars reaches 12 weeks after fruit set, while in Chausa and Mallika it takes about 15 weeks. The best way to observe maturity in mango is the colour of the pulp which turns cream to light yellow on maturity and hardening of the stone.
b) Harvesting : The harvesting in mango should be done in the morning hours and fruits should be collected in plastic trays and kept in shades. The fruits should not be allowed to fall on the ground as the injured fruits cause spoilage to other healthy fruits during packaging and storage. Fruits harvested with 8-10 mm long stalks appear better on ripening as undesired spots on skin caused by sap burn are prevented. Such fruits are less prone to stem-end rot and other storage diseases.
Fruits harvested by stick are injured / bruised due to impact resulting in decay, poor quality and attract low price. Traditional methods consume a lot of energy. To overcome these problems, a simple, low cost and portable mango harvesting device has been designed and developed at CISH, Lucknow. Mango fruits are taken into the pouch and held between the divider and knife and as the device is pulled the blade cuts the pedicel. The fruits are then conveyed through a nylon chute to collecting boxes without bringing down the device every time. This saves time and protects fruits from mechanical damage due to impact. It also protects operator’s hand from the sap which oozes out from the point of detachment.
c) Grading : If the fruits are graded according to their size, weight, colour and maturity, both the producer and consumer are benefited. 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.
d) Packaging : Wooden boxes are commonly used for packaging and transportation of mango fruits. Under dynamic transport conditions nails come out due to vibration and puncture the fruits which result 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, the Institute has designed and developed CFB Boxes of 5 kg and 10 kg capacity for packing and shipping of mango fruits successfully as an alternative to traditional nailed wooden boxes. The use of CFB boxes for packaging for the domestic market is also the need of the hour due to scarcity of the wood and environmental concerns of the country. For export purposes, CFB boxes are already in extensive use.
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.
Normally lid of the wooden boxes is nailed with an area of 5 to 7 cm high in the middle. This puts pressure on the fruits during transport and results into reduced quality. Therefore, the farmers should be very careful while packing the fruits.
e) 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 of Dashehari, Mallika and Amrapali should be stored at 12oC, Langra at 14oC and Chausa at 8oC with 85-90 per cent Relative Humidity. The fruits could be stored for 3-4 weeks in good condition at low temperature. The problem of 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 Dashehari 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.
f) Transportation : The truck has been adopted as the most convenient mode of transport due to its easy approach from the orchards to the market. However, these trucks were not found suitable for transporting this live material as they exert lot of pressure on the fruits and do not bosses temperature control devices. Therefore, it is imperative to design and develop suitable transport system. Reefer containers (Refrigerated vans) may be found useful for long distance transport and export purposes as they would help in reducing the postharvest losses.
Mango fruits have been utilized for long time at every stage of growth. While the raw fruits are utilized for products like chutney, pickle, amchoor, green mango beverage, etc. ripe ones are used in making pulp, juice, nectar, squash, leather, slices, etc.
a) Raw mango products
Mango fruits during early stages of growth are commonly used for sweet or sour chutney. As the fruits attain stone hardening stage, they become suitable for some other useful products like amchoor, pickle, etc.
(i) Pickle : Different kinds of pickle are made from raw mango fruits. However, pickle in oil is the most common among all. Such pickle contains 40 g salt, 50 g fenugreek seeds, 50 g ginger, 20 g turmeric, 25 g red chillies, 30 g black pepper, 30 g fernel and 300 g cooking oil per kilogram of mango slices. Small slices from mature green fruits are mixed with sufficient quantity of powdered salt and kept in sun till green colour desappears from the slices. Spices are then mixed in it and the slices dipped in boiled but cool oil. The prepared pickle is filled in clean glass jars and cured for couple of days in sun. Oilless pickle is another popular form of pickle from mango. The fruits are peeled, sliced into small pieces and mixed with 20 per cent salt, 7.5 per cent chilli powder and 1 per cent asafoetida according to the weight of pieces. The whole mixture is then kept in sun for few days with frequent stirring and then filled in clean glass jars. The jars are stored in clean dry place.
(ii) Amchoor : Mango slices from peeled mangoes are dipped in 1.5 per cent solution of potassium metabisulphite for 5 minutes and dried in sun or solar dehydrator. Amchoor is obtained by grinding the dried slices and thereafter, stored in air tight containers.
(iii) Slices : Raw mango slices dipped in 1.5 per cent potassium metabisulphite solution for 5 minutes, drained and then mixed with equal amounts of powdered salt are stored in polythene pouches. These slices could be used later for product preparation.
(iv) Green mango beverage : Whole raw mangoes roasted or boiled with equal amount of water and the pulp is extracted. To one kilogram of extract, 1.6 kg sugar, 1.6 litre water, 80 g salt, 20 g mint , 10 g cumin, 4 g black pepper and 20 g citric acid are mixed. Mixture is heated and filled in clean glass bottles. It may be used as raw mango squash. It is a modified version of ‘Panna’. Actually in ‘Panna’ sugar is not added and whole boiled / roasted mangoes are used after filtration through muslin cloth.
(b) Ripe mango products
Ripe mango fruit has characteristic blend of taste and flavour. It contains good amount of sugar, pectin, carotenoids, etc. Due to comparatively shorter storage life of mango fruits, it is essential to make their products immediately.
(i) Pulp : Fully ripe mangoes are washed, peeled and cut into slices. The slices are then homogenized into pulp which is filtered through a sieve to remove the fibres. The pulp is heated to 76-78oC and 2 g citric acid and 2 g potassium metabisulphite are added per kg of pulp. It is filled in sterilized glass jars and lids are sealed with wax.
(ii) Beverages (Juice and Nectar) : Mango juice may be prepared by mixing 1/3rd of fresh or stored pulp with 2/5th of water. Sugar and citric acid are so added that total soluble slides (T.S.S.) and acidity of the product reaches to 15 per cent and 0.3 per cent, respectively. The mixture is heated to 95oC, filled hot in clean, sterilized bottles and crown corked. The bottles are sterilized in boiling water for 10-15 minutes, cooled to room temperature and stored. The procedure for nectar preparation is similar to that of juice except that the pulp percentage is reduced to 15 per cent .
(iii) Squash : Squash is prepared by mixing 1 kg of pulp with sugar syrup (1 kg sugar in 750 ml water) . The whole mixture is heated to 76-78oC and then 25-30 g citric acid is added to it. The prepared squash is filled in clean, sterilized bottles and stored. At the time of use, three parts of water is added to one part of squash.
(iv) Slices : Firm ripe mango fruits are peeled and cut into slices. The slices are then transferred to boiling syrup containing 40 per cent sugar, 0.3 per cent citric acid and 350 ppm sulphur dioxide for 5 minutes. The slices are filled in clean jars and boiling syrup is poured until all the slices are covered. Finally, the jars are covered with lids and sealed with wax.
(v) Mango Leather or Aam Papad : Homogenized mango pulp is taken and potassium metabisulphite is added to it @ 2 g per kg of pulp. The pulp is then spread on trays smeared without and kept for drying in solar dehydrator or sun. After drying of one layer, another layer is spread over it and kept for drying. The process is repeated as per desired thickness. Finally they are cut into pieces and wrapped in butter paper or polythene cellophane sheet.
During the processing of mango, peel and stone are generated as waste (40-50% of total fruit weight). They are rich in various nutrients and many value added products could be obtained from them. Good quality jelly grade pectin (6.1%) and edible fibre (5.4%) could be extracted from ripe mango peel. Acceptable quality vinegar (5.2% acetic acid) and citric acid (20 g / kg peel) could be obtained from mango peel through microbial fermentation. Mango peel having low protein value (3.9 %) is a poor quality animal feed. The peel could be protein enriched more than five times (20 %) by solid state fermentation using Aspergillusniger. Mango peel has lignocellulosic composition and hence its complete break down is difficult. Its co-composting with cowdung in 3:1 ratio results in its successful biodegradation.
Mango kernel contains high amount of fat and starch. The oil extracted from kernel is of good quality and could be used in cosmetic and soap industries. The kernel flour (starch) after mixing with wheat or maize flour is used in chapaties. About ten per cent alcohol could be obtained from mango kernel by co-culture fermentation. In food processing industries, various enzymes are invariably used for pulp liquefaction, juice clarification, etc. Enzymes such as cellulase and pectinase from mango peel and amylase from mango kernel could be produced by microbial fermentation.
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