Mango

Post Harvest Technology

Introduction

• The mango (Mangifera indica L) is one of the most important tropical and subtropical fruit of the world and is popular both in the fresh and the processed form.
• It is commercially grown in more than 80 countries.
• India occupies 54% of the world's production of mango which is nearly 9.5 m. tonnes.
• The other leading mango producing countries of the world are China.
• Mexico, Pakistan, Indonesia, Thailand, Nigeria, Brazil, Philippines and Haiti.
• Less than 10% of total world production of mango is exported.
• The demand for mango in the world market is increasing day by day.
• It is reported that the markets for mangoes have increased in temperate countries because of social changes, promotion of fruit trade in developing countries and accessibility to international air cargo space.
• The expansion of mango trade has been possible because of successful post harvest management strategies to control diseases and insects.

Pre-Harvest Crop Management for Post-Harvest Disease Control

• Pre-harvest sprays with chemical fungicides have been shown to reduce post harvest diseases but the effects have not always been consistent.
• Thompson reviewed pre-harvest sprays of mangoes to control anthracnose.
• Recommendations are for field application of chemical fungicides, often followed by post harvest hot water treatment usually combined with the fungicide.
• In Florida cupric hydroxide at 2-4 g/litre or tri-basic copper sulphate at 3-6 g/lt + the organic sticker Nu-film 17 at 0.125% applied at monthly intervals at 57 litres/tree from flowering to harvest gave good anthracnose control.
• Benomyl at 0.3 g/lt +triton B 1956 at 0.15 ml/lt at 57 lt/tree at monthly intervals from flowering to 30 days before harvesting was also shown to be very effective.
• Mancozeb, chlorothalonil and Farbam were shown to be equally effective as field sprays against mango anthracnose in Florida.
• Trials carried out on Keitt mangoes in South Africa, showed that two pre-flowering applications of copper oxychloride then two applicatins of copper oxychloride from fruit set, ensured effective control of anthracnose.
• Sprays were applied to run off at about 20 lt/tree.
• In Australia, mancozeb applied at 1-6 g/lt active ingredient as a weekly spray during flowering, then as a monthly spray until just before harvesting, gave good control to mango anthracnose.
• In studies in the Philippines, the field sprays with mancozeb or copper were effective in controlling mango anthracnose and was superior to either Captan or Zineb.

Maturity

• Mango takes about 3 months from the time of fruit set to mature and ripen.
• Some varieties may take 3-1/2 to 4 months.
• Fruits are plucked from the tree when they are still hard and green.
• When a few semi-ripe fruits fall from the tree, it is traditionally considered that the fruits are mature for harvest.
• If picked immature, fruits develop white patches or air pockets and show lower amounts or Brix, acid ratio, taste and flavour, whereas over-mature fruits lose their storage life.
• Such fruits present numerous problems during handling.
• It is therefore desirable to pick the fruits at the correct stage of maturity to facilitate ripening, distant transportation and maximum storage life, and thus to increase their quality and market value.

There are 4 maturity stages to assess the correct maturity of mango fruit, viz

• The shoulders are in the line with the stem-end and the colour of the fruit is olive green
• The shoulders outgrow the stem-end and the colour is olive green
• The shoulders outgrow the stem-end and the colour becomes light
• The flesh becomes soft and blush develops.
• The experiments on storage studies showed that the fruit harvested at any stage of maturity mentioned above ripened normally, but those at the second and third stages gave the best taste and flavour.

• Changes in acid content of the fruit did not prove a satisfactory index of maturity.
• The starch content and specific gravity of the hard fruit are associated with maturity.
• Picking of fruits when their specific gravity is 1.01-1.02 is reported to give satisfactory results in respect of uniform repening and keeping quality.
• The attainment of full maturity, as indicated by sinking in water, appeared to be very essential for normal ripening of fruits under all conditions.
• Pressure tests have also been used as an indication of fruit maturity.
• They found a pressure reading of k gh/cm2 as noted on Magness Taylor Pressure Tester to be optimum for most of the grafted varieties.
• This was also found useful in the Indian varieties.
• The total soluble solids of 12-15 give a correct indication for maturity.
• In 'Langra' the specific gravity, acidity and starch content are quite relevant for predicting maturity.
• Starch acidity ratio provided a good index and any fruit of 'Langra' having a ratio of 4 or more could be considered fully mature.

Picking

• Injury caused by rough handling contributes to fast ripening, fungus infection and rot.
• Detachment of stem at the time of harvest causes fruit latex to trickle down the skin, which imparts shabby appearance to the fruit by blackening the skin.
• Hence picking of fruits with stem slightly above the abscission point is recommended.
• Dipping the fruits in hot water at 50-530C for 15 min is the most effective post-harvest treatment.
• The fruits in different parts of the country are harvested one by one by a bamboo-pole harvester and collected in a net-bag attached to it.
• The harvest season differs in different parts of the country, according to the varieties grown.

The major harvesting seasons are:

States	Harvesting season
Maharashtra	April-May (Ratnagiri) May-June (other areas)
Gujarat	May-June
Tamil Nadu	April-May
Telangana	April - May
Andhra Pradesh	April-May (coastal districts) May (Rayalseema)
Karnataka	May-July
Bihar, Uttar Pradesh and other parts of India	June-August

Grading

• In India the practice of systematic grading of mango, based on scientific grade standards, has not so far been followed by any agency engaged in the distribution of this fruit.
• The produce is seldom graded in the orchards.
• At best what the grower does is to remove immature, rotten or diseased fruits from the bulk.
• Only at the time the wholesalers or pre-harvest contractors purchase the produce, the mangoes are graded according to size and variety before the consignments are booked to the consuming centres.
• The 'topping' malpractice, where 25% of the better-quality, bigger fruits are placed at the top of each package, is still continued.
• Grade designations and definitions of quality have been prescribed under voluntary agricultural produce (Grading and Marketing Act, 1937), for 'Alphonso' intended for marketing within the country as well as for export markets, separately.
• The practice of sorting the fruits in several grades is common in Gujarat and Maharashtra, particularly for 'Alphonso', in Chittoor district of Andhra Pradesh for 'Bangalora', and for 'Dashehari' in Uttar Pradesh.
• Some growers and contractors use sieves having circular holes of 8, 7.5 and 7 cm diameter to distinguish fruits by simple marks on the package.
• The need for standardization of packages and grading in mango has become imperative in the context of an expanding export market for this fruit.

Packing

• The most popular containers used for packing mangoes are baskets of various makes, whereas crates, boxes, etc. are used occasionally at some places.
• Wooden crates are good containers, especially for expensive varieties which are packed in mature condition.
• The use of steel trunks or tin containers is limited, and 4-5% of the total despatches of mango from Ratnagiri and Vengurla are packed in such containers.
• There is no standardization of weight for any pack and it may differ from place to place.
• Cost of containers for packing mango also differs from place to place, depending upon the availability of raw material and labour.
• Padding or cushioning material in packaging of mango varies from grass, paddy or wheat straw, to paper shreddings and leaves of mango.
• At times no padding material is used.
• In some places, newspapers are used as lining material in different packages.
• Ventilated wooden boxes with paper shavings in alternate layers as cushioning material have been reported to be ideal for transportation of mangoes ('Dashehari' and 'Banganpalli' for long distance by rail).
• No sudden change in the existing system of package of this fruit seems to be possible.
• Steps have, however, to be taken to eliminate too many sizes and shapes of containers and to evolve tentative specifications of standard containers and methods of packaging.
• These may be drawn up in consultation with the trade, research organizations and Government departments, keeping the economy, availability of the raw material and existing systems of transportation in view.
• The experiments conducted by the Directorate of Marketing and Inspection show that wooden crates are better package material than others because these can withstand a longer transport with much less damage.

Pre-Packaging and Packaging for Export

• The mangoes may be packed in unit packs in 200-gauge polythene bags provided with ventilation through holes, to make the product more popular both at home and in foreign market.
• While packaging in boxes or baskets, individual fruits may be wrapped with tissue paper.
• This not only enhances eye appeal but also protects the fruits from disease, etc.
• Tissue paper (25 cm2) when impregnated with diphenyl at 30-40 mg/wrapper, checks spoilage during storage and transit.
• Each tissue paper must receive 30-40 mg of the chemical in an alcoholic solution.
• For packaging the fruits for export, corrugated cardboard boxes are in use now.
• These may be fabricated either with or without holes on the sides.
• The inside of these boxes is lined with criss-cross arranged card-board strips, making rectangles, which can hold 1 fruit each.
• The State Trading Corporation has developed attractive standard boxes of this type for exporting mangoes to European markets.
• Prior to packing, fruits are wrapped in tissue paper.
• Large-sized baskets and wooden crates of 25-35 kg capacity are also in use for shipping mangoes to the nearby countries.

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Ripening

• Mango is a climacteric fruit and its period of ontogeny is characterised by a series of biochemical changes initiated by autocatalytic production of ethylene and increase in respiration. Respiration is classified as:
• preclimacteric phase lasting for 3 days with slow release of CO2,
• a climacteric rise extending upto 6 days with a sudden spurt in CO2 production.
• a climacteric peak occurring between 6 and 10 days with softening of the fruit and
• a post climacteric phase lasting from 10-14 days with a decrease in CO2 production resulting in edible ripeness of fruit followed by senescence.
  
  
  1. The main changes that occurred during ripening of fruits is the break down of starch into sugars.
  2. There is a continuous decrease in the acidity of fruits during ripening.
  3. Pyruvic and L-Keto glutaric acids increased during the first 9 days and then declined during ripening of Pairi mangoes.
  4. During ripening there will be a decrease in citric acid and succinic acid and an increase in malic and uronic acids.
  5. The marginal changes in malic acid with a 2-6 times decrease in citric acid content.
  6. At ripening TSS content will be varied from 20% in Neelum and Amrapali to 24% in Dashehari and Chausa.
  7. The carotenoids pH and sugars increased during ripening but after a certain stage, the TSS started to decline.
  8. In general, levels of citrate and succinate gradually decreased during ripening while malate shows different changes with different cultivars a relatively high level of 'PEPC' (phosphoenol-pyruvate carboxylase) is released in cultivers Alphonso and Langra but low in Dashehari and Totapari during ripening.

Ripening Aids

• The Langra mangoes can be ripened at room temperature in open, in a wooden box lined with paper, in an earthen pitcher treated with carbide and in a box filled with wood wool.
• They found that the fully mature fruits ripened well under all storage conditions except with carbide treatment.
• In Alphonso fruits, ripening was very much hastened when the mature fruits were kept in a chamber saturated with ethylene gas released from 10,000 ppm ethrel solution containing sodium hydroxide pellets.
• Biochemical analysis of artificially ripened fruits showed no marked difference with regard to any chemical constituents as compared to the ones ripened by conventional method.
• The effect of ethrel and calcium carbide on Dashehari mango fruits will be ripened by placing 4 g of calcium carbide/kg fruits was superior in palatability and had attractive colour development.
• Such fruits were higher in TSS, sugars and carotenoid content but little lower in ascorbic acid content.
• Langra mangoes is ripened with calcium carbide and ethrel and concluded that from eating quality point of view, fruits ripened with calcium carbide (6 g/kg of fruits) was the best followed by ethrel treated (800 ppm) ones.
• Ripening with ethylene is the best method.
• Acetylene gas is liberated from calcium carbide by the addition of water or by contact with moisture in air is used as a commercial ripening procedure in Brazil and Senegal.
• The commercial use of acetylene as liberated from calcium carbide, often results in fruits that are soft and have good peel colour development, but are poor in flavour.
• Acetylene concentrations of 0.4 ml 1-1 for 24 hours at 25° C may advance softening and peel colour development but at a natural rate major repening changes were found to continue.
• Fruit ripened at 19°-21° C gave better quality characteristics than those ripened at 28°-30° C. mango ripening at 15.5°-18.5° C was satisfactory but the fruits were a little tart and required upto 3 days' subsequent exposure to 21°-24° C to develop a good flavour.
• In other work, 21°-24° C was recommended as the optimum ripening condition.
• Recommended ripening temperature for mango were 29°-31° C using ethylene at 10 micron 1/lt for 24 hours in 85-90% RH.
• A simple method was to place the fruits in baskets lined with banana leaves with calcium carbide.
• Which gave fruit of uniform colour within 2-3 days at Malaysian ambient conditions, but with inferior flavour than fruit ripened without calcium carbide.
• Calcium carbide was also used to ripen fruit in South Africa.
• Fruits were placed in a room maintained at 21.1°-26.7°C and 85-90% RH and calcium carbide was introduced at 1 oz per 72 cubic feet for 1-8 days, with ventilation every 4 hours.
• A similar practice was used commercially on mangoes for airfreight export from Brazil, where harvested fruits were kept under gas tight tarpaulins for 2-3 days before export.
• When the use of chemical aids in ripening is mainly intended for faster ripening, calcium carbide is more useful.
• Ethrel ripening though slow had better quality.

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Transport of Fruits

• If the mango is grown within a radius of about 8 km of the market, the transportation of fruits as head loads or by bullock cart, etc. is quite common.
• The huge quantities of fruit that arrive in selected cities from distant producing centres are transported mainly by road and rail, a smaller quantity by waterways and only very little by air.
• Owing to distinct advantages in transporting the goods by trucks compared with railways, there has been a definite shift in favour of road transport of mangoes.
• Trucks are now plying over long distances of 800 to 1,000 km, connecting the producing centres of one state with the consuming centres in the other.
• A survey made by the Directorate of Marketing and Inspection in 1965 revealed that mangoes are brought to the Calcutta market by trucks from the producing areas in Bihar, Uttar Pradesh, etc.
• In Delhi, up to 90% of the total arrivals are transported by road. In Madras city 83% mangoes are transported by trucks.
• The loss during transit by trucks was very small (about 1%) because the trucks run during night, thus avoiding the excessive heat of the day.
• When the fruit is transported by rail, particularly over longer distances, there is loss of 10-20% in the consignment, mainly on account of frequent delays in the movement of the wagons.
• Hence in spite of concessional freight rates offered by the railways for fresh mango, the shift has continued towards road transport.
• The consigner prefers road transport because of ready availability of trucks unlike wagons, their arrival to the destination in time, absence of pilferage enroute and facilities of road at the doors of the consigners and direct delivery to the market.
• Despite these advantages, transport by rail still prevails when the commodities have to be transported in bulk or when the distances involved are long.
• The air-conditioned coaches on the Indian Railways have done a commendable job in reducing the spoilage and extending the keeping quality.
• The coaches maintain a temperature of 12.8-15.60 C, with a relative humidity of 60%. Pre-cooling of the fruits is always better. Railway wagons or covered trucks can also be utilized for refrigerated transport by cooling them with ice. Walls of the compartment need to be insulated. Up to 1.5 tonnes of ice would normally suffice for each wagon for a run of 1 km. The air must be circulated in vans by fitting a fan inside.
• In West Bengal and Assam, transport of mangoes by boats is a common practice. This method of transport is the cheapest. Bombay receives considerable quantities of mango by coastal steamers from Konkan tract from January to the end of May.

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Storage

• Mango fruits are able to respond metabolically to the environment under which it is stored.
• Various methods are employed to extend the storage life of mangoes.
• They are low temperature storage, subatmospheric pressure storage, controlled atmospheric storage, irradiation and use of chemicals.

Low Temperature Storage

• Low temperature storage is one of the most effective means of extending the shelf life of mangoes.
• It reduces the rate of respiration and lowers the rate of ethylene evolution.
• The storage periods of 18-21 and 23-26 days, respectively are for ripe and mature green Carabao and Pico mangoes at 10° C. various cultivars of mango are stored at 12° C and ripened them subsequently.
• The ripening was retarded more effectively in immature than in mature Amelie and Kent fruits, whereas Sensation mangoes ripened rapidly during storage, regardless of fruit maturity at harvest.
• Fruits are sotred at 12° C for 33, 28, 21 and 15 days, respectively.
• The development of beta-carotene is slower at 16-20° C than at 20-28° C in many Florida mango varieties and suggested a temperature of 20-22° C and 85-90% RH for storage and proper ripening of mangoes to obtain acceptable quality.
• That precooled Langra and Dashehari fruits could be stored successfully at 7 and 90 C and 85-95% RH for 35-45 and 25-35 days, respectively.
• These fruits, after removal from cool store, ripened to a satisfactory palatability without affecting the sugars, though carotenoids development was low.
• Surface waxing coupled with low temperature storage of mango fruits reduced respiration, prolonged shelf life and also lessened spoilage.
• Carabao mango could be stored for 17-24 days 7.2-10° C and 85-90% RH with 5.1% loss, Pico mango for 17 days with 6.2% loss at same temperature and relative humidity and Raspuri mango for 4 weeks at 8.3° C and 85-90% RH with 6.8% loss.
• Bangalora, Khuddus, Neelum, Pedda, Raspuri, Safeda mangoes could be stored for 4-7 weeks at 7-90 C at 85-90% RH and Alphonso mango for upto 4 weeks at 8-10° C and 85-90% RH.
• Alphonso from India could be stored for 7 weeks at 7-90 C and 90% RH. Julie mango could be sotred for 2 weeks at 11-120 C and 90% RH and Zill mango for 3 weeks at 100 C and 90% RH.
• Dashehari mango at 120 C has a shelf life of 21 days and subsequently 6 days at ambient condition with around 75-85% RH.
• Chilling injury occurs in Dashehari mango when stored at 10° C and 75-85% RH for more than 14 days.
• Mallika mango could be stored in marketable condition for 10 and 21 days at room and low (12° C and 85-90% RH) temperatures, respectively.

Chilling Injury

• Storage of mango fruits for longer periods below a critical temperature level causes chilling injury.
• The chilling injury manifests as definite pitting on the surface, darkening and softening of the tissues.
• The chilling injury causes leakage of metabolites such as amino acids, sugars and minerals from the cells.
• There is an increased invertase and decreased amylase activities in chill injured fruits.
• The fruits show chilling injury symptoms after 10 days of storage at 4 and 8° C, and succinate oxidation capacity of mitochondria decreased. 4% calcium chloride impregnated at 350 mm Hg or 200 mm Hg subatmospheric pressure is effective in controlling the chilling injury in Baneshan mangoes upto 3 weeks.
• Observation of chill injured Baneshan mango fruits tissues showed that in the initial stages of injury, the damage was restricted to the surface of the fruit in the form of discoloured pits without affecting pulp beneath.
• However, with the advancement of damage, at the later stages both the peel and pulp appeared to be damaged more because of microbial attack (secondary infection) through the damaged (pitted) skin.
• Histological observations revealed that chilling injury damaged the cuticle and epidermis and exposed the sugar rich mesocarp for attack by micro-organisms.

Controlled-Atmoshpere Storage

• Controlled atmosphere (CA) or modified atmosphere (MA) storage, either alone or coupled with refrigerated storage has been recommended for various fruits and vegetables.
• Keitt mangoes are stored for 20 days at 13° C in an atmosphere of 5% CO2 and 5% O2. Mango has a fairly low tolerance to CO2.
• At 15% CO2 level, the fruits did not develop normal red colour, although the flavour was good.
• Haden mangoes could be stored for 6 weeks under 2% oxygen and either 1 or 5% carbondioxide at 10-11° C.
• Optimum concentrations for Julie and Amelie mangoes have been reported as 5% oxygen and 5% carbondioxide at 11° C for 4 weeks.
• Controlled atmosphere storage at oxygen levels of 1% resulted in the production of off-flavours and skin-discolouration, but storage at 12° C with 5% carbondioxide and 5% oxygen was possible for 20 days.
• Storage at 8° C with 10% carbondioxide and 6% oxygen was successful for 4 weeks for Haden and 6 weeks for Carlotta, Jasmin and San Querino.
• Controlled atmosphere storage in 10-15° C with 5% oxygen or with 5-10% carbondioxide and 3-5% oxygen had a fair effect on storage but was not being used commercially.
• In controlled atmosphere storage, trials to control infestation of fruitfly in mango fruits, it was found that fruits exposed to 50% carbondioxide with 2% oxygen for 5 days or 70-80% carbondioxide with less than 0.1% oxygen (Modified atmosphere storage) for 4 days did not suffer adverse effects when they were subsequently ripened in air.
• Lower levels of CO2 (10 and 20%) in combination with 5% O2 were, however, effective in reducing ethylene production during 3 weeks of CA storage at 120 C without affecting subsequent ripening in air.
• The above findings clearly indicate a great prospect in shipping mangoes by sea under CA storage.

Hypoboric Storage

• It is a type of CA storage with emphasis on reducing the pressure exerted on the storage material.
• This method not only reduces O2 concentration but also increased the diffusion of C2H4 by evacuating it from the tissues of the fruit, consequently extending the storage life.
• The fruits stored at 100 and 75 mm Hg started to ripen after 25-35 days as against control after 16 days.
• Pressure 152 mm Hg is optimum for storage of cultivars Irwin, Tommy Atkins and Kent for 3 weeks at 13° C and 90-100% RH.

Low Cost Storage

• Evaluation of zero energy cool chambers at different locations of the country was found to be satisfactory for short term storage of mangoes.
• The major advantage of cool chamber storage of mangoes. was the maintenance of fruit firmness by lowering the physiological loss in weight (PLW) and other metabolic processes.
• Eventually, 3-4 days more shelf life of mature green mangoes could be obtained in cool chamber storage as compared to ambient condition storage.
• Further, a 500 ppm bavistin dip helped in checking the microbial infection.

Irradiation

• Extensive studies have been conducted to determine the effect of r-radiation on the shelf life extension of mango.
• The optimum radiation dose for Alphonso mango is
  25 K rad, giving an extension in shelf life of 6 to 8 days at ambient temperature.
• The response of Kensington Pride mango to r-irradiation which caused delay in ripening of less mature mangoes, characterised by inhibition of skin colour, degreening and slow reduction of titrable acidity, while the fruits at climacteric stage was uneffected.
• The lower dose levels of irradiation in combination with other treatments to induce delayed ripening and reduced post harvest spoilage.
• A combination of hot water treatment (55° C for 5 minutes) followed by 30 Gy irradiation was found to be the best treatment in terms of shelf life extension and quality of mangoes.
• After this treatment, mangoes had a storage life of 38 days (at 15° C), 28% rotting and no irradiation injury.
• Irradiation can be used as a post harvest treatment to disinfest fruits off insects.
• It was observed that 300 Gy control mango seed weevil while 150 Gy was shown to control 11 species of Tephritid fruitfly and 75 Gy prevents the adults emerging from the fruits but more work is needed.
• Doses of irradiation in excess of 600 Gy caused lenticel spotting, surface discolouration and retardation of ripening of Kensington Pride mangoes, but irradiation at this level contributed to only minor improvements in disease control.
• However, irradiation followed immediately by hot benomyl treatment controlled anthracnose and stem-end rot during storage at 20° C for 15 days.

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Post Harvest Treatments

Fungicidal Treatment

• Pre and post harvest application of benomyl for control of latent infection of Colletotrichum is recommended.
• The anthracnose of mango can be controlled by dipping the harvested fruits in a 1000 ppm suspension of thiabendazole or benomyl at 55° C prior to storage.
• A pre-harvest spray of benomyl combined with anti-transparent vapour guard reduced anthracnose of mangoes during storage at 21.1° C more effectively than benomyl with Nu-film 17 (a sticker extender).
• Immersing the fruits in water at 53° C containing 0.5% benlate for 5 minutes is the most effective method for controlling Gleosporium mangiferae.
• Apply the combined spray of captan and benomyl for three times during the period of fruit growth and development greatly dimished therot development during storage.
• The post harvest dip using benomyl resulted in significant reduction of anthracnose in Kensington mangoes.
• The treatment of local mango fruits with hot water (52°+2° C) containing 500-1000 mg/lt benomyl for 5 minutes reduced the incidence of disease.
• Mustard and castor oil emulsions could protect mango fruits from Botryodiplodia rot.
• An antifungal agent consisting of a mixture of 5- (12-cis-heptadecenyl)- and 5- penta decylresorcinnol was isolated from the peel of unripe mango fruits.
• Their results supports the hypothesis that mixture of 5-substituted resorcinols is involved in latency of Alternaria alternata infection which causes anthracnose in mangoes.

Hot Water Treatment

Mangoes may be immersed in hot water before storage or marketing to control diseases.

• A common disease of fruit, which can be successfully controlled in this way, is anthracnose, caused by infections of the fungus Colletotrichum spp.
• Treat the mangoes at 53° C for 5 minutes and or 51-55° C for 30 minutes.
• In some cases, it has been shown that there is an interaction between water temperature and fungicide whereby at lower temperatures there is a greater need to add fungicide.
• The hot water treatment had little or no effect on the quality of marketable life of the fruits.
• In subsequent work, hot water treatment of mangoes to control fruitfully and anthracnose increased the rate of shriveling and the change in total soluble solids: acid ratio and reduced the fruit firmness and acidity during subsequent storage.
• Exposure of Julie mangoes to 55° C for 5 minutes resulted in scorch.
• In other work, the skin colour of mangoes was improved by both hot water and vapour heat treatment.
• Hot water containing fungicide can also be effective in the control of stem end rot caused by the fungus Dothiorella dominicana.

Vapour Heat Treatment (VHT)

• Vapour heat treatment was developed to control infections of fruitflies in fruit post harvest.
• A recommended treatment of mangoes is 430 C in saturated air for 8 hours then holding the temperature for a further 6 hours.
• Fruitfly in Carabao mangoes can be controlled by exposing the mangoes to high humidity hot air i.e. 460 C and 95% RH and above.
• The exposure time was judged by placing a temperature probe alongside the fruit seed and when it had reached 460 C, they were kept under those conditions for 10 minutes.
• By exposing Carabao mangoes to a core temperature of 460 C for 10 minutes by VHT resulted in significant reduction in both anthracnose and stem-end rot.

Waxing and Fruit Coating

• Fazil mango coated with paraffin wax by molten dip method was found to stay in good condition for 42 days when stored at 12.5° C and 90% RH, while the untreated mangoes rotted in 14 days.
• Coating with wax emulsion in water, the storage life of mangoes increased by 50% at room temperature.
• Alphonso fruits when dipped in 1.7 to 2.7% aqueous emulsion of fungicidal wax containing O-phenyl phenol lessened the physiological loss in weight and increased the storage life of the fruits.
• In case of Lucknow Safeda mango, the skin coating apparently checked the loss of ascorbic acid and titratable acidity, while total soluble solids and sugars continued to increase upto the end of storage period.
• The treatment of mangoes with 3% st-fresh wax increased the storage life to as much as 10 days (cv. Graham) or 11 days (cv. Long).
• If the wax concentrations are increased 5% or higher resulted in development of off flavour.
• The fresh Alphonso fruits treated with 6% wax emulsion recorded the lowest percentage of spoilage as compared to control fungicide (thiabendazole) alone.
• Another fruit coating, marked as 'Vapor Gard', is an antitranspirant.
• Its effect on the post harvest life of Harumanis mangoes was studied.
• The effect of coating the fruit in a 1.3% solution was to reduce water loss, retard firmness decrease, reduce the loss of ascorbic acid content, inhibit the malic enzyme activity and increase polygalacturonase activity compared to untreated fruits.

Film Wrapping

• The rapid development of semi permeable films and the growing use of this packaging material for pre-wrapping produce has led to consideration of the possibilities for establishing 'controlled atmosphere' produce package.
• A produce package is a dynamic system in which two main processes, respiration and permeation are occurring simultaneously.
• There is an uptake of O2 by the produce and evolution of CO2, H2O and other volatiles, and at the same time, specific restricted permeation of these gases through the packaging film.
• It has been found that polythylene bags retarded respiration and transpiration and helped increase shelf life and retention of the quality of certain fruits.
• Vinylite and pliofilm wrappers can be used for room temperature storage.
• By wrapping mangoes in polythylene, the storage life of fruits could be extended considerably with subsequent normal ripening.
• The wrapping individual fruits in plastic film has the merit of prolonging their storage life, reducing water loss and skin shrivelling and increasing the CO2 content and decreasing O2, thus slowing down respiration.
• The physiological loss in weight was reported to be lower in waxed mangoes wrapped in perforated polythylene than untreated ones.
• The exposure of fruits individually in polythylene bags increased the storage life at ambient temperature.
• Indian results have shown that wrapping in polythylene films will effectively increase the storage life of mangoes.
• This was confirmed by West Indian results which showed that polythylene wrapped fruits transported to Great Britain had all symptoms of delayed ripening.
• Usefulness of high molecular weight, high density polythylene (HMHDP) for extending the storage life of fruits and delaying the ripening was reported.
• A low physiological loss in weight and low percentage of spoilage as compared to control, when the Alphonso fruits were stored in 150 gauge polythylene with 10 vents.
• Shelf lives of ripe Baneshan mango fruits were extended upto 23 days in cool store (13+ 1° C and 75-80% RH), 12 days in zero energy cool chamber (23+ 3° C and 85-90% RH) and 8 days at room temperature (29.22 to 33.81° C and 56-66% RH) by treating the fruits with 500 ppm bavistin (in warm aqueous solution) and sealing the stem end with molten wax followed by individual film wrapping in 0.48% ventilated HM-films (10 micron).

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Processing

• Mango is perhaps one of the most important fruits of the world which can be utilized by the processing industry during the different stages of its growth, development, maturity and ripening.
• The products prepared both from ripe and green mangoes are highly popular in India and abroad.
• India dominated the world trade of processed mango products, eventhough hardly 1% of the total mango production in India is processed.
• Export of processed mango products is continuously increasing.
• In 1992-93, India exported about 36,600 MT of mango products valued at US$ 27,100,000.
• The major export product is canned mango pulp, which has increased over the past decade by about three times in volume and five times in value.
• Various processed products which can be prepared from both green and ripe mangoes are discussed here.

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Raw Mango Utilization

Green Mango Powder (AMCHUR)

• This is commonly known as 'Amchur' and is used in culinary preparation for traditional Indian cooking, Amchur is generally prepared by sundrying in open place.
• Studies have been conducted to improve the process by using slices of mangoes at an optimum stage of maturity (9-10 weeks after fruit-set) and by sulphite treatment of the slices to improve retention of colour and vitamin-C.
• A drying period of 10 hr in cabinet dried and 15 hr in sun is necessary to reduce moisture content to 2-3% when the tray load is 0.6 kg ft2 with a drying temperature of 55+ 5° C.

Mango Pickle

• Indian pickles are classified as salt pickles or oil pickles.
• Pickles made from seedling mangoes containing 5-6% acidity were found to be of best quality.
• Generally the oil used is either mustard or gingelly oil.
• Salt-cured slices are drained, mixed with spices and oil, packed glass jars and are sealed properly.
• Extra oil is added to from a 1-2 cm layer over the pickle to prevent exposure to air.
• Micorbial spoilage due to mould growth in salt pickles can be prevented by adding 200 ppm benzoic acid.
• Various recipes are avilable for preparation of pickles which are based on the regional preferences.
• Generally, the raw mango slices are treated with 10-20% of common salt, drained and mixed with partially ground spices like coriander, fenugreek, nigella, fennel, cumin seeds, turmeric powder and chilli powder.
• The whole mixture is filled into the jars and covered with mustard oil.

Mango Chutney

• Mango chutney is a kind of spicy jam which can be prepared from peeled mango slices.
• It usually contains 55-600 Brix TSS and 1.0-1.5% acidity.
• Mango chutneis are commercially important and they are classified as
  1. Sweet Chutney and
  2. Hot Chutney.
• Sweet chutney is prepared either from fresh or brined slices.
• The fruit pieces are mixed with canesugar and salt and cooked along with coarsely ground spice mixture to a jam consistency after adding vinegar/acetic acid.
• The hot chutney preparation is similar to that of sweet chutney, except that more spices and less sucrose are used in the recipe.
• Mango chutney is prepared with the dried/dehydrated slices had better overall organoleptic rating compared to chutney prepared from conventionally brined ones.
• We also standardised the technique of drying and packaging green/raw mango slices for subsequent use as mango chutney.

Raw Mango Slices in Brine

• Raw mango slices are preserved both in brine and powdered salt.
• Conventionally green/unripe mango slices are preserved with salt for later preparation of pickles and chutnies by adding 15-20% salt to prepared slices, draining the liquid formed therein and replacing it with fresh salt.
• An improved method consists of steeping the slices in 10% brine containing 200 ppm SO2 for 20 hr at 25° C for primary salting and 5% powdered salt with 200 ppm SO2 for storage.
• Dry salting results in greater softening and browning of slices.
• Steeping the slices in a 5% salt, 1.2% acetic acid, 0.1% potassium-metabisulphite (KMS) and 0.5% calcium chloride solution can be used to overcome this problem.
• The slices after a dip in 1.5% potassium metabisulphite solution were mixed with common salt and preserved for over 2 months in polyethylene pouches. Slices are preserved for over 6 months in 12.5% brine solution with 200 ppm sulphur dioxide.

Green Mango Drink

• It is a popular beverage during the summer in northern India.
• For preparation of panna, the prescribed ingredients include mango slices, sugar, water, salt, cumin seeds, black pepper and citric acid.
• The slices are boiled in water for 20-30 minutes and filtered.
• Powdered spices are extracted along with the fruit.
• The extracts are mixed along with sugar and boiled and filled into bottles.
• A new process of extraction of green mango pulp by baking revealed that baking of green mangoes having fully formed stones should be done at 200° C for 25 minutes or at 300° C for 20 minutes to obtain the physiological composition of pulp i.e. higher pulp yield, more retention of vitamin C. Green mango beverages prepared from the pulp obtained on baking (at 200° C for 25 minutes or 300° C for 20 minutes) were found to be organoleptically more acceptable.

Ripe Mango Products

• Ripe mangoes are utilized for preparation of various products like slices, plup, jam, squash, nectar, juice, RTS beverages, mango leather etc.

Mango Pulp or Puree

• Mango pulp or puree is prepared by homogenising peeled ripe mango slices. Mango puree is canned for long term storage and marketing.
• For Totapuri mango pulp, filled into can shaving 139.7 mm diameter and 181 mm height, the process time was reduced from 63 to 10 minutes when the filling temperature was increased from 73.9 to 87.8° C.
• Variable tinning quality of mango pulp coupled with high rate of spoilage.
• Alternative materials like wooden barrels high density polyethylene containers and flexible pouches have been recommended for mango pulp storage.
• Mango pulp with 350 ppm sulphur dioxide in 300 gauge polypropylene pouches could be stored for upto 5 months, while the pulp with out preservative could be stored only upto 3 months.
• Lucknow Safeda mango pulp could be stored well for 4 months at 4-6° C in sealed 200 gauge polypropylene pouches with 350 ppm, sulphur dioxide and sterilized at 100° C for 20 minutes.

Mango Concentrate and Aroma Recovery

Mango pulp can be concentrated by various methods like

• Freeze concentration
• Evaporation under vacuum
• Centrifugal separation of pulp and serum and subsequent recombination with pulp to produce concentrate.
• The loss of aroma is reported to be least in serum-pulp method of juice concentration and the product can be stored in aluminium pouches at 10° C for 11 months.
• The optimum concentration of mango pulp was 45-480 Brix and the quality of ready-to-serve beverages prepared from the concentrate was comparable to that from fresh pulp.
• However, mango juice extraction through enzyme liquefaction was necessary prior to concentration.
• The enzymes widely used for the purpose were cellulase and pectinase.
• Reducing the bulk of fruit-juice/pulp results in economy of handling, packing, storage, transportation and distribution costs.
• Demand for mango concentrate in export markets has been increasing.
• Mango pulp concentrate can be prepared by concentrating the extracted plup in a forced circulation evaporation under vacuum up to 300 Brix which facilitates easy handling and processing.
• The conditions should be standardized for stripping the aroma from mango pulp and concentrating it in an aroma recovery unit and restoring it to the concentrate prepared from stripped pulp to obtain a fully flavoured concentrate.
• Nectar prepared from such concentrate was comparable to nectar prepared from fresh pulp.
• The shelf life of aroma concentrate whtn packed in glass bottles with additives (sodium sulphitte) was 2 months, when stored at 25° C and 10 months at 2° C.
• Shelf life was 1 year at-18° C even without the addition of any additive.

Ripe Mango Powder

• It is a high value product and is very difficult to produce a quality product.
• Freeze dried mango pulp with added sugar increases the shelf life of the powder.
• Very little loss of flavour occurs, but the cost of production is prohibitive.
• Foam mat drying results in powder with poor sensory qualities.
• Spray drying mango pulp produces powder of good colour but lacking in flavour.
• Incorporation of sugar, milk solids, glycerol monostearate and alginate to mango pulp results in good quality spray dried powder.

Mango Slices

• Slices (peeled) obtained from ripe and semi-ripe mango fruits are preserved in sugar syrup.
• Varieties with fine texture and strong aroma are preferred for making the slices.
• Other varieties such as Dashehari, Totapuri, Baneshan and Fazli produced canned slices with mild flavour and pale colour.
• The varieties Baneshan, Langra and Dashehari have good pulp and slice yield while Bombay Green and Chausa produced poor pulp an slice yield.
• The varieties, Langra and Dashehari were quite rich in ascorbic acid and total carotenoid pigments respectively.
• Colour and flavour of the variety Dashehari were the best among the varieties studied during storage. However, texture of the variety Baneshan scored highest rating in canned and frozen slices during storage.
• The overall assessment showed that Dashehari was best as canned and frozen slices followed by Baneshan, Langra, Bombay Green and Chausa after 9 months of storage.
• Experimental findings revealed that storage of mature mangoes for ripening for the processing purpose may not be economical unless the prices of the mangoes are very low.
• The mango cultivar 'Mallika' was found to be the best for canningslices compared to other cultivars in relation to texture and flavour.

Frozen Mango Slices

• Retention of natural organoleptic quality of mango slices to the fullest extent is not achieved by canning or dehydration.
• Quality deterioration of mango slices can be considerably prevented by freezing techniques.
• Recently there has been phenominal increase in the production of frozen fruits and vegetables.
• Attempts to produce commercially viable frozen mango slices have not been successful so far.
• Poor texture due to slow freezing is the main cause.
• Cryogenic freezing which provides the desired faster freezing rate appears to be the only preservation technique capable of retaining all organoleptic qualities of the fresh mango slices.
• A laboratory scale trial was undertaken to produce cryogenically frozen crack free ripe mango slices which have great export potentiality.

Mango Nectar

• Organoleptic evaluation of canned nectar revealed that individually Dashehari was the best variety.
• However, judicious blending of varieties considerably imporved the quality of nectars compared to individuals.
• The varieties Chausa and Bombay Green which were not found ideal for making nectars individually were considerably improved by blending with Dashehari and Langra was found the best followed by Dashehari and Chausa and Langra and Bombay Green.

Mango Leather

• Mango leather or 'Am Papad' is another popular product which is prepared by drying mango pulp to around 15% moisture.
• Mango leather is prepared and proclaimed the ideal ratio of TSS: acid to be 25:0.5.
• Addition of pectin at the rate of 0.5 to 0.75% was stated to improve the texture of the dried product.
• Mango leather should not be dried in open sun as it may attract dust and insects during dehydration.
• The ideal sugar/acid composition is essential for the preparation of mango sheet leather of the mango cultivars Baneshan, Bombay Green and Dashehari were found to be 250 Brix and 0.5% acidity.
• Addition of pectin at the rate of 0.5% in the cultivar Baneshan and 0.75% in the cultivar Bombay Green and Dashehari was found to improve the texture of the sheet.
• Addition of sugar was found to increase the drying time in all the cultivars, while the addition of pectin had no such effects.
• During the storage of mango sheets of the cultivars, Baneshan, Bombay Green and Dashehari at different temperatures, acidity and reducing sugars increased with the increase in storage temperature.
• Carotenoids of the cultivar Bombay Green and Dashehari were well retained at higher temperatures.
• Ascorbic acid was completely lost at higher temperatures.
• Non-enzymatic browning increased with increase in temperature of storage.
• Sulphur dioxide was retained well in the samples having comparatively less moisture.
• The cultivars having good retention of carotenoids and less browning were organoleptically acceptable even after storage at higher temperatures.
• The ideal moisture to have storage stability was found to be 15% or a little more with a relative humidity between 63-70%.

Mango Fruit Bar

• Mango fruit bar is a confectionary prepared by mixing mango pulp with calculated amounts of sucrose heated to 80° C, cooled and mixed with potassium metabisulphite.
• The pulp thus prepared is spread on a tray and dried in a cross flow air dried at 70° C until the moisture is below 15%.
• The dried sheet is cut into suitable sizes and wrapped in cellophane or glossin paper.
• Pulp with thick consistency produces a dried product with better texture.

Mango Cereal Flakes

• Mango pulp is blended with small amount of wheat-flour and sugar at a fixed pH. the blended and homogenized mass is dried on an atmospheric double drum drier, rotation of the drum is adjusted to 2-3 rpm with the clearance between the driers of 0.35 mm.
• The product, which dries in the form of a crisp continuous sheet, is broken into smaller flakes and packed into air-tight tins.

Value Added Products from Mango Waste

• The major waste products during mango processing constitute 35-55% of peels and stones both in unripe and ripe mangoes.
• Value added products can be prepared from these wastes and simultaneously avoid the disposal problem.
• Peel of Totapuri mango can yield 15.7% pectin having 200-220 jelly grade.
• It has been observed that during extraction of pulp, pulper waste in addition to peel with adhering pulp is obtained.
• These wastes can be treated with pectic enzyme, then juice can be extracted and used in the preparation of nectar, vinegar or concentrated can be expressed and used as a colouring and flavouring agent.
• Mango peel can also be used for biogas production by anaerobic digestion.
• The results of pilot plant studies have shown that mango peel, supplemented with essential nutrients, can yield biogas at a rate as high as 0.68 m3 kg-1 volatile solids added, the gas contained 52% methane.
• The mango seed kernel is a rich source of carbohydrates, proteins, fat and tannins.
• Due to its blandness, plasticity and absence of toxic substances, the kernel fat (avg. 12%) has potential use for preparing sweetmeats.
• It can also be used in soap manufacturing and as a substitute for cocoa butter.
• The starch from mango kernel is recommended for food use.
• Mango seed kernels contain 47-63% starch, of which 19.22% is amylose.
• Gelatinization characteristics and temperature, paste clarity, netnogradation, swelling powder and solubility of seed starch have been studied.

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