2 IntroductionIndia is a leading producer of mango in the world. Mango is one of the most perishable fruits and heavy production of mango in a country like India necessitates storage till they reach consumers or processed. Further, mango is a crop which is harvested during hotter part of the year in India i.e. April to August. This results in high postharvest losses.Cold storage and application of skin coatings to control the ripening processes and reduce aging and water loss are established to reduce losses. Storage at lower temperatures and RH may lead to chilling injury to the fruits. The stage of harvesting for storage of fruits and storage containers, ventilation, handling also play a major role. Pre-packing of fruits and individual fruit wrapping may also prove to be beneficial in reducing losses.
3 Common deteriorative changes / problems in potato storage RottingWeight loss / shrinkageChilling injuryHeat injurySap burnJelly seedSoft nose
4 PHYSIOLOGICAL DISORDERS Sap burn: Dark-brown to black discoloration of mango skin due to chemical & Physiological injury from exudate (sap) from cut stem.Skin abrasions: Abrasions due to fruit rubbing against rough surfaces or each other result in skin discoloration and accelerated water loss.3. Chilling injury: Symptoms include uneven ripening, poor color and flavor, surface pitting, grayish scald- like skin discoloration, increased susceptibility to decay, and, in severe cases, flesh browning. Chilling injury incidence and severity depend on cultivar, ripeness stage (riper mangoes are less susceptible) and temperature and duration of exposure.
5 PHYSIOLOGICAL DISORDERS Heat Injury: Exposure to temperatures above 30°C (86°F) for longer than 10 days results in uneven ripening, mottled skin and strong flavor. Exceeding the time and/or temperature combinations recommended for decay and/or insect control, such as 46.4°C (115.5°F) water dip for minutes (depending on fruit size) causes heat injury (skin scald, blotchy coloration, uneven ripening).5. Internal flesh breakdown (stem-end cavity): Flesh breakdown and development of internal cavities between seed and peduncle. This disorder is more prevalent in tree- ripened mangoes.Jelly Seed (premature ripening) : Disintegration of flesh around seed into a jelly-like mass.Soft-nose: Softening of tissue at apex. Flesh appears over-ripe and may discolor and become spongy. This disorder may be related to calcium deficiency.
6 PATHOLOGICAL DISORDERS Anthracnose : Caused by Colletotrichum gloesporioides, begins as latent Disorders infections in unripe fruit and develops when the mangoes begin to ripen. Lesions may remain limited to the skin or may invade and darken the flesh.2. Stem-end rot: Caused by Lasiodiplodia theobromae, affects mechanically-injured areas on the stem or skin. The fungus grows from the pedicel into a circular black lesion around the pedicel.
7 PACKAGINGFruits are placed in layers, with a straw padding in-between.Temperatures between 19-21°C during ripening improve fruit qualityWooden boxes are commonly used for packaging and transportation.CFB Boxes of 5 kg and 10 kg capacity for packing and shipping of mango fruits are also available.For export purposes, packaging in CFB boxes is essential . Paper scraps, newspapers, etc., are commonly used as cushioning material for the packaging of fruits which prevents bruising and spoilage 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 honeycomb nets helps in optimum ripening & less spoilage.
8 RIPENING For viewing video click the link given below Ripening of mango is commonly done in the field right after harvest and before packaging, by increasing the temperature of the fruit. This may be done by either leaving the fruit exposed in a shed for up to two days on the ground, or wrapping fruits in newspaper and again in plastic. Temperatures above 25°C cause uneven ripening. Temperatures above 35°C slow-down the ripening process by inhibiting the enzyme ACC oxidase that is responsible for the formation of ethylene. These high temperatures increase water loss and decay incidence very significantly.For viewing video click the link given belowPacking Mangoes for Natural Ripening ---Health friendly method to ripen mangoes ---
9 Uniform bulk ripening of mango Mango is harvested in a mature but unripe condition, and are subsequently ripened.Normally mango ripens slowly, leading to high weight loss, desiccation, and uneven ripening.Usually ethrel spraying or dipping of fruits in ethrel was recommended for enhancing ripening, but t may cause some problems if commercially available ethrel is impure.Ethylene gas has been commercially used in modern ripening chambers, but this requires huge investments and are not economically viable option for farmers and small traders.Exposing fruits to ethylene gas in the plastic tents is a simple alternative economical method for enhancing ripening of fruits.A small quantity of sodium hydroxide is added to ethrel to release ethylene gas, and fruits are exposed to liberated gas in an air-tight portable plastic tent. Fruits are placed in the ventilated plastic crates inside the air-tight tents of known volume. Required/ calculated quantity of ethrel in a container is placed inside the tent to which measured quantity of sodium hydroxide is added for releasing ethylene gas; and the tents are sealed air-tight immediately. A small battery operated fan can be placed inside the tent for uniform circulation of released ethylene gas. After hours of exposure, fruits are taken out for completion of ripening process at the room temperature.Mango fruits exposed to 100 ppm ethylene gas for 24 hours could ripen in 5 days as compared to the ripening in 10 days of the non-treated control fruits; without adversely affecting quality.ICAR News, Vol 15, No. 4
10 Recommended storage conditions Optimum Temperature 13°C (55°F) for mature-green mangoes 10°C (50°F) for partially-ripe and ripe mangoes Optimum Relative Humidity %
11 Rates of Respiration Production To calculate heat production multiply ml CO2/kg·hr by 440 to get Btu/ton/day or by 122 to get kcal/metric ton/day.Rates of Respiration ProductionTemperature10°C(50°F)13°C(55°F)15°C(59°F)20°C(68°F)vml CO2/kg·hr12-1615-2219-2835-80To calculate heat production multiply ml CO2/kg·hr by 440 to get Btu/ton/day or by 122 to get kcal/metric ton/day.
12 Rates of Ethylene Production Rates of Respiration ProductionTo calculate heat production multiply ml CO2/kg·hr by 440 to get Btu/ton/day or by 122 to get kcal/metric ton/day.Rates of Ethylene ProductionTemperature10°C(50°F)13°C(55°F)15°C(59°F)20°C(68°F)ul C2H4/kg·hr
13 Responses to EthyleneExposure to 100 ppm ethylene for 12 to 24 hours at 20 to 22°C (68 to 72°F) and 90-95% relative humidity results in accelerated and more uniform ripening of mangoes within 5-9 days, depending on cultivar and maturity stage.CO2 conc. should be kept below 1% in the ripening room
14 Responses to Controlled Atmospheres (CA) Optimum CA 3-5% O2 and 5-8% CO2CA delays ripening and reduces respiration and ethylene production rates.Postharvest life potential at 13°C (55°F): 2-4 weeks in air and weeks in CA, depending on cultivar and maturity stage.Exposure to below 2% O2 and/or above 8% CO2 may induce skin discoloration, grayish flesh color, and off-flavor development
15 Glimpses of Modern Cold / CA Storage Structures
16 COOL CHAINCool chain is essential during the transport of export quality commodity all the way from the farm to the customer. This helps in maintaining the temperature inside the box at the same low level as in the cold storage.The various stages of the cool chain are :1. Cold store at the farm.2. Refrigerated truck from farm to the airport3. Cold store at the airport.4. Building up of the pallet in a cold store at the airport.5. Loading the aircrafts directly from the cold store in a short time.6. Cargo aircraft maintains cold store temperature in hold.7. Off loading direct into a cold store in the receiving country.8. Refrigerated truck to the customers.
17 Let us sum upThe most critical factor affecting the postharvest shelf life of mangoes is their temperature management. The temperature range of 20 to 23 °C (68.0 to 73.4 °F) will result in fruit of the best appearance, palatability, and decay control when ripening mangoes. Mangoes can be held at 10 to 13°C (50 to 55°F) to extend their shelf life. Holding mangoes outside these temperature ranges will result in fruit with less than optimal quality, and can injure the fruit. The ripening rate can be accelerated by the treatment of mature-green mangoes with 100-ppm ethylene for 24 hours. Relative humidity of 90 to 95% should be maintained during all postharvest handling steps to minimize water loss and shriveling of mangoes.Several methods have been evaluated to extend the shelf life of mangoes beyond that possible through postharvest temperature management. These methods generally rely on the control of the availability or action of O2 and CO2 and ethylene during ripening to delay ripening (and thus an extension of storage life) by 2 to 10 days.