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Storage of Grapes

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Storage of Grapes

Introduction

Grapes are cultivated in many countries of the world. India produces only about 2.77 per cent of the total world production. However, in productivity India stood first with 23.50 tonnes /ha.

Grape is one of the most perishable fruits and during the process of distribution and marketing, substantial losses are incurred which ranges from a slight loss of quality to total spoilage. Post-harvest losses may occur at any point in the marketing process, from the initial harvest through assembling and distribution to the final consumer. The causes of losses are many: physical damage during handling and transport, physiological decay, water loss, or sometimes due to glut in the market and there are no buyer.

After harvesting grapes are to be kept in shade. Cooling is necessary to reduce the rate of fruit respiration, retard the development of decay and most importantly to minimize water loss from the fruit. In order to control decay of table grapes, fumigation with sulfur dioxide is a common practice. However, it is important to consider that grapes treated with sulfur dioxide will necessarily call for storage under low temperatures.

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Storage of Grapes

Post harvest diseases of Grapes

Anthracnose/ Bird eye spot: Elsinoe ampelinaBotrytis Bunch Rot or Gray Mold of Grape: Botrytis cinereaBlue mould rot: Penicillium digitatumStalk end rot: Aspergillus nigerRhizopus rot : Rhizopus nigricans

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Storage of Grapes

2. Botrytis Bunch Rot or Gray Mold of Grape: Botrytis cinerea:Infected berries first appear soft and watery. Berries of white cultivars become brown and shriveled, while purple cultivars develop a reddish color.Healthy berries touching infected berries will become infected. Rotted berries generally shrivel and drop to the ground as hard mummies .

http://agritech.tnau.ac.in/crop_protection/crop_prot_crop%20diseases_postharvest_grapes.html

Source: http://agritech.tnau.ac.in/crop_protection/crop_prot_crop%20diseases_postharvest_grapes.html

1. Anthracnose/ Bird eye spot: Elsinoe ampelina : The disease mainly spread due to splashing of rain water. Initially small, reddish circular spots develop on berries which eventually develop in the lesions. A pinkish mass of fungal spores (conidia) exudes from these structures during prolonged wet weather condition

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Storage of Grapes

3. Blue mould rot: Penicillium digitatum : Scanty growth - white  and turn bluish green are seen. Decay the berries Infected tissues become soft and watery and emits a moudly flavour

4. Stalk end rot: Aspergillus niger Brown rot at stalk end is start point of attack the pathogen. Rotting begins as a small, circular to oval, water soaked spots are  brown in colour.Infected berries are soft and emit bad odour

5. Rhizopus rot : Rhizopus nigricans : Round irregular, light brown and water soaked lesion appear on fruits. Decaying fruits emits fermented, moudly smell. Source: http://agritech.tnau.ac.in/crop_protection/crop_prot_crop%20diseases_postharvest_grapes.html

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Storage of Grapes

Physiological Disorders of Grapes

1. Internal browning : It’s a physiological problem that develops during cold storage .

2. Browning & Bleaching of Berries: browning is mainly caused when berries are removed from the cold storage while bleaching occurs when sulfur dioxide penetrates the wound & severely bleach the surrounding tissues. It affects its marketability.

Source:httpwww.rootsofpeace.orgdocumentsPostharvest_Technology_and_Methods_for_Grapes_and_Raisins-developed_by_UCD_for_ROP-2005.pdf

3. Freezing or low temperature injury: Berries develop freezing injuries during storage hence it is advised to maintain the optimum temperature of storage

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Storage of GrapesPhysiological Disorders of Grapes --cont--

Postharvest berry drop: This is due to weak pedicel attachment to the berries. This is common in Anab-e-Shahi, Cheema Sahebi and Beauty Seedless. Spraying of NAA (50 ppm), a week prior to harvesting can minimize the post-harvest berry drop.  

Uneven ripening: Presence of green berries in a ripe bunch of coloured grapes is called uneven ripening. It is varietal character and a problem in Bangalore Blue, Bangalore Purple, Beauty Seedless and Gulabi grapes. Within a variety this problem varies from bunch-to-bunch. Generally inadequate leaf area and non-availability of reserves to a developing bunch is the reason. Cultural practices like cluster thinning, girdling and use of growth regulators can reduce uneven ripening. Application of Ethephon (250 ppm) at colourbreak stage is recommended to reduce the problem.

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Storage of Grapes

Packaging

• For local market, grapes are packed in bamboo strip baskets using newspaper and grape leaves as cushioning material. One basket contains 6kg of grapes.• For distant markets (within the country), wood or corrugated cardboard boxes are used for packing. Old newspapers, hay and paper shreds are used as cushioning material. The size if packing is 6 or 8kg in wood boxes, and 2 or 4kg in cardboard boxes. • Grapes for overseas markets are packed in five-ply corrugated fibre board boxes, printed and labeled attractively. The standard dimensions of the carton are 50 cm. x 30 cm. x 12 cm. to accommodate 5 kg grapes.• For the European market, bunches of grapes of approx. 300 to 700 gms. are packed in food grade plastic pouches. They are then wrapped in polythene sheet along with grape guard and tissue paper.• Grapes are packed in ventilated cardboard boxes using dual release sulphur dioxide releasing pads (grape guard) as an in packing material to check the postharvest diseases during transit and storage

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Storage of Grapes

Recommended storage conditions

Optimum Temperature: 0°C Optimum Relative Humidity: 92-96% Exposure to temperatures above 0 °C (32 °F) can greatly increase shatter and decay, especially in tightly packed clusters.

The shelf life of grapes is only one week at room temperature. The storage life of grapes can be increased by employing suitable means to reduce desiccation, decay due to growth of fungi e.g. Botrytis, Cladosporium, Alternaria etc. and bio-chemical deterioration. Harvesting the over-ripe grapes during hot hours of the day, careless handling to cause bruises and injuries to the berries at harvest and packing stage can reduce the storage life of grapes. Under optimum conditions of storage, the maximum storage life of Anab-e-Shahi variety is 40 days, Muscat 45 days, Thompson Seedless 30-60 days etc

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Storage of Grapes

Methods to increase the shelf life of Grapes:

Type of treatment Period of Application Effect

Spraying of fungicides- Captan (0.2%),

aureofungin (500 ppm.), DCNA (2,6-

dicholoro-4-nitroaniline)-0.2%

3-4 days before harvest Reduce decay of berries in

storage.

Application of growth retardants- NAA

(500 ppm.), kinetin (50 ppm.)

Before harvest Reduce berry drop during

storage.

Spraying of growth retardants- B-9

(2000 ppm.), CCC (2000 ppm.), Alar

(500 ppm.), maleic hydrazide (500

ppm.), phosphon-D (500 ppm.)

At harvest or berry softening

stage

Retain the freshness of grapes

for a longer period.

Sraying with Calcium nitrate (1%) Ten days before harvest Reduce the physiological loss in

weight.

Source: nhb.org

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Storage of Grapes

Response to CA Storage: Not currently used at commercial scale

Response to Ethylene: Stimulation of Botrytis cinerea (gray mold) growth can occur on berries and stems in the presence of ethylene. Production from American grapes is < 0.1 μL kg-1 h-1.

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Storage of Grapes

Rates of Respiration Production

Temperature 0°C 4to 5°C 10°C15 to 16°C

20 to 21°C

25 to 27°C

mg CO2 kg-1 h-1 3 5 8 16 33 39

To get ml kg-1 h-1, divide the mg kg-1 h-1 rate by 2.0 at 0 °C (32 °F), 1.9 at 10 °C (50 °F), and 1.8 at 20 °C (68 °F). To calculate heat production, multiply mg kg-1 h-1 by 220 to get BTU per ton per day or by 61 to get kcal per metric ton per day.

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Storage of Grapes

Let us sum up• India produces only 2.77 % of the total world production but in productivity India stood first with 23.50 tonnes/ha. Grape is one of the most perishable non-climacteric fruits. The causes of postharvest losses are many: physical damage during handling and transport, physiological decay, water loss, or sometimes due to glut in the market and there are no buyer. After harvesting grapes are to be kept in shade.

• Cooling is necessary to reduce the rate of fruit respiration, retard the development of decay and most importantly to minimize water loss from the fruit. In order to control decay of table grapes, fumigation with sulfur dioxide is a common practice along with storage under low temperatures.

• For local market, grapes are packed in bamboo strip baskets (6 Kg cap.) using newspaper and grape leaves as cushioning material. One basket contains 6kg of grapes. For distant markets and exports, grapes are packed in five-ply corrugated fibre board boxes (50 cm. x 30 cm. x 12 cm) with cap. of 5 kg fruits.

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Storage of Grapes

Let us sum up –cont--

•Optimum storage temperature is 0°C and RH 92-96%. Exposure to temperatures above 0 °C (32 °F) can greatly increase shatter and decay, especially in tightly packed clusters. Shelf life of grapes is only one week at room temperature.

•The storage life of grapes can be increased by employing suitable means to reduce desiccation, decay due to growth of fungi e.g. Botrytis, Cladosporium, Alternaria etc. and bio-chemical deterioration. Under optimum conditions of storage, the maximum storage life of Anab-e-Shahi variety is 40 days, Muscat 45 days, Thompson Seedless 30-60 days etc.