TIME AND STAGE OF HARVEST AND TIME AND STAGE OF HARVEST AND HARVESTING TECHNIQUES FOR GRAPESHARVESTING TECHNIQUES FOR GRAPES

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HARVESTINGHARVESTING

Grape is a non-climacteric fruit and hence harvesting should

be done at full ripe stage to get maximum quality.

Signs of ripening of grape include formation of waxy layer on

berry skin, softening and development of typical colour of

specific variety, easy detachment of berries from stem on

pulling, changing of taste from sour to sweetness and

thickness of juice reaching values up to 18 to 20oBrix.

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Ripening process in grapes is highly influenced by auxin-

ethylene relationship.

Ethrel application (250 ppm) improves colour development,

quality and uniformity in ripening.

In case of raisin grapes, ultimate yield of dried product depends

on drying ratio and hence it is advisable to allow berries to

ripen fully on vine so as to decrease water content and

increase Brix values.

In certain areas, these are harvested one to two weeks after

pruning canes which causes berries to abscise more easily

from clusters.

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Table grapes are harvested by clipping bunches from vines

with minimal handling after judging individual bunches for

maturity.

Harvesting is done two to three times over a period of several

weeks.

Ripening is judged mainly based on sugar-acid ratio, which

determines proper blend for table purpose. Sugar- acid ratio

might be a more reliable indicator for grape harvesting.

However, the harvest of varieties with lower acid content (0.40

– 0.75%) could be based on TSS content alone, while for the

varieties with high acid (more than 0.95%), the criterion should

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The varieties with medium acid content (0.75- 0.95%) should

be harvested based on the TSS/acid ratio.

The ratio must be higher for low acid varieties than for high

acid varieties to maintain a given level of acceptability.

This ratio should be 20 to 50, below which fruits are too acidic

and beyond which they are too sweet.

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Thomson Seedless 32.83 Bhokri 31.95

Beauty Seedless 17.54 Pusa Seedless 29.24

Delight 44.75 Hur 31.77

Per I ette 19.32 Bharat Early 27.98

At the time of harvest the sugar: acid ratio should be 27 to

37. The TSS: acid ratios worked out for a few varieties are

as follows.

In wine grapes, harvesting time depends

mainly on type of wine to be made.

Refractometer reading is the most

important parameter to be considered.

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During growth, the pH of grapes constantly undergoes

change, starting with low in the immature grape and

reaching a high value in the over ripe stage.

pH of juice is also important but is very

difficult to adjust in the winery and wines

with pH above 3.6 are potentially unstable.

pH measurement is an expression of the free or

active acidity at any stage in the development and

represents the state of balance of the chemical

constituents at that time.

It would appear reasonable, therefore, to draw the conclusion

that pH can serve as an indicator of maturity.

Generally white wine grapes are harvested at 19-23° Brix,

more than 0.7% acidity and pH above 3.3.

Criteria for red wine grapes are 20.5-23.5° Brix, more than

0.65% acidity and pH above 3.4.

Random samples of a few hundred berries from different vines

are often taken for lab quality evaluation at a few days

intervals and harvesting time is fixed accordingly.

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Grape should not be harvested until they are fully ripe. There

are fully ripe.

There are many indicators to the proper stage of grapes for

picking but the taste is the most valuable indication of the

ripeness of the bunch.

For this purpose, the greenest berries, which are always near

the tips, should be tasted. If they are good to eat, the entire

bunch is ripe for picking.

Fully ripe bunches should be picked for local consumption

while for distant markets, bunches should be picked when still

hard ripe so that they do not spoil during transit

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Ripe grape bunches should be clipped with scissors without

injuring the berries.

During handling, the natural bloom on berries must not be

rubbed off.

Harvesting should be done during the coolest period of the

day.

Bunches should not be exposed directly to the sun. trimming,

grading and packaging should be done in shade.

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Bunches should be graded according to the

fruit quality, maturity and size and different

grades should be packed in different

containers

Undesirable berries viz .unripe, over ripe,

small, misshapen, sun burnt, decayed, soft

and bruised ahould be trimmed.

For nearby markets, mulberry or bamboo baskets

can be used, where as for distant market, wooden

boxes of 4-5 kg capacity or Corrugated Fibre Board

(CFB) cartons should be used.

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A number of factors influence yield from grape vines, the main

ones being variety, training and pruning methods, climatic and soil

conditions, management practices and also age of vines.

About 6-10 t ha-1 can be obtained from vineyards with proper

management and care. Average yield in India (21.5 t ha-1) is the

highest in world.

Economic life of grape vines is about 20years.

YIELD

StorageStorage

The grape berries can be kept without spoilage for 7 days at

room temperature.

Grapes can economically be stored up to 40-45 days in cold

storage.

The optimum storage temperature recommended is -2 to -

1.50C.

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