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