Post-Harvest Profile of Grapes - Agmarknet

After harvesting, the bunches in some cases are put directly in CFB
Boxes/Wooden Boxes/Bamboo Baskets at the field itself for transportation to
markets. But, it is desirable that soon after harvesting the produce should
be properly screened to sort out damaged, shrivelled and diseased berries
taking care to keep the natural waxy bloom on the surface.
Some times, the harvested produce is treated/fumigated with sulphur dioxide to
sterilize the fruits. It prevents attack of bacteria and fungi from cuts/wounds.
PHYSIO-CHEMICAL CHANGES DURING DEVELOPMENT OF GRAPE BERRY:
The growth of grape berry is three-phase process:
i) During the first phase, volume of berry development increases rapidly
and cell division of the pericarp attains highest rate.
ii) In second phase, auxin level reaches at the maximum and ascorbic
acid which initially remains at a low level, increases towards the end
of this phase.
iii) During the third phase, change in colour and consistency of berries
further increase in volume due to the presence of inherent sugar water
and decrease in ascorbic acid content. The state of colour change in
berries is technically known as ‘Verasion’.
The stage of berry development can be further classified into green stage, ripening
stage, ripe stage and over ripe stage. The green stage begins with setting up
of berries and extends up to ripening stage which is characterised with rapid
increase in size of berry, low quantity of sugar and consistently high acidity
in hard structured berries. Ripening stage starts with initial level of ripening
to the fully ripe stage of grape, during this stage berries become soft and
exhibit changes in colour. The green coloured varieties turns into white or
yellow with the increase in sugar content and decrease in acidity. The
colour change in red and black coloured varieties become more intense. In
over ripe stage, the sugar contents increase due to evaporation and
decrease in acidity. The berries are subject to fungal infestation, pest attack,
shriveling and drying in this stage. The strength of the skin provides
safeguard for post harvest handling at various stages.
FACTORS AFFECTING GRAPE BERRY RIPENING:
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