Wine Production : Vine to Bottle - Vinum Vine

105
Green harvesting of fruit is generally regarded as good policy;
in wet summers when the grapes swell rapidly and the amount of
sunshine is reduced, many growers consider it to be essential.
Rain at harvest time is a nightmare, invoking a mood of depression
throughout a vineyard area. Grey rot can set in very quickly as the
grapes expand by taking up water from the soil, resulting in those
in the middle of the bunch being compacted and damaged. Bunch
thinning can help reduce this problem. If fruit comes in wet it will
be dilute, each grape skin holding water – you have only to shake
out a mackintosh after being out in the rain to appreciate how much!
Growers at the best of properties have occasionally gone to extraordinary
measures to dry out wet grapes – helicopters hovering over
the vineyards and giant blow-dryers at the reception in the winery,
for example. Mechanical harvesters can prove their worth here, for
if rain is forecasted they can get in the crop very quickly. However,
many small properties may rely on the use of a contract machine, and
this will not be available to them at the time it is most needed.
Provided the fruit is healthy, a grower may take a gamble and delay
picking until after the rain, hoping for an Indian summer to achieve
more ripeness. If hand harvesting takes place, growers may be
instructed to leave damaged or rotten fruit on the ground. Sorting
tables may be placed at the ends of rows of vines or at the winery
reception.
CHAPTER 16
16.3 Handling fruit in the winery
The elimination of unwanted fruit is the first stage of improving quality
in the winery. There may be sorting tables at grape reception, or new
techniques may be undertaken, such as immersing the grapes in
water – the rotten ones fall to the bottom – and then drying the
remaining sound fruit. If excess acidity is a problem, the must may
be de-acidified using calcium carbonate. As briefly discussed earlier,
one recent and very expensive technique is the employment of must
concentrator machines – these cost up to £80 000 so they are not
for the small producer. Vacuum evaporation of excess water results
in a concentration of sugars. Machines employing the principle
of reverse osmosis, a technique only authorised in the European
Union since 1999, concentrate flavours and remove excess alcohol.
The largest must concentrator machines can extract 1500 litres