On Sat, 16 Sep 2006 BoyPete wrote:

There is a very old vine in my mums garden, laden with masses of grapes.
They are too tart to eat, so I thought 'wine'
Some are ripe to the point of being soft, others are still green. I have all
the equipment to make wine from concentrates, but don't know how to process
the grapes. Can I mix the less ripe with the ripe. That'll do for a start

If they are too tart then they are not good enough for making wine. Your
best bet is to pick them at different times as they ripen. However, be
aware that grapes are seldom as ripe as they look. Leave them all as
long as you possibly can and, to be any good for wine-making, they
should taste fairly sweet.

To be more scientific you need to measure the sugar content. Either a
hydrometer (which you can buy quite cheaply from any shop that sells
wine-making equipment) or a refractometer (much more expensive) will
help you determine the specific gravity.

To use a hydrometer you would need to crush a bunch or two of grapes in
order to extract enough juice to immerse the hydrometer. The reading
should be at least 1.060 to be able to make wine. Any less and you will
have to add sugar, but the resulting wine will be very sharp.

I have a refractometer. This can measure the sugar content in a single
grape. If you lived near to me you could bring a few grapes over and I
could measure them for you.

You don't say whether they are black or green grapes.

Anyway, give a bit more information and I can probably give you more
help. I have about a hundred vines at the moment and will be harvesting
my grapes the week after next. At the moment the specific gravity varies
between 1.055 and 1.070. Hopefully by the end of the month the average
will be around 1.065 to 1.075 and that will give me a pleasant table
wine to last me for most of the year.

David

--
David Rance http://www.mesnil.demon.co.uk
Fido Address: 2:252/110 writing from Caversham, Reading, UK