Help! just been given a load of grapes

[bert7cosby]

Hi I have just been given a bag full of red grapes 4.7 kg in total by a friend, I don't want them to go to waste as they are slightly to sour for eating. Would love to make some kind of wine out of them and any help in doing so would be greatly appreciated.

 

[bobsbeer]

There have been a few threads lately about making wine from grapes so do a search. But basically, destem, crush in a bucket and throw in a crushed campden. Leave for 24 hours and drain the juice into a fermenter and add a decent wine yeast. How much time on the skins depends whether they are red or white. If red ferment with the skins to get the colour and tanin.

 

[tonyhibbett]

If they are too sour to eat they are possibly under ripe therefore low in sugar and high in acid. 4.7 kg after crushing and pressing should yield around 3 litres of juice. To correct any deficiencies, the cheapest and simplest solution is to add sugar syrup. Most wine kits are designed on this basis.

 

[bert7cosby]

Great ill give it a go, how do I know how much sugar syrup will be required.
May start the process tonight and give feedback so that I can get some pointers along the way.
thanks all
Brett

 

[tonyhibbett]

You need a hydrometer to measure the sugar in the juice. Without this information, I can't say how much extra is required.

 

[bert7cosby]

squashed the living daylight out of them last night and added 1 crushed campden tablet. I will test gravity tonight.
Cheers

 

[bert7cosby]

Just tested the sg and its sitting at 1050. Is that about right ?

 

[tonyhibbett]

It suggests that they are under ripe and on the lowest limit of viability. However I had some grapes which were fully ripe at this level and therefore the acidity was acceptable. It depends on the variety. In this case only sugar, (not syrup) at the rate of 80 g per litre of juice would need to be added. If you have no means of testing the acidity, such as suitable litmus paper, a pH meter or titration kit, you will have to rely on taste. If the taste is acceptable, then there is no need to dilute with water, but if it tastes too sharp, I need to know how much juice you have. Assuming it's 3 litres and you aim to make a gallon (4.5 litres) of wine, you will need 1.5 litres of syrup containing 550 g of sugar. Once this has all been thoroughly mixed with the juice, the gravity should be around 1085. The syrup will reduce the acidity by 1 third. Fermenting with oak chips will give you a smoother wine.

 

[bert7cosby]

Ok so I have just poured all the juice and pulp into a fv and it comes up to the 4l line.
I measured the ph with a strip and its no 3 on my card which I think is quite acidic.
Am I best to put yeast in now or shall I add sugar first ?
Also I have a carton or red grape juice can I top it up with this ?
Thanks for the help

 

[Tim_Crowhurst]

If you have a hydrometer, you want to add sugar until you reach an SG of around 1075-1090 - assuming you're aiming for table-wine strength at the end. It is easiest option to add as a syrup. Use 100ml of the grape juice to dissolve about 300g/10-12oz of sugar, and add slowly until you reach the desired SG.

Check the acidity again after you've added the sugar. If the pH is above 3.2, you're fine. Below that and you'll want to add some precipitated chalk to increase the pH. You want a lower pH for a white wine than for a red.

For the rest of the grape juice, most of it you won't need but it'll be worth freezing a few 100ml batches to use topping up after racking.

 

[tonyhibbett]

If the grape skins have lost most of their colour, strain out all the pulp and get out as much liquid as you can. Leave overnight to settle, then siphon off from the sediment. This will leave you with about 3 litres. Check the gravity again. If it's still 1050, proceed with syrup as I suggested. The carton of grape juice is a good idea because it seems you don't need to dilute with water to reduce acidity and the grape juice will be less acidic than what you already have and will retain body and depth of colour. Add the whole carton after siphoning off the juice and check the gravity and pH again. If the gravity is still 1050, add 400 g of sugar but no water, and stir well. You will probably now have about 4.5 litres. The gravity should now be around 1090. Add yeast and store in a warm place.