I have access to concord grapes which I think are ready now (as in right now). How bid a window do I have before it is too late to harvest? Once picked, can I keep them refirgerated until I can crush them? If so, how long will they keep? It's going to take forever to crush them as I only have an old orange juicer for the job. Once juiced, I plan to freeze the juice because I'm not ready to do anything with them for a week or two. Will this work? I'm also planning to freeze the skins in case I need them.
I hbope to get some responses soon. If not , I will proceed as above and hope for the best.
It is very important with grapes to test them before picking. If they have a brix over 21 they should be fine to harvest but in general terms the higher the better. In the absence of pests or disease there is no real risk from leaving them to hang longer - they should just ripen more, though I have no experience of concord grapes which are not a traditional wine variety. I can't imagine using a juicer to process grapes - usually they are crushed with the traditional bare feet (or crusher/destemmer) and then pressed. You can ferment with the skins, but this is usually for red wines. After fermenting you can take off the free run, and there is a lot less skins. Freezing seems unnecessary - how difficult is it to pop them in a fermenter with some yeast?
if you decide to pick now the grapes would be better off in the frezer than the fridge they will last longer and they will go through a cell structure damage which will help in extracting more juice from the grape. i would not use a juicer to crush grapes though i would use a wine bottle or my feet if had a real lot.
I used to raise concord grapes for commercial juice production. We sold to Welches and Coca Cola. We would start harvesting at 16 brix. Grapes had to be at processor within 8 hours of harvest or they would start fermenting on their own.
Ya there are a lot of wine making grapes out there that can not get over 20 brix. Its a little late to do this, but i would run a extended massoraiton on them. Add some so2 and let them sit in the refridge for about 3 weeks warm them up to pitching temp and throw in your yeast. keep all the skins and seeds in, until 1/2 the brix are gone, then press. You get more body and tannin by doing EM.