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I never use any chlorine-containing cleaning compounds in my winemaking and don’t recommend it to anyone. There are plenty of alternatives for cleaning, one of my favorites being sodium percarbonate.
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The first step I would take is to look at the package and/or the packing slip that came with the grapes . . . I hope they say Syrah. If you still doubt the paperwork, certainly get in touch with your juice supplier and ask to see the paper trail from the lot of juice you received.