Adding vinegar to tanks during fermentation

I have recently read a letter from the Pickle Packers to the FDA from 2011 saying vinegar should be allowed to be added to tanks during fermentation of pickles and vegetables.  I can't find a response to this from the FDA that says it is ok or if it is considered an acidified product.  We are looking into doing some new products for a customer and I was wondering if this is allowed or considered acidification?  We are currently a fermenting only facility.

That's tough, I would not consider it acidified if your pH is naturally low due to the fermentation of your product. However if you need the vinegar to get under 4.6 then the food isn't safe without it and it would be considered acidified.

As with all acidified/LACF inquiries, it is best to involve a competent process authority to help you craft an argument either way. I recommend covance who are very helpful and willing to consult over the phone.