Enterprising grape farmers produced liquid and semi-solid grape concentrates, often called “wine bricks” or “wine blocks”. This demand led California grape growers to increase their land under cultivation by about 700% in the first five years of prohibition. The grape concentrate was sold with a warning: “After dissolving the brick in a gallon of water, do not place the liquid in a jug away in the cupboard for twenty days, because then it would turn into wine.”
My mama says that during prohibition, the packets of yeast sold in the stores had the recipe on the back for making home-made mash, with a warning that following those directions would be a violation of federal law.
Now that’s real “truth in labeling”.