Assuming that "juyce of hops" means what you can squeeze out of a cone, let's figure it like this:
- From Hops Production, (Rybacek 1991): 100 fresh hop cones weigh 1.6 to 2.6 oz...we'll just say 2 oz.
- Cones are picked at 80% moisture content, meaning they are 4/5ths water
- 100 cones could yeild 4/5 x 2 oz = 1.6 oz of "hop juyce" if you were able to really squeeze the buggers
So in theory, you could get 4 oz with only 250 cones but you would need at least a 12:1 compression ratio to make sure you burst the lupulin glands to get out all the oils and alpha acids.
Of course, this assuming everything was perfect, which it never is, so let's figure you would need double that or about 10 oz to start.
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Now let's do assumption #2, he's talking about the oils.
When we bring in our hops, we need to do analysis which includes boiling down the hops to extract the oils for measurement. I'm not a chemist nor do I do this part but I believe industry standard for many varieties is around 1.5 grams per 100 grams of hops.
Converting that to ounces, that means to get 4 ounces of oils, we would need to start with 267 ounces of hops.
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Assumption #3, "Hop juyce" was actually some liquid produced by boiling the hops in water to isomerize the acids, extract the oils, and turn it into a liquid that could be easily stored for long periods of time. The more I think of it, this makes more sense. Instead of trying to store bales of hops in the back of my lagering cave or wherever, I just boil down the hops into a tea and store that bacteriostatic fluid in a barrel to add to my beer toward the end.
I'm not sure how thick of a tea they would make, so its hard to say how many hops would be needed.
I have no idea if they did this or didn't back then but it would be interesting to find out.
Where did that recipe come from and can you post more?