A: A fold is the relative measure of strength of vanilla extract. Single fold vanilla is typically what the consumer buys at the market. For food processing, two, three or four fold vanillas are typically used. A single fold vanilla contains the extractive matter of 13.35 ounces of vanilla beans, containing less than 25% moisture, in one gallon of 35% aqueous ethyl alcohol. Two fold uses 26.7 ounces of vanilla beans, contains twice as much extractive matter and is twice as strong. Three fold and four fold are just three or four time the content of one fold. This is a standard of identity set by the FDA for Pure Vanilla.
Regular standard vanilla is one fold:
If 1 US gallon= 3.79L
then 13.35 oz/3.79L or 3.52oz per liter
If 1 oz = 28.35g
then 100g vanilla beans per liter of Vodka.
Luc H.