When you look on a bottle of Four Roses Single barrel bourbon you may be confused to see “OBSV” or “OESF”. These initials indicate the recipe that was used for that barrel. Hopefully, this page helps you decode the Four Roses bourbon. The first letter in every recipe is “O”. This indicates that it was produced at the Four Roses Distillery in Lawrenceburg, KY. The third letter will always be “S”, which designates straight whiskey distillation. The recipes become a lot clearer when you realize there are only two variables in each recipe, the mashbill and the yeast.
Four Roses uses ten different recipes for their bourbon compiled of two mashbills and five unique strands of yeast.
E = The mashbill that is 75% corn, 20% rye, 5% malted barley
B = The mashbill that is 60% corn, 35% rye, 5% malted barley
K = Yeast K rich in spiciness, full bodied
Q = Yeast Q slightly fruity, spicy, medium bodied
O = Yeast O is floral (rose petal), spicy, medium bodied
F = Yeast F is more herbal
V = Yeast V is delicate fruit, spicy and creamy