Oh what a nice find! From Fr. Schnippel's Called By Name blog, drawing in turn from Sanitas Contra Gentes:
Blessing of Beer:
V. Adjutorium nostrum in nomine Domini.
R. Qui fecit caelum et terram.
V. Dominus vobiscum.
R. Et cum spiritu tuo.
Bene+dic, Domine, creaturam istam cerevisiae, quam ex adipe frumenti producere dignatus es: ut sit remedium salutare humano generi, et praesta per invocationem nominis tui sancti; ut, quicumque ex ea biberint, sanitatem corpus et animae tutelam percipiant. Per Christum Dominum nostrum.
Et aspergatur aqua benedicta.
V. Our help is in the name of the Lord.
R. Who made heaven and earth.
V. The Lord be with you.
R. And with thy spirit.
Let us pray.
Bless, + O Lord, this creature beer, which thou hast deigned to produce from the fat of grain: that it may be a salutary remedy to the human race, and grant through the invocation of thy holy name; that, whoever shall drink it, may gain health in body and peace in soul. Through Christ our Lord.
And it is sprinkled with holy water.
You had better believe we'll use this prayer at this year's annual Assumption Feast (scheduled for August 19 at the Nativity of the Blessed Virgin Mary, just outside of Cashton, WI. If you're in our neck of the woods, e-mail me about joining us for a sung High Mass, procession, and feast afterwards featuring abundant victuals and homebrew.)
Thanks for the link, Father Schnippel!