A great resource that many of us in the mid-west don’t take advantage of is the black walnut tree. It can be tapped as a source of syrup, the leaves can be harvested as a bittering agent, the very young walnuts can be harvested for pickling or Nocino, and of course you have a strongly flavored nut that is produced from the tree.
From the brewery aspect, the black walnut tree offers a lot of potential. Obviously, the sap can be fermented, but also the leaves can be added along with hop additions to add unique bittering experience to the beer. Have you ever peeled the husk of a green walnut? You’ll notice a unique odor that bursts that I’d explain as an earthy eucalyptus aroma, but lacking the clear-your-sinuses menthol. If you’ve never had a chance to sample a nocino, be sure to check out Wood Hat Spirits’ black walnut liqueur.
Let’s talk about walnut syrup. It’s difficult to find in the stores and a lot of the ones that you can find are boiled bark that is then mixed with sugar. Real walnut syrup is harvested a lot like maple syrup is from our northern friends. Trees are tapped and sap is collected when days begin a thaw and nights are still cold. This fluctuation in temperature causes the tree to act like a hydraulic pump… pulling water from the ground in the day, then pushing it back down at night. This movement of water can bring .25 – .5 gallons of sap, per tree, to your collector in one day. This season runs from late January to really mid March… with a 2-3 week spike in the middle. I can’t tell you when exactly, we all know how the weather is around here! Anyway… this sap is boiled down and evaporated. Yield is roughly 1 cup of super sweet syrup to 1 gallon of sap.
This syrup is highly fermentable just like maple syrup is. Taste wise, it is very close with the exception of an earthy flavor that accompanies the walnut syrup, and its flavor compliments many styles of beer. There just hasn’t been a lot of experimentation with it… until now!