Sugarbush

I spent the weekend west of Minneapolis with the family of a buddy whose family has some land on their place with maple trees. They tap about 700 trees to make maple syrup. The process of evaporating the sap down to syrup was fun and rewarding. It felt like we were really making something--here's some sap, and now here's some syrup, a value added product that we just made.

The process and equipment is relatively straightforward (boil sap down to syrup), but complex enough that one has to know what they are doing if the final product is going to be good and the equipment is going to be maintained. The sap has around a 1.5% to 2.5% sugar content; pure maple syrup has a 67% sugar content. That means 30 to 50 gallons of sap are needed for one gallon of syrup. We made almost 30 gallons of syrup, some from sap with 2.5% sugar and some from 1.6% that had been collected previously and stored in a refrigerated tank.

Because of the density of the syrup, one guideline for when it is finally syrup is that the temperature is 7 degrees above boiling. But that can vary from day to day depending on barometric pressure. Another way is to look at it for sheeting, which is sort of like condensing sugar in candymaking. The definitive measure is to check the density with a hydrometer that will float higher in the liquid the more dense (more sugar) it is.

The system these guys have set up is very cool. Sap is collected in a tank downhill of the trees via tubing that is connected to the taps. The tubing is also connected to a vacuum pump that creates a negative pressure in the tubing and can harvest as much as 100% more sap. Sap from the downhill tank is pumped back up to the refrigerated tank at the sugar shack for storage or evaporation. This is where it gets fun.

A fire is made and stoked in the evaporator where the sap is heated. The evaporator has two pans. The aft pan has a series of ribs in it--like an accordion--to maximize the surface area the heat can hit the water making the 4-foot pan more like 24. As the sap gets hotter and thicker, it is replaced by fresh sap and the natural change in density moves it into the forward pan where it progresses through a series of channels, where it continues to thicken until it gets to the end of the process and is ready to be drawn off at 67% sugar. Then it is filtered and stored for bottling.

I quickly felt comfortable with how the system works, but most of my contribution was in stoking the fire. We burned about a cord of wood during the day. The stack temperature was around 500 degrees, so the furnace temperature would have been significantly higher.

It was also quite a social event. Friends and neighbors stop by to talk and look at the work. Others who make syrup compare notes. All in all a very fun time. It makes me think it may be fun to have a hobby of this sort in the future. Maybe we'll have to factor the availability of such hobbies into our discussions of future places of residence.