How we process the sap

In the previous blog, I discussed how we collect sap. This season we collected about 58,000 gallons of sap. We process the sap every day that we collect it. First we process it through a reverse osmosis machine that removes some of the water.

The towers contain membranes. The sap is pumped through the membranes at high pressure and pure water is removed, The output is a more concentrated maple sap.

If you recall from the previous blog post, our raw sap was 1.6 Brix. This photo shows the concentrated sap that was output from the RO machine. It is 12.8 Brix, as measured on the refractometer. 

The Jones “Rule of 86” was devised in 1946 by C.H. Jones, a scientist and educator at the University of Vermont. The gist of the rule is that if one divides 86 by the sugar content of sap, you can estimate the amount of sap required to produce a gallon of syrup. The rule has been revised and the recommended dividend is now 88.2.

So it takes 55 gallons of raw 1.6 Brix sap to produce a gallon of syrup whereas it takes just 6.9 gallons of this concentrated 12.8 Brix sap to produce a gallon of syrup. So boiling concentrated sap is a huge savings in fuel and time. 

We cook our concentrated sap over a wood fire. Cooking over a wood fire is the traditional way of making maple syrup and it reduces our dependence on fossil fuels. Chad needs to stoke the fire about every 15 minutes.

The sap is cooked in a set of pans called an evaporator. Our back pan holds about 40 gallons and is covered to boil more efficiently. Clouds of steam rising from the sugar house show the water evaporating from the sap. More concentrated sap is automatically added to the back pan as water evaporates.

Here Jim is monitoring the boil.

 Our front pan is not covered, and it holds about 15 gallons. Here you can see the sticky bubbles.

When the syrup in the front pan reaches 66.9 Brix it is drawn off and filtered. Donna is drawing off finished syrup by opening the spigot.

As syrup is drawn off the front pan more sweet from the back pan is automatically added to the front pan.