Homemade maple syrup

Four species of maple can be used for sap production in Minnesota. Commercial producers generally prefer sugar maple or hard maple (Acer saccharum) for the sweetest sap. You can also gather sap from red maple (Acer rubrum), silver maple (Acer saccharinum) and boxelder (Acer negundo).

Sugar maple is a common tree throughout Minnesota’s forested regions, although it’s most abundant in the state’s eastern and northern regions. In addition to producing sap for maple syrup, sugar maple has been widely planted as a shade and ornamental tree. It’s also valued for lumber, which is used extensively in fine furniture.

Trees grown in yards, pastures and woodlands can all be used for maple sap production.

You don’t need much equipment to produce maple syrup. But a few standard items will increase efficiency and product quality:

• Drill with a 7/16-inch bit for standard spouts or, preferably, a 5/16-inch bit for newer small spouts or spiles.
• Collection spouts, spiles or taps for each taphole.
• Collection container — like a bucket or plastic bag — or tubing line for each taphole. Only use food-grade material.
• Metal cans with plastic liners for storing sap.
• Large food-grade stainless steel boiling pan and heat source for boiling down the sap. Size depends on the amount of sap.
• Large-scale thermometer calibrated at least 15 degrees above the boiling point of water (i.e. a candy thermometer).
• Wool, orlon or other type of filters for filtering finished syrup while it’s hot.
• Storage facilities and containers for the finished syrup. Only use metal, glass or plastic food-grade containers.

Trees suitable for tapping must have a trunk diameter no smaller than 10 inches measured at 4 feet above the ground. Recent studies suggest you place no more than two taps in any tree greater than 20 inches in diameter. For the best sap production, a tree should have a short trunk (sometimes called a bole) topped with abundant foliage. 

The key to good maple grove management is cutting practices that favor the development and retention of such trees.

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  Select a spot on the trunk. It should be about 2 to 4 feet above the ground, and appear to have sound wood. 
• Drill a hole 2 inches into the wood. Slant it slightly upward so the sap can flow downward. 
• Insert the collection spout. Lightly tap it into the tree. 
• Attach a bucket, plastic bag or tubing line to the spout. If you’re collecting sap with open buckets, install a cover so rainwater and other debris don’t get in.

Sap flow

Sap doesn’t flow from maple trees every day of the tapping season. It flows when there’s a rapid warming trend in early to midmorning, following a night when the temperature gets below freezing. So the amount of sap produced varies from day to day. 

Normally, a single taphole produces between 1 quart and 1 gallon of sap per flow period, accumulating 10 to 12 gallons in a season. The flow period may range from a few hours to a day or more.

When to collect and boil sap

Collect and boil down sap as soon as possible for high-quality syrup. During prolonged flow periods when this is not an option, collect sap at least every two to three days or more often, if required. 

If you have low temperatures and favorable storage conditions, you can keep sap one to two days with little reduction in syrup quality. If the sap gets warm before boiling, you may get a darker, off-flavor, poor-quality syrup.

How much sap you need

Sap has an average sugar concentration of 2 percent. At that concentration, you would need 43 gallons of sap to produce 1 gallon of syrup. 

But, the amount of sap needed to produce a gallon of maple syrup varies depending on its initial sugar concentration. To produce standard-density syrup, you’ll need less sap when sugar concentration is above 2 percent and more sap when it’s below 2 percent.

The process of making maple syrup is a matter of boiling the sap so it concentrates into a sugar solution of a predetermined level. Heat allows maple syrup to develop the characteristic color and flavor that make it so desirable.

Approaches to syrup production

Large commercial operations use a continuous feed evaporation process. Sap may also be concentrated using a reverse osmosis (RO) machine before final evaporation. In such operations, the evaporation pan is arranged so sap can be continuously added and drawn off. 

Small operations use a batch approach. The evaporation pan is filled with sap and more sap is added as necessary to replace what’s lost by evaporation.

When there’s enough concentrated sap, the pan is finished-off to produce the correct density syrup.

How to boil sap

Boil sap outdoors or in a well-ventilated area so large amounts of steam can escape. The process may take several hours.

• Fill the evaporating container with sap. 
  • A large shallow pan with high sides is preferred.
• Begin heating the sap. 
  • As the level of sap in the pan reduces through evaporation, add more sap. 
  • Occasionally skim the surface of the boiling liquid to remove surface foam and other materials. 
• Heat until the sap changes color and the boiling point begins to rise above the boiling point of water, which is 212 degrees Fahrenheit. 
  • Finished syrup boils at 7 degrees Fahrenheit above water’s boiling point, or about 219 degrees Fahrenheit. As the boiling sap approaches this point, carefully control the heat to prevent burning and overheating.

Once sap reaches the desired boiling point, the syrup is ready for filtering and packaging. 

• Pour the hot syrup through a filter. 
  • Use a suitable pre-filter paper and a wool or orlon filter designed for maple syrup. 
  • Filtering removes most suspended particles and some sugar sand, and improves the syrup’s appearance.
• Package the syrup. 
  • Do this when the syrup is above 185 degrees Fahrenheit so the heat sterilizes the container. The preferred temperature is 190. 
  • Place filled and capped containers on one side so the hot syrup sterilizes the cap. 
• After cooling, store in a cool, dry place.

Maple syrup may be converted into other highly desirable products, such as maple sugar, maple candy and maple fudge. To produce them, concentrate finished syrup to a greater density and stir the highly concentrated syrup.