Maple Production
Many stories surround the discovery of maple syrup. One such story is of a Native American that stuck their tomahawk in a tree, causing sap to drip out. The sap, which looked like water, was later used for cooking, and it reduced to syrup, imparting a sweet and distinctive flavor to the food. From then on, maple syrup became an important ingredient in cooking. It was given the name “sinzibukwud,” or “drawn from wood,” referring to the process of harvesting sap from trees.
Early settlers cut gashes in maple trees, which allowed sap to flow. They soon discovered that drilling a hole in the tree resulted in good sap flow and caused less damage to the tree. Early on, sap was collected in either wooden or clay trough-like containers. Eventually, wooden buckets called keelers replaced them. A wooden spout, or spile, was placed in the hole to allow the sap to drip into the bucket.
Although equipment has modernized, the basic process of producing maple syrup remains the same. Trees are tapped when they reach a diameter of about 12 inches. A 5/16” diameter hole is drilled 1 ½ to 2” deep in the tree each year. Some maple producers use metal spouts and buckets to collect sap. Others use a network of plastic tubing that connects trees to a central collecting tank.
Sap is only available during the dormant stage of the tree and flows only when temperatures are above freezing. Nature causes sap to flow within the tree as warmer temperatures remove the frost from the tree itself and the ground surrounding the tree. Therefore, it’s practical to tap trees in early spring with the approach of warmer weather.
As temperatures rise and frost leaves the ground, sap flows less freely, eventually stops, and will not flow again until colder weather freezes the ground, setting the stage for another thaw. Varying weather conditions and rapid changes from subfreezing temperatures causes sap flow, which contributes to a good maple season. It’s a common belief of maple producers that cold nights and warm days are necessary for maple syrup production. In Pennsylvania, that season usually falls between late February through early April, barring any unusual weather conditions.
Once sap is collected, it’s brought to the sugar house where there are several large storage tanks. It takes about 50 gallons of sap to produce one gallon of syrup. Many of today’s maple producers use a reverse osmosis machine, which separates the water from the sugar, leaving concentrated sap. This sap moves to the evaporator—a wood fired or oil fired pan—where the remaining water is evaporated by boiling. The evaporator is a two-part arrangement, as modern evaporators have a series of flues in the bottom that trap heat and give additional boiling area over the earlier flat-bottomed evaporator. Most evaporators are covered by hoods, which carry the steam from the boiling through vents in the roof. A great white plume of steam rising from a sugar house is a familiar sight in spring!
As the sap becomes more concentrated, it flows through a connecting pipe into the front pan of the evaporator, the syrup pan. This flat-bottomed pan has a series of baffles that direct the flow of sap so it’s most concentrated in the section of the pan closest to the draw-off valve. This controlled flow pattern prevents the more dense sap from intermixing with the less concentrated, resulting in a better product.
Sap becomes syrup at approximately seven degrees above the boiling point of water. Since this changes with elevation and barometric pressure, the temperature at which sap becomes syrup also changes. Most syrup producers check the density of their product using a hydrometer.
Because of the volume of syrup and the amount of heat involved in the large evaporator, many producers draw syrup off the evaporator and transfer it to a finishing pan where it’s easier to control the density. Finishing is usually done in a small flat-bottomed pan with a controllable heat source. The finished syrup is then filtered to remove impurities, graded, and packaged in containers for immediate sales or in drums for later use.