Maple Syrup Production

A seasonal labor of love for over 30 years.

Sprague's Maple Syrup Collection and Processing

Sprague's Maple syrup is made from pure maple sap, collected from sugar maple trees in very late winter and early spring. The sap is a very dilute liquid containing from 1% to 7% sugar, varying from tree to tree and usually averaging around 2% sugar. It takes approximately 40 gallons of this sap to produce 1 gallon of pure maple syrup.

As the end of winter approaches, Sprague's Maple Farms break roads through the snow to the sugar house, and throughout our maple woods. They then proceed to wash and sterilize all their sugaring equipment.

Next comes the tapping of the sugar maples. A 7/16 inch hole is drilled into the tree to a depth of about 1 1/2 to 2 1/2 inches. Into this is driven a "spout." These spouts are rather like modified pieces of pipe from which the bucket is hung or pipeline is run. A cover keeps dirt and rain water out of the buckets until collection; pipeline carries the sap directly from the tree to the storage tank.

From the tap to the tank

To make top quality maple products the sap must be fresh and cold, which means it must be gathered and boiled often. In some modern sugar orchards small plastic tubing is attached directly to the spouts. The sap then flows through the small plastic tubes to larger pipes, and directly to the storage tank, thus saving the labor of gathering the sap.

From the storage tank the sap flows, to the "evaporator". Evaporators are large pans, varying in size according to the size of the operation. A popular size is 5 feet wide and 16 feet long. Most evaporators have two pans; the flue pan and the syrup pan.
The sap flows first to the flue pan, which has a bottom made of flues to provide a greater heating surface, and then to the flat bottomed syrup pan. The pans are divided by partitions, which creates a continual but very slow movement of sap from the point where it enters the evaporator around the many partitions and finally out of the evaporator as syrup.?

To evaporate the tremendous amount of water in the sap, a large quantity of fuel must be burned. Sprague's sugarmakers use a modern reverse osmosis machine in conjunction with an energy efficient 4' X 14' Lighting Evaporator.

It takes a long time for the 2% sap to be condensed by the evaporation process to the exact density of maple syrup. If cooked too thick the resulting syrup will crystallize. If the syrup is too thin it will be apt to ferment. Sprague's Sugarmakers use a hydrometer to check the density. When the hydrometer settles in the liquid syrup to a mark designating the correct density, the syrup is drawn from the pan. It is then filtered again to remove the nitre (or sugar sand) which has developed in the boiling process.?

From the filtering tank the maple syrup flows into small retail containers or into 35 and 50 gallon drums to be packed later. The syrup is packed hot and each can must be sealed according to New York State law. Only the finest quality syrup carries Sprague's Maple Farms name.

How and why does maple sap flow?

"Maple sap flow may occur anytime during the "winter" dormant season when air temperatures fluctuate above and below the freezing point. In the northern United States and adjacent Canada this can occur from early October through the following April. However, the largest flows take place in late winter and early spring during the months of February, March and April.

During this period, winter begins to lose its grip in many parts of the maple region. Colder days and nights give way to periods when temperatures during the day frequently rise above the freezing point. When these warmer daytime temperatures are followed by below freezing periods, usually at night, strong sap flows can be expected.

Fluctuations in air temperatures above and below freezing during the dormant season cause maples to develop strong positive sap pressure (well above atmospheric pressure) provided there is adequate available soil moisture. Current theory suggest that when temperatures fall below freezing, negative pressure (suction) is created within the sapwood of maple trees as a result of sap freezing, carbon dioxide dissolving in cooled sap, and gas contraction during cooling. As a result of this negative pressure, water moves from the soil into the tree increasing the sap volume. When the temperature then rises above freezing and the frozen sap thaws, forces (including pressure from released gases, osmotic, caused by the presence of sugar and other substances dissolved in the sap, previous gas compression, and gravity) act on the increased sap volume to create a positive pressure. This pressure develops first in the twigs, then in the trunk, and finally in the roots of the maple tree. The positive pressures that develop can be considerable, rising to 40 or more pounds per square inch in untapped trees. When temperatures fall, the process is reversed and pressures are reduced. Below freezing temperatures are required for strong negative pressures to again develop. Much weaker sap pressures develop if below freezing temperatures are not reached and sustained long enough for ice to form within the tree. The presence of sucrose in sap may also be involved in the maple sap flow mechanism.

Sap flow occurs when a wound is made in the sapwood of a maple tree which has positive sap pressure. Sap flow from the wound will continue as long as the pressures inside the tree are greater than atmospheric pressure outside the tree. This period of sap flow (pressure dissipation) will vary from a few (1 or 2) to several (15 to 20) hours in length. Length of the sap flow period and the amount of sap produced appear to be affected by several environmental and tree metabolic factors including the minimum and maximum temperatures experienced, sap sugar concentration, the duration of the freezing and thawing cycles, and the availability of soil moisture. For strong sap flows to be repeated, a suitable temperature cycle above and below freezing must again occur to allow strong positive sap pressure to develop. Sap flow temporarily ceases during the "maple season" when suitable temperature cycles do not occur (cold or warm periods) and ceases entirely when suitable temperature cycles end for the year.

The sugar in maple sap is the product of photosynthesis which occurred during the previous growing season. Photosynthesis produces carbohydrates which are predominately stored in the tree in the form of starch, although some may be stored as sugars (primarily sucrose). During the winter, in maple trees, some of this starch is converted to sucrose and is dissolved in the sap. The amount of sugar in the sap will depend on many factors including the genetics of the individual tree, the quality of the site on which the tree is growing, tree health, environmental conditions the previous growing season and time in tapping season. Sap sugar contents are sometimes lower at the beginning of the maple season, rise rapidly and then slowly decline as the season progresses. However, this may vary depending on weather conditions present the previous growing season."

The previous excerpts are from the American Maple Syrup Producers Manual -Bulletin 856 - Chapter 6: Maple Sap Production - Tapping, Collection and Storage -Physiology of Sap Flow