Maple Syrup Production

A TOUR OF OUR “FACTORY”

Our Store/Candy Kitchen and Sugar House
Our Store/Candy Kitchen and Sugar House

When we step out through the double doors of our gift store/candy kitchen, we look straight across the valley at our largest sugar bush.

A sugar bush is a forested area of sugar maple (acer saccharum) and black maple trees (acer nigrum) that are tapped to make maple syrup and maple sugar. We collect sap from thousands of tap holes on our own farm, with many trees providing two or more taps. The number of taps we drill annually has varied over our more than three decades of syrup production; we’ve had as few as 500 and as many as 3500 taps.

A View From Our Store Across the Valley at Our Largest Sugar Bush, Winter
A View From Our Store Across the Valley at Our Largest Sugar Bush, Winter
A View of Our Store From the Far Side of the Valley, Within Our Sugarbush
A View of Our Store From the Far Side of the Valley, Within Our Sugarbush

TAPPING OUR TREES

A healthy maple tree can be tapped each year with no harm to the tree. Every spring, after the maple season ends, tap holes dry up as the woody tissue around each tap hole dies. Over the course of several years, the tree covers over old holes with new wood; this leaves a slight scar on the outer bark.

The young outer layers of wood on a maple tree are alive, and new wood is produced each year (this creates the annual “rings” that can be used to determine the age of a tree). Older sapwood eventually becomes part of the dormant core wood or “heart” of the tree. Eventually the scarred tissue around old tap holes becomes part of the “heart” of the tree, as new sapwood grows over it each year.

When we tap a tree, metal or plastic spiles are pounded into tap holes that we have drilled in the maple trees. Tap holes are 5/16″ in diameter and between 1″ and 1.5″ deep. They are drilled at a slightly upward angle to insure that the sap will flow out of the hole, through the spile, and into the bucket or plastic tubing system.

SUGARING WITH PLASTIC TUBING

Buckets hanging from trees are an effective means of collecting sap, but we find that plastic tubing systems are more efficient and less labor-intensive.

An "Antique" Metal Bucket and Metal Spile Hanging From Our "Museum" Wall
An “Antique” Metal Bucket and Metal Spile Hanging From Our “Museum” Wall

Plastic spiles replace the wood and metal ones. Plastic tubing replaces the buckets, and this runs directly to large gathering tanks, or directly into our sugar house. Our system uses approximately 15 miles of branch line tubing (5/16″ diameter) and about two miles of larger mainline tubing; mainline tubing is similar to the ordinary plastic water line leading to your house. Many branch lines feed into a mainline as the mainline winds down the slope to large collection or holding tanks (in some cases directly into our sugar house).

Our Tubing System
Our Tubing System

Tubing systems may be vented or closed. With sufficient slope, closed systems, such as we use, provide greater sap yields through the creation of natural or artificial vacuums. We add vacuum through vacuum pumps, which draw extra sap through the system and increase our yield per tap hole by 75%. Even with artificial vacuum we remove less than 10% of the sugar in the tree; there is little danger of taking valuable nutrients from the tree.

Mainline Tubing with Artificial Vacuum System
Mainline Tubing with Artificial Vacuum System

One last feature of the tubing system worth noting is the use of drop lines. These are the vertical lines that connect the spiles to the branch line. These lines allow the spiles to be moved to new holes around the tree each spring without re-plumbing the line. These lines also allow for the separation of CO2 gas and sap. All plants use carbon dioxide to live and maples are no exception. Much of what comes from the tap hole is CO2 gas; if this CO2 is not separated from the sap, it can contribute to vapor locks that inhibit the flow of sap.

After the season, all the tubing must be washed so that the system is sterile at the beginning of the next season. This is done by forcing disinfectant through the whole system and then rinsing. This process alone takes up to a week. Before the next season the tubing system must all be repaired where necessary, and new holes must be drilled. The largest problems in maintaining such a system come from animals like squirrels and deer; these animals chew holes in the tubing in their search for food.

SAP COLLECTION

We have many sap storage tanks in our various sugar bushes. The mainlines, described above, flow into these tanks. The sap in these gathering tanks is pumped out into a gathering tank aboard a truck or wagon. It is then driven to a dumping station behind the sugar house. The sap runs by gravity from into more storage tanks.

Sap Storage Tanks Inside Our Sugar House
Sap Storage Tanks Inside Our Sugar House

A good sap run will yield 3000 or more gallons of sap per day. In order never to lose a drop, we have a storage capacity of some 6000 gallons. Sap degrades quickly after it leaves the tree. Keeping the sap cool and bacteria free can increase its life. However, this gift of spring usually begins to spoil or ferment within 24 hours and must be processed immediately to make a high quality syrup. The sap is exposed to ultraviolet light upon entry into the sugar house to kill bacteria and slow fermentation. Screening also filters out bits of wood, etc., which might be brought along with the sap. However, closed tubing systems such as ours eliminate many of the impurities that used to make their way into buckets in the past.

Frozen Sap in a Holding Tank
Frozen Sap in a Holding Tank

OUR TRADITIONAL WOOD FIRED EVAPORATOR

Our Evaporator In Our Sugar House
Our Evaporator In Our Sugar House

The evaporator room is where the syrup is actually made. Maple sap is a colorless liquid, easily mistaken for water, except for a slightly sweet taste (2% to 3% sugar content). It takes 30 to 45 gallons of sap to make one gallon of syrup, depending on the type of sugar bush, the year, the time of the season (early or late), and the quality of the sap. In the room pictured below, we boil away enough of the water to go from 2% to 3% sugar in sap to 66% sugar in syrup.

This long, low stove with chimneys is our wood fired evaporator. It measures 5’x 12’. The evaporator boils off about 250 gallons of water per hour. The fuel wood for the season is stored in the adjoining wood shed. It takes one full cord (4′ x 4′ x 8′) of fully dried hardwoods to fuel the evaporator for 8 hours. If the evaporator were oil fired, it would need 75 gallons of fuel oil to replace that full cord of wood. The evaporator produces approximately 6-7 gallons of syrup per hour of operation. To save wood and be more energy efficient we also use a reverse osmosis flltering unit that concentrates the sap before it goes to our wood fired evaporator.100_1203 When we do this our syrup production from the wood fired evaporator jumps as high as 25 gallons per hour of operation. The wood is moved from the woodshed on a trolley rolling on an overhead track.

Our Woodshed
Our Woodshed

The evaporator is fired from the firebox at the front end, nearest the doors to our woodshed. The firebox is airtight; the air necessary for combustion is provided by 3 fans. This system provides the right amount of air in the right places in the firebox to ensure the most efficient combustion possible. The fire rushes under the length of the “cooker” (evaporator pans) to the large smokestack at the back of the evaporator. A well-fired evaporator creates little smoke, and creates a slightly “sweet smell” as combustion is quite complete.

Evaporator Front-End, With Firebox Door
Evaporator Front-End, With Firebox Door

When boiling, the sap moves through the evaporator from compartment to compartment in very large, connected “pans”, which form the top of the firebox. The evaporator pans, together, form a long channel (about 50 feet long) with fresh sap entering one end of the channel and syrup being drawn off on the other end. These pans are perfectly level so evaporating water lowers the level in the pans uniformly and opens a float valve to add fresh sap at one end. Fresh sap entering “pushes” liquid forward in the channel, gradually thickening as it moves along, and syrup taken off the other end “draws” near syrup to replace it. The process is continual with sap always coming in and fully cooked syrup being “drawn off” every 15 minutes or so.

Empty Evaporator Pans
Empty Evaporator Pans

 

While the pans usually have only about 1 1/2″ of liquid in them, the thickened sap tends to foam wildly as it approaches the syrup state and uses the full 10” height of the uncovered front pan. The covered portion of the larger, rear pan (the flue pan) is a third pan (called a “piggy back” pan) where the sap enters first. The steam from the bottom flue pan combined with air forced into the sap by a large fan produces the preliminary evaporation at a temperature below the boiling point of water. The sap next enters the flue pan, which has long, narrow chambers extending below the pan into the firebox to greatly increase the surface area of the pan for greater heat exchange. The fire rushes between these long, narrow flues allowing this pan to do the majority of the evaporation.

A steam hood covers the “piggy back” pan. The steam hood, combined with a wooden curtain hanging overhead, helps to contain the large volume of steam and direct it to two opened roof doors overhead which release the water to the sky from whence it came.

Steam Hood and Roof Doors (closed)
Steam Hood and Roof Doors (closed)

WHAT IS SYRUP?

Syrup by U.S. federal statute must test at 66% sugar or 11 lbs. to the gallon. This point is reached at 7.1 Fahrenheit degrees above the boiling point of water. We draw off syrup from the evaporator at this point. However, there are some complications; the boiling point of water changes with barometric pressure. While we may be making proper density syrup in the morning, we may have to make adjustments in the afternoon should the weather change. We do that by measuring density in a sample of hot syrup with a hydrometer. This instrument floats at different heights in a sample of syrup depending on the liquid’s density. We take samples several times hourly, measure density (which in this case is a measure of sugar content) and adjust the thermometers accordingly.

Syrup is drawn off from the evaporator at this valve.
Syrup is drawn off from the evaporator at this valve.
An electronic thermometer for automatic draw-off
An electronic thermometer for automatic draw-off

FILTERING

When the syrup is removed from the evaporators it is a muddy liquid due to the presence of different solidified minerals found naturally in maple sap. These minerals come from the soil and are taken up by the tree roots. We filter the syrup through heavy felt and paper cloths to remove these minerals, called sugar sand, and create a beautiful clear syrup: our final product. This can be done in a filter tank by gravity, as well as in a filter press under pressure. We prefer the filter press as it filters finer particles out thus producing a clearer final product. Sugar sand is a harmless, but gritty tasting substance that would settle out if the syrup were left undisturbed for too long.

Our Filter Press (Front)
Our Filter Press (Front)

PACKING

After filtering, the syrup is stored in 30 gallon drums. When needed, it is reheated to 190° F and packed hot in consumer containers. Properly hot packed syrup will remain delicious for many months, even years. Within the limits of federal standards there are three color designations for maple syrup that are all grade A. They are all 66% sugar and all of good flavor but are markedly different in taste. These colors, or subgrades, are light amber, medium amber, and dark amber. The variety you prefer will depend on your tastes. However, the darker colors do coincide with a heavier flavor. We determine grade using a grading kit (which compares a syrup sample to colored plates of glass) as well as by taste to avoid any “off” flavors. This is all done just prior to packing. We may blend several barrels produced at different times to create the flavor we are looking for.

Syrup Grading Kit
Syrup Grading Kit

We pack medium amber maple syrup as our standard color grade (it is by far the most common and most popular grade). However, light and dark amber maple syrup is available on request at no additional charge.

Canning Syrup
Canning Syrup