Tips on Managing Sugar Sand

Every year, I have a few questions about the universal problem faced by all sugarmakers – fighting heavy niter build-up.  With heavy flood runs, this can be increasingly problematic to battle.

Here is one question I received:

Does anybody have any advice on how to get this pasty mud-like stuff to filter better. I have been battling this for three years now and don’t know why, any advice would be greatly appreciated!

This was my answer to his question:

You have a problem that hundreds of producers have every year. So you are not alone in your question of how to deal with this problem.

Niter is caused by minerals precipitating out of the sap as it boils, and every woods if different in the amount produced. In fact, the amount of niter you battle in your sugarhouse is correlated with the mineral content of the soil in your sugarbush. When we boil sap, it is very similar to lime forming on a pan after you boil hard water several times.The only difference is that we are keeping the niter in solution and filtering it out. That is the key to removing niter. You must keep it in the solution until you run it through your filter, and you need to keep your syrup very hot and filter it immediately. If the filters cool for a long period of time, sugar will likely crystallize on the filter and slow flow. If you are using a felt or orlon filter, always use a pre-filter. In fact, try stacking several filters in layers and when the filter flow slows down, you can just pull off the top layer and continue to filter the syrup.

If you use a filter press, make sure you use enough filter aid to initially charge the filter. Even though filter presses have filter papers in between the metal plates, it is the filter aid that actually does the filtering. Make sure you use enough filter aid, but do not over do it. Mix the filter aid and the syrup completely before running the press. Keep the syrup hot and try to run larger batches. If you run small batches, the filter press cools and you will not be able to run as much syrup through until you change filters. Watch your pressure and change filters when the pressure starts to build excessively. This should prevent blowouts and having to re-filter.

Normally we filter with a conventional filter tank with a stack of 5 to 10 pre-filters on the tank and 1 orlon filter. I try to put enough pre-filters on for the better part of the day. After we filter, we transfer to a 20-gallon heating tank. Heat the the syrup to 185 and then run it through a pressure filter into 15 gallon drums. I try to never bring syrup back to boil or more niter will precipitate out.

Hope this helps and good sugaring.

Author: Les Ober, Geauga County OSU Extension

The Finishing Pan: Where The Art and Science of Making Maple Syrup Meet

The old timers called it an art, modern maple producers call it a science. In reality, it is probably a little of both. One thing is for certain, what happens in the finishing pan determines the success or the failure of a season. It is here that all of the maple syrup quality standards rise or fall. Here the right density meets the right color and the right flavor. The science is using instruments to determine the exact time to draw off the syrup. The art is that sixth sense of knowing when everything has coalesced for the perfect draw-off.  The result is golden amber maple syrup with the perfect maple flavor.

There are several types of finishing pans on the market today. The reason for the difference is to manage niter or sugar sand. Niter is the mineral content in the sap that precipitates out in the boiling process. To manage niter, most front pans are designed to either change to a side or to a pan with a lower niter deposition. Reverse flow allows the operator to switch sides when niter builds. A variation on design is the one-sided draw-off which utilizes reverse flow and a series of valves to redirect the flow of sap from one side to the other. An example of this would be the Leader Revolution. The other style is the cross flow in which there are multiple front pans connected by stainless tubing. In this configuration, the pan closest to the draw-off point is rotated with a clean pan. The best policy is to start with a clean pan every day and change during the day when needed. Pans can be cleaned with white vinegar and hot water. This is a very effective way to clean pans with a minimal amount of elbow grease. The amount of niter present in sap varies from season to season and from woods to woods. If improperly controlled the result can be a scorched pan.

Once the sap, or in this case concentrated sap, reaches the front pan or finishing pan, the sap is approximately 19% sugar. This is sap that has not been run through a reverse osmosis unit. It has been concentrated by boiling only. RO concentrate enters the pan at a higher concentration. As the concentrated sap is crossing over into the front pan, it should reach 213 degrees at 29.9 inches barometric pressure. It is also at this temperature that the concentrated sap is not only becoming denser but also starts changing color. As the density increases, the sugars react with the heat to form the amber color we associate with pure maple syrup. It is also at this time when the bacteria in the sap can interact with the heat and the sugars to darken the syrup. All of this happens in the finishing pan and over a relatively short amount of time. This reaction can occur quickly and if the operator is not paying attention, syrup can actually burn or caramelize further darkening the color. In this case, the density often goes past 66 Brix as well resulting in a thick heavy syrup and potential profit loss.

To make sure we pull the syrup off at the right density, we can use a variety of instruments. The most common and least expensive are the thermometer and the hydrometer. Most evaporators come with a thermometer that is placed at the point of draw-off. Water boils at 212 degrees Fahrenheit at sea level and a barometric pressure of 29.9 inches of mercury (Hg). Because syrup is rarely produced in a location at sea level and the barometer is seldom at 29.9, producers must make some adjustments. We must boil water near the evaporator and reset the thermometer that is used to make syrup. This process of adjusting to match the barometric pressure must be done daily and whenever the barometer changes due to weather front movement. This can occur quite often during an average sugar season. This is why most producers prefer to use a hydrometer for the final test, and use the thermometer to give them an approximation of when to draw-off.

The hydrometer is the judge and the jury. There are two lines on a hydrometer.  The top line is for hot syrup and the bottom line for cold. Use the top line. Always use a hydrometer cup full of syrup that is at least 211 degrees Fahrenheit. Bring the instrument up to eye level or set it on a stable object close to eye level for the most accurate reading. Producers need to test their hydrometer annually against a calibrated refractometer. Hydrometers get jarred around and the paper containing the scale can move or become dirty and give a false reading. If the reading is inaccurate, replace it. A refractometer (the instrument used to verify hydrometers) is very accurate, the new ones are digital, and refractometers make temperature adjustments on the fly – however, they are also cost prohibitive for many.

The automatic draw-off is a great tool for any producer in any size operation. It makes drawing off syrup a lot easier, especially when boiling RO-concentrated sap. It is nothing more than a digital thermometer hooked to a valve that draws the syrup off at a very precise temperature. Everything I said about the syrup thermometer applies to automatic draw-offs. Most producers set there draw-offs with a hydrometer. During the sequence of opening and closing the auto draw-off, the syrup is actually being drawn off within a small band of temperatures. The thing to remember is that the draw-off will open at a very precise temperature, but if the flow is slowed by foam or a valve coming into the draw-off is restricted, the temperature will rise above the desired level resulting in denser syrup.  All automatic draw-offs should be installed with a valve between the pan and the draw-off. This allows the producer to adjust the flow of sap coming off the pan. Open the pan valve so a steady stream flows through the draw-off mechanism, and try to avoid a heavy stream that will result in a large batch. The draw-off should close and the temperature on the readout should drop 4 to 6 degrees and then quickly come back to the desired temperature. The result is a series of small batches coming off in a relatively short amount of time. The producer needs to check the final product in the bucket or tank when the auto valve closes and adjust the draw-off settings accordingly. It is very easy to get a denser product than desired if you are not making continual fine-tuning adjustments. It is not a set-and-forget instrument. Today there are newer auto draw-off that compensate for barometric pressure but again the cost may be prohibitive for smaller scale producers.

Another area to consider during the finishing process is foam control. You only control foam in the front pans at the point of draw-off and only if the flow out of the draw-off point is being held up by the foam. If this happens, a single drop of defoamer will reduce the foam to the point where the bubbles will decrease and flow will increase. Avoid using defoamer anywhere else as it causes the gradient to break down and syrup densities will intermingle. If you are foaming over in the front pan, it is usually because the foam is not properly controlled in the flue pan. Occasionally it may be necessary to knock this foam down but try to avoid this if possible.  If the foam is properly controlled in the flue pan there should be minimal problems in the front pan. The only exception would be coming into the first draw-off after a layoff. All types of sap will behave differently during the initial draw-off. Watch for increased bubbles and denser steam, this is a sign that you are making syrup across the front pan. In this case do not panic, just slow your boil down and stabilize the evaporator as quickly as possible. The result is usually one big batch of syrup followed by reduced boiling temperature. The next batch should be normal – if not, look for the problem.

Author: Les Ober, Geauga County OSU Extension