Reverse Osmosis 101+

Ohio Maple Days 2022 did not disappoint.  The food was fantastic, the vendor room crowded, and the presenters shared a wealth of knowledge of expertise across a wide range of subjects.  Joel Oelke, Regional Sales Manager with Leader Evaporator/H2O Innovation, shared an encyclopedic wealth of knowledge regarding reverse osmosis leading up to the lunch hour.  Before we get into a few highlights, be sure to mark your calendars for next year’s conference December 8th and 9th!

At its simplest, reverse osmosis is a process by which sap is passed through a membrane to remove water thereby concentrating sugar.  The pure water pulled out of the sap is referred to as permeate.  The increasingly sugary solution – concentrate.  The benefits are obvious – it saves space on numerous fronts and greatly improves efficiency at the evaporator by reducing time, fuel, and labor.  While the list of pros is long, suffice it to say – reverse osmosis is one of the biggest technological revolutions the maple industry has experienced in the last 100 years.

While reverse osmosis is a true game changer for maple producers, the technology is also one of the most complex and expensive pieces of equipment in the sugarhouse.  It is easy to become intimidated by what’s necessary to implement and maintain a unit, and mistakes chalked up to the “school of hard knocks” can be expensive.  Here are just 5 rules of thumb that I pulled from Joel’s presentation to share in this article.

#1 – RO’s efficiency rating (how many gallons can a unit process per hour) is given at a solution temperature of 55 degrees Fahrenheit.  Because sap is kept at cooler temperatures to ensure syrup quality, you need to factor the lower temperature into your unit’s efficiency rating.  This is especially important to consider if you are shopping for a new RO unit.  Here’s a simple figure to calibrate your RO’s operating efficiency.  If you purchase a unit rated at 600 gallons per hour but expect to run sap at an average temperature of 40 F, you can multiply 600 by an efficiency downgrade of 0.75 (or 75%) and expect a 450 gallon per hour operating rate.

#2 – A second factor influencing RO efficiency is the concentrate level you are trying to achieve assuming you start around 2 Brix.  The more you want to concentrate your sap, the less efficient your unit will be.  Let’s continue with the example we started above in italics.  If you want to take 2% sap to 8% concentrate, your RO unit will run at the temperature-corrected peak of efficiency and achieve your calibrated 450 gallons per hour rate.  However, if you concentrated to something higher, say a 12% level, your operation would get dinged with an additional 30% loss in efficiency.  Here’s what the math would reveal – 450 gallons per hour multiplied by 0.70 = 315 gallons per hour.  Below is another figure to help you calculate the efficiency factor of concentration.  Remember, you must factor in both penalties – sap temperature and concentrate level – to properly estimate your efficiency rating.  And this all assumes you are running a clean, properly-maintained RO unit!

#3 – The desugaring, rinsing, and washing cycles are what keep your expensive reverse osmosis investment operating at the peak of performance.  Long story short – each cycle is critical to maintaining your unit.  And do not – especially in the wash cycle – generalize across all RO units.  Specific models and manufacturers use different membranes which are tailored to different types of soaps and chemicals as well as amounts of each.  Consulting the manuals and consulting with your RO manufacturer reps – just like Joel – is best practice for getting maximum life and performance out of your reverse osmosis technology.

#4 – Don’t let your improved efficiency get you in to trouble.  What I mean is this – sap that goes through a reverse osmosis unit comes out as warmer concentrate.  So, A) the process of reverse osmosis physically warms the concentrate above the temperature that it went in the machine, and B) you aren’t concentrating just sugar with an RO unit, you are concentrating everything – including microbes and bacteria.  The warmer concentrate coupled with a denser community of “nasties” can get a producer in big trouble if the evaporator is not synced up in work flow and their facility can not properly keep concentrate cool.  Stopping short of laying out any specific recommendations for how to integrate and streamline your sugarhouse sap-to-syrup processing, just know that the clock is ticking extra fast once you start concentrating sap.

#5 – If you properly size, run, and maintain an reverse osmosis unit, you can expect roughly a 3-year payback on your purchase when accounting for saved fuel and labor.  A rough cost estimator predicted a $4 cost savings per finished gallon of syrup using fuel oil in a 110 gallon per hour evaporator.  Obviously there a lot of moving parts for each unique scenario, but the bottom line is this asset does not 10 years to recoup costs.

Hopefully these quick 5 points help you make sense of reverse osmosis and how you might consider incorporating or upgrading an RO unit in your sugaring operation.  Thanks for an extremely informative talk Joel!

Fall Maple Assessment – Get Ready for Next Season, Part II

Read the first installment of our autumn mini-series “Get Ready for the Season” here.  The first article focuses mainly on the woods, and Part II sticks to the sugarhouse.

It is perfectly natural after a long hard season to put off sugarhouse cleanup and maintenance. This can be a major mistake. Getting the sugarhouse ready for the next season starts immediately after last season has concluded.  Dirty unmaintained equipment sitting around in warm weather can promote the worst of unsanitary conditions that will surely haunt you into the upcoming season.

Let’s start with storage tanks. Not everyone can afford bright shiny stainless-steel tanks that are easy to clean. Many producers substitute more affordable plastic tanks. Unfortunately, plastic tanks have earned the reputation of lowering syrup grades due to rapid microbial growth. All of the elements for rapid growth are present. The sap supplies the food and the tanks warm quickly. Where do the microbes come from? They are hiding in the porous interior of the tank. That porosity is what makes it almost impossible to thoroughly clean a plastic tank. You may get by for two or three years but sooner or later the tanks will have to be scrapped. The cost of three or four plastic tanks over a ten-year period can add up quickly. Consider the economic value of a stainless tank that should last forever if handled and maintained properly.

Reverse osmosis (RO) has revolutionized the dynamics of the maple syrup industry. For the commercial producer, the RO has drastically slashed labor and fuel expenses. When it comes to maintenance, the most critical element is maintaining the primary filter or membrane. Membranes that are not maintained properly can be severely damaged. Damage can lead to the passing of sugar into the permeate tank. This results in a hidden loss of profits going down the drain. Always check your permeate for abnormally high sugar content. Washes of both soap and acid are used in the cleaning process followed by an extensive permeate rinse. A properly maintained membrane should last for many years. Another critical but oft overlooked issue are increased levels of chemicals being discharged from the sugarhouse. When you are using an RO, you are discharging thousands of gallons of liquid through your sugarhouse drains. You are also discharging acids and soaps through the same drain. If possible, neutralize the chemicals by bringing both acids and soaps back to a neutral 7.0 pH before you flush them down the drain. Neutralizing agents are readily available from your maple dealer.

Producers tend to overlook where and how they store there concentrate before boiling. When you concentrate sap, you are creating the perfect storm for a microbial outbreak. You are doubling, and in some cases tripling, the amount of sugar in the tank. When you run the sap through an RO you also boost the concentrated sap’s temperature by at least 20 degrees Fahrenheit. Assuming the concentrated sap is housed in a relatively warm sugarhouse, it makes no difference if you are using a stainless or plastic tank, microbial populations always explode in concentrated sap. The first line of defense is to boil the concentrate as soon as you can to prevent grade deterioration. If you only have enough money to purchase one stainless steel tank, make the purchase for your evaporator feed tank. This is doubly true if you are concentrating with reverse osmosis.

One of the best maintained pieces of equipment in any maple operation must be the evaporator. After all it is the center piece of most sugarhouses. Producers tend to take pride in how their evaporator looks inside and out. Here are a few things to consider before you start the season. Make sure all of the fittings and gaskets are functioning properly. It is good idea to do a test boil before using. You do not want to waste sap or concentrate if there is a malfunction. During the season, always start each day with clean niter-free syrup pans. Do not let niter build up. Excessive niter can cause a pan to overheat and even burn. Make sure you are using defoamer properly and in the proper place. If you are going to be shut down for a long time due to a warm spell, plan on draining your pans to prevent microbial buildup. Attempting to keep the liquid on the evaporator will only lead to contamination of fresh sap when it arrives and the production of poor-quality syrup. In a freezeout situation, make sure to inspect your pans to make sure they are not freezing solid. If they are, light a fire and thaw out your pans so they do not break. Again, emptying the pans is not a bad idea. Along with your evaporator make sure your filter press and auto-draw off are functioning properly. Improper maintenance of your evaporating and filtering equipment can result in the production of poor-quality syrup that will cost you money in the long run.

After the season, make sure everything is cleaned and stored properly. There are many ways to clean an evaporator and it comes down what works for you. Avoid using any kind of detergent in the cleaning process. Hot water and elbow grease wins out every time. At the end of the season, make sure your syrup is stored properly. There is nothing worse than opening a barrel of your top grade, only to find out it has spoiled. Syrup is best stored in a location where it stays below 70-degree Fahrenheit. Even though you hot pack your syrup it is wise to roll the drums, if possible, several times during the offseason. This agitation helps eliminate moisture condensation from collecting at the top of the drums due to temperature fluctuations.

If you are planning to upgrade your sugarhouse, keep in mind that this is the best time to make sure your facility can pass a state or federal inspection. All of the rules and regulations are available online through OSU Extension.

You have now done a comprehensive evaluation of your sugaring operation. What are your most cost-effective “low hanging fruit” items? Act now – season will be here before you know it.

Ohio Sugarbush Highlighted by NRCS – New VIDEO

As you brush the dirt off your knees and shake the cobwebs from your head (what a crazy syrup season!), here is a new video featuring one of our state’s own maple producers – Bill & Dee Belew of Messenger Century Farm in Chagrin Falls, OH.  You’ll remember that we have highlighted the EQIP (Environmental Quality Incentives Program) and other NRCS programs (such as the Conservation Stewardship Partners program) as excellent opportunities for maple producers to improve their woods AND their operations.  This video is a marvelous example of just that.

A special thanks to Brooke DeCubellis who produced the video.  Brooke DeCubellis serves as the Natural Resources Conservation Services (NRCS) public affairs specialist in Ohio.  In this capacity, she creates and leverages communication strategies and products supporting NRCS objectives throughout the state.  She maintains effective working relationships with regional partners, highlights local producer conservation efforts and shares technical and financial resources to further natural resource stewardship within the state.  Brooke is a skilled communications professional, with more than ten years of experience in federal and state government work, specializing in media relations, public engagement, photography and videography.  Thanks Brooke for shining a light on a fine example of what Ohio sugaring is all about!

Choosing the Right Fuel (Evaporator Series *BONUS* Post)

When it comes to selecting a fuel source for your evaporator, operators should choose based on efficiency, not convenience. To convert 2% sap into 66 brix syrup, 400,000 BTU are required – this is constant for all fuel sources. The two most popular fuel sources, in today’s maple world, are wood and fuel oil.  Additional choices include natural gas, liquefied petroleum (LP) gas, and various wood products such as pellets have been adapted to fuel maple evaporators.

I created the above figure based on estimates generated from the Southern Maine Renewable Fuels Institute.  Based on the statistic above – 400,000 BTU are required to produce a gallon of syrup – I derived production cost estimates for each fuel source and compared burner efficiency. Fossil fuels have a slight edge when it comes to fuel efficiency. The reason they are so efficient is based on the type of burners used and the ability to extract a higher percentage of heating units from each fuel source.

How do you choose the right fuel source for your maple operation?

The ambiance of making syrup on a roaring wood fire has never been challenged. Wood is by far the most popular fuel source for evaporators. It is readily available. And most producers look at dead wood scattered about the sugarbush as something that needs to be disposed of anyway. For that reason, the true value of wood is seldom considered. As we will see later, the value of wood is very close to the value of fuel oil when it comes to making syrup. The true value of wood is based on the dollar value of cordwood. There is an old saying “cordwood has no value until it cut and stacked.” Its value is representative of your time and labor.

A standard evaporator will produce 22 gallons of syrup from a cord of dry wood. Without the major advances in wood burning technology, most open evaporators are rated at 40-60% efficiency. Heat units are lost at multiple locations across the evaporator. You can quickly see why many producers made the shift to more efficient oil evaporators even though they now had to pay for fuel. The efficiency of a wood-fired evaporator is in the design. No matter what the design, the basic principle of operation remains the same. A wood-fired evaporator draws heat from the flame produced in the firebox. The heat consisting of flame and burning gases is drawn by air movement under the pans and out the stack. The arch is designed to pull and lift the flame up a moderate incline eventually compressing the heat into the flues of the rear pan. The heat exits the evaporator through the stack at temperatures of 600-800 degrees F. Stack dimensions must be designed correctly for proper draft. Wood needs to be placed in the evaporator to facilitate maximum heat without choking the air and dampening the flame. This usually means the firebox should not be filled to the top. You need to allow space for air to enhance the flame. The wood should be fired at regular intervals. A general recommendation is every 5 minutes.

There have been many changes in modern wood arch design that increase the overall efficiency of the evaporator. Forced air injection along with highly insulated arches and firing doors make the modern wood-fired evaporator as efficient as their oil-fired counterparts. Some are rated 85-90% percent efficient. Such high-performance levels are the result of being able to totally burn the wood that is loaded and the ability to re-burn gasses given off during the combustion process (gassification).

Fuel oil is another popular choice among maple producers, and there are several reasons for this. Fuel oil burns clean and hot and is an ideal choice for larger operations that require high volumes of fuel. This logic has been tempered in recent years with the increasing use of reverse osmosis to produce high Brix concentrate and reduce fuel demands. Efficiency is relatively high nearing 80%, and 1 gallon of syrup can be produced for under 4 gallons of fuel oil.


Bio-diesel Evaporator.

Unlike wood-fired arches, oil-fired evaporators require a minimal draft. Oil-fired arches are designed to develop radiant heat. The burner flame creates a ball of radiant heat and that heat then hovers beneath the pans. Temperatures in an oil arch can reach 1000 degrees F. The movement and intensity of the heat is controlled by a barometric damper that restricts the movement of air through the stack. The damper maintains a uniform temperature by controlling the airflow thru the evaporator. If this control device is not present, the heat can quickly be lost up the stack and the performance of the machine will be impaired. The burner nozzle size and fire rate determine the intensity of the heat. If everything is working correctly, the flame will burn cleanly and the flame ball of burning fuel oil will be suspended in the middle of the fire box never touching the sides of the arch.

Natural gas is very similar to fuel oil. In fact, the burners today are very similar in operation. Natural gas is convenient and is probably a cleaner source of fuel than oil; additionally, efficiency mirrors fuel oil. Though the original natural gas burners were often inconsistent resulting in hot and cold spots across the pans, there is now little difference in performance as compared to oil-fired evaporators. The biggest drawback is the availability of natural gas. Unlike oil that can be hauled to a remote location, gas needs to be piped in and is not readily available everywhere. If you are fortunate enough to have natural gas available, it is an excellent fuel option.


Natural Gas Evaporator.

The biggest drawback for oil and gas is the variability in cost as the oil market fluctuates. In 2020, we are living in a down cycle for oil and gas and prices are more appealing entering the 2021 syrup season. Within a few years, that could be a completely different story. Time will tell.

I would be remiss if I stopped the article there.

Regardless of what fuel source you choose for making maple syrup, the best single investment a producer can make is to add reverse osmosis to their operation. Despite the high initial cost of reverse osmosis, the cost of processing syrup is reduced significantly and the pay-off is long-term. Reverse osmosis not only allows a producer to process sap quicker, but it also opens the door to expand one’s operation. The savings on fuel are obvious. Before ROs, as reverse osmosis is commonly called, became popular the size of the operation was limited to the amount of sap that could be boiled on an evaporator. The only way to add capacity was to add evaporators, and some of the larger operations were running four, five, and even six to handle peak sap flow. Today, those same operations now employ modern RO systems with multiple membranes that can handle sap coming from thousands of taps. And using less time and space to do so. Reverse osmosis revolutionized the North America Maple Industry.

Author: Les Ober, Geauga County OSU Extension

All Things Evaporators: Part IV

In this final post of the evaporator series, we will examine a few remaining factors to account for when considering the boiling process for maple syrup. As you will see, a few instruments enable the necessary precision to ensure a high-quality batch of syrup every time.

In case you missed them, here is Part I, Part II, and Part III of the series.

Barometric Pressure Matters

One of the biggest factors influencing the boil in an evaporator is barometric pressure. Barometric pressure and weather fronts are frequently responsible for the day-to-day erratic behavior in the way sap boils. The boiling rate is directly associated with the barometric pressure on any given day. If you experience a high barometric pressure, sap boils faster; with low barometric pressure, the boil slows. Meteorological shifts can happen several times per day, and whenever pressure fluctuates the boiling point of water (212 F) will vary. Producers must adjust their thermometer to accurately produce syrup consistently at 219 F. Make sure you calibrate your thermometer in boiling water before the start of each boil and throughout the day as needed. A thermometer will give you a ballpark reading, but to get ultra-precise and guarantee 66 Brix syrup of the highest quality, additional instruments should be utilized.

Having the Right Instruments

You will choose one of three instruments to determine your syrup density coming off the evaporator.  Only one is the best and most accurate for reading syrup straight off the evaporator. As previously stated, syrup’s finishing point is 219 Fahrenheit, 7 degrees above the boiling point of water. Because barometric pressure influences boiling point, using only a thermometer can result in inconsistent finished syrup density. One better option is to use a refractometer, but the syrup sample has to be temperature-stable and filtered to get an accurate reading. For this reason, we do not recommend using a refractometer on syrup coming directly off the evaporator for obvious and practical reasons. (Refractometers are, however, the instrument of choice for measuring the density of cooled and filtered syrup during canning).

The most recommended instrument to determine the density of hot finished syrup is the hydrometer.  A hydrometer should be floated in a sample of finished syrup that is at least 211 degrees F. Hydrometers have two lines, one for cold and one for hot. You will use the hot line for your syrup density determination straight off the evaporator. Bring the instrument up to eye level or set it on a stable object close to eye level for the most accurate reading. The hydrometers red line should float even with syrup level in the container. Most hydrometers also have two scales, one for Brix and one for Baume (Baume measures specific gravity of a solution). The Brix scale is the most popular and frequently used today. Avoid letting scale build up on the outside of the glass as it will impact the density reading, and producers should regularly validate their hydrometers for accuracy. Once you confirm finished syrup of the proper density, you will filter your syrup for clarity and to remove niter. You can then use a color comparator to determine the grade of your syrup.

Conclusion

The evaporator has become the center piece of many maple operations. It is the first thing visitors see in your sugarhouse no matter what time of year they visit.  It is also one of the most essential pieces of equipment in your operation.  After all the process of making syrup requires that we must heat maple sap to 7 degrees above the boiling point of water to produce pure maple syrup. This results in the caramelization of maple sap into maple syrup. The addition of heat to maple sap results in the amber color we desire and the maple flavor we love.

Author: Les Ober, OSU Extension Geauga County

A Few Thoughts on Finishing Maple Syrup

Cold weather has set in and that has allowed me to scan the maple chat rooms. Many of the questions that keep popping up are about finishing maple syrup. Is it too thick or too thin? Should I use a thermometer, hydrometer, and/or refractometer? Here are some of my thoughts on the subject.

Most of these questions are coming from backyard producers with a relatively small number of taps. Making syrup on a flat pan or hobby rig is not an easy task. You deal with a lot more “what if’s” than you would on a big evaporator. The process is simple – build a fire under your pan and bring your sap to the boiling point of water. Use a thermometer to monitor the process. That thermometer reading will vary from day to day depending on the barometric pressure. When the temperature goes 2 degrees Fahrenheit above the boiling point of water, add more sap, preferably pre-heated sap. Continue the process until all your sap is in the pan and begins condensing down. At that point, stop boiling, take the liquid into the house to store, and finish the batch. Most hobbyists follow this procedure and it works well. The trouble starts when you have a rig that looks like a big evaporator but does not run like a big evaporator. Many hobby rigs have channels and a heater pan and that is good. Sap should come into the back channel and gradually work its way to the channel on the opposite side near the front. Higher density syrup should move ahead of the lower density syrup. The problem comes in when you have to decide how much sap to let in at any one time. It works okay as long as you can maintain a steady flow into the rig. You need to maintain a depth of 2-3 inches across the entire evaporator. Overflow the hobby rig with liquid, and you will kill the boil. Once this happens, the sap of lesser density intermingles with the heavier density syrup. Big problem! Despite the fact you have channels, you are now no better off than you would be with a flat pan. On commercial evaporators, we have a thing called a float that automatically maintains the level of sap moving across the rig. With a hobby evaporator, you are the float and maintaining the proper level takes time and experience.

A few words on syrup-testing instruments. As stated above, you absolutely must have a thermometer. Two other tools that I recommended are a hydrometer and a refractometer. The hydrometer is necessary and a refractometer is nice if it fits your budget. Others have mentioned the Murphy’s Compensation Cup. I have used one for the last three seasons, developed by Smokey Lake – the Murphy’s Cup is a very useful tool.

I have two ways of measuring density directly off the evaporator. Here is the formula I use. First, I draw a sample into a hydrometer cup once the temperature reaches 7 degrees above the boiling point of water. Remember thermometers need to be calibrated. With your hydrometer cup filled with hot syrup that is above 211 degree Fahrenheit, insert the hydrometer into the cup. When it hits the top red line, you have syrup. I check this several times. Once I have the syrup where I want it, I pour one of the samples into the Murphy Cup. This device has a dial with corresponding numbers to those on a hydrometer. You insert your hydrometer into the cup and let it settle for 3 to 5 minutes. When the reading on the dial and the hydrometer match, you are at the right density. After that, I can fine-tune my auto draw-off for subsequent runs. On the last run, we are hitting between 66.0 and 66.5 Brix with this system. Refractometers are available in digital and analog versions. The digital versions seem to be the most popular. They are very useful to check syrup prior to bottling. Do not use a refractometer at draw-off, a refractometer’s reading is only accurate on temperature-stable and filtered syrup. The only reason for us to have a refractometer in the sugarhouse is to check the sugar content of concentrate coming off your reverse osmosis unit.

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