Evaporators & Finishing

Buckeye Teaching Evaporator: The First Boil!

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Exciting developments at the Ohio State University-Mansfield campus!  We installed a teaching maple evaporator under our new pavilion near the research sugarbush and just completed our first boil last night.  This step is fairly monumental for Ohio State Maple, and there isn’t anything quite like the feeling of seeing that first draw-off.  Somehow we’ve got a grainy image of that moment last night to commemorate the experience!

First things first – a formal thank you to Roger and Suzie Gortner for continuing to do our production sap processing.  They have made exceptional maple syrup from our OSU trees for the past 5 years and will continue to be instrumental in that regard.  We literally could not do it without them, and we’re grateful that it’s an arrangement that works for both parties involved.

But now for the first time ever, we have our own evaporator.  No, it is not sized to keep up with a production woods of almost 1,200 taps, but it is perfectly sized for demonstration boils on a teaching scale.  With help from local producer Galen Smith from Mount Vernon, OH, our team set up an 18” x 66” drop flue evaporator early in winter of 2023-24.  After a test boil to dummy out a few variables (or maybe to dummy out the dummies…us!?), we put fire under sap concentrate on Wednesday, February 14th – Valentine’s Day.

Four 5/16″ lines kept sap flowing from our larger sap tank into a holding chamber that our reverse osmosis unit was drawing off.  We adjusted the PSI on our RO to almost perfectly sync and match the raw sap movement with our RO processing speed.  After some adjustments to align the 2 processes, we were taking sap from 2.1 to 4.6 Brix concentrate.  6 hours later, we were halfway there…

Eventually, we crept up to 7 degrees F over the point of boiling water.  You know what happens next.

A teaching evaporator with small-scale RO unit allows us to now teach via-demonstration tree-to-bottle workshops and seminars on an Ohio State campus, provide more complete tours for events like the upcoming Maple Madness event on Saturday, March 2nd (more on that in a second), and sets the table for a new Sustainability Theme GE course debuting in Spring of 2025 – Maple: A Sweet Taste of the Past, Present, & Future.

So yes, come visit us on Saturday, March 2nd at the OSU-Mansfield Maple Pavilion.  We are excited to host folks for pancakes and syrup between 10 AM-1 PM, tours of the sugarbush and nearby vernal pool wetlands all day long until 5 PM, and good fellowship with one another for the Ohio Maple Madness Tour.  Once you are on campus, just follow the signs!

Pennsylvania Maple Boot Camp: REGISTER Now

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Maple Boot Camp is going on the road for 2023 and pit-stopping with our neighbor to the east: Pennsylvania.  Scott Weikert and the good folks at Penn State University are hosting this year’s event from September 6-8 in Somerset, PA.  The agenda is fairly similar to last year’s event that we hosted at the OSU-Mansfield campus during the month of June.

To kick things off, attendees can sign up for a bonus maple syrup grading workshop morning of Wednesday September 6th.  The registration link is here.

The official Maple Boot Camp will kick off right after lunch that same day and continue for two and a half days through Friday mid-afternoon.  We hope to see you in Pennsylvania for this signature maple educational opportunity.  It is an excellent deep dive for beginners or small producers thinking about growing their operation.  Veterans will undoubtedly learn a thing or 3 though too as they interact with maple experts and producers from West Virginia, Pennsylvania, Ohio, and New York.

The Pennsylvania Maple Camp provides intensive, hands-on training for beginner and intermediate maple producers.  The 3-day curriculum begins with sugarbush assessment, then builds sequentially through all phases of maple syrup production from sap collection to boiling, bottling and sales.  Participants will gain the skills necessary for the safe, efficient, and profitable production of maple products.  Camp will include classroom lectures as well as outdoor, hands-on exercises.  Come one, come all, see you in Pennsylvania for Maple Boot Camp!

Maple Cost-Share Assistance – NRCS EQIP Program

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Special thanks to Keith Libben & Timothy Fulks for writing this article for the OSU Maple site!

The USDA Natural Resource Conservation Service (NRCS) has long been a well-known resource for agricultural producers in Ohio, especially with our livestock producers and our crop farmers.  Their Environmental Quality Incentives Program (EQIP) is the flagship conservation program for NRCS and has provided millions of dollars in incentives to producers over the years to address resource concerns that negatively impact soil, water, air, and animal health.

EQIP works by providing farmers, ranchers, and forest owners financial incentives to install conservation practices that help address resource concerns.  Common practices funded include cover crops, manure storage systems, and nutrient management planning.  But did you know that EQIP can now assist Ohio’s maple syrup producers?  Recent changes to the practices available in Ohio intended to improve air quality can now provide some assistance in the sugar shack.  The practices available are intended to improve air quality by improving efficiency in the sugar shack and in turn reducing emissions from burning fossil fuels or wood.  Practices that are currently eligible include reverse osmosis systems, sap pre-heaters, and improved efficiency evaporators.

Interested in getting some financial assistance to make some upgrades at the sugar shack?  This is the general process:

  • Producers need to reach out to their local NRCS field office or Soil and Water Conservation District and get an application in for EQIP.
  • From there, NRCS will coordinate with you to set up a time to visit your sugar bush and assess your operation. Other professionals may be necessary to determine what practices may be appropriate for your operation.
  • NRCS will use this information to develop a conservation plan and cost share estimate. Once this is complete, your application will be submitted for ranking and consideration for funding.
  • NRCS will reach out to you if your application has been selected for funding. Now the ball is in  your court to decide if you want to sign a contract for the funding assistance.  If you sign the contract, you agree to install the required practices per all relevant NRCS standards and specifications.
  • Once installation of the practices is complete and verified, you’ll receive your contracted financial incentive.

It is important to not think of EQIP as solely a coupon to get a steep discount for a new evaporator or reverse osmosis unit.  Such narrow thinking will probably not result in a competitive conservation plan.  Rather, leverage EQIP to design a more holistic approach to improving your overall property.  Additional woodland, wildlife, or cropland practices can also be applied to increase your plan’s ranking score and up the odds of being successful.  Talk to your local NRCS office today to see how they may be able to help!

Additional Questions:

How much cost-assistance will I receive?  NRCS re-evaluates costs of implementing practices on a yearly basis.  For most successful applicants, they will receive their contracted payment of 75% of the projected cost upon completion.  For historically underserved applicants, the cost share rate is set to 90%.

What are the maple-specific EQIP practice codes?  Practice 228 Agricultural Energy Assessment and Practice 374 Energy Efficient Agricultural Operation are the codes that can be leveraged for evaporators, sap preheaters, and reverse osmosis units.

When do I need to get my EQIP application submitted?  NRCS accepts new applications on a continual basis, meaning there is no true deadline.  However, submitted applications do join a stack of documents for the next ranking session which typically occurs in late fall.

 

Remember to join us on Saturday, December 9th for the 2023 Ohio Maple Days.  One of our featured afternoon speakers this year will discuss EQIP’s cost-share opportunities for maple producers in detail.  Registration should go live in late July-early August.

Reverse Osmosis 101+

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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

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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.

Maple Assistance Opportunity through EQIP

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The Environmental Quality Incentive Program, EQIP for short, provides financial and technical assistance to agricultural producers and woodland managers to combat environmental concerns and provide natural resources benefits.  Maple Producers should be excited to know that several maple practices are now eligible under EQIP.

How does EQIP work in the first place?

EQIP is a voluntary program, and contracts are available for a single year ranging up to a full decade.  The list of EQIP practices is long.  If you can imagine an environmental issue facing a farmer or woodland owner, you can safely bet there is an EQIP practice (or 3!) to meet that need.  Successful applicants to receive EQIP assistance paid at either a 75% or 90% rate to implement the recommended activity on their property.  Historically Underserved applicants, which includes Beginning Farmers, Limited Resource Farmers, Socially Disadvantaged Farmers, and Veteran Farmers, can tap into the higher 90% rate.

How does maple fit in to EQIP?

There is no set-aside pot of money allocated only for maple producers.  To improve your chances to get maple-related assistance, you should couple forestry- or wildlife-related practices.  Think tree or shrub plantings, managing grapevines or invasive species, or improving your woods through a Timber Stand Improvement (TSI) cut for just a few examples.  If you are a farmer, there are plenty of other practices to consider as well.  The more comprehensive and realistic your application to EQIP is, the better your odds of being a successful awardee.

So what are the maple-specific EQIP practices?  There are functionally 2 practices – reverse osmosis and sap preheaters that fall under Practice Code 374 – Energy Efficient Agricultural Operation.  Once you break up the size of sap preheaters into small/large and bracket RO units as small/medium/large capacity, the number of specific items actually grows to 5.  The 2 graphics below will explain more of the cost rate assistance details.

When/how do I apply?

The very first step is to determine if you are eligible to apply, and the initial process starts with establishing records with the Farm Service Agency.  Once eligibility is determined, you can proceed with your application.  All the applications are ranked against one another for funding priority.  In other words, EQIP ranks applications to ensure their dollars are going as far and as efficiently as they possibly can.

When to apply is just as important as How to apply.  The next batch of EQIP applications will be finalized and ranked on January 14th for the Fiscal Year 2022.  Though applications can be submitted year-round, any application received after mid-January will be considered in the 2023 batch of applications.

Who can help me apply?

You should contact your local NRCS service center and get in touch with the ODNR Service Forester covering your territory.

When will I find out if I got EQIP assistance?

It’s hard to know an exact date; however, once when successful applicants are notified, the final step is to sign contract documents once they are ready.

 

Don’t be discouraged if you miss the January 14th deadline, you can always be working on your application for the next Fiscal Cycle.  While there is no guarantee that maple producers will be so well-positioned to benefit from EQIP in coming years, EQIP is a wonderful program that can benefit your maple operation but in much broader ways as well.

Author: Gabe Karns
Special thanks to Gary Graham for forwarding information about the Practice Code 374 eligibility.

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

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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

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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

All Things Evaporators: Part III

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Part 1 and Part 2 of our Evaporator series focused on managing the flue pans and the syrup pans in your evaporator rig. Now the focus will be on controlling two factors that can wreak havoc on the syrup-making process: foam and niter.

Controlling Foam

Foam occurs naturally during the boiling process, and foam problems become more prevalent later in the season when bacterial growth is greatest. A bad foaming issue can make it appear as though your evaporator is boiling over.

Let’s look at the practice of defoaming an evaporator. Think about the last time you boiled syrup on the stove to make candy. A pot with syrup will boil over very quickly. To prevent this, you can smear butter along the rim of the pan. On an evaporator, we do the same basic thing only on a larger scale. Foam build-up starts in the flue pan. Foam bubbles contain liquid that is being pulled away from the pan surface suspending it above the hot liquid below. This reduces the depth of liquid in the pan. Shallower liquid will boil off faster creating hot spots that show up first as areas of intensified steam. These steaming volcano-like hot spots are the first indication you may be headed for trouble. All of this can be avoided by keeping foam to a minimum. Regardless of where the hot spots are located, there are only two places to put defoamer, in the inlet corner of the flue pan and, only if needed, at the draw-off point. One of the biggest mistakes is to put defoamer randomly across the middle of the pans, especially in the syrup pan. Doing this disrupts the gradient, kills the boil, and promotes intermingling of syrup of different densities. This is the most common reason for drawing off the dreaded big batch.

Today we use commercial food-grade defoamers or organic products like canola oil to defoam a pan. There are several methods to place defoamer into the evaporator. One is to simply put it in by hand. If this method is used, the defoamer should be put into your evaporator somewhere near the rear of the flue pan. The most consistent results can be obtained by placing a precise number of drops into the flue pan every 5 to 10 minutes or every time you fire the rig. The number of drops used varies anywhere from 3 drops for small rigs up to 10 drops on larger rigs. The width of the evaporator determines the number of drops, and the rule of thumb is 1 drop for every 6-8 inches of evaporator width. Three drops in a 2-foot rig, 4-5 in a 3-foot rig, and up to 10 drops on a 6-footer would be appropriate application rates.

The biggest problem I have (and I suspect other producers as well) is remembering to place the defoamer in the flue pan because we are not using wood and not firing on regular intervals. A timer works well to remind you to keep on schedule. Other methods would be the use of a defoamer cup in the corners of the pan or injection devices that administer a precise number of drops over time. Defoamer cups work well on larger rigs where the boil in the flue pan is very aggressive.

If your syrup tastes a little oily, you are probably using too much defoamer. If you are an organic producer using organic canola oil, be especially wary of over-application. These cooking oils are not as effective as commercial defoamer and require higher application rates. Over-application can result in off flavors or a greasy feel to the syrup when tasted.

Controlling Niter

What is niter, or as the old-timers called it – sugar sand, and where does it come from?

Niter is a suspension of minerals and other solids that precipitate out of the sap during the boiling process. The amount of niter present in sap varies from season to season, from woods to woods and time of year. These suspended solids are removed during the syrup filtration process. The prevention of niter build-up is critical.

In an evaporator heat must be transferred through the thin metal surface of the pan into the liquid to create the boil. A portion of the suspended solids tend to adhere to the heated metal surface of the pan. In extreme cases, the caked niter will scorch, burn, and that excess heat will eventually buckle the metal pan. Allowing niter build-up insulates the liquid from the pan surface causing the metal surface to burn. Due to the higher concentration of solids in the sap, niter build-up tends to increase the closer you get to the draw-off point. Depending on the volume of syrup moving through the evaporator, removing niter must be done once daily or several times during a boil. As you move further away from the draw-off point, niter build-up is a lot less and the boiling action tends to break the niter down. However, all your front pans need to be cleaned and rotated on a regular basis. Starting the day with a clean syrup pan is a necessity.  Pans can be cleaned with the use of white vinegar and hot water. This is a very effective way to clean pans with a minimal amount of elbow grease.

Author: Les Ober, Geauga County OSU Extension

All Things Evaporators: Part II

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Scroll down or click under the Evaporators and Finishing Archive tab to read Part I.

Managing Your Syrup Pan

What happens in the syrup (or front) pan determines the success or failure of every producer’s season. It is here that all the standards of maple syrup quality come together. Ideally, 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 is moving toward the perfect draw-off. That sixth sense is something that requires experience and is often handed down generation to generation. If the science and art come together properly, the result is golden amber maple syrup with the perfect maple flavor.

When sap transitions from the flue pans to the syrup pans, many gallons of water have already been removed leaving a sap concentration of roughly 18-19 Brix. If syrup represents 1 gallon of the remaining liquid, approximately 9 more gallons of water still need to be evaporated in the syrup pans. The speed at which this happens is relative to the size of the evaporator you are running and the quality of your fuel source. In most rigs, the transition happens quickly, and operators must devote their undivided attention to avoid problems and ensure a quality product.

Unlike flue pans, the front or syrup pan is a flat bottom designed to create a surface with even heat exchange. There are several types of front pans on the market today. Traditional drop flue evaporators were equipped with a standard reverse flow pan which allowed the operator to change the side used to draw off when niter (sugar-sand) built up. Over the years, this style of evaporator has seen modifications.

One improvement included designing the pan so that the flow can be reversed while allowing the draw-off to remain on one side. This is accomplished with a series of valves and external plumbing directing the flow of sap from one side to the other. An example of this would be the “Leader Revolution Pan.” Producers found this improvement to be helpful to avoid the movement of draw-off equipment from one side of the rig to the other.


Cross flow design on a raised flue evaporator.  Electronic floats calibrate sap depth between the back and front pans.

Another front pan configuration is the cross-flow design. Cross-flow pans are installed setting across the arch hooked in series with the draw-off near the front of the last pan. There can be anywhere from two pans on a standard rig to four pans on bigger rigs designed to handle “High Brix Concentrate”.  Because niter tends to accumulate in the draw-off pan first, that pan needs to be switched out to avoid excessive niter build-up. Most producers using this system have one or two extra pans cleaned and ready if the draw-off pan needs to be switched.

The depth of the sap in the front pan is determined by the design of the evaporator. A drop flue rig will maintain the depth set by the flue pan float, but a raised flue rig allows producers to set a separate depth in the front plan. Producers should carry approximately 2 inches of liquid across the front pans allowing syrup to boil evenly to the draw-off point. As pointed out in the first evaporator post, if hot spots develop, that area of the pan will tend to boil faster increasing the risk of burning. The trouble usually occurs when you draw off large volumes of syrup at one time. This causes the liquid level to become very uneven, you might have 2 inches in one part of the pan and only a half-inch in another.  Removing small batches more often will prevent uneven syrup levels and ensure a steady even boil.


Site gauge for monitoring sap depth on a raised flue evaporator.

It bears repeating that producers should pay close attention to bubbles in the sap. As liquid temperatures go above 219 F, the liquid will gravitate toward the hot area, localized boiling becomes more intense over the hot spot, and steam and bubbling from the more intense boil becomes more concentrated and noticeable. The result is that the sap is becoming more concentrated in the hot zone. This means the sap is becoming more concentrated in that area. As concentration increases and sap thickens to syrup, the thicker liquid will not flow evenly toward the draw-off point, and you could be headed for trouble. At this point, you need to let more liquid into that portion of the pan to re-establish flow toward the draw-off. Maintaining a constant even flow of syrup in the form of low volume draw-offs stabilizes the process. Make all your adjustments in small increments and remember it takes time for that adjustment to affect the process.

Three important factors must be controlled to maintain a constant boil.

  • First, maintain a steady even fire in the firebox.
  • Second, control your foam in the flue pan.
  • Finally, control niter build-up.

In Part 3 of this series, the focus will be on controlling foam and niter build-up in the syrup-making process – come back next week!

Author: Les Ober, Geauga County OSU Extension