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!

Maple Assistance Opportunity through EQIP

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)

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 I

A Simple Yet Complex Process

Many producers refer to boiling as the art of making maple syrup.  Boiling on a modern evaporator is a process requiring about 45 minutes to move from the inlet at the start to the draw-off at the finish.  Bringing 2% sap through a float at the back of the machine and moving the sap forward  through a series of channels until it reaches 66 Brix at the opposite end may sound quite simple; however, properly boiling syrup is a very complex scientific process based on physics, chemistry and microbiology.

To meet USDA Standards, maple syrup must be at least 66 percent sugar. This is referred to as syrup density which is measured in Brix. Brix is a measurement scale based on the percentage of sugar in a sample. Because Syrup is made up of over 98% Sucrose sugar, we simply define the density of maple syrup as percent sugar. In this case, 66 Brix syrup would be 66 percent sugar. Once we know the percentage of sugar in sap, we can determine the amount of sap that it takes to make a gallon of syrup. To do this we apply a simple formula – the “Jones Rule of 86” – where you take the factor of 86 and divide it by the percent sugar to obtain the number of gallons of sap required to make one gallon of syrup.  For example, 86 divided by 2% sugar content sap equals 43 gallons of sap to produce one gallon of syrup.

You can start to see how chemistry and a little math plays a role in converting sap to syrup. What about physics? When sap is boiling, a gradient is formed causing the heavy syrup to move in front of the lower density sap. If the pan on the evaporator is boiling, then the two will not mix unless you suddenly lower the temperature in one section of the pans. Disrupting the boil results in an intermingling of sap temperatures which causes a drop in boiling intensity. The result is the dreaded big batch and improper syrup density.

Microbiology comes in to play when colonies of microbes begin to increase. Lack of microbial sanitation is the most common reason for the darkening of syrup potentially resulting in an off flavor. Microbial action changes the sucrose to invert sugars (glucose and fructose). As the percentage of invert sugar increases, heat causes syrup color to darken. It is possible to darken the syrup to a level where the color and flavor are severely impacted. If you ignore any or all of the science involved, you could end up with something that you will definitely not want to put on your own table let alone sell to your neighbor.

Managing Your Flue Pan

The flue pan is where all the heavy lifting of the boiling process is done. There are two basic types of modern evaporators, raised flue and drop flue. The level of sap in a pan is controlled by a float box. With a drop flue, you only have one float box controlling the depth of the sap throughout the entire machine. The sap level is maintained at 1.5-2 inches from back to front. Two inches depth is a safe starting point for beginners. Any change you make to the float at the back of the evaporator will be transferred forward to the draw-off point. Thus, all changes should be minimal and incremental. A raised flue evaporator has two floats, one for the back pan or flue pans and one for the front pan or syrup pans. Though you are still running just one evaporator, you can control two separate processes. The double float design allows you to run your depth in the back pan at 1 inch while running the front pan between 1.5-2 inches. The dual control increases evaporator efficiency, more rapidly boils off water, and better controls the draw-off process. The shallower you can run the back pan the more heat you transfer into the sap and the harder the boil. If you run your back pan too deep, the boil slows, and efficiency is reduced.


Raised Flue Evaporator with device to evacuate away steam from boiling process.

Which style of evaporator you prefer is strictly a personal preference. And once you learn your evaporator’s sweet spot, once the depth is set, you can generally leave it alone. All evaporators should have at least one sap level gauge on the flue pan (raised flue evaporators should have a second gauge between the two front pans). A properly calibrated gauge allows you to know the exact sap level no matter if the flue pan is hooded or clouded with steam.


Drop Flue Evaporator with reverse front flow pan.

When running your evaporator, the basic goal is to maintain a boil across the entire rig with the hardest boil occurring in the flue pan. There is an old saying among maple producers, “You haven’t earned your producer’s badge until you have burnt a pan.” Trust me if you have never scorched a pan, or come close to burning one, consider yourself lucky. Usually the most common reason for burning a pan is human error, usually caused by a distraction. When you are running a rig, you are dealing with extreme heat. Stack temperatures can run between 600-1000 degrees F. You are applying that heat to a relatively small skinny volume of liquid (2 inches spread across the surface of the pan) separated by a thin layer of stainless steel. The only thing that keeps that metal from melting is the thin layer of sap on top. If the sap boils out because you forgot to turn on a valve or you ran out of sap, bad things happen very quickly. Uncontrolled high temperatures can go from a scorch to buckling a pan in just a few short minutes. Your season could be over if you cannot find a replacement.

Tracking bubbles in your sap is a good way to monitor your boil. The bubbles in the pan should be moving slowly in one direction toward the draw-off. If the boil decreases and the bubbles move back and forth then an adjustment needs to be made immediately. If you spot trouble the first thing you must do is avoid panic. Move quickly and precisely. This is where knowing what to expect and what to do is vital and that only comes with experience.

Stay tuned for Part II next week!

Author: Les Ober, Geauga County OSU Extension

Maintaining the Quality of Maple Syrup Through the Proper Handling of Maple Sap

The taste of pure maple syrup is one of nature’s most enjoyable flavors. If it is produced properly, the taste ranges from sweetly delicate to a pronounced robust, uniquely maple flavor. However, maple syrup that is improperly made or handled can be just as unforgettable for other reasons. Maple producers need to be very conscious of how easy it is to destroy the quality of the product they are producing. They need to take every precaution to preserve the integrity of this unique product. How sap is handled during the course of the season will determine the volume of high quality syrup produced.

Maple syrup is made up of 98.5% sugar. The level of sugar is measure in Brix or a percentage of the sugar present in the product. For all practical purposes, we simply say that the product is maple syrup when it reaches 66 Brix or contains 66% sugar. For this reason, maple syrup in Ohio and elsewhere must be finished at 66 Brix.

Simply stating that syrup is all sugar smooths over some of the important details. The primary sugar in maple syrup is Sucrose; however, there are small amounts of Glucose and a trace of Fructose present. Glucose and Fructose sugars are referred to as the invert sugars, and invert sugar levels can determine if a specific batch of maple syrup is usable to make certain value-added maple products. The remaining portion of the syrup is composed of various minerals, amino acids, and organic acids. The most common organic acids are Malic and Fumaric acid, the same found in many fruit juices. The presence of these acids is a relevant fact and has a bearing on how maple syrup is processed.

The quality of maple syrup normally declines as the season progresses. The sap that comes from the tree when the weather is cold and the taps are fresh will most often produce the lightest and the highest quality syrup of the season. The primary reason for this is the relatively low level of bacteria found in the sap. Research done at the University Of Vermont by Dr. Mariafranca Morselli documented the fact that sap inside the maple tree is essentially sterile; however, because sap is normally 1.5 to 2.5% sugar, it becomes an ideal medium for bacterial growth. Once a tree’s sap reaches the taphole, environmental conditions cause bacterial colonies in the sap to flourish. This bacterial growth is responsible for two processes, one inside the tree and another outside. First, bacteria will cause the taphole to dry out and heal thus reducing the flow of sap from that tap. And second, sap containing large concentrations of bacteria will produce darker grades of syrup. A study by Legace, Petri, Jacques and Roy found that:

The presence of microorganisms in the sap has the ability to breakdown the sucrose molecules, the main organic component sap, into glucose and fructose subunits. These subunits react with the heat in the evaporation process to cause the darkening of the syrup and an intense, caramelized flavor.

Morselli & Wahlen also found that if producers can keep sap from being contaminated with bacteria, trees will produce light colored syrup almost to the end of the season. Maple producers can learn much from these studies. Best practices, such as not blowing in the hole to dislodge wood chips, drilling holes straight and clean, properly seating the spout, and regularly replacing or cleaning spouts and drops, all help prevent bacterial growth.

Bacterial growth that starts at the taphole will multiply and flourish as the sap is collected and stored prior to evaporation. This is the reason that sanitation is so important during the collection process. Tubing systems have solved many problems when it comes to collecting sap, but they have also created a few. Sap being collected with a vacuum tubing system moves sap quickly away from the tree to the collection point. It creates a cleaner environment for sap collection unless it is improperly maintained. Unfortunately, poorly maintained tubing presents one of the highest risks for increased bacterial growth. Stagnant sap sitting inside of tubing warms quickly, and research done by Morselli and Wahlen at the University of Vermont, found that bacterial populations sitting inside warm tubing systems double every twenty minutes. Therefore, tubing systems need to be installed properly and maintained with tight lines all sloped toward the collection point.

Changing spouts every season and rotating drop lines on a regular interval enables modern-day producers to achieve a high level of vacuum line sanitation. The invention of the Check Valve Adapter (CVA) by the researchers at Proctor Research Center has totally changed the way we think of taphole sanitation. The research done at Proctor documented that sap actually siphons back into the tree in the absence of vacuum. CVAs prevent that back siphoning from occurring. The other important revelation was that if we can maintain vacuum on the lines even during periods of minimum flow, lines are kept cooler and bacterial growth is minimized. The result is that in many maple operations the only time that vacuum is turned off is when the temperature goes below freezing for a prolonged period of time. We are definitely changing the way we run our vacuum tubing systems and it has not only improved syrup production but also syrup quality.

At the end of the season all collection lines need to be thoroughly cleaned and drained. If possible they should be rinsed again before the start of the next season. Sanitation is no less important in bucket operations. Buckets should be washed before the start of every season. During the season sap needs to gathered often, and buckets should be washed, dried, and stored quickly at season’s end.

Once the sap arrives at the sugarhouse it should be processed quickly. Do not allow sap to sit in open tanks for long periods of time. Collection tanks need to be drained and washed down between runs. To speed up processing, evaporator capacity should be properly matched to the volume of sap coming into the sugarhouse. Producers who struggle to keep ahead of the sap flow and allow large volumes of sap to sit unprocessed for long periods of time often struggle to make top quality syrup.

There are several techniques that can slow bacterial growth and speed up the processing time. Sap can be exposed to ultraviolet (UV) light. Morselli and Wahlen found that sap treated with in-line UV lamps reduced bacteria by 99.4 % early in the season and reduced bacteria 86.2 % later in the season. Evaporation rates can be increased by using pre-heaters or enhanced evaporator units such as the Steam-A-Way or Piggyback. By far the most popular means of cutting down on processing time is by using a reverse osmosis (RO) machine. The invention of the RO has revolutionized the maple syrup industry. Because of the use of modern RO technology, extensive expansion of maple operations is now possible. Modern RO machines can concentrate sap from 2% to over 20% before it ever goes through the evaporator. However, a word of caution, sap that has been run through the RO process is subject to increased bacterial growth, therefore concentrated sap needs to be processed as soon as it comes out of the RO to prevent darkening of the finished product. Of course, the final step in the syrup-making process is proper setup and operation of the evaporator and the maple syrup filtering systems. Once again proper sanitation of all the processing equipment is very important if quality is to be maintained.

The purpose of this post is to get you to thinking about the importance of sanitation and the role sanitation plays in the process of making high quality maple syrup. The beginning of the season is the time to adopt good sanitation practices.

Author: Les Ober, Geauga County OSU Extension