Sanitation

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!

How to Combat Buddy & Sour Sap – The Path to QUALITY Syrup (Part 4)

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Prevention of sour sap is all about sanitation. Here are a few things to consider when developing a sanitation plan for your maple operation. As soon as the previous season ends, producers using tubing need to clean and sanitize their lines. There are many ways to do this, but the most important thing is to make sure it gets done. As the new season approaches, inspect your lines for sanitation problems, consider replacing not only the spouts but the drops and tees if needed. As the new season begins, producers using high vacuum should consider running your vacuum 24/7 to keep your lines clean, clear, and cool.  During the season, make sure you wash your holding tanks often to prevent microbial scum buildup.

Where sap is held for a long period of time, avoid using plastic tanks for long term sap storage. Plastic is porous and retains bacterial inoculum that will quickly generate bacterial growth. These plastic tanks are often referred to as commercializers, named after the old commercial grade of syrup that nobody wanted. Once a plastic tank becomes contaminated, they are almost impossible to clean and should be replaced.

In the sugarhouse, making quality maple syrup starts with your reverse osmosis (RO) unit. Concentrate must be evaporated as soon as it comes off the RO. Bacteria multiply quickly in concentrated sap. This is the result of a higher percentage of sugar in the concentrate. There is also an increase in the sap temperature as it moves through the RO. It may enter the RO at 40 degrees F or less, but when it comes out, it will be closer to 50 degrees F. High Brix concentrate, elevated sap temperatures, and a warm sugarhouse are the perfect recipe for taking good sap and turning it into a microbial cesspool if not careful. This is one of the reasons many producers are now considering using refrigerated milk bulk tanks to store concentrate. This cools the concentrate and allows more time to manage the boiling process.

Producers often accept the fact that concentrate left on the evaporator overnight will produce a darker grade syrup, at least until fresh sap is introduced.  This does not have to happen if managed properly.  Small evaporators should be drained if possible. Larger evaporators can be equipped with a wash system that allow the entire evaporator to be cleaned and drained. Once the syrup leaves the evaporator, the process of sanitation continues. Syrup should be filtered and placed in a stainless-steel drum after being reheated to at least 180 degrees F. There is an inherent risk when you attempt to drum syrup at lower temperatures. Spoilage happens when barrels are packed at low temperatures. The hot syrup and cold barrel causes condensation (H2O) which combines with the remaining air in the barrel ultimately resulting in mold and fermentation.  It is best practice to place filled barrels in a cool place like a basement or a barn that does not heat up. Another practice worth looking into, is to build a cool room by equipping  a small insulated room with an air conditioner.

When you re-open a barrel of syrup, you should have syrup that is ready to bottle. When you bottle your syrup bring the syrup back up to 185 degrees for packing. Syrup packed below 185 F is subject to spoilage and reduced shelf life. Going above 190 also creates several problems. And if the syrup peaks above 200 F, the syrup will start to foam, and niter will start precipitate. The only solution for this scenario is to filter the syrup again. You will also overheat your jugs causing them to contract and suck in if they are not 100% filled. Plastic jugs should always be filled within a half inch of the top and laid on their side to kill any bacterial that may have found its way in the jug.  If you pack in glass bottles, make sure you put your bottles in the oven at 200 degrees for a few minutes. Hot glass will not condensate moisture and you can eliminate most problems with this simple step. It is always good to pack several times over the course of the year to maintain the highest quality in your syrup.

Many years ago, there was a use for commercial outlet for sub-standard syrup. The majority was sold to the tobacco industry. It was used to sweeten chewing tobacco. That outlet for the most part no longer exists. There are places where substandard syrup could be used but its objectionable flavor drastically lowers its value. For this reason, there is now a movement to prevent this type of syrup from getting into the market. Bulk buyers no longer want to handle sub-standard syrup and if they buy it they are not going to pay very much for the product. In addition, there is a currently an effort by the International Maple Syrup Institute and others to promote educational programing to raise producer awareness about ways to avoid producing this kind of syrup. The reality is that there is very little economic return from sub-standard syrup production. With rising costs of equipment and inputs the production of anything less than top quality saleable syrup in today’s high demand market is foolish.

There you have it – a 4-part series starting with a lesson on phenology and how to track growing degree days, relating growing degree days to tree bud development, appreciating the differences between buddy sap and sour sap, taking sanitation seriously at every single phase, and PRESTO! viola! alakazam (if only it were that easy!!) – you are making QUALITY maple syrup!

Off-Tasting Syrup: Understanding the Culprits (Part 3)

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Now that we have talked about tree phenology and maple buds and growing degree days, let’s the talk more about the main prize of every sugarmaker’s dream – QUALITY syrup!  As we get ready to embark on a new maple season, let’s go over some of the things that will help you to improve the quality of your syrup in 2022. We all know that paying attention to detail in the woods will pay off with big rewards; however, the place where paying attention to detail is most important is when the sap or concentrate is on the evaporator. The finishing process can make or break your operation. Maple production is becoming a very competitive business, and the producers making the highest quality syrup will rise to the top.

Here is an oversimplification of what happens during the syrup-making process.  Once bacteria are introduced into the sap, a conversion of sugars takes place. A portion of the maple sap, which is almost 100 percent sucrose, is converted into glucose and fructose. This portion of the sugar content makes up the invert sugars present in syrup. When the sap is heated (The Maillard Reaction – something you can read more about here) the color of the syrup and the flavor of the syrup is formed, largely based on the amount of glucose and fructose sugars and other factors happening at the same time.  Thus, the level of microbial interaction plays a vital role in determining the color, grade, and corresponding flavor profile of the syrup produced. So, as you can see not all microbes are bad, in fact they are essential to everything we love about maple syrup!

Sap flowing from the maple tree is sterile, so where do the microbes come from?

Microbial activity begins as soon as sap is exposed to the outside environment. Early in the season microbial development is slow due to the normally cold temperatures, but once warm weather arrives (above 50 degrees F), more and other strains of microbes begin to multiply in the sap. As the microbes interact with the sap, the syrup produced darkens and develops an increasingly bold and pronounced maple flavor. Microbe colonies continue to expand eventually resulting in very dark and viscous syrup with an unpalatable strong flavor. Because this degradation of the sap is more likely to occur at the end of the season, low quality syrup is often associated with tree budding which happens at approximately the same time.

If you did a taste comparison, you would notice is a definite difference between buddy syrup and sour sap syrup. Buddy syrup has a chocolate flavor akin to what a Tootsie Roll tastes like while sour sap syrup has a bitter sometimes fermented taste that stays in your mouth. If you boil buddy sap, it will produce a pungent unforgettable smell. Sour Sap thickens to the point where it cannot be evaporated and will be difficult to draw off the evaporator. In extreme cases, you can pour a stream out and it will suspend in midair. This is referred to as “ropey syrup”. Sour sap is a result of intense microbial activity that builds anytime during the season when environmental conditions are right for bacterial growth. Buddy syrup comes from sap collected when the buds emerge naturally from the tree. This is a normal physiological growth stage that occurs every year.

Both processes require and progress with seasonal warming. In a normal season, the two tend to occur simultaneously and accelerate at the end of the season. Though the two are correlated, it is important for producers to understand the differences if you want to avoid the problems associated with each.

 

New Article Series Launches Next Monday

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This short post will serve as a sort of guidepost, a table of contents or roadmap if you will, for the next month or so worth of content.  We are excited to bring you a 4-article series on maple phenology.  Phenology is a fancy word for describing nature’s calendar.  We’ll discuss one of the most practical and accessible tools for tracking phenology – the growing degree day, or GDD for short.  Second, we’ll seek to understand and document how GDD is related to species-specific patterns in maple bud and bloom timing and why that matters for maple producers.  Then over the course of two installations, Les Ober will break down why an improvement of one’s understanding of maple season timing is particularly important towards the season’s end and how you can minimize and prevent unwanted bouts with “sour” or “buddy” sap.  After all, our main goal is promoting sustainable production of high quality maple syrup!

Ohio Maple Days 2021 Presentations AVAILABLE

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Despite being virtual due to COVID-19, 2021 Ohio Maple Days – or more accurately Ohio Maple Day sans the “s” – was a success.  The audience, two hundred or so strong, heard presentations on tapping and updates from our ACER grants in addition to how production might be increased with red maple.  A big thanks to this year’s speakers and an extra round of applause for the committee who worked hard on an event that looked quite a bit different than in years past.  One silver lining to having a virtual event is that the sessions are easily recorded.

Visit the Ohio Woodland Stewards Maple page and scroll to the bottom of that webpage to access the different presentations.  Let us know what you think and send us any questions, comments, concerns, or suggestions to talk topics for next year!

Handling Sap and Syrup During the Season

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The maple season is now underway and this is a good time to talk about handling your sap during and after collection. How you handle your sap prior to boiling will strongly affect the quality of the syrup you make. When quality syrup is the goal, timing is everything, and the clock starts as soon as the sap leaves the tree and doesn’t stop until it hits the evaporator.

When sap comes from the tree, it is sterile. That all changes once the sap starts to drain from the taphole. The air and surfaces surrounding the tap contain an abundance of microbes. The sap supplies the food source and a media for the microbes to grow and multiply. Research at Center Acer in Quebec found 21 different strains of microbes present in sap. At first you would think that could be problematic, but the reality is, you need certain strains of bacteria to produce the color and flavor that is unique to maple syrup. For microbial growth you also need the right temperature. Once the environment warms the sap, microbes multiply rapidly. Producers can monitor the potential for microbial growth by checking the temperature of sap. If the temperature is close to freezing, growth is suppressed. Below 40 degrees Fahrenheit, the growth of bacteria is slow, but once the temperature rises above 50 Fahrenheit microbial growth is rapid. The chances for 50 degrees and above temperatures are greatest at the end of the season.

When sap leaves the tree, the sugar is 100% sucrose. Once the sap is exposed to bacterial action, a small fraction of the sucrose is converted into glucose and fructose, often referred to as “invert sugars.” When maple sap containing sucrose, glucose, and fructose is heated, you create an amber color and a unique maple flavor. The problem is when undesirable bacteria begins to outnumber the good bacteria. This changes the chemistry of the sap. As the invert sugar level increases, syrup begins to take on a darker color and a stronger maple flavor. This produces the different grades of syrup. Syrup early in the season has a light color and very mild flavor. The maple syrup produced at the end of the season is often darker and stronger flavor. Syrup containing higher levels of bacteria can develop a very strong almost bitter off-taste known as sour syrup. The syrup consistency takes on a thick almost rubber like appearance and is often referred to as ropey syrup. Sour sap is often confused with buddy syrup because it happens most often at the end of the season. Buddy syrup is caused by sap coming from trees where the buds are getting ready to bloom. The chemistry is completely different from sour sap. Sour sap can happen any time during the season when a warm spell causes extreme flushes of bacteria growth. Sour sap can be prevented with good sanitation practices. Buddy syrup is a natural occurrence every year at the end of the season.

The quality of syrup produced from buckets and bags is best early in the season. Once the hole is drilled and the spout is exposed to the air, microbial development and taphole healing begins. Your season has begun, and you are now on the clock. A normal season for a bucket, bag or gravity tubing producer is 4 to 6 weeks. During the cold periods early in the season, the sap stays fresh just like it would if you put it in your refrigerator. Keep your sap below 40 degrees Fahrenheit and you are fine, but let it heat up to over 50 degrees and you asking for trouble. That happens readily at the end of the season. What many producers forget is that the bucket is an incubator for bacteria if it is not cleaned out regularly throughout the season. Leaving sap sit in a dirty bucket for any length of time is a problem. Remember bacteria does not grow in a clean dry bucket. If you are in a warm spell wash out your buckets and place them upside down next to the tree. If you are in a extended cold period, you should collect your buckets and let them hang until the next run. And never let stale sap sit a bucket, hot or cold.

As for tubing, we have discussed tubing sanitation multiple times over the years and those articles are in the Ohio Maple Blog Archive. Keep your lines as clean as possible throughout the season. This is difficult unless you are on continuous high vacuum. I know it sounds expensive to run the pumps 24/7, but it works to your advantage by keeping the lines cool and dry when the sap is not running. Another essential is to follow the tubing sanitation guidelines, installing new spouts every year, and new tees and drops every three years. You will improve the quality of your syrup.

Once you get the sap to sugarhouse, there are additional things you can do to improve quality. Sap that is going to be stored for longer periods of time needs to be stored in a stainless steel tank. Avoid poly tanks for sap storage. Plastic tanks are incubators for bacteria. Older galvanized tanks, like galvanized buckets, need to be discarded because of the risk of lead contamination. For the backyard producer, make sure your tank is in the shade. Pack around it with snow if possible. You can even freeze some sap and put it in the tank during warm spells. What ever it takes to keep your sap cold, take those necessary precautions. Anytime your sap reaches 50 degrees Fahrenheit and you can’t immediately cool it back down, boil immediately.

What about the evaporator? Boil your sap as quickly as possible. If you are using a reverse osmosis machine, make sure you do not let your concentrate sit. Boil it as soon as it comes through the RO. You double, triple, and in some cases, quadruple the sugar concentration in your sap, and bacteria builds fast in concentrated sap. If you are using a small evaporator, it is a good idea to drain and flush your rig. Leaving partially boiled sap on an evaporator in a warm sugarhouse can result in ropey syrup. Once the syrup is filtered get it into a barrel or a container as fast you can. Do not let it sit around. Pack your drums hot and do not open them until you are ready to use them. Do not store syrup drums in a warm building. Move them into the basement where it is cool or package the syrup at 185 degrees Fahrenheit shortly after the season. From the tree to final container, paying attention to details pays big dividends.

Author: Les Ober, Geauga County OSU Extension

When the Season Comes to an End

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The season has come to an end and now you are faced with the arduous task of cleaning up you maple operation. Where do you start and what do you use? For most equipment, the answer is simple – lots of hot water and elbow grease. A good place to start is with the tanks that hold both sap and syrup. Most are stainless steel and are easy to clean with a pressure washer. We found that a tank washing nozzle that fits your pressure washer is a valuable tool. The specially-designed nozzles enable you to spray to the side and reach areas that a standard spray tip cannot reach. There is no substitute for stainless steel equipment if you can afford it.

Plastic totes and poly tanks have become popular because they are relatively inexpensive but they are harder to clean. Plastic totes, while affordable, may only last about two or three seasons if you get off your cleaning schedule. It does not take long for the plastic to become so contaminated with bacterial spores that you have to discard and replace. However, if you keep poly tanks cleaned they will last for years. Another simple tip is to clean as soon after the season ends as possible. Allowing totes and tanks to sit dormant allows bacteria to build and grow making cleaning more difficult.

Your evaporator needs to be sugared off and flushed out as soon as possible. I often flush the pans with clean water and then refill them with permeate from the RO and let them soak. If permeate is not available, use water. I will drain and refill the pans with clean water and then add the proper amount of pan cleaner following label directions. Once the pan cleaner has done its job, I drain the pans and use a high pressure washer to finish the job. Do the process correctly and your pans will look brand new. Make sure all your float boxes are clean, replace gaskets if needed. Soak your auto draw off temperature probe and your hydrometer in a 5% vinegar solution to remove any residues or films. The thermocouple in the auto draw off probe works best when there is no niter on the probe. Clean your filter press thoroughly and lubricate parts with a food grade lubricant. It is good practice to remove all extra filters from your sugarhouse and store them in your house, somewhere dry and rodent-free. If you use a filter tank, you will need to clean filters and make sure they are completely dry before story to ensure no mold will develop over the off-season. Any filters with problems, even minor, should be discarded, and you should purchase new inventory for the next season.

Reverse osmosis units (RO) should be soap washed and thoroughly rinsed immediately after the last time you use them. Make sure all of the permeate is drained out. Once you break down the RO, return your membranes to the storage vessels with a cup of permeate in each one. Once everything is clean, you should send the membranes in to your dealer for cleaning and testing. There is nothing worse than starting a season with a bad membrane that is passing sugar. Make sure your high pressure pump and your feed pump are free and fully drained. Inspect the membrane housings and get them as dry as possible. Many times with the recirculating motors and pumps on the bottom of the membrane towers, dampness can cause the pump shafts to seize and seals to deteriorate. Because evaporators and ROs require the use of chemicals that are incompatible – phosphoric acid and basic soap – keep them separate and out of reach of children. Be careful when you mix pan cleaner and always follow the directions on the label.

The most controversial portion of a maple system to clean is most certainly the tubing. It seems everyone has his or her own way of dealing with the miles of tubing stretching through the woods. I have cleaned tubing just about every way possible over the years. We have sucked water, pumped water and air, water only, air and tubing cleaner, and just plain did not clean at all. In my experience, using water and air worked well until we tried to pump up too steep of slope and had a blowout that may have had enough force to launch a satellite. Sucking water through the lines left a lot of liquid in the lines that eventually turned to green snot. The method we now use seems to work. We pull taps with the vacuum, nip off each old spout, and immediately use a Stars Company (out of Quebec) line plug to seal the drop line and maintain vacuum on the system. Done properly, the sap in the lateral line will not suck back into the drop line. We then use a paint marker to mark the old tap hole which greatly speeds up next season’s tapping process. Once all of the taps are out, we back flush the mainlines with clean water. Next we close all of the main lines and open the end of each lateral opening long enough to pull air through the lines and keep vacuum on the system. Doing this should remove 80% of the liquid from the lateral and main lines. At this stage, we successively open the ends of each main line and let air in with the vacuum on. Once the vacuum on the entire system drops to zero shut off the pump. At some point before the next season, we then install new spouts on all the drops and let the lines air out completely. This method may seem excessive but it does work. We have a small amount of green sap at the start of the season, but nothing we could not easily filter and could possibly have been avoided by flushing the system again before the season.

A word of caution when it comes to using tubing cleaners. They have to be completely flushed from the lines before the next season. Never use Isopropyl alcohol – it is illegal in the United States. Also be aware that some cleaners attract Mr. Bushy Tail and his friends – never a good thing for tubing operators.

Once your system is cleaned, bring in all releasers and clean and sanitize them thoroughly. They are made of PVC which makes a good home for bacteria. Go over the mechanism and use lubricant provided by the manufacture to lubricate all of moving parts. The last task is to care for your vacuum and transfer pumps. Change the oil or drain out the water on liquid ring pumps. On the new rotary claw pumps change the oil and fog the pump with a pump oil. You need to make sure rust does not build up. The same is true for rotary vane pumps which are more maintenance-free but putting some oil on the vanes never hurts. All gasoline motors should be drained and the gasoline replaced with SeaFoam or a similar product. Never leave gas with ethanol in the tank. Drain the crank case oil and replace it with fresh motor oil and you will be ready to go for next season. Lastly, make sure you transfer pumps are drained and stored somewhere that will not fall below freezing.

Author: Les Ober, Geauga County OSU Extension