Canning and storage

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!

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

Handling Your Maple Syrup Crop after the Season

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 Every once and awhile it is good to go back and revisit an old post with a good message – here is one from 2013 with a few additions.

Maple syrup is often referred to as “liquid gold.” Increased demand for maple syrup and the escalating value of this year’s crop has added new meaning to this term of endearment. Once the season is over, you need to use a little TLC when it comes to storing maple syrup so it will maintain its quality and value. If you have not sold all of this year’s maple syrup and have some left in the sugarhouse, you need to pay careful attention to the inside temperatures of those buildings. With all of the recent hot weather, syrup stored in non-insulated structures can quickly reach high temperatures and spoilage can occur. You may think you safeguarded your product by packing the syrup hot in a sealed container. Maybe not!

Most syrup is stored in stainless steel barrels that were packed in February and March. Syrup should go into barrels hot and sealed with as little air as possible. The drums then cool to the ambient temperature with the syrup soon reaching the same temperature inside. Steel as a general fact transfers heat and cold well.  The syrup on the inside of a steel barrel will remain cold for a long period of time due to its viscosity and mass. However, this also means that if the steel on the drum’s exterior warms quickly to 80 degrees Fahrenheit or above and stays warm, the result is condensation that will develop between the warm steel and the cool syrup on the inside. If this moisture develops in the interior air space, molds can form. This is the same thing that happens to jugs when they are not heated properly to 185 degrees. If the product is not above 66 Brix, syrup can even ferment. The worst culprit for spoiled syrup is a partially-filled drum that is then topped off with hot syrup. This scenario can be avoided by repacking the entire drum between 150 and 180 degrees Fahrenheit. It is always best to completely fill a drum with hot syrup right off the filter press, seal it, and store it.

The best solution for long term storage is to build a cool room. You notice I did said cool, not cold. A walk in cooler would be the best case scenario but most producers cannot afford such a luxury. Take a small space big enough to hold several drums of syrup. This could be a closet or small room in a building. Insulate the room and stick a window air conditioning unit through the wall. When temperature exceeds 80 degrees Fahrenheit for any length of time, kick on the air conditioner and cool the room to just below 70 degrees. At that temperature, the syrup will stay relatively cool in the barrels. Your biggest struggle is to get the syrup through the hottest months of the year. Another trick is to rotate the drum occasionally, this moves the syrup inside the drum and should dissipate any moisture that forms on the interior metal wall of the drum within the residual air space, thus reducing the chance of spoilage if the drum was packed correctly to begin with.

Author: Les Ober, Geauga County OSU Extension

Things You Can Do to Ensure the Quality of Your Maple Syrup

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This post is in response to Dr. Michael Farrell’s article on maple syrup quality from the most recent Maple News. First let me say that the article was not only excellent but very timely. The article addresses an issue that all maple syrup producers should consider as another season is upon us. What I hope to do is highlight some of the areas in the production process where syrup quality can be compromised often resulting in off flavors. The University of Vermont and the Vermont Ministry of Agriculture has provided an excellent tool for identifying the sources of off flavors in maple.

After producing maple syrup for over 40 years and teaching seminars on maple syrup production for close to 20, I have made or personally witnessed most of the common mistakes that lead to off flavors and poor syrup quality. In this article I will go over some, but certainly not all, of the factors that lead to poor syrup quality. The good news is that most of the factors can be controlled by producers with best practices, in turn meaning you control the quality of your syrup. The Map of Maple Off Flavors (linked above) identifies 5 primary areas where off flavors occur: Mother Nature, defoamer, processing, chemicals and others. I want to address each area in order of how they would occur from start of season to finish.

When you start out the season, you need to be aware of several problem areas that can lead to off flavors. Most problems arise from the previous season’s equipment maintenance and show their ugly faces as the new season kicks off. When producers ask how they should clean equipment, my response is with a lot of water and elbow grease – and my answer is the same from large-scale producers all the way down to backyard hobbyists. Anytime chemicals are used to clean equipment, residuals left behind can compromise flavor. If you use chemicals on your pans to clean them at the end of the season, you need to thoroughly scrub away any chemical residue. If you use a tubing cleaner, make sure it is flushed entirely from the system. If you store filters make sure there is no mold on those filters when you dig them out of storage. (And never use detergents to scrub away mold on filters, THROW THEM AWAY!) The list could go on. A final guideline for this area is to always store your chemicals in a secure place away from your syrup processing so as to avoid unintended contamination of your final product. Most of the above is common sense but they need to be mentioned.

Probably the biggest culprit for off flavors comes during the processing stage. This is where the majority of mistakes are made that result in off flavors. When we grade syrup, we look at 4 primary areas density, color, clarity, and flavor. Even though each is judged separately they are actually all interrelated. Syrup must be 66 Brix to meet USDA standards and if it is below 66 Brix it can ferment and cause an off flavor. Syrup above 67 Brix normally does not have an off flavor but the higher density can cause crystallization in the bottom of each container resulting in lost revenue to the producer. As syrup moves across the front pan, density and color changes rapidly. Density changing with the rapid removal of water that increases sugar concentration, and color as heat changes the sugar molecules. Anything that interferes with flow of sap through the evaporator can cause the syrup to get darker and possibly cause an off flavor. Many feel that density is the most critical part of the process and at times reaching the proper density can be very difficult. Improper density management can lead to two off flavors that are very common in syrup – fermented and scorched. And these off flavors are often accompanied by undesirable colors as well.

We use three tools to measure density, the hydrometer, the thermometer and the refractometer. All sugarmakers use a hydrometer. Hydrometers should be inspected or checked for possible problems and replaced if suspect. Often the paper with the scale printed on it can slip resulting in the wrong Brix reading. Hydrometers can become coated with film resulting in inaccurate readings. A good hydrometer will give you an accurate reading only if it is used at the right temperature. Temperatures below that require consulting a chart to convert to the right Brix reading based on the specific temperature. Maple syrup boils at 7 degrees Fahrenheit above the boiling point of water or 219 degrees, and many producers use a thermometer to determine the draw off point. The only problem is that the 219 reading is only accurate if the barometer is at 29.9 Hg barometric pressure. Therefore, a thermometer needs to be recalibrated every time the barometric pressure rise or falls. Having an accurate syrup temperature is especially vital when it comes to setting an automatic draw off.

The final tool is what many consider the grand judge and jury of maple syrup density – the refractometer. For a refractometer to work properly, syrup must be finished and stable in temperature. This was pointed out the other day in a conversation with Robert Crooks of Marcland Instruments. For a refractometer to work properly, it has to be able to refract light coming through the sample and that can only be done accurately if the sample in the instrument is a clear finished sample. Taking a sample of cloudy unfiltered syrup will lead to an inaccurate reading. The temperature of the syrup also affects light refraction. Even though refractometers are built to automatically compensate for temperature, temperature must be stable. If you leave freshly drawn off syrup set in a container, it will continue to evaporate water until it cools down. Think of what happens to a pot roast when you pull it from the oven, it continues to cook beyond the temperature when you pulled it from the oven. This is why it is best practice to cover containers of hot unfiltered syrup in order to stop moisture loss. If you use a refractometer to set the draw off, run a sample of syrup through your filter and allow the sample to sit for 15 minutes before taking your refractometer reading. This will give you the most accurate reading from your refractometer.

If you use a conventional auto draw-off, be aware that it takes time to complete the draw off process. This means that syrup will be drawn off over a range of temperatures. Therefore set the draw off to actuate slightly below the desired temperature and it will finish slightly above. Using a hydrometer is the best way to set your draw off. However, make sure you are reading the hydrometer at the recommended syrup temperature. You can use a refractometer but remember it must be used on a finished, stable-temperature product, and this process may take more time than you have to make a correction on the draw-off.

As sap moves across the evaporator, a temperature gradient sets up. Ninety percent of the water is removed by the time the sap reaches the middle of the front pan, so syrup needs to move from the middle of the syrup pan to the outlet relatively fast to avoid darker and denser syrup than desired. A common mistake is to allow the pans to cool during the firing process. Anytime you cool off the pans, the temperature of the sap drops and this causes the boiling temperature to drop resulting in the sap on one side of the gradient to mix with sap on the other. Keeping constant and stable heat levels on the front pan is must and particularly crucial for wood-fired evaporators.

Another problem is foam control. Excessive foam in the back pan can cause problems with your float and may interfere with your ability to control the level of the sap in the evaporator. If this happens you will need to use a defoamer to control the problem. When using defoamer, the only place the defoamer should be added is at the point where sap enters the rear pan, and occasionally a couple of drops if needed at the draw-off if foam builds up as you are drawing off. This should be done at regular intervals placing the prescribed number of drops (2 drops per foot of width) where the sap enters the evaporator. Never spray defoamer across the front pan to control foam. Using defoamer in this manner will impede the boil and break down the temperature gradient. This can lead to the dreaded big batch.  If the front pan is foaming excessively, then the foam is not being properly controlled in the back pan, correct the problem back there. Use only small amounts of defoamer, excessive use can result in an off flavor. Organic producers must use safflower or canola oils which are very poor defoamers. And be careful with organic products as well because an excessive amount can produce off flavors.

Another potential problem (there are a lot of them, right?!) is niter build-up which can lead to scorching in your evaporator. Any niter build-ups will insulate the bottom of the pan from the syrup creating a potential hot spot which can eventually result in a scorched spot on the pan. You must keep liquid in contact with the pan at all times. Always keep your pans as niter free as possible by rotating sides or using a clean set of pans between batches. Using a good syrup filtering system to remove niter is vital if you want to produce syrup that meets the highest clarity standards. You should be able to read newspaper print through a sample bottle of syrup that has been properly filtered. Cloudy syrup with a lot of niter can produce an off flavor. Remember every time you heat your syrup to a boil, more niter will precipitate out and needs to be re-filtered. That is why you do not want to bring your syrup to a full boil when canning. 185 degrees Fahrenheit is the required temperature for canning.

As maple producers, we fight the growth of bacteria through our entire system. When bacterial colonies multiply in sap, they convert Sucrose sugar molecules to Glucose and other invert sugar molecules. This increase in invert sugar, when exposed to heat, will lead to a darker finished product. This is most prevalent at the end of the season when the bacterial content of sap is at its highest. Bacteria can affect the entire process of making syrup from the taphole to canning. Because sap has sugar content, it is a perfect media for bacterial growth. It goes without saying you can never be too clean when it comes to making syrup. Sap needs to be collected in clean equipment, it needs to be kept cool, and it must be processed quickly. If you start with a properly sanitized system at season’s beginning, you will have far fewer issues at season’s end – though issues may still crop up. Maple producers need to know when to end the season. Producing syrup late in the season when the trees are near budding and the sap is out of peak condition has little value to you and even less to the industry’s customers.

As you can see, there are many factors that a sugarmaker must consider in order to maintain the highest standards of product quality. From equipment sanitation to efficiency throughout processing, paying attention to details is critical and is what separates the best producers from the rest of the pack. Making the highest quality product possible should be your goal. Your reputation as a maple producer depends on it.

Author: Les Ober, Geauga County OSU Extension

How Will You Store Your Maple Syrup?

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Hopefully this is a question you are asking because of a bumper crop! But even in any year, if you have not sold all the year’s maple syrup and have some left in the sugarhouse or in a tool shed or in the corner of your garage, then you need to watch the inside temperatures of those buildings. In outdoor non-insulated structures, temperatures can elevate quickly and spoilage can occur. You may have thought that you covered your bases by packing syrup hot in a sealed container. But maybe not!

Let’s look closer at how syrup is packed and stored. Most syrup is stored in stainless steel barrels that were packed in February and March. The syrup went in to the barrels hot and each barrel sealed. Inside a thirty gallon drum there will always be a little room for air no matter how carefully you pack. The drums then cool to and fluctuate with the ambient temperature of the time of the year and soon the syrup inside takes on the same temperature. Steel transfers heat and cold well, but 30 gallons of syrup is a lot of volume and will remain cold for a long period of time due to its viscosity and mass. However, when outside temperatures warm to 80 degrees and above and stays hot, the steel on the outside of the drum heats up quickly often forming a layer of condensation between the warm steel on the outside and the cool syrup on the inside. When this moisture gets into the air space inside the barrel molds can form. This is the same thing that happens to jugs when they are not heated to 185 degrees Fahrenheit, and if the product is not above 66 Brix, syrup can even ferment.

The best solution for keeping your syrup in tip-top condition is to build a cool room. You notice I did not say cold. A walk in cooler would be the best case scenario but most producers cannot afford such a luxury. Take a small space big enough to hold several drums of syrup. This could be a closet or a small room inside a building. Insulate the room and install a window air conditioning unit through the wall. When temperatures go over 80 degrees F for any length of time, fire up the air conditioner and brings the room to just below 70. At that temperature, the syrup will stay relatively cool in the barrels and always trends towards being colder than the outside temperature. This strategy should get you and your syrup through the hot months, then once the daytime temperatures cool off into early fall, you are out of the woods!

Author: Les Ober, Geauga County OSU Extension