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Ready for the 2020 maple season

Dave Klish

We have finished tapping all previously tapped trees around the sugar house and await the warm temperatures needed for the sap to flow. Right now we are well below freezing and will not see any warming until midday Monday (4 days out). When it does warm we also will be adding new lines to tap several previously untapped maples. I think we will be able to get almost 100 new taps from those trees (most trees unless they are up over 20″ diameter only get 1 tap.) We will have the vacuum pump running and be adding more taps in the mornings, then we will process in the afternoon into the evenings if needed, depending on the quantity of sap we get in the tanks. All sap is pulled by vacuum directly to tanks just outside the sugar house. At this time we have not boiled any yet. I’m quite sure the sap will flow enough next week as long as the forecast does not change. For our first boil we need a minimum of 300 gal of sap.

When sap flows well we can get well over 300 gal in a day, but if the weather isn’t warm enough we get too little to boil and if we don’t get enough after 2 days we dump the sap and clean the tanks, sap must be processed, it does poorly if held too long, 36 hrs is about it with temperatures up to 40 F, if closer to 50 F 24 hrs is all we can hold it. This is generally only an issue for having that first boil, after that we can process as little as about 150 gal, because the evaporator is still holding semi processed sap that has already boiled hard.

The evaporator runs in a continuous flow, from the inlet float to the outlet as finished syrup. Sap (or more accurately concentrate from the reverse osmosis (RO) flows into the float box on the flues pan, from there it is channeled to the front corner of the flues pan thru a SS pipe and flows out into the flues of the evaporator. On my 3′ x 8′ evaporator the flues pan is 3×5′ with each flue being 10″ deep, the flues make far more surface area exposed to the intense heat under the pans making it boil harder. The flues pan has several flues in the 3′ width, each running lengthwise. In that pan there are 2 main sections. From where the concentrate first enters the flues it boils and gradually flows to the back of that half of the flues pan. Then it crosses to the other half of the flues pan boiling hard until it reaches the front corner. The super concentrated sap then exits the flues pan (over 75% of the evaporation takes place in the flues pan) and flows to one of 2 float boxes on the syrup pan. That pan is reversible flow so I can change the direction of flow by closing one valve and opening another. Anytime I change direction of flow I also need to move a float from the old inlet to the new inlet side and move the automatic draw off valve to the new outlet.

In the syrup pan, there are 4 channels running from side to side. As the super concentrate flows into either section 1 or 4, it boils as it slowly flows to the end of that channel, where it crosses to the next channel. By the time it has reached the outlet box with the auto draw valve it then flows into a draw off tank. The auto draw is controlled by temperature and the necessary temperature is checked and adjusted as needed. We use an electric boil temperature meter which tells us what to set the auto draw at based on the exact barometer reading at that time at our location, as the air pressure changes the boil temperature changes. We keep the auto draw set at 7.3 degrees F above whatever the boiling point of water is at that time. You might think water boils at 212 F but that is only at sea level at 29.92 ” of mercury barometric reading. Some days it can remain unchanged for several hours, on others it can change every half hour enough that the draw off temperature needs to be adjusted.

Once it is at the correct density for maple syrup, it flows into a draw off tank, once we have been at full boil the first time of the season, we usually draw off 5-7 gal of syrup every hour. Part of that range is because sometimes we run the RO enough that the evaporator is being fed with concentrate at 8% sugar, while at other times we concentrate it to 12% sugar. My RO only removes 75% of the water in the sap as it flows thru the RO once, thus if the sap starts at 2% sugar we finish the RO at 8% in one pass. If we start at 3% we finish at 12%. We can also remove more if we have the time to do it on 8% concentrate, run thru a second time and get 12%. My RO does not go over about 3-14% concentrate, far more costly RO’s can go much higher. In fact Vermont’s Proctor Maple Research Center concentrates to 34-35% in one pass. A few other huge operations also have RO’s that can go to 35%, but most buying an RO in a higher price range than mine can go to somewhere between 15% and some others as high as 22-24%, the 35% RO’s are a new generation of RO, having developed in the last 2-4 years. An RO is basically just a filter, that allows water molecules to flow thru the membrane(s) while not allowing sugar molecules pass. The sap is pushed thru by a high pressure pump, my RO runs at up to 280 PSI, better ones run at 4-600 PSI and I don’t even know how high a pressure the super RO’s run at, but it must be much higher than 600 psi I would think.

Back to my flow, after the syrup is in the draw off tank (it holds up to 28 gal of syrup) it is then pumped to a 2′ x 6′ finisher. Once in there it is brought back up to a temperature of 205-210 F, verified for density by using a hydrometer, corrected if needed. If slightly too dense, we just draw some more almost syrup and blending it into the finisher, if too thin it is heated more to evaporate more water off. Now that we use the auto draw valve we generally only need slight adjustments in the finisher. From the finisher once at the perfect density of 66.9% sugar (all from sugar in the sap and only increased by removing excess water,first in the RO and then in the evaporator. Maple syrup can not be made by just removing enough water to get to 66.9% sugar in the RO. The maple flavor is developed in the evaporator. In fact, my evaporator 3×8 has a 3×5 flues pan and a 3×3 syrup pan. Evaporators made for those RO’s getting up to 30+% concentrations re different or their syrup would have very little flavor. The Proctor Center I told you about has a 7×20′ evaporator, their flues pan is only 4 or 6′ long, the rest is all syrup pan (a syrup pan has a flat bottom) so the super concentrate has enough time to develop the full maple flavor.

Back to my flow, again. From the finisher the syrup is pumped thru a filter press where the niter is removed. Niter is mainly excess minerals that precipitated out of the sap as it was concentrated. In concentrating the minerals can not all stay in solution and they precipitate out. If maple syrup was not filtered, it would be very cloudy. From the filter press the syrup is either sent to my bottler (if I need to pack more syrup for retail sales) or it is pumped into a stainless steel barrel. I have barrels ranging from 16 gal up to 26.5 gal. I used to have some 30 gal and 40 gal barrels, but I decided I like the 26.5 far better as my largest SS barrels because I don’t like to pack more than that at any one time in any one grade (color) at one time. I far prefer storing my reserve maple syrup in 26.5 gal or the smaller 16 gal barrels because of the bottling as I pack more retail containers.

Any syrup that was sent to the bottler is then heated if needed up to 185-187 F and bottled. Some in glass but most in plastic jugs because syrup sells for a lot more in glass because the cost of the glass is far higher than the plastic jugs. I bottle as needed through out the year, often every 3-6 weeks as needed.

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