What is the maximum sugar content possible before I boil?

After maple season I am going to try and make birch syrup. Given the significantly lower sugar content of birch sap, I want to consider a couple methods to increase the sugar content. Basically, I am trying to find out how to maximize the sugar content of the sap and thereby minimize the boiling needed.

Maybe this is a stupid question, but if I use an RO (e.g. RO bucket) there is a sap input and two outputs, one for water and the other for concentrated sap. Should the concentrated sap go into a separate container or feed it back into the sap input container?

If I capture the concentrated sap into a separate container and then repeat the process, how many times can I pass the sap concentrate through the RO before it stops extracting water? In other words, what is the maximum sugar content that can be achieved using an RO?

When maple sap partially freezes, it is my understanding that the hunk of ice floating in the bucket is just frozen water and the sugar is left in the bucket. Although birch season is when nighttime temps are above freezing, I might have access to a freezer. After I maximize sugar content to the greatest extent possible with an RO, would I be able to increase the sugar content further by partially freezing the concentrated sap and scooping out the precipitated ice?

Is there anything else I can do to extract water from the sap and thereby increase the sugar content before I boil?

Thank you

Edward
Massachusetts
2021: 12 taps on buckets (1 tap per tree)
200 gallons of sap (had to toss 40 gallons)
4-compartment evaporator (17”x23”)
4 gallons of syrup

Lots of people bring their brix up into the 20's and 30's before boiling. It all depends on the quality of your process and RO. I personally bring my sap up to between 10-15% before I start boiling after I run it through my RO.

I dont know how many gallons you are talking about or how fast an RO bucket works. You can certainly recirculate your concentrated sap back into your original container and keep running it until you get the desired brix you are looking for. Most smaller producers recirculate to some extent to get their sap where they want it.

Freezing it helps to remove water. Some people refuse to do that because they feel they are losing some sugar. To each his own on that one. Many people have test5ed the ice, some find 0% sugar, others find a little. Depending on your quantity of sap, and ice, and ability to boil dictates how far you want to go with saving your ice.

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Originally Posted by edward

After maple season I am going to try and make birch syrup. Given the significantly lower sugar content of birch sap, I want to consider a couple methods to increase the sugar content. Basically, I am trying to find out how to maximize the sugar content of the sap and thereby minimize the boiling needed.

Maybe this is a stupid question, but if I use an RO (e.g. RO bucket) there is a sap input and two outputs, one for water and the other for concentrated sap. Should the concentrated sap go into a separate container or feed it back into the sap input container?

If I capture the concentrated sap into a separate container and then repeat the process, how many times can I pass the sap concentrate through the RO before it stops extracting water? In other words, what is the maximum sugar content that can be achieved using an RO?

When maple sap partially freezes, it is my understanding that the hunk of ice floating in the bucket is just frozen water and the sugar is left in the bucket. Although birch season is when nighttime temps are above freezing, I might have access to a freezer. After I maximize sugar content to the greatest extent possible with an RO, would I be able to increase the sugar content further by partially freezing the concentrated sap and scooping out the precipitated ice?

Is there anything else I can do to extract water from the sap and thereby increase the sugar content before I boil?

Thank you

Edward
Massachusetts
2021: 12 taps on buckets (1 tap per tree)
200 gallons of sap (had to toss 40 gallons)
4-compartment evaporator (17”x23”)
4 gallons of syrup

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I'm wood-fired and we take it up to about 15% in a single pass. I've heard that you shouldn't go higher than that for wood-fired but I'm not sure why.
Ken

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Originally Posted by edward

After maple season I am going to try and make birch syrup. Given the significantly lower sugar content of birch sap, I want to consider a couple methods to increase the sugar content. Basically, I am trying to find out how to maximize the sugar content of the sap and thereby minimize the boiling needed.

Maybe this is a stupid question, but if I use an RO (e.g. RO bucket) there is a sap input and two outputs, one for water and the other for concentrated sap. Should the concentrated sap go into a separate container or feed it back into the sap input container?

If I capture the concentrated sap into a separate container and then repeat the process, how many times can I pass the sap concentrate through the RO before it stops extracting water? In other words, what is the maximum sugar content that can be achieved using an RO?

When maple sap partially freezes, it is my understanding that the hunk of ice floating in the bucket is just frozen water and the sugar is left in the bucket. Although birch season is when nighttime temps are above freezing, I might have access to a freezer. After I maximize sugar content to the greatest extent possible with an RO, would I be able to increase the sugar content further by partially freezing the concentrated sap and scooping out the precipitated ice?

Is there anything else I can do to extract water from the sap and thereby increase the sugar content before I boil?

Thank you

Edward
Massachusetts
2021: 12 taps on buckets (1 tap per tree)
200 gallons of sap (had to toss 40 gallons)
4-compartment evaporator (17”x23”)
4 gallons of syrup

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If you do freeze your concentrate for additional separation you could always thaw the ice fairly quickly in a pot, not getting it too hot, and then send your ice melt back through the RO and check it to see if you generate any sugar content after it goes through making sure you are not letting any sugar over the dam. Let me know how that goes if you do it.

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Originally Posted by edward

Should the concentrated sap go into a separate container or feed it back into the sap input container?

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People do it both ways. Most do one-pass. Two-pass and recirculation processing will heat up the sap/concentrate and increase microbial growth rate, which in birch is already a problem.

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In other words, what is the maximum sugar content that can be achieved using an RO?

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You won't need to worry about it with your equipment, but technically hi-brix or HyperBrix systems will go to 35-36 Brix if you push them. Perhaps up to about 40 Brix if conditions are optimal.

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After I maximize sugar content to the greatest extent possible with an RO, would I be able to increase the sugar content further by partially freezing the concentrated sap and scooping out the precipitated ice?

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Possible, but not simple. If you don't get it cold enough you'll get no ice. Too cold (for too long) and it'll all be ice. If you have an RO, use that and skip this.

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Is there anything else I can do to extract water from the sap and thereby increase the sugar content before I boil?

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Focus on improving your RO system. If you have multiple trees to choose from and can't tap them all or process all the sap, test the sap sugar content of each tree and only collect from those with the highest sap sugar.

Thank you Dr. Perkins!

Last night, I did first black birch RO of the season on 15 gallons. Like last year, about 3.5% max. This is same 100 psi max system on which I recently got maple, sycamore and black walnut to almost 6%. Reread a paper on gray birch saying composition is like 60 fructose to 40 glucose. Have been blaming super soluble fructose but, could it be the relatively insoluble glucose that is the real problem? Read that honey from mustard flower is mostly glucose and always crystalizes where as honey from Tupelo flowers never does since it is mostly fructose.
This batch is for birch beer but am planning a below atm pressure boil on more later when I will attempt to start with 1 gallon of 10% via freeze-thaw iterations. Estimate is that it will take 30 more gallons of .4% sap.

I freeze-thaw quite a bit. Just tried the 1.6 gallons of 3.5% birch and got 1 quart of 4.8%. It froze overnight as opposed to taking over 2 days to freeze and over 2 days to thaw a 5 gallon bucket. BUT, the first quart out of the bottom of an f-t 5 gallon bucket of 1.8% maple is always > 10%...it just takes forever!

If you are using a ROBucket, the RO will let you know when you have reached max. Those little pumps are limited in pressure thay can produce. When youy are at or near max the water out hose will be extremely slow flow. At that point you have reached max. From there you can try the freeze method, remove from freezer as the ice is about 50% of the total. Remove the ice. It will have some sugar in it, but there will be very little. As you run repeated passes into a separate container, cool the remainder after each pass, the RO raises the temperature and heat is the enemy. As you have concentrated the sweet, you have also concentrated the microbes and they feed on the sugar. and the warmer they are the faster they multiplyYou don't really want to boil the sap like you did maple sap, it's best to let it simmer at about 180F.
Good luck!

Pressure: Running homemade 4 memb 500 gpd with 8800 pump. Chicken out at 100 psi due 125 psi max 5 micron housing warning. Down to trickle then anyway. What would happen if I put 5 mic upstream without a second booster pump? Would I need a recirc line?
F-T protocol: Hustle all concentrate into a 5 cf freezer chest ASAP after system hits max brix. Many variables to freeze-thaw. Where to start optimizing? Best results with 5 gallon buckets frozen for 3 days, then completely thawed, then vac pump from bottom of bucket in half gallons till Brix down to about 50% over orig sap conc (sap = 2 ish, cut off at 3 ish) YES, that is a 6 day turnaround but this is lab stuff anyway. THEN re-RO leftovers which are now WAY below original sap concentration. Always still ice cold at start: frequently big ice chunks left at this stage. Suggestions?
Simmering: Straight 1 gallon electric skillet boil in 2022 was like tar, 2023 boiled RO'd sap at 200 F max: you could see through it but it took forever! Had never seen the 180 F recommendation before. Thanks, have to try that. Did fan experiments on water. Fan held run flat out boil temp to 190 F AND boiled same amount in same time. But blowing dust into my syrup makes me queasy. Bubbling copper pipe air did about same. At least there you could probably filter the air. Also tested boiling starting with one gallon, by quarts and a steady drip. All took about the same time. BUT, recently read that keeping sap low in boiler lowers residence time and makes lighter syrup. Did you do any of this when simmering at 180 F?