Vacuum boiled Maple Syrup.

So I know I've been none existent on this forum this year. Mainly because I've been spending every extra second I've got getting my vacuum boiler fully working before birch season. Well now it's fully operational and I ran a bunch of maple through it. I've made 1qt of syrup finished it at about 100 degrees F at about -28 inches of mercury. It's very thick, about the consistency of honey and has no smell. It seems that the low temp boil caused the sugar sands to stay dissolved in the syrup, so in spite of it's thickness it was easy to filter. I don't know what the brix value is I have no way to measure it. Considering how thick it is I'd say very high! As for the flavor you'd have to ask my chickens. I haven't tasted it yet, because even though I was continuously sterilizing the sap with a UV sterilizer, the interior of the container was perfect for botulism growth if the bacteria had managed to hide in a dark corner adhered to the wall. So if my chickens don't show any signs of poisoning by tomorrow I'll taste some. Better safe than dead. Anyway, I've attached somes images of the syrup. Next up, grade A birch syrup!
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Notice how thick this is as it falls.

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Quite a while after pouring there are still bubbles suspended in the syrup!

This is very interesting to me. How did you get the vacuum? I could easily preheat my sap to more than 140 degf by using a heat exchanger from the home heating loop of my wood fired boiler. I would only need about 24" vacuum to boil sap at that temp. Then I could heat it to 185 for a while to sterilize and bottle it. Or I could just use vacuum instead of an RO and then finish on the kitchen stove to get some carmelization. So howja doit?

Very interesting indeed. How do you know its to syrup tho if you have no way to check it? And if you went thru all that spend 20 bucks and get a hydrometer!

I believe there used to be evaporators that used the heat from the steam of the primary evaporator to boil sap in another pan kept at a partial vacuum. The vacuum pans sat above the primary pans like a piggyback as I recall.

Well my syrup has started to crystallize so it's high brix. I haven't seen any place to buy the proper hydrometer, I'm sure they'er around I just haven't bothered. I think I need to add a little distilled water to it and shake it up. I can tell how much water is in it approximately based on the temp and pressure it's boiling at. The machine has a Plexiglas lid so I can inspect the sap during the boil down. Once it becomes syrup it's pretty obvious, but the machine automatically shuts down once the temp exceeds 100F and if you can't keep the temp below 100F at -28 inches of mercury than you don't have much water in there anymore. Since the temp never gets much over 100F using plastic isn't a problem. Foam is no problem in a near vacuum, it just doesn't happen.

Maybe you guys didn't see my posts last year, but the reason I built this machine is mainly to make palatable birch syrup. The first year I got into sugaring I decided to make some birch syrup too. I made about a cup, but it was the color of molasses. Last year I built my vacuum evaporating machine. It was all manual and I over looked keeping the sap/syrup sterile as it boiled down. I made some grade A birch syrup with it, but since it was made in an oxygenless environment perfect for growing botulism I didn't dare taste it, it also had an off smell. Basically it spoiled as it boiled down. It also had the consistency of jam, most likely from the bacteria growing in it.

This year I bought computer controls ect and a tore apart and old uv sterilizing water pitcher my wife was going to throw away and upgraded my machine. For things to work the way I like I need a pressure lower than most vacuum pumps used in the sugaring industry today. So I got a pump used for emptying car AC systems. It's capable of of getting down to less then 1% of atmospheric pressure. I use the machine to not only pull the sap out of the trees but to boil it down in the vacuum at the same time. The lines go right from the trees to a vacuum storage chamber then from there into the boiling chamber. The releaser most people use to get the sap out I use to remove water distilled out of the sap.

My birch trees just started to run so I'm switching over from the maples. I can't wait to make the first edible grade A birch syrup!

Is there something special about the 100 °F limit? I can understand keeping it below the caramelization temp of fructose (230°F) and glucose (320°F), but it seems to me that you could get it hot enough for pasteurization and still keep it under "molasses limit". Am I missing something?

if you live in Mason, The Maple guys in Lyndeborogh are very close. hydrometers, cups, etc.

When I did the birch syrup originally I was careful to keep the temp as low as possible. I never let it boil, in fact I kept it below 200F the whole time. It took a long time and still came out molasses. Since birch contains almost all fructose it doesn't caramelize (correctly) alone it just burns. To caramelize (at least the kind you want) you need both fructose and glucose together. So you need to completely avoid temperatures which could potentially alter the structure of the sugar. Beyond that incorporating plastic in my design was much cheaper (and way easier to rapidly prototype), which necessitated low temps.

Is it a rotary vane pump?

I believe it is. Other people on here have used the exact same pump as a sap puller.

What pump is it? I might be able to use it at 140 °F.

The label plate isn't on it any more so I don't have the brand any more, but if you search HVAC vacuum pump on google you'll find many. They and low CFM but high vacuum.

Vacuum and temperature aside, what does it taste like?? It seems to me that syrup with no smell would also have no flavor. If you're trying to make corn syrup, start with corn...it's a lot cheaper.

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Originally Posted by Ittiz

The label plate isn't on it any more so I don't have the brand any more, but if you search HVAC vacuum pump on google you'll find many. They and low CFM but high vacuum.

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Cool. The cheap ones seem to be mostly Robinairs.

I'll find out this evening how it tastes. After putting it in a jar for awhile I found that it does have a light maple smell. Again the main goal for this is lighter birch syrup, which generally has a very strong flavor. I only ran maple as a test to see if the machine was working correctly before the birches began to run.

How efficient do you think it was vs. an RO for volume reduction? Does it use a lot of compressor oil?

Vs RO, I don't know, I never ran RO. I tried to set up RO up once, but everything just cost so much money I gave up before I got too far into it. The oil needs to be replaced often if you have to pull a vacuum from full pressure since water tends to condense in the pump. If you run the pump periodically to maintain a vacuum the oil lasts longer.

So I tasted the syrup. It's quite good, the flavor is a light mix between maple syrup and honey. I plan to try and make some candy with the sugar that is crystallized out.

Great. Thanks for telling us about your experiment. I would love to hear what happens with the birch. I tasted birch syrup tonight for the first time. I made a tiny batch starting with just 48 Oz. of sap. I like the taste, but it would be great to see if it can be lighter.

So I had to end my experiment a little early because I got the flu and didn't have time to deal with my sap, so it fermented. I then got a bit of a scare when I looked into my concentrate (sealed inside the vacuum chamber) because it had a nasty looking layer of stuff. The inside should have been sterile because it was never opened since the last time the UV light ran. I opened it up and took a whiff and looked at the material and realized it was sugar sands. I just never noticed it before since I was always boiling it.

Since the sap was soured I decided to boil down the concentrate I already had, which was from about 10 gallons of sap total. The final result was about a quarter of quart. A dark tan color with the sugar sands still in it. The flavor is very fruity with a slight tang and none of that "molasses" robustness. Unlike traditional birch syrup I think it would go very good on pancakes or crepes, especially for anyone who likes to put fruit on top. The syrup seems like it'd be better for candy too since it tends to just harden rather than granulate like maple.

That is really interesting, thanks for all the updates. But the whole time I was reading it I was still wondering if any chickens died.

SDdave

No chicken's were harmed in the making of this syrup :)

So I've got some pics. The syrup on the left is the maple I did in the machine. 100% red maple. I'd say grade A light. The machine made the maple syrup too thick I think. This is after I strained the sugar crystals out.

The one on the right is the birch syrup. 100% black birch. I'd say grade A dark by the looks of it. I didn't let the machine "finish" it because how thick it made the maple syrup I watched it till it changed consistency. Yes there is a point when it's boiling in a vacuum that the boil suddenly changes. The transition is rapid and noticeable. The birch syrup is quite a bit thicker than the maple, mostly because of the different sugars don't crystallize out like sucrose in maple does. So I'd say the brix value on the birch is 70+ while the maple is between 66 and 68 brix most likely.

Besides trying the birch on pancakes/waffles, which I plan to do, I'm also going to make some experimental candies with it. Since the birch syrup hardens like glass and has a robust fruity grade B like flavor, it seems ideal for candy making.

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Very cool. Thank you. I look forward to hearing how it tastes on pancakes.

Interesing !!! do you have any photos of your vacuum boiling machine. :-)

I do, but I'm going to refrain from posting them on here. I'd prefer to not reveal too much about how the machine is built and operates until I have a patent.

Understandably, keep up the good work ! Will wait for the reveal ! when the patent comes in!

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Originally Posted by Ittiz

I do, but I'm going to refrain from posting them on here. I'd prefer to not reveal too much about how the machine is built and operates until I have a patent.

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Not to dissuade you, but when you submit the application, be prepared to describe in detail how your device operates and is different from other vacuum evaporation pans that are commonly used in the (primarily cane) sugar industry.

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Originally Posted by PerryW

I believe there used to be evaporators that used the heat from the steam of the primary evaporator to boil sap in another pan kept at a partial vacuum. The vacuum pans sat above the primary pans like a piggyback as I recall.

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You might be thinking of vapor-compression evaporators. Cornell (Lew Staats) operated one for many years at the Uihlein station.

Dr Perkins,

When thinking about scaling up I've thought about possibly licensing the technology to companies that build the beet/cane sugar evaporators (no way I could manufacture anything myself beyond a prototype). Although I've looked at their designs compared mine and they seem substantially different. Their machines produce a substantially different product as well. The devil may be in the details though, I haven't actually looked at the patents they hold. If it's the case they already hold patents for a similar enough design, at least I had fun designing/building the machine and accomplishing something no one else (to my knowledge) has.

I still haven't tried my birch syrup beyond a taste yet either, too busy with RL work lately. Hopefully I'll get a chance this week.

So I finally had a chance to taste the syrups on waffles and I think I need to heat them up to help the sugar sands precipitate out. The maple syrup had a mineral flavor, sort of like those vitamins your mother used to give you as a kid. The birch syrup had a fruity flavor, however the initial overwhelming flavor was metallic. The interior of the machine was plastic and enamel so I know it wasn't from that. Although the birch syrup seems more acid than maple and can probably pick up metal ions more easily.

So now the questions are how much heat and how to apply it. If you heat it with hot metal you'll caramelize the sugars on the metal. If you heat it with an intermediate liquid through a heat exchanger (double boiler), you can stay below the critical temps, but will that cause the bad tastes to precipitate out? Interesting experiment.

I'll probably do some kind of makeshift double boiler setup.

How many CFM was your vacuum? How many inches of Hg were you able to maintain during this process?