Foaming like crazy

[Swingpure]

In a nutshell:

"Foam" refers to two things:

1 - There is a type of foam formed of big light bubbles that form and pop quickly. It forms all the time, but some sap does this more than others - it may depend on the tree and or the time of the season. The main downside of this foam is that it leaves residue on the side of your pan, which (especially if you have high heat on the sides of your pan) can scorch a little. This is not a very big deal, but can lead to off-flavors in your syrup - mostly a burnt-caramel type flavor. And it's typically very subtle. The solution to this can involve scooping foam if you like, but I always ignored it. The thing is, if you don't have heat on the sides of your pan it won't scorch, so it's just not an issue. I guess if you have a super-hard boil you could get enough of this type of foam that it could cause some of the foam to boil over the sides, which would not be good.

2 - The second type of foam does not happen all the time. It only happens when sap gets close to syrup. Then the consistency changes. It gets much thicker, and when it boils, you get lots of small bubbles that don't pop as quickly, but instead tend to build up. Think of a liquid flowing sponge. I know you recently made maple candy, so you may have noticed that if it boils hard it will boil over. On the stove you can just turn the heat down, but on the evaporator, not only you can't you, but you don't want to. Instead if you add defoamer it can make the bubbles pop faster. So what is the risk of this kind of foam?

The risk is huge. First of all, this foam is progressive. The foam is an insulator. The more it foams up, the less heat gets released, causing even more of the syrup to foam. So bad goes to worse very fast. Second of all, down at the level of the pan, once the foam gets past a certain point, there's nothing but foam touching the surface of the pan. Foam is not a good heat conductor, so your pan can quickly go from 219 to 800 degrees. You now have horribly scorched sugar on your pan, and these temperatures will permanently warp your pan.

In addition to destroying your pan, you can also have all your syrup destroyed by having all that horribly burnt sugar (and nitre) in it. If that's not bad enough, your syrup can also boil over, making a big sticky mess, and even catching on fire.

The key thing about foam type 2 is that it typically only happens as your sap gets to high sugar percentage. So if you only go to 30 - 40% sugar on your evaporator, and then finish elsewhere, you may not need to worry too much about it. On my old setup, I didn't use a drop of defoamer for 5 years.

Hope that helps,

Gabe

Very informative and detailed and will likely will save me from some disasters. I very much appreciate it and understand what you are saying.

One question, to determine if you are 30 - 40% sugar, do you use a refractometer, or a hydrometer, or is there a simpler way of telling? I likely would have got it to about 60 on the Brix scale before taking it off the evaporator.

[berkshires]

Very informative and detailed and will likely will save me from some disasters. I very much appreciate it and understand what you are saying.

One question, to determine if you are 30 - 40% sugar, do you use a refractometer, or a hydrometer, or is there a simpler way of telling? I likely would have got it to about 60 on the Brix scale before taking it off the evaporator.

I never bothered to test on the evaporator, I just boiled until I had cooked it down enough to bring it home. But you can get in the ballpark with just a good a digital thermometer.

GO

[Swingpure]

I never bothered to test on the evaporator, I just boiled until I had cooked it down enough to bring it home. But you can get in the ballpark with just a good a digital thermometer.

GO

So, let’s say the boiling point of sap on that day is 217.5° F. Would you remove it if it was let’s say 215°?

[Swingpure]

I know you recently made maple candy, so you may have noticed that if it boils hard it will boil over. On the stove you can just turn the heat down, but on the evaporator, not only you can't you, but you don't want to. Instead if you add defoamer it can make the bubbles pop faster.

I meant to mention this when first responded to your post. While making the maple candy it try to boil over on a few occasions, and I did have to lift the pot to stop it. Eventually it stopped trying to do that.

Your example really helps me understand the two types of foam and when I should add the drop of canola oil.

Just out of interest, is there something unique about canola oil, or could one use corn oil or avocado oil?

[ecp]

Swingpure

The only real unique thing about canola oil is that it is not a large allergen and works alright. Synthetic defoamers work way better, but you can not be organically certified if you use them because they are an additive to the syrup. Any fat will kill the foam but may add flavor to the syrup. Old timers used butter, milk, cream salted port fat, bacon, and I'm sure other things were used these just what I know of in my region. I can say I've never heard of using corn or avocado oil, but they certainly have the possibility of working and may add an off flavor to your finished syrup.

Have fun with it.

[berkshires]

So, let’s say the boiling point of sap on that day is 217.5° F. Would you remove it if it was let’s say 215°?

Sorry, I don't understand your question. If you're aiming for some specific gravity then use whatever you would normally use to test it. If you want ballpark, then look up the boiling temperature of the sugar you are aiming for and take it off when it gets there.

Me, I always just boiled until I had reduced it enough to be able to bring it home, and if the syrup pan started to foam up I would add more from the next pan down. Or I might scoop off some nearup first and then add more of the next lightest sap.

Keep in mind that I'm tailoring what I'm discussing to stream tray pans (what I used to use, and what you plan to use). When you work with stream tray pans and are not drawing off syrup the procedures are a bit different. So some of the things people are discussing here may not be appropriate to your situation.

Gabe

[berkshires]

I meant to mention this when first responded to your post. While making the maple candy it try to boil over on a few occasions, and I did have to lift the pot to stop it. Eventually it stopped trying to do that.

Your example really helps me understand the two types of foam and when I should add the drop of canola oil.

Just out of interest, is there something unique about canola oil, or could one use corn oil or avocado oil?

When I make confections I usually put a little vegetable oil on a paper towel and then run it around the inner surface of the pot. It's a tiny amount but it does the trick.