Frozen sap % question

[hansel]

What do you do when your 3/4 full buckets are frozen solid...and I mean solid. Now all the sugar is locked up in ice. I don't see how I can discard any of it now as it melts.

The sugar will be the first to melt. The first third of melting is definitely keep. Separate that out then check until the melted sap is too low of a percentage for you to bother with.

[Michael Greer]

My buckets are frozen solid today, so if I throw out the ice, the sugar content will be ZERO. Freezing the buckets under just the right conditions will indeed leave you with a higher sugar content, but it's seldom exactly the right condition.
As to freezing sap in the chest freezer....heating and cooling are the largest uses of energy in the house. Those freezers are costing you plenty...most of your electric bill I'm guessing. The cold sky of a winter's night is free.

[Cedar Eater]

So--- without taking Losses, efficiency or Energy Cost into account, We are looking at 2600 to 417 (boiling vs freezing)..

No equipment efficiency or coefficients have been taken into account here, but I expect, based on the math, that in comparing a propane propane burner to freezer... the freezer would win, hands down...

But the issue here is cost (expense), not energy efficiency. The comment that some are taking exception to is that freezing is an expensive way to concentrate the sugar. You being Canadian, you probably pay much more for electrical power than we pay here in the US. At least that's my understanding based on hearing from other Canadians when discussing electric evaporators. If we compare only electrical methods and take only concentrating into account, ROs win over freezers or boilers, but then we go into the other aspects of concentrating sugar. Without the sterilizing effect of boiling, concentrated sap will spoil more quickly and it will never caramelize into syrup.

So boiling has to happen eventually. But until it does, energy cost and, as you say "throughput", along with less concrete issues like the cost of sap storage and whether the labor of boiling is work or recreation are the factors of "expense", not energy efficiency. In other words, leaving reverse osmosis out of the picture, using heat pumping to do what you could do with evaporation is only cost effective when you impute the costs of your labor high enough and the cost of cold sap storage low enough.

Which brings us back to convenience. Is it more inconvenient (expensive in all senses) to boil with "free" wood, propane, natgas, or electricity, or is it more inconvenient to manage the storage, freezing, and concentrating of sap by pumping the heat out of it? My freezers are full of mostly venison in the Winter and Spring, so I would have to buy another freezer which will sit idle and take up space until the next sap season. That would be far more inconvenient than evaporation, especially considering how minimal evaporation labor is with electric evaporators. If someone else fills their freezers late in the year and has plenty of capacity during sap season, there are still the issues of ice management and duty cycling of their freezers (shortening their lifespan) to add into expense.

[Clinkis]

You seem to be missing the point that I've been trying to make. No one is suggesting that producers should throw away their RO's and evaporators, start buying chest freezers and trying to make finished syrup in them. I'm just saying that a small producer who wants to save some boiling time could use this as an inexpensive option. Obviously it's not practical on a large scale.

I'm pretty much out of venison now so I have lots of room in mine but luckily I have an RO. Hopefully put a couple wild turkeys in it soon.

[Cedar Eater]

But the point is that it may not be as inexpensive as you think and it won't be for those who lack the freezer space and have different priorities. The extra that they spend on electricity might mean a commitment of extra time at their day job to pay for that juice or it might mean that something else in their budget has to give. The post you took exception to said only, "Concentrating by freezing is more expensive than concentrating by boiling, but it will cut down on the evap time." To which you asked me "How do you figure?" Obviously, I can't say for certain what would happen in your case, but I can tell you how to find out. Load your freezer with sap and monitor the power consumption for however long it takes to get the sap to the right level of frozen. Calculate the cost of that extra power. Add the time cost of doing it and then compare it to the cost of boiling ordinary sap, including the time cost of boiling. Then you'll know.

Good luck in your turkey hunting.

[Clinkis]

Perhaps it best we just agree to disagree on this. I'm pretty sure we can both come up with numbers and situations to support our arguements. I strongly believe that in some situations it would make sense and be cheaper and in other situations it wouldn't.

[saphound]

The sugar will be the first to melt. The first third of melting is definitely keep. Separate that out then check until the melted sap is too low of a percentage for you to bother with.

Interesting. Is that because the sugar was the last to freeze so it would be contained in the outer couple inches of ice, and so would be the first to melt? I didn't chuck any of the ice because we have no snow and I needed it in there to keep the sap cold. Collected today, all the ice had melted and all the combined sap tested at 1.9. Was going to boil today but it was wicked windy and I boil outside and have a hard time keeping a good boil in high wind. Now this weekend is going to be cold.. lows around 10F..highs around 30F. I think I'll chuck some ice this weekend and boil on Monday.

[helptheold]

The sugar will be the first to melt. The first third of melting is definitely keep. Separate that out then check until the melted sap is too low of a percentage for you to bother with.

Interesting. Is that because the sugar was the last to freeze so it would be contained in the outer couple inches of ice, and so would be the first to melt? I didn't chuck any of the ice because we have no snow and I needed it in there to keep the sap cold. Collected today, all the ice had melted and all the combined sap tested at 1.9. Was going to boil today but it was wicked windy and I boil outside and have a hard time keeping a good boil in high wind. Now this weekend is going to be cold.. lows around 10F..highs around 30F. I think I'll chuck some ice this weekend and boil on Monday.

Very interesting. I was thinking of doing the freezer method (just a few taps) and asked my husband what he thought as he is a chemist. He said that since the sugar freezes last, it will actually be in the middle of the bucket. So his advice was to chuck the stuff that's melted first & keep the center. But what you're saying is different from that so now I'm interested to see which is correct! Gonna get a refractometer next year & turn him loose on a few buckets for experimentation. If I'm lucky I'll get him interested enough so that he'll try to build a RO for me. Sometimes he misses the lab work.

[Cedar Eater]

Very interesting. I was thinking of doing the freezer method (just a few taps) and asked my husband what he thought as he is a chemist. He said that since the sugar freezes last, it will actually be in the middle of the bucket. So his advice was to chuck the stuff that's melted first & keep the center. But what you're saying is different from that so now I'm interested to see which is correct! Gonna get a refractometer next year & turn him loose on a few buckets for experimentation. If I'm lucky I'll get him interested enough so that he'll try to build a RO for me. Sometimes he misses the lab work.

I would think that since the sugar is heavier, the water ice would normally float above it until the very last and maybe the bottom would even be unfrozen syrup. But how would you ever control what melted first?

[berkshires]

But how would you ever control what melted first?

Sugar water has a lower melting point than plain water. So the sugar water melts first.

Gabe