Agitating sap

[johnallin]

Pretty quiet around here lately...I've been reading but not much posting.
I did come across an interesting article in Maple News though about a project CDL and a Vermont producer have been working on where they're re-circulating and "agitating" sap. If i read it correctly, air is introduced and it looks like it either releases bad bacteria or introduces good...(all that is above my pay scale though)

So; in an effort to increase ratings - and have something to read at the end of the day - I thought I'd start a thread.

Anyone else try this? It seems like a simple enough process. I installed an H20 Innovation air injection/bubbler system last season in flue and syrup pans with good results and this has me thinking.

[fred]

Speaking of agitating....

Several producers have done this for the last 2 years. At this point they have almost figured out what works and what doesnt. At this years annual meeting cdl dealers had enough feed back through experiments with their set ups to create a commercial outfit to make it work well. They turned sour and buddy sap into a usable finished product. This will nearly eliminate the junk market when used properly

[johnallin]

Speaking of agitating....

Several producers have done this for the last 2 years. At this point they have almost figured out what works and what doesnt. At this years annual meeting cdl dealers had enough feed back through experiments with their set ups to create a commercial outfit to make it work well. They turned sour and buddy sap into a usable finished product. This will nearly eliminate the junk market when used properly

Nothing's more fun than agitating. Did I ever tell you how good my Leader Clear Press works??

Here's the link to one of the Maple News articles:
https://www.themaplenews.com/story/get-it-bubbling/258/

[DrTimPerkins]

This process (adding air to sap) works by reducing some of the off-flavor precursors and by allowing for the development of more strong flavors (by having more time elapse and/or by diluting and reboiling, similar to the metabolism off-flavor removal process). In the case of the VT sugarmaker (Bob White), they are very interested in developing a certain good flavor. In the case of the Cornell work and much of the work in Quebec, they are more interested in reducing/removing buddy (or sour) off-flavor. In both cases, there is a great deal more to learn, but progress is being made.

[johnallin]

I may pipe my air injection system into my sap tank.
I’d think a few minutes of that should add lots of oxygen.
It’s charcoal filtered air, so should not introduce any off flavor.

[minehart gap]

If I am recalling what I have read correctly, if you introduce air into the sap while the sap is cooking it may and usually does lighten the color and subsequent taste of the finished syrup but if you are to introduce that same air into the sap before it is processed it will both darken and embolden the flavor of the finished syrup.

So does that mean that at the end of the season one could in theory introduce air for the purpose of reducing off flavor and inadvertently darken the finished product but introduce air in the evaporator while cooking the sap and lighten it back with a more delicate flavor?

[johnallin]

Matt
I got the same impression. We definitely made lighter syrup this year with air injection but I think our taste wasn’t the same. It would seem that one may cancel the other?

[minehart gap]

John, would you mind further explaining the taste comment. I was under the impression that the taste was the same taste that you would expect from the color of the syrup that was created.

I am considering building and installing one (in the evaporator) for next spring but don't like the idea of changes to the taste.

[Super Sapper]

One thing to watch would be increasing the temperature of your sap. The temperature of compressed air is usually increased going through the air compressor. This could be why it darkens the syrup.

[JoeJ]

I was at Bob White's sugar house on the Vermont Maplerama tour where he was demonstrating him sap agitating system. He was using a SS Goulds water pump to recirculate the water (sap) through 2" PVC pipe with a series of 1/8 holes drilled in it. If I recall it correctly, I think that Bob talked about recirculating the sap for 12 hours. What I do remember is that he said DO NOT USE A COMPRESSOR WITH ANY OIL IN IT.

Joe

[johnallin]

John, would you mind further explaining the taste comment. I was under the impression that the taste was the same taste that you would expect from the color of the syrup that was created.

I am considering building and installing one (in the evaporator) for next spring but don't like the idea of changes to the taste.

To me, it seemed that our syrup taste this year was not as maple as in past years. Could be the lighter color (and flavor?) due to air injection, or any number of things.

[johnallin]

One thing to watch would be increasing the temperature of your sap. The temperature of compressed air is usually increased going through the air compressor. This could be why it darkens the syrup.

The H20 Air injection does not use an air compressor, rather a high volume air blower drawing through 3 charcoal filters. Sounds like a 747 Jet engine...

[DrTimPerkins]

One thing to watch would be increasing the temperature of your sap. The temperature of compressed air is usually increased going through the air compressor. This could be why it darkens the syrup.

None of this is terribly surprising. Length of time, temperature, number and type of microbes, and aeration will all influence (hasten) many of the biological factors and chemical reactions resulting in more color/flavor development, and in some cases, reduce the level of precursors of off-flavor. The difference is that (some) people are now looking to go towards darker/stronger syrup, whereas most of the efforts maple producers have taken over the past 100 yrs has been aimed at going the other way (towards making lighter syrup).

[DrTimPerkins]

If I am recalling what I have read correctly, if you introduce air into the sap while the sap is cooking it may and usually does lighten the color and subsequent taste of the finished syrup but if you are to introduce that same air into the sap before it is processed it will both darken and embolden the flavor of the finished syrup.

Air injection into pans produces light syrup. Air injection into sap produces darker syrup. A little paradoxical isn't it. ;^)


So does that mean that at the end of the season one could in theory introduce air for the purpose of reducing off flavor and inadvertently darken the finished product but introduce air in the evaporator while cooking the sap and lighten it back with a more delicate flavor?

You might think so, but no. The reaction with air injection IN THE PANS is not a bleaching effect, but rather is a prevention or reduction of of color/flavor formation effect (I won't get into the chemical reasons, but it is largely due to a reduction in temperature resulting in a reduction in caramelization of invert).

The air injection INTO SAP effect is different. In this case you are:
1. volatilizing (reducing) off-flavor precursor compounds in the sap that result in poor flavor
2. enhancing formation of invert (higher temperature, more oxygen, longer time period) which increases color/flavor formation.
3. altering the biome of microbes in the sap.
4. increase the rate of biological and chemical reactions in sap leading to color/flavor development.

All of these factors INCREASE color/flavor development (and can, perhaps, decrease some off-flavor precursors), thus darker syrup is formed upon boiling. Essentially you are controlling the fermentation level in the sap. The danger is the possibility of turning your sap/syrup ropey.

Now if you used air injection in your pans to process aerated sap, you'd make lighter syrup, but it wouldn't be quite as light as if you had not aerated the sap. It would certainly be possible to vary the amount of air injection in the pans to be able to produce somewhat lighter or darker syrup according to your wishes (dial-a-grade syrup).

[Meuphrat]

Sap aeration and it’s effects on flavor and grade are very intriguing.
Been hearing a bit about it but if anyone has recommended ways to best set it up (hopefully without breaking the bank) I’d be interested. Or articles or other threads...

Dr. Tim could you elaborate a bit on the danger of going ropey due to aeration? The factors at play and what to watch our for?

Thanks so much!

Mike
The Bunker Farm
Dummerston VT

[DrTimPerkins]

There simply is not sufficient research on the subject to give good answers. Aeration of sap MIGHT help in some ways by reducing microbial growth (or at least the bad microbes) and promote the development of stronger flavors (darker syrup) as well as help reduce volatile precursors of some off-flavors (metabolism and/or buddy perhaps), but it is still far from being a tried and true method. Too many variables and uncertainties to give recommendations at this time. As far as ropey sap goes...microbes + time + temperature result in spoilage. If the improper microbes are around...it'll eventually go ropey. Aeration might delay it a bit (maybe).

[sapper117]

We have been experimenting with Sap aeration this year. On the positive side: The passive evaporation loss (1-2%) is nice and the ability to keep the sap from freezing at night was very helpful. On the negative side once temps warmed up we got lots of scum/bubbles as the bacteria went into overdrive, especially in the RO concentrated sap. Side by side taste tests of both cold/warm aerated syrup to the non-aerated control syrups we had trouble distinguishing them apart. Since we boil outside all our syrup tends to be darker/more robust, so we couldn't really tell a difference but we are also not experts.

I do think there are some potential benefits to aeration from the evaporation and the freeze prevention, but is is also another 110v device running overnight..

I would love to see a more detailed control study of sap aeration benefits besides just late season sap salvaging.

J

[L&msugarbush]

This is very interesting! From reading this article it reminds me of a large producer in Canada whom does the opposite! By filling their sap storage tanks from the bottom of the tank, they create an environment where they create less aeration/Via bacterial growth… So if anybody’s doing this aeration of sap,(and I understand why you would want to do it!) has anybody tried using a protein skimmer in their sap tank… Similar to what you would use in a saltwater fish tank to Skim off the bacteria, Or is there a different method(perhaps charcoal filter?) Or does it not need to be done at all?

[82cabby]

has anybody tried using a protein skimmer in their sap tank… Similar to what you would use in a saltwater fish tank to Skim off the bacteria?

Interesting idea.

Just to save people from googling it, as I remember a protein skimmer essentially is a column full of water from the tank. A pump generates bubbles in the water. The bubbles create a foam which consists largely of proteins (wastes). This foam builds up and spills over into a container which is then cleaned out. The purified water returns to the tank.