Formulating a recipe with birch sap

Question

Formulating a recipe with birch sap

Dale

2019年10月13日 12:33

Background

Based on my searching here and elsewhere, brewing with birch sap is quite uncommon with brewers (although I did find one brewer that mentioned brewing with maple sap). So I'd like to get a list of things to think about as I develop a beer recipe based on birch sap. Brewing with sap is different than using syrup because knowing the flavor of the sap once concentrated is unknown in the case of using sap.

Specific Gravity / Flavor Concentration

From what I have been able to ascertain so far, the sap, right out of the tree is in the 1.004 to 1.007 range. One approach would be to heat the sap and use it as my mash and sparge water. In that case, there may be very little birch flavor in the final product. On the other end of the spectrum would be to gently evaporate¹ the sap until the specific gravity gets to a place that would make a beer on it's own, without grain. That would yield the strongest birch flavor, but might be "too much".

Flavors

I have tasted birch sap out of the tree², and it's almost like pure water, but I don't know how the flavor would change if the sap was concentrated by evaporation. Based on what that taste would be, then hops could be selected that would mesh appropriately.

Fermentability

If the out-of-the-tree specific gravity is, say, 1.005, is there any way to tell how much of that will be fermentable sugars, and what will be left as residual sweetness? Or even how much of that gravity is caused by dissolved sugars versus something else (minerals?).

Recipe Guidelines

Are there any rules of thumb for birch sap based beer recipes? Or rules of thumb from maple sap based beer recipes? What techniques could be employed to select a reasonable starting point for the brewing of a birch sap beer?

Footnotes:

_{1. Boiling apparently causes a poor shift in flavor towards "burnt"}

_{2. I cut a branch off of a river birch tree in my yard last spring and the sap dripped for weeks. I had to taste it.}

Topic adjunct specific-gravity recipe-formulation ingredients homebrew

Category Mac

tempest_col · Accepted Answer · 2019年4月9日 00:19

Last spring, I brewed an extract recipe (Belgian-style golden strong ale) using birch sap instead of water. The recipe called for cane sugar, which I decreased by my estimate of the sugar content of the sap (don't know if I actually needed to do this, but it felt scientific).

The beer turned out fantastic, my favorite so far that I've made. To be fair, there's probably no discernible difference, as @match postulates, and that it's all in my head. But it made for a cool provenance when sharing it: "See that tree over there?"

Note: I seem to remember hitting the recipe FG, suggesting that the majority of the dissolved matter in the sap was fermentable.

match · Accepted Answer · 2018年1月13日 21:57

I've made birch sap wine before now and there was no real discernable difference between that and sugar-water wine.

I have read that to make birch syrup you need to reduce 100:1. 1.005 in sugar solution equates to 13g sugar/L, so it seems plausible that the majority of the dissolved contents are sugars (and salts, minerals etc).

To be honest I think birch sap in beer and wine (when not concentrated) will serve mostly as an interesting talking point, and possibly add slight nutritional benefit to the yeasts (and maybe the drinker?). For flavouring I think you'd need to do a reduction first to a full or partial syrup to have an effect on flavour. What exactly the flavour of birch sap would be, when compared to maple syrup, I don't know - though birches are quite high in tar and turpentine-like oils in the bark, so there's a chance the flavour might be more bitter, chemically or smokey than maple.

Formulating a recipe with birch sap

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