Kettle Sour- Taste more or less sour after fermentation?

[TNJake]

I'm currently making my first kettle sour beer that will have a raspberry fruit addition after primary fermentation. I've been tasting samples periodically while its been souring but I'm wondering how this will compare after the yeast remove the sweetness and turn it into wonderful alcohol.
I will also be adding Vinter’s Harvest raspberry puree which will add some simple sugars, tartness, and fruit flavor.

Ethanol is slightly alkaline so that may increase the PH a bit but carbonic acid from carbonation is of course acidic. There are things altering the PH up and down but right now what I'm more interested in is the taste and how it will be impacted without the sugar to make it into a sweet tart liquid.

So am I right in thinking that this is going to taste more sour after fermentation?

 

[deadwolfbones]

It will definitely taste more sour after fermentation (not after the boil, as your title states).

 

[TNJake]

It will definitely taste more sour after fermentation (not after the boil, as your title states).

ha, I definitely was not thinking when I wrote in the title. --- fixed---

Ok follow up question, is it safe to assume it will ultimately be more sour after the fruit addition as well?

Of course its added sugar but that should be consumed leaving behind the tartness of the raspberries.

 

[RPh_Guy]

Ethanol is slightly alkaline so that may increase the PH a bit but carbonic acid from carbonation is of course acidic. There are things altering the PH up and down

We don't taste pH. We taste acids.

The raspberries may or may not increase the sour taste. Fruit acid content varies considerably.

 

[deadwolfbones]

In my experience berries like raspberries and blackberries do boost sourness, but as @RPh_Guy said it depends on the specific berries.

 

[TNJake]

Another question with this beer but outside of my original question: how about calculating ABV after a secondary addition like this raspberry puree?
My first though was the delta SG in primary is used to calculate ABV of course (X), then the increase in SG after sugars added starts a secondary SG then use the final SG to have your secondary delta to calculate ABV gain 2 (Y). X+Y =total ABV.
I'm not sure this is correct though with the gain in sugar at secondary.

Anyone know this information?

 

[SanPancho]

Fruit is all simple sugars, the assumption is that it all ferments out. Calculate the brix or gravity added by the fruit, add to your OG and then calculate for ABV via FG. I think this is what you’re planning. The hardest part is figuring your new volume. Sugar dissolves, but fruit doesn’t. Depending on how much you add it can be negligible or it can be sizable.

 

[Electricbrew]

*EDIT - I realize now that I may have misunderstood, if you are saying let the beer reach final gravity, then add fruit and take new gravity of total volume, then you should be fine just adding that gravity to OG. You would just have to make sure the fruit is mixed well into solution or it will give a wrong gravity (so doing it the below way may be more accurate) but I’ll leave the information below as it may be helpful for others*

Unfortunately you can’t just calculate the gravity of the fruit and add it to the OG, that’s going to give a higher abv than is correct (unless your fruit adds no additional liquid to the fermenter) In fact, if the sugars in the volume of fruit liquid are lower than your OG, your final ABV will actually drop as a result of adding fruit. You need to calculate it as a percentage of total volume; something like this:

New OG = (OG*A)+(FruitOG*B)
Where
OG =original gravity
A= % volume of original wort
FruitOG= gravity of fruit addition
B = % volume of liquid added by fruit

This won’t be 100% accurate, but is close enough for a homebrew level. I calculate the gravity of the fruit by taking a sample before I add it to the fermenter, but there are also calculators online I believe to give an estamate.

For example (because I know I’m bad at explaining)

If your OG is 1.055, 5 gallons
And you add 1/2 gallon of fruit juice at 1.045:
Take .5/5.5 = 0.09
5/5.5 = 0.91
So, (.055*.91)+(.045*.09) = (.05)+(.004) = new OG of 1.054

Use this number in conjunction with you FG post fruit addition to calculate ABV

At least this is how I’ve been doing it, someone please step in and correct if I’ve been doing it wrong

 

[TNJake]

*EDIT - I realize now that I may have misunderstood, if you are saying let the beer reach final gravity, then add fruit and take new gravity of total volume, then you should be fine just adding that gravity to OG. You would just have to make sure the fruit is mixed well into solution or it will give a wrong gravity (so doing it the below way may be more accurate) but I’ll leave the information below as it may be helpful for others*

Unfortunately you can’t just calculate the gravity of the fruit and add it to the OG, that’s going to give a higher abv than is correct (unless your fruit adds no additional liquid to the fermenter) In fact, if the sugars in the volume of fruit liquid are lower than your OG, your final ABV will actually drop as a result of adding fruit. You need to calculate it as a percentage of total volume; something like this:

New OG = (OG*A)+(FruitOG*B)
Where
OG =original gravity
A= % volume of original wort
FruitOG= gravity of fruit addition
B = % volume of liquid added by fruit

This won’t be 100% accurate, but is close enough for a homebrew level. I calculate the gravity of the fruit by taking a sample before I add it to the fermenter, but there are also calculators online I believe to give an estamate.

For example (because I know I’m bad at explaining)

If your OG is 1.055, 5 gallons
And you add 1/2 gallon of fruit juice at 1.045:
Take .5/5.5 = 0.09
5/5.5 = 0.91
So, (.055*.91)+(.045*.09) = (.05)+(.004) = new OG of 1.054

Use this number in conjunction with you FG post fruit addition to calculate ABV

At least this is how I’ve been doing it, someone please step in and correct if I’ve been doing it wrong

I was planning on bringing down to final gravity, mixing well, then checking gravity again to get a +delta gravity and adding the new drop down to FG.
I see the issue with trying to mix to solution so I'll probably go with a volumetric calculation method as you suggested.

Is there any reason a refractometer wouldn't work for pre-fermented fruit puree?
I've never used it on anything viscous or chunky.

 

[isomerization]

Fruit is all simple sugars, the assumption is that it all ferments out. Calculate the brix or gravity added by the fruit, add to your OG and then calculate for ABV via FG. I think this is what you’re planning. The hardest part is figuring your new volume. Sugar dissolves, but fruit doesn’t. Depending on how much you add it can be negligible or it can be sizable.

Fruit doesn’t dissolve, but the significant water content will. Sugar additions are almost always going to decrease the abv, with the exception of sweet cherries (in my experience at least).

 

[Electricbrew]

I personally have never used a refractometer, so maybe someone else will chime in, but when I’ve used my hydrometer for viscous liquids I’ve just diluted it evenly in my graduated cylinder and then adjusted the gravity (so if I mixed 50/50 fruit/water I would take the gravity and multiply by 2 to get what the fruit purée is). Not sure if that’s accurate / correct or not or if it would work for chunky fruit (I’ve usually added juice / fine purée using this method) but sometimes you gotta do what you gotta do

 

[SanPancho]

Yes, @isomerization makes a good point- the water in the fruit is also something to consider. More of a concern with whole fruit vs puree tho.

Whole fruit theres no real way to get a sugar level without doing like @Electricbrew describes, but you gotta puree the fruit first to measure it. Packaged puree is so much easier.

If you buy puree you just do the calcs based of the fda label. (Or at least i do) Grams of sugar times servings divided by total packaged volume. Then convert brix to gravity.

 

[TNJake]

If you buy puree you just do the calcs based of the fda label. (Or at least i do) Grams of sugar times servings divided by total packaged volume. Then convert brix to gravity.

I have not checked the packaging yet but I'm sure that this can be done in my current brew. I will be using Vintner's Harvest Raspberry.

 

[TNJake]

So if this ends up being too sour would adding some malto be reasonable at all?

I am considering brewing a non-sour batch and blending them too, that's just more work and I already have some other beers planned. IF this is the best course of action, would another or larger raspberry addition likely be needed?