balancing acid in fruit beer

[GeneDaniels1963]

I am wanting to make a dark beer with DME, and add some blackberry juice after the main fermentation is done. I am thinking 2 lb per gal. But it always seems that enough berry for a strong taste make the final result a bit more acidic than I care for.

So, I am wondering if a way to combat this is by adding some crystal malt as a steeping grain. Will the residual sugars offset the berry acid? I am thinking about 8oz of 60L crystal for one gal of wort.

Any thoughts?

 

[mabrungard]

The acidity due to tart fruit juices can be neutralized by adding a basic buffer like chalk. While chalk is properly dismissed as a water additive due to its slow solution, the stronger acids in the fruit juice and the beer should be capable to dissolving the chalk and neutralizing the acidity. There should be some slight fizzing or bubbling as the reaction occurs.

Measuring the titratable acidity and calculating the chalk addition is one way to figure out how much chalk to add. But just adding a known mass of chalk to a known volume of beer and tasting the result could be simpler. Do avoid over-dosing with chalk since that can leave your beer tasting dull...and possibly 'chalky'.

 

[RPh_Guy]

Wouldn't potassium carbonate be a better option, since it's faster at precipitating acids and doesn't leave a chalky taste?

 

[mabrungard]

I’m less enamored with potassium than sodium. I’m less concerned with chalk than sodium bicarbonate or potassium carbonate.

 

[RPh_Guy]

I'm just wondering why you'd prefer calcium carbonate over potassium carbonate.

Potassium carbonate is widely preferred in winemaking because it's faster and has less risk of off-flavor. I can list references.

 

[mabrungard]

You have a good point, but that is for wine and this is beer. However, a fruit beer probably is more similar to wine than many beers. You could be right. I am just not a fan of adding potassium ion.

 

[RPh_Guy]

The potassium binds to the acid, forming an insoluble salt, causing it to precipitate out of solution. Therefore if you dose the K2CO3 correctly based on the TA, the amount of potassium ion left after reacting with the acid would likely be negligible.

At least that's what happens in wine. I don't see why it would be any different for beer.

 

[Jag75]

@RPh_Guy - just curious but are you a chemist or something in that field? If I'm being rude tell me to kick rocks lol.

 

[RPh_Guy]

@RPh_Guy - just curious but are you a chemist or something in that field?

Pharmacist (Doctor of Pharmacy). I have lots of training in chemistry and microbiology -- very handy when learning about the science behind making wine and beer.

 

[Jag75]

Pharmacist (Doctor of Pharmacy). I have lots of training in chemistry and microbiology -- very handy when learning about the science behind making wine and beer.

That's what I figured ty sir

 

[GeneDaniels1963]

The potassium binds to the acid, forming an insoluble salt, causing it to precipitate out of solution. Therefore if you dose the K2CO3 correctly based on the TA, the amount of potassium ion left after reacting with the acid would likely be negligible.

At least that's what happens in wine. I don't see why it would be any different for beer.

Can I use potassium carbonate without testing for TA?

 

[RPh_Guy]

Can I use potassium carbonate without testing for TA?

Sure.

However, I would try to calculate it based on the average TA for whatever fruit and whatever quantity you used.

 

[JimRausch]

I do a series of 'fruit moons' each year. Base is Wayne/Nilo's Blue Moon American wheat from elsewhere in the forum. I split the batches and add blueberries, raspberries, cranberries, or apricots. Tried grapefruit juice twice- not a fan. But when the fruit ferments completely leaving a dry. tart beer with little fruit character, I counteract it by backsweetening with a little xylitol at bottling time. 1/2 cup per 3 gallons seems to work best for me. A lot of what we perceive as 'fruit' is sugar sweetness, so adding back a little helps bring out the flavor.

 

[mabrungard]

Well, I see that you’re right about a precipitate in wine. But unless a fruit beer has significant tartaric and/or malic acids, that reaction won’t occur. So the benefits of this base are lost in beer.

 

[RPh_Guy]

... unless a fruit beer has significant tartaric and/or malic acids, that reaction won’t occur. So the benefits of this base are lost in beer.

I agree 100%. Changing the pH alone will not alter the sour taste.

However, I think his fruit beer does have significant amount of malic acid that can be reduced with this method.
The primary organic acid in blackberries in malic acid, which is presumably causing the tartness that he wants to reduce.

I'm inclined to believe that the malate would still bind with potassium in beer, just as it would in wine, and thus be removed through precipitation. I don't see why any of the chemistry would be different.

Reference for organic acids in blackberries:
https://www.sciencedirect.com/science/article/pii/S030881460500796X