Acid adjustment

[Zog]

I have 3 gallons of pear juice with a pH of 4.1. I'd like the pH to be about 3.4.

How do I calculate how much acid blend to add?

I've read that 3 to 4 grams per gallon yields a 0.1 change, but I'm not clear if this change is referring to pH or TA.

 

[lawrstin]

Can you share your recipe? Add 1g/L of wine to reduce pH by .1 unit. Trial and error is required when making adjustments because the ratio of acids in the blends is not usually known. Go slow.

 

[Snafflebit]

One gram of tartaric acid in one liter will raise the TA up 1 g/L. So, I think the 0.1 change is referring to lowering pH.

The rule of thumb I have seen before:
1 g of tartaric acid in 1 L will reduce pH by 0.1
3.7 L is about 1 gallon
Therefore 3 to 4 grams per gallon yields a 0.1 drop of pH.

However Zog you are trying to make a drastic change in the pH. It would be good to see your recipe. Adjusting to that pH level could make your wine technically correct but not tasty.

Adjusting TA is straightforward, more acid equals higher TA. Adjusting pH is tricky due to the buffer systems in juice and the large change from 4.1pH to 3.4pH.

Taste the juice as you increase acid. You could adjust half the sample and get it right, then add it back to the whole batch and finally add again that same amount of acid. It is better to do this than mess up all your juice.

 

[Stressbaby]

pH is not linear, it's logarithmic. There is really no formula. There are also buffering differences, I believe, that affect the pH depending on the type of wine.

I just took a look at my notes on some 3 gallon batches and this might put you in the ballpark...
1t acid blend dropped hibiscus 3.54 to 3.39
3t acid blend dropped plumeria 3.38 to 3.21
7.5t acid blend dropped lavender 4.01 to 3.41
16g acid blend dropped dandelion 4.01 to 3.69

Maybe start with 1T then go 1t at a time until in the right range. It's way easier with a pH probe.