Lemon Juice / Vinegar - Interchangeable?

[keepitlow]

Some simple cheese recipes use lemon juice or vinegar to curdle the milk. Are they pretty interchangeable?

[Cheese Head]

Good question, they are both coagulants, beside the obvious resultant taste, I think the main question is the acidicy you are introducing, or rather will 5 ml of lemon juice have the same result as 5 ml of vinegar.

Which raises the question of how acidic is your lemon juice (ie fresh, bottled) and your vinegar (normally 5% concentration but varies around the world)?

FYI, I built an info page on acids here.

[wharris]

(puts on my cape)

This sounds like a job for a pH Meter-Man!


I'll check when i get home....

[linuxboy]

At the same concentrations in solution, it takes more acetic acid for the same volume of citric acid to coagulate milk. The pKa value of acetic acid is 4.756, and citric acid is 3.128. Keep in mind that pKa is logarithmic. Lemons and limes typically have 5-8% citric acid, and household vinegar is 5%. So as a rule of thumb, you need to use 1.5x vinegar when a recipe calls for lemon juice.

If a recipe calls for citric acid powder (such as for mozzarella), then you need to calculate the equivalent volume for a 5% solution, and multiply by about 1.5 to get the same vinegar content.

[wharris]

 I hate it when I have to look things up in order to understand it. 
http://en.wikipedia.org/wiki/PKa

Nice post.

[DeejayDebi]

Linuxboy - I love your explainations! Not just a simple Yes but why and how.
Thanks!

[wharris]

Agrees with Debi.  Linuxboy does have quality posts.