An aliquot jar is one of those Sourdough bread baking hacks that help sourdough beginners gauge how far along they are in their fermentation.
The gist is, you take a small chunk of your sourdough dough after you’ve built up the dough’s initial strength and put that in a small jar.
You put this aliquot jar next to your main dough so it has the same conditions as your main dough.
Since your tiny dough in your aliquot jar is an exact copy of your main dough, you look at the tiny dough in your aliquot jar to figure out if your main dough has 1.5x risen or 2x risen, etc.
Keep in mind, though, that if your kitchen has big temperature swings, the aliquot jar might not be as reliable.
Since the small dough sample can heat up or cool down faster than the main dough, it might not give you a perfect picture of the fermentation.
It’s also important to use cylindrical-shaped aliquot container —like an empty spice jar.
Another thing I want to point out is that I’ve only ever used the aliquot jar method ONCE. Once I got good at sourdough baking, there is no need for it anymore.
And like many Sourdough baking hacks, it works for some bakers, and for others it doesn’t. So take it with a grain of salt.