How To Collect Whey for Lacto Fermentation

How To Collect Whey for Lacto-Fermentation from

When people first start learning how to ferment foods, invariably one of their first questions is “Where do I find whey? I don’t see it in the supermarket.”

To answer this question, I’d like to make a couple of points:

It is possible to ferment foods without whey, so if you are severely intolerant to milk, you can still ferment foods using sea salt. So, finding whey is not always necessary. Whey is not usually sold in the supermarket as a product labeled “whey”. It’s usually called “yogurt”.

Wait, what? Whey is just yogurt? Pretty much!

Yogurt contains two parts – the solid and the liquid. Have you ever left a container of yogurt in the refrigerator for a few days, and when you take the lid off, there is a layer of liquid at the top? That liquid is whey.

So all we really need to do is separate the whey from the rest and we’ve already conquered the first step to fermenting.

To separate the whey, the first thing we need to do is buy yogurt. (If you’ve already made yogurt, of course you can use that instead. I’m going under the assumption that you’ve never fermented before and have nothing to start with.) You’ll want a pretty good quality, plain yogurt. When I need a starter culture, I buy a locally made, grass-fed, cream-top yogurt that works really well. If you don’t have something like this, then try searching for a plain, organic yogurt.

Next, we need to strain the yogurt.

I have heard of people using strainer bags to drip their yogurt. They look something like this:

and the basic idea is that you pour all the yogurt into the bag and hang it above a container so that the whey will drip out of the bag and into the container below. That said, since I was too excited to learn how to ferment things, I didn’t have the time to order a muslin bag. Instead, I came up with my own system:

How To Collect Whey for Lacto-Fermentation from

What I lack in patience, I make up for in creativity!

Above is the whey-straining-system I concocted. I put a hand strainer (note: use nylon mesh instead of metal) over a pyrex measuring cup. I then lined the strainer with one sheet of paper towel. While the strainer does have very small holes, the paper towels helps it strain even finer so large chunks of yogurt can’t slip through when you aren’t paying attention. Then I dumped the 16oz container of yogurt into the strainer and let it sit for about an hour. When you come back to it, you’ll have lots of slightly golden whey just waiting for you in the bottom container. It should look roughly similar to this:

How to Collect Whey for Lacto-Fermentation from

Now that you have your whey collected, you can use it to start fermenting foods, or store it in the refrigerator for when it’s needed. I used the 0.5 liter jar from Bormioli Rocco to store my whey.


    • I haven’t tried it, but it would be a different type of fermentation. Whey is a lacto fermentation – meaning a bacterial culture of the lactobacillus bacteria. Kombucha is a mix of both bacteria and yeasts. Yeast fermentation usually produces alcohol, and to my knowledge, is used to produce rice wine. Therefore, based on my current knowledge, I wouldn’t ferment rice with kombucha and would instead stick to a bacterial culture.


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