How to Use Milk Gone ‘Bad’ – Buttermilk Substitute

Has your milk gone sour? Do you need a substitute for buttermilk? These are two problems that can fix each other!

I admit it. I have let milk go ‘bad’. 

It hurts my frugal heart that I have left milk to sour in my fridge. 

Sometimes it is because I forgot about it, sometimes I knew it was there and I was going to get to it tomorrow – you know that tomorrow that never seems to come.

If you are anything like me, then you have probably had some milk go bad on you as well. And thought to yourself, ‘I wish there was some way that I could use this instead of throwing it out!’

You are in the right place if that is you!

How do I Know When to Throw Away Milk?

Before we get into sour milk, I want to discuss when I do throw milk away. I want to use the milk I paid for, but not at the expense of my families health.

I throw away milk that has obvious mold. Mold looks like pink or black spots. Mold milk gets thrown away.

Milk that has become one layer of milk solids, gets thrown out.

If I pour the soured milk out and all I see is white. When I smell it and I only smell a slightly acidic smell and if I see NO mold at all in the container, then, and only then, do I use it.

This is what has worked in my home. None of us has EVER gotten sick from the food made with this milk when I follow these rules.

If you are interested in learning more about mold and if they are dangerous, the USDA has an article on it. I have linked it here.

Why did my Milk Go Sour?

The quick answer is fermentation!

First, we have to admit that there is a current mental block about using the milk that smells sour. I grew up with my mother throwing it away. You may have too. Getting past the habit that tells you that you can’t eat it because it is not your normal is hard. It took me a while.

I use quotes around bad because the milk is not bad. We just think it is bad because we cannot drink it. It has actually begun the fermentation process where the lactic acid in the milk has acidified the environment so that none of the actually harmful bacteria can live any more.

It really is fascinating when you put it into that context! 

The milk has entered into its next stage of life, so let’s use that fermentation for good!

Can I Use Sour Milk?

I have gotten myself past the mental block that made me throw sour milk out. It took me a while, but right now I have sour milk in my freezer ready to use. I had that moment where I let the milk go sour and then I realized that I make sour milk on purpose for recipes ALL the time.

Any time that a recipe calls for buttermilk, I use a buttermilk substitute. I replace it with sour milk!

Buttermilk is just milk with more acid in it, so why not save the sour milk that happens naturally and add it to the freezer to use as a buttermilk substitute!

How to Store Sour Milk?

If I have a lot of sour milk (2 cups +), I pick a few recipes that I would use a buttermilk substitute in and I measure out the correct amount of milk for that recipe.

I pour the measured milk into mason jars and label the top with a piece of paper that tells me what is in the jar, how much is in there, and when I added it to the freezer. 

If it is a small amount of sour milk (less than 2 cups), I have to decide whether I have time to make a recipe using that amount of sour milk today or if I need to freeze it for another time.

Freezer biscuits or tortillas are my favorite way to use sour milk because they use a lot of pantry staples. I almost always have all the ingredients for tortillas and biscuits.

If I need to freeze the sour milk, then I would pour it into a measuring cup so that I know the amount I have and follow the steps above.

Sour milk is any milk that has started to curdle ( an unplanned ferment).

When it is newly sour and you pour it into a cup it will have little curds that are the size of crumbs and as it sits undisturbed in the fridge those curds grow bigger and bigger.

I usually catch my sour milk when the curds are about rice sized.

Eventually, the curds will grow together to form that slab of milk solids that I do not use.

What is Buttermilk?

Buttermilk is exactly what it sounds like. It is milk that is left over from the butter making process.

When you whip the heavy cream into butter you are left with the butter you have worked so hard to make and the buttermilk that has all the leftover milk products that are not incorporated in the butter.

Buttermilk is slightly acidic which is why it is used in baking. The acidic nature of buttermilk reacts well with the basic baking powder or baking soda, which adds nice lift to the product you are making. 

How to Make Your Own Buttermilk Substitute?

You can use sour milk that you create with milk and vinegar. Non-dairy milks will work too.

You can use milk that has soured naturally in your fridge, after you have confirmed there is no mold.

Making homemade buttermilk substitute with vinegar is easy and quick. You probably have all the ingredients you need in your home right now!

Can I Use Buttermilk Substitute in Baking?

Yes, absolutely!

Use sour milk or vinegar milk whenever a recipe calls for buttermilk.

You can add it in place of regular milk in muffins, pancakes, waffles, or quickbreads to add extra lift to them.

The acid in sour milk helps with the rise reaction with baking powder and baking soda. This is part of the reason why sourdough discard helps make these quickbreads fluffier. The discard is acidic as well. 

What Recipes do you Love that Call for Buttermilk?

Let me know what recipes you love that use buttermilk in the comments down below!

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