How to Make Homemade Yogurt

Why you'll love it

Knowing how to make a lot of your kitchen staples can be a very useful skill to know, especially if you are working on a budget. It is also great if you love trying out new things, want a fun weekend project, or like being able to know exactly what is in your food. For me, one of the most compelling reasons if just how satisfying it is knowing you were able to make your own homemade yogurt just like making your own brioche or ciabatta at home. it can give you a serious sense of accomplishment. 

You also never have to worry about the grocery store running out of your favorite yogurt flavor. If you save a bit of your homemade yogurt before adding in your favorite flavors, you can reuse it to make more when you are running low.

If you want to make your own yogurt, you have a few different options. You can use a yogurt maker and yogurt culture, or you can use your favorite plain commercial yogurt with milk and the tools you have at home. This homemade yogurt recipe uses the latter. We use starter yogurt from the stores and no special equipment. There are even instructions on how to make the perfect yogurt without a kitchen thermometer and using your five senses instead. 

Ingredient overview

This particular recipe only requires two ingredients, but for the sake of giving full knowledge and understanding, I will also review yogurt culture and how that works if you wanted to try using that method down the line. 

• Plain yogurt - Using regular yogurt is one of the easiest and most accessible way to make yogurt at home. The kind of yogurt you use will determine what the final product you end up with will be like. I recommend using a brand you like. Please remember it has to be plain with no added sugars or flavorings. 
• Milk - The kind of milk you use will have a major impact to the final flavor and texture of your yogurt. The higher percentage of fat used, the thicker the milk will be. I recommend whole milk or 2% milk. Non-dairy alternatives do not work very well in this particular recipe and you will need to add other ingredients to thicken the yogurt. 
• Yogurt cultures - You can buy yogurt starters/cultures to make your own yogurt. They are typically freeze-dried in powder form. Usually, they are only found online, but you can find a wider variety of cultures you may want in your yogurt that aren't in the yogurts in grocery stores. 

Optional tools

To make homemade yogurt, you will need a starter. You can buy freeze-dried starter cultures, but store-bought yogurt works too, and is what I use in this recipe. If you use store-bought yogurt, you have to use plain yogurt - the more culture varieties, the better it is for you. If you want flavored yogurt, you can add your flavorings after the yogurt is finished. You also need to use a heavy bottomed pot that can retain heat well and a way to keep the pot warm. You can either keep the pot in the oven with the light turned on, or wrapped in a towel. My oven light gets the over really warm, so I wrap my pot in a towel and leave the oven light on for only an hour or so before turning it off. I also recommend an instant read thermometer to keep track of the temperature of your milk, especially if you are using the stovetop method. 

How to make: 3 methods

The original recipe for making homemade yogurt uses no special equipment, with notes on how to use minimal tools that will help you. I have also included instructions for using a slow cooker or a pressure cooker if you would like to try experimenting with one of these methods - luckily the same basic process is used with each method. The method I use and prefer is the stovetop method. 

How to make yogurt on the stovetop

1. Add the milk to a heavy-bottomed pot and heat until the milk is scalding hot and steaming. It should be rumbling, but not at the boiling stage. Scrape the sides and bottom of the pot constantly to avoid the milk burning. 
2. Allow the milk to cool until it is comfortable to the touch - about 110F. Take a cup of the warm milk and mix it in with the yogurt, then stir the yogurt and milk mixture back into the rest of the milk. 
3. Cover the pot and keep in a warm, dry area for at least 6 hours, preferably overnight. 

How to Make Yogurt in a Crockpot

If you want to make yogurt in a crockpot, all you need is a bit of extra time. It is a slower process, but perfect for someone who wants to make double or triple the yogurt. 

1. First, you must heat the milk on low in the crockpot. This will take roughly 2 -3 hours. 
2. Then you turn off the heat and allow the milk to come down to the temperature of bath water. 
3. Mix some of the milk with the yogurt and then mix the yogurt mixture into the milk in the crockpot. 
4. Keep the crockpot off, but in a warm area 6-8 hours, or preferably overnight.

How to Make Yogurt in an Instant Pot

Luckily, there should already be a yogurt option on your instant pot which makes it easy to use, but the exact process may still be confusing. 

1. First, you need to add the milk to the instant pot and set the yogurt setting to boil (the valve should be set to sealing). 
2. Once it is finished, allow the yogurt to cool down to bath water temperature. 
3. Use some of the milk to stir into your yogurt, then add the yogurt to the milk. 
4. Now you want to set the instant pot to the normal yogurt setting (the valve should be set to sealing or venting). Your timer can be set for 8 - 12 hours, depending on how tart and thick you like your yogurt.

The science behind making yogurt

The cultures and good bacteria are what makes yogurt what it is. It ferments the milk's natural lactose sugars into lactic acid. This thickens and sours the milk into the tangy delicious yogurt we know and love. 

We heat or scald the milk before adding the yogurt or cultures for two reasons. First, it is to kill any microbes or unwanted bacteria that might have found their way into your milk Second, it denatures the lactoglobulin, which is a whey protein. We want this to happen because lactoglobulin prevents the yogurt from coming together into a smooth, velvety texture. 

The longer you allow the milk to scald, the more water evaporates and allows the milk proteins and fats to concentrate, giving you a thicker yogurt. I recommend not scalding the milk too long your first few times until you become more comfortable making yogurt. 

Cooling the yogurt is an important step because milk that is too hot will kill off the yogurt cultures. Letting it cool to about the temperature of a warm bath is perfect for encouraging the culture to multiply.

The incubation process when you leave the mixture set is one of the most important moments of making yogurt. Keeping a consistently warm environment allows the cultures to work at their best. The warmer the temperatures, the faster the yogurt will be finished, but you run the risk of producing more whey and end up with yogurt that breaks more easily. Lower temperatures takes longer, but it will be more delicate. 

The longer you allow the yogurt to set and give it very long incubation period, the more potent it will be. Even leaving it to set in the refrigerator and giving it a few days before you start eating will encourage a delicious and potent yogurt. 

Expert tips

1. The flavor of your homemade yogurt will be influenced by the type of store bought yogurt you purchase and the cultures they use. I usually use Oikos Greek Yogurt or Fage.
2. If you use the oven light method, it will create a warmer environment which I've found also makes the yogurt thicker and therefore produce more whey.
3. The fat content will change the thickness and flavor of the yogurt.
4. If you are using freeze-dried cultures, you can stir it right into the milk. Otherwise, we thin the yogurt with some of the milk before adding to the whole batch so it can evenly disperse. This can also help give you a creamier texture. 
5. The longer you let the yogurt set and the thicker it is, the more tart the yogurt will be. (I prefer a very thick, tart yogurt)
6. There will probably be some whey sitting on top of your yogurt. If that happens, you can either mix it back in for a thinner yogurt, or strain it out  with cheesecloth for thicker yogurt. If you strain it out, don't throw it away! You can use it in your baking in place or water, milk, or buttermilk for a delicious tangy flavor. I love it in my pancakes and muffins!
7. When you make yogurt again, reserve ½ cup of your homemade yogurt to make a new batch. You can keep doing this until the yogurt gets a funny taste or smell which is a sign that the bacteria is weakened. When that happens, start over with store-bought yogurt

Storage

I recommend pouring your finished yogurt into mason jars with lids that are screw on finger tight. You can use smaller jars for single servings as long as you can get an airtight closure. Keep the yogurt in the back of the refrigerator to keep the temperature consistent. 

Adding sugars and fruits will decrease the freshness of the final yogurt. Plain yogurt should last two weeks, but you if you plan on using the yogurt you made to make a new batch, you need to do it within the first week to ensure the cultures are strong enough.