No matter what part of the world your yogurt culture came from, or what kind of bacteria it contains, or what kind of milk you are using, there are some basic procedures that you will follow to produce a tasty, nutritious, fermented result.
Ingredients and Supplies You Will Need
Milk. You can use pasteurized milk (homogenized or unhomogenized), raw milk, whole milk, reduced-fat milk, skim milk, or even powdered milk. You can also use other creamy substances such as rice milk, nut milk, soy milk, coconut milk, etc.
Yogurt culture (also called starter). This can be an already-made yogurt, or a dried culture. There are many varieties of yogurt culture, each of which will produce a characteristic yogurt: mild or tart, thin or thick, gelatinous or pourable.
Clean container(s). Glass is best for making yogurt. Food-grade plastic can also be used but is not an ideal choice for yogurts that incubate at warm temperatures. You can make yogurt all in one large container, or you can make it in single-serving containers. Clean is very important! Any sort of food or soap residue can contaminate the culture and give you poor results.
Cover. You can culture yogurt with or without a lid. If you culture without a lid, you should have some sort of cover such as a clean towel, or a coffee filter, to keep dust and other particles from getting into the yogurt, and to keep the cat from drinking it while you are not looking. Once the yogurt is complete, you’ll need to have some sort of lid for the container, to keep the yogurt fresh.
Pot for heating milk. Not all yogurts require that you heat milk, but for those that do, you will need a pot that will hold the quantity of milk you’ll be heating. Stainless steel or glass is a good choice. A double boiler will help keep the milk from sticking to the bottom of the pot.
Cooking thermometer. If you are making a non-heated yogurt, you’ll need a thermometer that measures lower temperatures than a cooking thermometer. Check the instructions for the yogurt culture you are using to find what temperatures you’ll need to measure, and make sure your thermometer covers that range.
Insulator. This can be a yogurt making machine, a crock pot, an insulated cooler, or even just a dishtowel. Whatever type of yogurt you make, you will need to keep it at a certain temperature while it incubates.
Timer. Nothing fancy is required. Any method you have to tell time and remind you when the yogurt needs to be looked at will work.
Measuring cups and spoons. You’ll need to measure the yogurt and milk that you’re using. Whether you are making one cup at a time, or several gallons, make sure you have the measuring tools you need.
A place for the yogurt to incubate. The yogurt will need to sit for 6 to 48 hours (depending on the type of culture you use). You need to have a place that it can rest, undisturbed, at a constant temperature, and away from anything else you might be culturing.
Get all your equipment and supplies together. Having all your gear in one place will make your yogurt-making experience much easier than if you have to be rustling around for spoons and cups and lids while you’re also trying to maintain temperatures.
Prepare the culture. What you do here will depend on what type of culture you are using. If you are using yogurt from a previous batch, there’s nothing to do but measure it. A powdered one-time use culture can also just be measured. If you’re using a dehydrated live culture, you may have to activate it before adding it to the milk. Make sure you have read your instructions carefully and you know what steps to take.
Prepare the milk. If you are making a heat-set (thermophilic) yogurt, heat up the milk to the desired temperature, then let it cool down to the incubating temperature. If you are making a countertop (mesophilic) yogurt, all you need to do is set out the milk in the container you’ll use to incubate it in. If you are going to add thickeners to the milk, this is the time to do it.
Add the culture to the milk. This is a pretty simple step! Just make sure the culture is completely mixed in to the milk.
Let it incubate. This is a little trickier than it sounds. When you are first working with a new yogurt culture, you will need to figure out the correct balance of time and temperature for the incubation. You need to let the yogurt sit long enough for the milk proteins to coagulate, but not so long that the yogurt begins to separate into curds and whey.
Refrigerate. Once the yogurt has reached its peak consistency, you should refrigerate it. This will stop the culturing, and also add a little extra firmness.
Fix, amend, enhance. Once the yogurt is completed, you can add flavorings or fruit, or even additional thickeners.