How to Make Homemade Yogurt (and Yogurt Cheese)
Making your own yogurt is easy and fun! Yogurt is a mildly fermented food which is very healthy and tastes terrific. Yogurt is produced by inoculating milk with a starter culture that includes one or more strains of friendly bacteria. These bacteria feed on the lactose sugar in milk, causing the liquid to curdle into a more solid, custardy food with a pudding texture and a lightly sour taste. This fermentation process also improves the nutritional quality of the milk, resulting in about 20% more protein and plenty of enzymes to help you better digest the milk. Yogurt tastes delicious with fresh fruit, in cereal, or blended into a smoothie. You can also make yogurt from goat or sheep’s milk, or even from other types of non-dairy “milk,” including soy milk, coconut milk, almond milk, and rice milk.
To make yogurt, you need some milk and yogurt culture, as well as a container, mixing spoon, and an optional bowl for mixing. You also need a means of warming the cultured milk at a low temperature during fermentation, which can be accomplished using a heating pad, yogurt maker, or oven on a low setting. The container can be a glass jar, ceramic bowl, or any non-metallic vessel (metal may interfere with the fermentation process). Containers and utensils should be sterilized in hot water before beginning, and the milk should be at room temperature or a little warmer. If you heat the milk to a boil first and then allow it to cool to room temperature, this will result in a thicker yogurt. If you use soy milk, which does not contain lactose, then it’s helpful to add a spoonful or two of sugar or maple syrup to encourage the fermentation process.
To the room-temperature milk or soy milk, you then add the starter culture, which can be either freeze-dried, powdered yogurt starter or a good-quality commercial yogurt. (Yogurt starter is available from many online stores; it comes in little foil packets like baking yeast, and when stored in the refrigerator, can last for up to a year or more.) If you use a commercial yogurt as a starter, then you need to follow some important guidelines in selecting it. First, buy the plain stuff (no flavors, no sugars, and no colors added). Second, you need to use yogurt with “active cultures,” which should be noted on the container. If there are no active/live cultures, or if it has been pasteurized AFTER the yogurt fermentation, then the stuff is useless as a starter. Some yogurt containers use the words “cultures added after pasteurization,” but in lieu of this additional information, you may just have to experiment and find out which type works best. Third, I would avoid any yogurt that has added pectin or another thickener listed as an ingredient, since this is evidence that it is not all that pure and its cultures were not potent enough to do the job on their own. Fourth, consider that more bacterial diversity is probably a good thing; many yogurts are made with no more than three or four cultures (generally L. acidophilus, S. thermophilus, L. bulgaricus, and/or L. bifidus), while a few health-oriented brands also use other Lactobacillus species such as L. casei, L. reuteri, and/or L. rhamnosus. Studies have proven that each of these additional species provides numerous benefits as probiotics and/or immune system enhancers. Also, the more commonly used S. thermophilus, and L. bulgaricus (two of the cultures normally used) do not survive the gastrointestinal journey in high enough numbers to colonize your digestive tract. Fifth, try to buy organic yogurt if it’s available, since you know your starter culture will be free of pesticides, hormones, steroids, and whatever else they feed big-dairy cows these days. This is an even more important consideration for the milk you buy to make your yogurt, which should be either organic or from a high-quality dairy. However, any milk labeled as “ultra-pasteurized” may be difficult to culture; ultra-pasteurization heats milk to a very high temperature, which changes its structure to a point where bacterial enzymes have a tough time digesting it. Trying to make yogurt from ultra-pasteurized milk will usually result in a wet and sticky mess. If I had a choice between ultra-pasteurized organic milk and non-organic milk, I would choose to make yogurt with the non-organic milk.
If using dried starter, follow the package directions. If using commercial yogurt as a starter, then mix in approximately one part yogurt to six parts milk. Yogurt should be heated to slightly above typical room temperature (70 degrees F, or 21 degrees C) to accelerate its biological activity, though a weaker yogurt can be made at room temperature. You can warm it in an oven or on top of a heating pad that does not get the mixture much hotter than lukewarm. Temperatures above 112 degrees F can kill the good bacteria, so if your oven or heating pad gets hotter than this, it will start to cook the milk instead of fermenting it. The proper fermentation time depends on whether you like a mild, drinkable yogurt (as little as 3 to 4 hours) or a dense, sour yogurt (7 to 8 hours or longer), and it depends a little on the air temperature as well. I find that the strength of the starter culture also plays a big part in fermentation time, and this can vary greatly.
The lazy (and most reliable) way to make yogurt is to buy a yogurt maker, which is essentially an electric warming device that keeps the mixture at an optimum temperature for yogurt formation (between about 108 and 112 degrees F). Several high quality yogurt makers are widely available from online stores, including models by Euro Cuisine, Yogourmet, Donvier, Salton, and other brands. Some yogurt makers have a single large container for making yogurt, while others come with 6-8 small, individual-sized yogurt containers. Yogurt is delicious eaten plain or with some maple syrup, honey, fresh fruit, sprouted wheatberries, granola, or other cereal. Remember to save a few ounces of your yogurt to use as starter culture for the next batch!
Making yogurt cheese
You can make a spreadable cheese (resembling cream cheese or sour cream) from yogurt. You will notice that when you make yogurt, it becomes more solid and sour the longer you let it ferment. Make sure to start the cheese with some mature yogurt, not the particularly runny stuff; give it a few extra hours of fermentation time for good measure.
Ingredients and supplies:
A few ounces of strong yogurt
Large glass jar, measuring beaker, bowl, or clay pot
One square of cheesecloth or large coffee filter
Strainer that fits over this container or an extra-large piece of cheesecloth
Large rubber band or twine (to hold the cheesecloth, if you use this instead of a strainer)
Wrap your homemade yogurt in cheesecloth or a coffee filter. Using the strainer or extra cheesecloth (with rubber band or twine if needed), suspend this package above the container. Make sure it has room to drip. Put this in refrigerator, unused oven, or anywhere else it will fit and be relatively undisturbed. Leave and allow it to drain for 24 to 48 hours. Your main goal here is to strain out the water (whey) from the yogurt or kefir, leaving a solid mass which can be used like cheese. This recipe makes a nutritious, low-fat cheese. Be aware that your yogurt will continue to ferment during this time, so if you want a milder version, then you might want to put the cheese into the refrigerator as it drains (this will slow down the fermentation). Use the finished product as you would use cream cheese or sour cream. And don’t forget the whey: this liquid byproduct makes a refreshing drink on its own!