Yogurt and the Preparation Thereof by the Interested Homebrewer
Many will, of course, think that this is an odd subject for a beer-related page and perhaps it is. However, I have been making my own yogurt for much longer than I have been brewing and find that there are many parallels between brewing and yogurt making. First, there is the similarity of the equipment required. Second, there is some similarities in the processes themselves and lessons learned in brewing good beer are transferable to the yogurt making process. Perhaps the most important parallel is the comparison of the homemade product with what is mass-produced for commercial consumption. The yogurt you can produce yourself is a long way from the bland, gelatin-stiffened, fruit-sweetened concoction that is passed off as yogurt in grocery stores. Real yogurt is a rich, mouth-puckering food that is well worth the minor effort required to produce.
I have been making yogurt of around 25 years and the description that follows is the cumulative description of these years of experimentation. For additional discussion on this subject,
The Joy of Cooking has a short and to the point description of yogurt-making in its Know Your Ingredients chapter that I can only slightly improve upon here. But, to get on with things:A Short History Lesson
Yogurt is simply milk that has been soured by various strains of Lactobacillus. The most common strains found in active cultures are
L. bulgaricus and L. acidophilus. Yogurt was originally made with ewe's milk and, if you happen to have a nursing ewe around, you are welcome to repeat the original recipe. I haven't. Cow's milk is too easy to come by. Yogurt was originally discovered in Central Asia by the nomadic tribes there. In antiquity, the vessel of choice for storing liquids was a bladder made from a goat or a sheep's stomach. Kind of gross by today's standards, but back then, they were convenient and easy to come by. However, when milk was stored in these bladders, the lactobacilli left over from the bladders' previous owners (the natural habitat of lactobacilli is some mammal's stomach) thought they had died and gone to bacteriological heaven. In the warm Central Asian climate, yogurt was quickly formed. These early yogurt makers quickly discovered that to make more yogurt, all they had to do was refill the yogurt bladder with milk when it was empty and let it sit overnight. However, since most people are not equipped with fresh goat stomachs and probably wouldn't want to use them if they were, the modern yogurt-making process requires somewhat more sophisticated equipment.Equipment required:
Almost all of this you already have around the house, if you are a brewer.
Cooking pot
- Something roughly twice the volume of yogurt you wish to make. Stainless steel is the material of choice, primarily because you can aggressively scour it when you scorch milk on the bottom of the pan (This will happen on occasion). I use a 2-gallon stainless steel stock pot to make 1 gallon of yogurt.Thermometer
- A must have for yogurt making. You should have one that is accurate and easy to read in the 100° F to 200° F (35° C to 90° C) temperature range.Chiller
- Your standard wort chiller, although, since milk and beer are two substances that never go well together, I have made a mini-chiller that is dedicated to yogurt-making.Incubation/Storage Containers
- Yogurt is made in the same container you store it in, so anything that is convenient will work here. I generally use several 2-qt Tupperwareâ or RubberMaidâ containers or, if I am going to be taking yogurt for lunch, I just refill store-bought yogurt containers.The Recipe and Process:
Yogurt may be made with any milk from skim to half-and-half. I recommend using whole milk. Originally, milk for yogurt was boiled down to about two thirds of its original volume. This made sense when your supply of sheep's bladders was limited. However, boiling milk causes its own set of problems, so don't do it. I simulate the original concentrated milk process by adding powdered milk to the milk I'm using for yogurt. I typically add about 1.5 cups of powdered milk to 1 gallon of whole milk for my recipe. Don't add any water here, add the dry milk to your whole milk and dissolve it. This 'concentrated' milk will make the lactobacilli happy and pay you benefits in your final product.
The yogurt you are making is going to be much tarter than what you have bought in the store. You might want to balance this tartness somewhat by adding about a tablespoon of sugar or honey to your concentrated milk. Suit yourself here; I find that more than a tablespoon results in something that is too sweet and typically I don't add any sweetener at all.
Heat the concentrated milk to 180
° F (82° C), no more, no less. This is hot enough to kill off any rogue bacteria or yeast in the milk, but still cool enough to avoid congealing any of the milk protein. I keep time at this temperature to a minimum. Typically, I'll heat to 180° F, add my wort chiller, and, when the temperature stabilizes at 180° F again, just turn the burner off. I would point out here that you should be stirring the milk all the while you are heating it up. Milk scalds on the bottom of your pot very easily and it is a tremendous pain to clean off when it does. You've been warned.......The secret at this point is to cool the milk down rapidly to avoid its being recontaminated by any of the bugs floating around your kitchen (and, believe me, there are a lot of them regardless of how clean you think your kitchen is). This is where the wort chiller comes in. Mine will cool a gallon of milk down to the proper temperature in less than 5 minutes. Not only does this make for better yogurt, but it speeds up the process tremendously. If you don't have a wort chiller (or don't know what one is), don't get tense about it, just cool your milk in a sink full of cold water.
Cool the milk to between 106
° F (42° C) and 110° F (47° C). Pay attention to this temperature range; it is important. Add your yogurt culture and don't be generous. Lactobacilli are happiest doing their yogurt thing when they are not cheek-to-jowl with their neighbors. A tablespoon of starter per gallon will easily do the job.But what about the starter? Where did this come from you ask? If you've made yogurt before, it is just a small amount left over from your previous batch. If you haven't, just go to the grocery store and buy a small container of plain yogurt (low fat variety, not no-fat). Check the side of the container to assure yourself that it says 'contains active yogurt cultures'. Most of the major brands will say this. Personally, I've had a 100% success rate with either Dannon
â or Columboâ brands.Once you've stirred the starter in, pour the milk into whatever container you've chosen to incubate/store your yogurt in and let the bacilli do their thing. The best incubator I've found is a gas oven that was a pilot light. The pilot light keeps the interior of the oven just warm enough to keep the bacteria happy and it's an isolated place where your developing yogurt will not be disturbed. Just as lactobacilli don't like a lot of company around while they are souring milk, they also do not like to be jostled. If you are only equipped with a modern oven with no pilot light, preheat the oven to 120
° F prior to making your yogurt. Turn the oven off when you are ready to incubate the yogurt. A modern oven is sufficiently well insulated that it will retain heat long enough for the lactobacilli to do what they need to.Once you've put the yogurt into incubate, you're job is done. Give the bacilli 12 hours or so (overnight is my yogurt making standard) and then refrigerate. Once it's cold, enjoy! You'll note that your yogurt may not be as solid as the commercial stuff. That's because they use gelatin to stiffen theirs. This let's them use less and lower fat content milk, which without the gelatin would give them something like soup. The extra milk solids added in this recipe gives a thicker consistency naturally.
Troubleshooting
If you've followed this procedure and ended up with a thin, gruel-like yogurt, the problem is probably one of the following: