Depending on how much you think your time is worth, making your own yogurt can be a great money saver. Since we live in Thailand, where time is abundant and money is scarce, this more than halves our yogurt bill. In the States we just did it for the cachet. No, actually, it tastes better this way since you get to pick the milk you use.
I took this recipe from David B. Frankhauser's nifty site all about cheese making. I present it here essentially without modification, except to say, if you don't have a fancy thick bottomed pan or double boiler, don't worry. Just don't scrape the crud off the bottom after scalding the milk. This recipe is for 1/2 gallon of milk. The recipe for a whole gallon, with pictures, is here.
- 1/2 gallon milk (I prefer whole milk for the taste, but it doesn't matter since the bacteria metabolize the lactose, not the fat)
- 1/2 cup fresh plain yogurt with live culture
- 2 big old pots or pans
- sterilized jars with lids
- an insulated cooler
- a funnel
2. In the meanwhile begin heating your milk on medium low heat. Scald the milk. That means let it start to boil until it begins to climb the sides. Do not stir it, but remove the skin from the top when it's done.
3. Begin heating another pot or two of water (depending on the size of your cooler and height of your jars) to about 55˚C or 130˚F.
4. Cool the milk to about 50˚C/122˚F. You can speed this up by placing the pot in a sink full of cool water while monitoring the temperature.
5. Mix some of the warm milk into the 1/2 cup of yogurt, then inoculate (or infect, depending on how you want to look at it) the pan of scalded milk with that mixture, being careful not to scrape burnt milk off the bottom and sides as you stir.
6. Pour the inoculated milk into the jars and put the lids on. This is where a funnel might come in handy. We use a 1/2 gallon milk jug with the bottom cut off.
7. Put the jars in the cooler, filling it with enough 55˚C/130˚F water come up to the necks of the jars, but not over the lids.
8. Seal the cooler and wait 3 hours. Don't open it or disturb the jars until it's done, because you'll lose heat and piss off the bacteria. Pretend you're making dumpling, or popovers, and that they'll be ruined if you peek.
9. Allow the jars to cool before placing them in the fridge.
Options: Some yogurt cultures contain both mesophilic and thermophilic bacteria. This recipe favors the thermophiles in order to kill any unwanted mesophilic contaminants (like Streptococcus) lurking in your kitchen, evading your sloppy sterilization technique. 55˚C is actually the cutoff point for yogurt cultures. If you want a more diverse mix of bacteria from your original culture to survive in your yogurt, you might try lowering the temperature of your milk to 43˚C/110˚F (this is the "correct" temperature for yogurt making) and water bath to about 47˚C/116˚F. It takes the same amount of time, and results in a milder, less acid yogurt with a smoother texture. If you would like to sweeten your yogurt (gross!), add sugar to the milk before you scald it. For "fruit on the bottom" yogurt use smaller jars, and put a spoonful or two of pasteurized (canned) jam or fruit preserves in the bottom before you pour in the inoculated milk.
Yogurt is good for your tummy.