Three Simple Foods, continued, by Carol Wallwork first posted online Nov. 20, 2008

Let me now make the case for making your OWN yogurt, croutons and salad dressing which can save you at least $200 a year, plus give you more control over what you eat.  The kicker is we’re only talking about a 30 minute a week time investment.
____________________________________________________
Homemade Yogurt
Shortly after moving back to the States from England my Mom gave me a Salton yogurt maker.  It was a plastic container that held 5 glass yogurt cups. You plugged it in to maintain a steady 105 degrees to incubate milk with yogurt bacteria, transforming it into yogurt.  The word Yogurt is from Turkish, Yoghurmak, meaning "to thicken." 

Making yogurt:
                 32 oz. skim milk
                           1/2 cup plain, non-fat yogurt with live cultures
                           1/2 cup powdered milk
Turn on your yogurt making machine so it will warm up as you make the yogurt.  Pour 32 oz. of skim milk into a saucepan.  Turn heat on high.  The most critical moment of any of these recipes is at this moment:  Set the timer for 1 minute.  Have your digital thermometer at the ready because warming milk can spike from 95 degrees Fahrenheit to 115 degrees in 3 seconds.  Milk above 110 degrees will kill yogurt bacteria.  Milk below 100 degrees will not grow yogurt bacteria.  So you want the warm milk to to be in the 105 to 109 degrees range.  Not lower than 105 though for you will be adding cold yogurt culture and frozen powdered milk, which will lower the overall temperature of your milk.
Keep track of how long it takes to get the milk to the ideal temperature so it will be easier next time. if you go over 110 degrees it will cost you time. If this happens place the pan of milk in a sink with 3 inches of cold water to lower the temperature.

When the milk is 105-107 degrees remove from heat.   Whisk in the 1/2 cup of powdered milk--always do this step first because it will lower the temperature quickly if you’re anywhere near 109 degrees or even slightly over the 110.
Now add 1/2 cup of yogurt.  Whisk quickly but thoroughly before pouring it into the yogurt cups.  Incubate 8 to 10 hours.  Viola! 
Time:  It takes about 10 minutes to make yogurt, including clean up. 
Cost:  A quart of milk cost about 75 cents.  I buy a quart of Butterworks Farm (Vermont) plain organic skim yogurt for $4.00.  I use 1/2 cup for each batch, times 8. So add 50 cents.  Several people in my house eat yogurt so I use a quart of starter within two weeks.  But if you don’t need that volume Stonyfield Farms sells 6 oz. cups of plain lowfat yogurt for about $1 each.  Electricity for a small appliance for 10 hours is about 10 cents.  Each batch makes seven 6 oz. cups of yogurt for about 20-25 cents/serving. 
Potential Savings: You can save between 30 -70 cents per serving,  A serving of yogurt a day savings range from $109 to $255 per year. 
Caveats:  Purists incubate their yogurt in a jug next to their warm wood stove.  Most modern homes don’t have such a constant heat source so that’s how yogurt makers come help.  Online prices range from $25-$50.  A Euro Cuisine from William Sonoma is $50.  A digital thermometer cost $10-$15. Allow 2 to 6 months to recoup your investment.  But both tools can last 10 years or more.
I do not use my yogurt to culture more yogurt although you can.  Imagine cultivated tomato seeds to the seventh generation--less vigorous, less tasty and smaller.
Ingredients: 
Yogurt:  I use Butterworks Farm organic whole milk yogurt with live cultures because this brand doesn’t use pectin as a thickener. Milk and yogurt culture are the ONLY ingredients.  Almost all other yogurts add pectin.

Pectin is a natural chemical isolated from fruits that is used commercially as a gelling agent. It’s often used in jams and jellies.  Yogurt cultures naturally thicken milk to make yogurt, creating a milky solid of pudding consistency.  Yogurt made with pectin distorts real yogurt into a solid as firm as Welch’s grape jelly.  It saves time--and money--for pectin ‘sets’ the yogurt much faster than incubation does.  I’m not a chemist but I suspect there’s less yogurt culture because of this accelerated process. 
Powdered milk:  I use State Brand Instant Nonfat Dry Milk because its made in New Ulm, Minnesota and I like to support businesses in the Dakotas and Minnesota.  I store it in the freezer.  

Yogurt maker buttons lets you time how long you warm yogurt.  A rule-of-thumb: longer time, stronger yogurt, both taste and yogurt culture