Combine the water and dry milk powder. Heat it to 180 degress. Cool it to
110 degrees. Mix in the store bought yogurt. Incubate in a warm place for
4 to 8 hours. This is quite cryptic, for more detailed information, read
on.
Each cook develops her own way of preparing home made yogurt through trial
and error. I am going to describe my method, followed by some other common
methods and ideas. But first there are a few things you need to know.
Yogurt is cultured from acidophilous bacteria, which you can sometimes buy
in powdered form at the health food store. I have never actually seen it,
but I've heard tell about it.
Yogurt can also be cultured from store-bought yogurt which contains "active
yogurt cultures" or live bacteria. Read the label and it will tell you if
the yogurt contains active cultures or not.
I always use prepared yogurt as my culture. I buy a large container of
plain store brand yogurt from the store. I bring it home and scoop it into
a couple of icecube trays. Then I freeze it. When it is completely frozen,
I take the frozen yogurt cubes and pack them in a plastic freezer bag. Each
time I make yogurt, I use one cube as the starter. You can use your own
yogurt as a starter too, but eventually it loses it's power due to the
introduction of foreign bacteria, usually after using it about 3 or 4 times.
I like to use a new frozen yogurt cube each time I prepare yogurt. I've
had my best results this way.
When making yogurt with powdered milk, it is good to use more dry milk
powder than you would to just make fluid milk. For instance, normally I
would use 1 1/3 cups of dry milk powder to make a quart of milk. When I
reconstitute milk for yogurt, I add an extra 1/3 cup of dry milk powder,
using 1 2/3 cups of dry milk powder for a quart of yogurt. This makes the
yogurt thicker and also higher in calcium. Even when preparing yogurt from
fluid milk, the results are better if you add a little extra powdered milk
for thickness.
To begin, I get out my double boiler. I measure the water (3 3/4 cups) in
the top of the double boiler and whisk in the powdered milk (1 2/3 cups).
Then I put the lid on top and let it sit for several minutes over the bottom
of the double boiler (which is filled with water), heating at medium high
heat. Every now and then I check the milk. The water below the milk is
boiling. When it looks like the milk is almost ready to boil, I take it off
the stove. You can use a candy thermometer if you like. The temperature
should be at least 180 degrees. The reason you heat the milk is to kill off
any bacteria which could interfere with the yogurt starter. The few times I
have made yogurt without heating the milk first, I wound up with runny
yogurt. My best results come when I heat the milk first.
You could heat the milk directly on the stove if you liked. I don't do this
because I have scorched the milk many times this way. Instead, I prefer my
double boiler method. Next I take the top of the double boiler, containing
the hot milk, out of the bottom, and set it on my washing machine to cool.
The washing machine is metal, so it cools the pan down faster. The pan has
to cool down to 110 degrees. This is when the bottom of the pan is
comfortably warm when you place your hand on it. If the yogurt is too hot,
it won't work, the heat will kill the starter.
While the milk is heating, I take out a large mouth quart size canning jar
and place a frozen yogurt cube in it. By the time the milk is cooled down,
the starter cube will be thawed. When the milk is cool enough, pour about
1/3 of it into the canning jar over the starter yogurt. Stir it up with a
wire whisk or a fork to mix it up completely. The starter yogurt should be
totally combined with the milk. Pour in the rest of the cooled milk and
stir again. Put a lid on it and shake it up to make sure it is all
liquified together. Now it is time to incubate the yogurt.
I do this in my electric oven. I set the stove dial half way between off
and two hundred degrees, or at approximately 100 degrees. The light which
signifies the oven is on, pops on for a moment, and then pops off when the
temperature is reached. I set my jar of yogurt in the oven and leave it for
between 4 and 8 hours, usually overnight, or while I'm out for the day. I
take out the yogurt when it is thick and done. It works every time. My
yogurt has a very mild flavor, which the kids like better than the sour
stuff we used to get from the store.
There are many other ways to incubate yogurt. It should rest undisturbed
while it incubates. Some people pour the warm milk combined with the
starter, into a large preheated thermos and let it sit overnight. Other
folks set the yogurt on top of a warm radiator, or close to a wood stove, or
in a gas stove with the pilot operating, or on a heating pad set on low.
Sometimes I have placed the jar in a pan filled with warm water, to keep the
temperature even. This worked pretty well when I incubated the yogurt next
to the wood stove. It kept the yogurt at a uniform temperature, even with
occasional drafts from the front door opening and closing. The heating-pad
method is supposed to be pretty reliable. You set it on low and then cover
the heating pad with a towel, place the yogurt on top of it, and put a large
bowl or stew pot upside down over the yogurt. This makes a little tent
which keeps the heat in. I don't have a heating pad, and have never
actually used this method myself, but a good friend swears by it. Another
friend uses a medium sized picnic cooler to incubate her yogurt. She places
the jars inside the cooler and then add two jars filled with hot tap water,
to keep the temperature warm enough. After 4 hours, check the yogurt to see
if it is thick enough. If it isn't then refill the water jars with more hot
water, return them to the cooler, and let the yogurt sit another 4 hours.
When I tried this method, it worked very well. It took a full 8 hours, but
the yogurt was perfect, and I liked not having my oven tied up during the
day. Also, there was little danger of getting the yogurt too hot while it
incubated, and drafts weren't a problem because of the closed nature of the
cooler.
After the yogurt is thick, place it in the fridge. It will stay sweet and
fresh for about a week. You may prepare more than one jar at a time if you
like. I just included the method for a quart because this is the size
canning jar I use. Narrow mouth canning jars would probably work too, but I
prefer the wide mouth ones because it is easier to stick a measuring cup or
ladel down inside of it, to scoop the yogurt out. I usually prepare two
quart jars at a time. The prepared yogurt is good mixed with jelly, fresh
or canned fruit, served with granola for breakfast, or substituted for sour
cream in many recipes like stroganoffs. It is also nice pureed in fruit
smoothie blender drinks, or stirred into gelatin or popscicles before
freezing them. It can also be stirred half and half with regular mayonnaise
to make a very tasty low fat mayonnaise. This mixture can be used in just
about any recipe which calls for mayonnaise.
Learning to make yogurt is a trial and error process. Most people don't have
perfect or consistant results the first few times they make it. With a
little practice though, anyone can learn to make it. When you get a little
skill at it, the entire process becomes second nature, and you will have
sweet fresh yogurt available whenever you like.