Yogurt at Home
is a coagulated, sour dairy food. Human beings have probably consumed
fermented milks, such as yogurt, since they first milked cows and other
animals. Beofre modern times, however, people did not know of the need
for sanitation, adequate refridgeration, and heat treatment of milk
to prevent spoilage. Milk fermented naturally (or spoiled) if it was
left unconsumed. The quality of the product depended on the microorganisms
present in the original milk. Since the discovery, about 100 years ago,
of the microscopic organisms that cause fermentation and spoilage of
milk and other foods, we have learned how to control fermentation to
produce uniform, high-quality products.
Milk quickly spoils if it is not handled under strict sanitary conditions
and is not properly refridgerated. The type of fermentation that occurs
under such conditions may differ widely from one time to the next. Cultured
dairy foods, however, are produced by controlled fermentation, using known
types of harmless, active bacteria to create the desired flavor and body.
The fermentation in most cultured dairy foods are:
acid fermentation. Some bacteria break down the milk sugar (lactose)
to produce lactic acid, a sour-tasting compound. When enough acid
has developed, it coagulates (clabbers) the milk protein.
Pure cultures of bacteria are necessary to develop the desired flavor,
armoa, and body in cultured dairy foods. Dairy-food processing plants
maintain these pure cultures under strict sanitary conditions. The cultures
are added to milk or cream as starters to make commercially processed
buttermilk, sour cream, yogurt, cottage cheese, and cheeses. Because commercial
cultured dairy foods contain pure cultures of the right kind of bacteria,
they are ideal starters for homemade products. Purchase the freshest products
to use as starters, because bacteria become less active with age. Before
adding the starter, it is essential to heat-treat (pasteurize) the raw
milk or cream to destroy harmful bacteria and other microorganisms that
may intefere with a proper fermentation and the development of a good-flavored,
wholesome product. To pasteurize the milk or cream, heat it to 145 F (62.8
C) for 30 minutes.
Yogurt at Home
Yogurt is a cultured dairy product that can be made from whole, lowfat,
or nonfat (skim) milk, with added milk solids from either nonfat dry milk
or evaporated milk. Any type of milk can be used; cow's milk is traditionally
used in the United states, but other countries have been known to make
yogurt from milk of water buffalo, yak, goat, horses, and sheep.
The bacterial culture used in making yogurt differs from those used in
other cultured dairy foods. Yogurt bacteria grow best between 100 F and
105 F (37.8 C and 40.6 C).
Yogurt may be served: as is; as a custard with berries, peaches, or apple
pie; seasoned with salt and chives or chopped green onions; as a topping
for fruits; or with sweets, such as honey, maple syrup, jelly, or molasses.
Anyone who likes buttermilk should like yogurt.
The nutritive value of yogurt is about the same as the milk from which
it is made. The protein and calcium content may be slightly higher than
that of whole milk because of the added nonfat dry milk solids.
boiler that holds 5 cups
thermometer with a range of at least 100 to 200 F (37.8 to 93.3 C)
container that holds at least 5 cups (glass jar, crockery, or stainless
4 to 5 cups
quart pasteurized milk (whole, lowfat, or nonfat)
cup nonfat dry milk or 13-ounce can evaporated milk
to 1/2 cup commercial, unflavored yogurt
1/2 package unflavored gelatin
nonfat dry milk or evaporated milk to the quart of fresh milk.
Optional If you prefer a firmer yogurt, dissolve the unflavored
gelatin in the cold milk. You could also heat the milk mixture
to 180 F (82.2 C) in the double boiler and hold the milk at that
temperature for up to 45 minutes. The longer the time, the firmer
the finished yogurt will be. Keep the double boiler covered during
the heat treatment. Cool the milk to 120 F (48.9 C).
the milk to 120 F (48.9 C). If you add gelatin be sure it is completely
dissolved. Pour it into the sterilized container. Cool it to 110
F (43.3 C).
1/2 cup of the warm milk (110 F or 43.3 C) and throughly blend
it into the commercial, unflavored yogurt. Blend this mixture
into the remaining warm milk. You can leave the milk in the large
container and cover it. Or put the milk in clean 1/4 pint bottles
or other small containers and cover with loose fitting caps. (Clean
custard cups or jelly glasses are satisfactory for home use, because
the yogurt can be eaten directly from the container in which it
the container(s) in a pan of water at 110 F (43.3 C). Let the
milk ripen at that temperature until it has thickened and has
a tart, acid flavor. The ripening period usually takes 3 to 6
hours. If you prefer a sharper flavor, lengthen the incubation
the ripened yogurt from the water bath and chill it in the refridgerator.
Refridgerate the yogurt until it is used. Yogurt should keep for
a week or longer if held at 45 F (7.2 C), or lower (normal refridgerator
Written by John C. Bruhn