Many centuries ago, the Mongols of Asia were reported to eat a strange food that had medicinal properties, and it was said that they enhanced its flavor by mixing the sour-tasting food with the blood of horses.
When the secret recipe of this food; which was believed to extend human life, was brought from Constantinople to France, King Francis I bought the formula for a large sum.
In 1931 a Spanish businessman, Isaac Carasso, produced the food and sold it in pharmacies throughout Europe. With the advent of World War II, Carasso;s son, Daniel, bought the formula to the United States. The food, then named Danone, after Daniel, was slow to catch on because people thought that the sourness meant it had spoiled. Fruit was added to balance the sourness and sales of the product, renamed Dannon yogurt, improved.
In the 1970's, yogurt became known as a high-protein, low-fat health diet food. Some people concluded that it must be good for you if health-conscious people were willing to eat something so sour.
In 1985, television advertisements for Dannon yogurt showed happy Asians eating lots of yogurt. They looked healthy and very old. The ads reinforced the notion that yogurt promotes longevity.
LONG LIFE
Scientific-sounding claims that yogurt is good for you can be traced to the turn-of-the-century theories of Elie Metchnikoff, a respected Russian biologist who won a Nobel prize for medicine in 1908. Metchnikoff believed that our life span is limited by bacteria. In his book, "The Prolongation of Life", he stated the intestinal tract harbored great numbers of bacteria that produced toxins that slowly poisoned the body and caused premature death.
He called this process, "autointoxication by putrefactive bacteria," and believed that surgical removal of the colon where the bacteria lived would extend life. However, because colon surgery carried considerable risk, he recommended another treatment that he believed would rid the human intestine of harmful bacteria.
Metchnikoff had studied the culinary practices of French, Russian, and Bulgarian peasants and noted that the Bulgarians, who consumed about three quarts of yogurt a day, had remarkable longevity. He concluded that the lactobacilli bacteria, Long Life
Which are present in yogurt, establish colonies in the intestines and displace the harmful bacteria. Although it was unproven, Metchnikoff wrote books that popularized his theory. He also ate lots of yogurt, and announced that he expected to live to the age of 150. Later, tests showed the Lactobacillus bulgaricus bacteria do not colonize in the human intestine, leaving Metchnikoff with no scientific basis for his beliefs.
When we are born, our intestines are relatively sterile and free of bacteria. As daily food is consumed, the intestines quickly adopt colonies of bacteria. Adult intestines contain a vast range of flora, lactobacilli, streptococci, staphylococci,
coli form bacteria, and yeast. In this competitive environment, the yogurt bacteria are unable to establish colonies.
To be fair to Metchnikoff, the idea that intestinal bacteria can be harmful may have some merit. Today, medical experts say that there is a correlation between bowel cancer and the high dietary intake of animal fat and protein. It is possible that the putrefactive bacteria (those that consume protein) may somehow produce carcinogenic compounds from cholesterol and bile salts. But even if this is so, eating lots of yogurt is not likely to be much of a remedy because the bacteria in yogurt don’t colonize in our digestive tract, and yogurt contains animal fat and protein. Where does this leave the health claims about yogurt? Is it good for you even if it doesn’t make you live longer? Is it a good diet food? Let’s look at how yogurt is made.
MAKING IT ALL GEL
Yogurt is fermented milk, a product that can easily be made at home. From the cook’s point of view, two major changes take place when milk is converted into yogurt: It turns from sweet to sour, and from liquid to a semi-solid gel. These changes are caused by the bacteria Lactobacillus bulgaricus and Streptococcus thermopiles. Cows’ milk contain about 4.8% lactose and the bacteria consumes much of this sugar, producing the sour-tasting lactic-acid, C2H4 9OH COOH. It is this acid that causes protein in the milk to coagulate.
Milk contains many types of protein, and it is the type known as casein that is involved in making yogurt. Casein molecules are normally packed into microscopic bundles called micelles. T milk’s normal ph of 6.5, the micelles are dispersed throughout the milk. As the lactic acid builds up, the ph gradually drops to 4.5, and the acid alters the casein molecules so that the micelles link together in chains and clusters. The linked micelles form a semi-solid network known as gel. The other ingredients of the milk, such as vitamins, enzymes, unfermented lactose, fat, water - remain in the spaces of the gel-like protein network. During the conversion of milk to yogurt the amount of lactose is reduced, but the food value of the other components in milk is largely unchanged.
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