Yogurt is about as ancient as milk. Its beauty lies in its simplicity; yogurt was the first and most immediate way to preserve milk by extending its life (hence nutritional value) for several weeks. The key is fermentation, which is triggered and controlled by the addition of two bacteria, lactobacillus bulgaricus and streptococcus thermophilus.
The ancient tradition of preserving milk began around 5,000 years ago in Central Asia and the Middle East, where the climate is warm and the land lean, making it ideal for grazing ruminants. Harold McGee, author of On Food and Cooking, describes it most lyrically: “When our ancestors took up dairying, they adopted the cow, the ewe, and the goat as surrogate mothers. These creatures accomplish the miracle of turning meadow and straw into buckets of human nourishment. And their milk turned out to be an elemental fluid rich in possibility, just a step or two away from luxurious cream, fragrant golden butter, and a multitude of flavorful foods concocted from friendly microbes.”
In adults, yogurt has health benefits that far outweigh those of milk. In the early 20th century the Russian Nobelist Metchnikov proved through science what was common belief for centuries in Greece and the Middle East: that eating yogurt will make you strong and make you live longer. Lactic acid bacteria have been proven to eliminate toxic microbes in the digestive system.
There are many varieties of Greek yogurt, each with its own texture and flavor. From left to right: strained Greek yogurt; sheep's milk yogurt made in clay; cow's milk yogurt.
SHEPHERDS AND THEIR YOGURT
Greek yogurt, renowned the world over for its quality, density, and unabashed, delicious sour taste is a product of the country's pastoral traditions. Up until fairly recently, yogurt production was ruled entirely by farming and seasonal conditions. Greece has always been a land of sheep and goats. Cows were animals of labor, used to till the land and draw heavy loads, and rarely reared for milk. Sheep and goats provided most of the milk Greeks consumed. Yogurt was always made with sheep's milk and was seasonal, produced from late fall to early June.
There were two reasons for the seasonal production. Sheep produce milk from the moment they lamb until the summer, when the heat and the shortness of plants to graze on naturally will condition them to dry up. The heat of a Greek summer was never ideal for dairy production. Yogurt needs to be kept cool once it is set, and until the 1950's refrigeration was rare outside cities. The storage cellars, cool enough from fall to spring, lose their chill in the summer.
Yogurt was made immediately after the milking, when the temperature of the milk is the same as the animal's and ideal for the addition of the lactic acid bacteria that turn it into yogurt. The shepherd would simply add a little yogurt from the last batch as starter to the fresh milk. He would keep the containers covered and warm, probably in the room where he made his cheese. When people began boiling the milk that was used to make yogurt, they knew they had to wait until it cooled back down to “sheep” temperature before adding the starter.
Yogurt, the quintessential shepherd's product, was a specialty of the itinerant shepherds' tribes that roamed much of Greece. In the mountains of Epirus in Northern Greece, the Vlachs, for example, were a pastoral people with a strong tradition of cheese making. They made yogurt in wooden tubs.
The wood was permeable enough to store traces of the lactic acid bacteria, which were moistened and revived with the milk of the following season. Today the Vlachs are no longer nomadic, but some continue to make a heavenly yogurt in wooden receptacles, called tsanaka. Although not strained, the yogurt is thick and very flavorful because the milk is boiled long enough to condense it.
Another common way to preserve the starter was to dip a cheese cloth in the yogurt, then dry it and carefully preserve it until the next season.
In most other parts of Greece the yogurt was set in terracotta bowls glazed on the inside, still a popular way to set yogurt today, and with good reason: The ceramic bowls are porous, thus enabling the whey (water content) to leak out slowly, beading up on the sides of the bowl. By losing water, the yogurt gets thicker, and the natural sweating evaporates and cools the yogurt. In the cellar, the yogurt continues to ferment. As it ages it thickens and sours, which helps extend its preservation.
Temperature and timing are the secrets to making great yogurt. The milk has to be inoculated at a precise degree of heat, and then has to sit, unmoved, in a precisely heated room (an incubator) for a specific amount of time. Finally it has to be quickly chilled.
The yogurt maker has to be exacting in his technique. Fudge it, and the yogurt will be too runny or too sour.
Greek strained yogurt is extremely versatile. Toss it with olive oil (l), mix it with luscious Greek honey, top it on fruit, or savor it in a classic tzatziki.
GREAT WITH EVERY MEAL
Sheep's milk is far richer in protein and fat than either cows’ or goats’ milk. The yogurt it produces is dense, creamy, flavorful. I asked Sotiris Kitrilakis, a renowned Feta expert and advocate of Greek artisan foods, how we Greeks traditionally eat yogurt, and he gave me a perplexed look. “But with bread, of course!” he answered, and at that moment I remembered my father.
Growing up, my family wasn't fully attuned to the pleasures of good food. We did not scour the Greek countryside in search of the best little taverna, the cleanest lamb chops, the most fragrant retsina. We visited old churches and ancient ruins. But there was a small number of food staples—country bread, oranges, pistachios, and yogurt— that ruled our weekend destinations.
In my family's mind they did not belong in the category of luxuries, but in the category of essentials, hence it was perfectly acceptable to plan our weekend outings around the visit to the baker (he baked in a wood-fired oven), the orange seller (he sold the juiciest oranges out of his pick-up), and the best yogurt maker in Attica. Every Sunday night my Dad ate bread and yogurt for supper, his eyes beaming as he reveled in the flavors that took him back to his boyhood. This, he never failed to say, was the best of all meals.
In Greece, yogurt is an addition to every meal: scooped over rice pilaf, dolloped in tomato sauce; served with stewed and fried vegetables, meatballs, and grilled meats. It is used as a sauce, baked over chicken and certain beef dishes until it sets and thickens like béchamel. It is used as a condiment, stirred with shredded cucumbers and garlic to make the well-known dip tzatziki, or spooned onto savory squash and cornmeal pies, a tradition in Greece's northern mountain regions. In some areas it is even served as a cool summer soup.
Swirled with honey or spoon sweets, yogurt is divine. Strained sheep's milk yogurt was rare, and used in lieu of cream in desserts such as roasted caramelized quince, or as a pudding with honey and walnuts.
A more regular treat, still a favorite with children today, is “yogurt skin,” scraped off the top of the yogurt and sprinkled with sugar.
STRAINING FOR TASTE
In Europe, the health benefits of yogurt were acknowledged early last century, and yogurt production in the West catapulted into a huge industry. The large yogurt dairies in Western Europe are defined by two factors: They make yogurt with cows’ milk, and they add fruit and fruit preserves. Cows’ milk yogurt is thin in texture and can be very acidic. Adding sweetened and preserved fruit makes the yogurt richer in texture and erases the sour flavor. Yogurt has become synonymous with a healthy, sweet snack.
In Greece, the dairy industry has also adopted the use of cow's milk which is plentiful and produced year round. But instead of sweetening the sour and thin yogurt, we use a time-old technique: We strain it. The result is astounding: a dense, creamy mass which has lost most of its sourness with the whey. Strained yogurt became more and more popular after the Second World War. Large modern dairies devoted entire rooms to yogurt draining; Cheese cloths bulging with yogurt would hang from the ceiling, dripping the green-yellow whey into plastic drums. Today the titans of the dairy industry no longer use cheesecloth. They strain the yogurt centrifugally, a more efficient, automated practice.
We Greeks have taken to strained cows’ milk yogurt. Greek-style strained yogurt has recently exploded in the U.S. and European markets. American chefs and cooks don't restrict it to Greek or Mediterranean cuisines. It appears everywhere, a beautiful re-incarnation of a stellar ancient food.