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The Sweetness of Soured Milk: Making Your Own Kefir, Buttermilk and Sour Cream by Louella Hill

May 23, 2013

Louella 2 web  Alli with babies web     Spoons web

Many of the foods you find in the supermarket today are modern foods–foods that humans have only recently started eating. Think of how we’ve tinkered with so many foods; stripping grains, bleaching sugars, emulsifying liquids. Think of how many foods we can buy today that our great grandparents had never heard of. Even the foods we might considered simple and unadulterated–a jug of milk, a bag of salad mix, a basket of berries–are arguably ‘new’ to our diet in that we’re eating them every day instead of rarely or once a year. Fresh milk is a perfect example of a seemingly ancient food that is actually a modern addition to the adult diet.

Fifteen thousand years ago, when humans were busy domesticating goats and sheep, was also the advent of humans drinking milk beyond infancy. Milk was fresh or non-soured while leaving the udder but quickly started souring due to ambient microflora in the nanny’s (female goat) or ewe’s (female sheep) teats. On a warm day, these microflora needed only a short window of time before they’d transformed the milk from a sweet, lactose-rich broth to a tangy, fermented delight. Fifteen thousand years ago, sour milk was the norm!

Today, every supermarket in American holds gallons and gallons of non-soured milk. Ironically, none of it really fresh–or hours out of the teat–and much of it is even weeks old. Pasteurization, homogenization, refrigeration and cross-country roadways have all helped this modern milk stay in an unnatural state. While milk is a key ingredient in many of dishes we eat (and the morning beverages we depend on), it is also an anomaly when placed in historical context. The human gut has spent fifteen thousand years adapting to sour, not sweet, milk.

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Luckily, souring your milk by making kefir, buttermilk, sour cream and other fermented dairy products is surprisingly easy. Most of these foods are made through a nearly identical process: warm the milk, inoculate it with microorganisms (a splash of buttermilk or a gurgle kefir will do), then hold at a warm temperature for approximately 8 to 20 hours. During this time, the microorganisms are busy multiplying. They’re turning lactose into lactic acid and making the milk more digestible. They’re also making a less safe food into a safer food. The more acidic environment inhibits the growth of unwanted, harm-causing bacteria. Fresh milk, on the other hand, is a blank canvas, waiting to be colonized by whatever crosses its path.

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In addition to the health and safety benefits of sour milk, there are other perks to worth mentioning. When you make your own fermented dairy, you can:

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Karin tastes Creme Fraiche

*   Make a zero-waste food: If you buy milk in glass jars and incubate in reusable containers, you’ll have nothing to throw away. More, you can reduce your exposure to questionable plastics.

*   Control the type and amount of added ingredients: Most commerical dairy products have stabilizers and / or loads of sugar. When making your own, you control what gets added.

*   Save money: If you buy one gallon of high-quality milk and convert it into four quarts of freshly made kefir, it’ll cost you approximately one quarter as much money as if you bought that same amount of kefir pre-made.

*   Eat fresh, truly probiotic foods: When you make your own cultured dairy, you are inoculating milk (or cream) with active microorganisms then letting those microorganisms grow and prosper. Because these microorganisms are most active in the first several days following inoculation, you can now have the privilege of eating these foods when their probiotic activity is at its peak.

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Melanyann considers the sourness

How to Make Kefir, Buttermilk and Sour Cream


  1. Warm 2 quarts of organic milk (for buttermilk, kefir) or 1 pint organic heavy cream (for sour cream) to 75-90°F.
  2. Add 2-3 tablespoons recently purchased plain kefir or cultured buttermilk. Use buttermilk as the inoculate if you are making sour cream. Choose a brand you like the flavor of to use as the inoculate (this inoculant, interestingly, is referred to as ‘the mother culture’). Stir the inoculant in gently for 10 seconds then transfer milk or cream into clean glass jars.
  3. Cover jars with lids then hold at 75-90°F for 6 to 18 hours. You can leave the jars fermenting for even longer if you’d like (up to 48 hours). I swaddle my jars in a down jacket or sleeping bag to keep the incubation temperature constant. You can also use a picnic cooler filled with warm water. Make sure to keep the incubating dairy in a vibration-free location (not on top of the washing machine). Make sure the temperature stays constant (no sweltering window sills, please).
  4. When the milk or cream smells sour and looks slightly or significantly thickened, transfer jars to the fridge. For sour cream, extend the shelf life by stirring in 1/8 tsp salt. For the kefir or buttermilk, enjoy by blending with fruit and sweetener.

Written by: Louella Hill, also known as The San Francisco Milk Maid (www.sfmilkmaid), a home birth mama and a professional cheesemaker. She teaches cheesemaking classes throughout the Bay Area and makes lots of cheese and fermented dairy products for her strong-boned family.

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Mary and Flavia enjoy lunch after class

One Comment leave one →
  1. Tiffany Khaler permalink
    June 17, 2013 4:43 pm

    Louella simplified this knowledge and made it quite approachable. We are enjoying fresh kefir and sour cream every week now!

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