Friday, March 7, 2008

Kids Make Yogurt, Then Strawberry Smoothies

Here's the dirty little secret about yogurt: If people knew how easy it was to make it, there wouldn't be nearly such a need for it in the dairy case.

Making yogurt is as simple as heating milk on the stove for a few minutes then inoculating it with a live yogurt culture. It's an overnight fermentation process similar to the one we use to make our sauerkraut. The key ingredient is the bacteria that go to work on the sugars (lactose) in the milk, lowering the pH to a more acid environment, which creates a distinctively sour flavor and also gives yogurt its keeping quality.

I consider yogurt making one of the many kitchen miracles that expose the kids in my "food appreciation" classes to the science of cooking--in this case some of the biological aspects of cooking. Having discovered the beneficial effects that microbes can have on food, humans have been making and eating yogurt for millenia.

According to food authority Harold McGee, the word "yogurt" comes from the Turkish root for "thick." Heating the milk prior to fermentation changes the structure of milk proteins, causing them to link together. All of this remained a mere curiosity to most Westerners until the 20th Century, when the Nobel Prize-winning immunologist Ilya Methnikov linked yogurt consumption to the health and longevity of certain groups in Bulgaria, Russia, France and the United States.

Now yogurt has an immediate association with healthful eating, although fat, saturated fat and cholesterol are still important considerations, as with any dairy product. Kids usually are a bit put off by the sourness of plain yogurt, but immediately warm to the idea of adding fruit to create a smoothie. Smoothies are a great way to package body-building proteins with the nutritional benefits of fresh fruit.

To make a batch of fresh yogurt at home, start with a quart of the best whole milk you can find. In a pot over moderate heat, bring the milk to 195 degrees (17 degrees below the boiling point). Use an instant-read thermometer or a candy thermometer to monitor the milk's temperature and adjust the burner as needed.

Lower the heat and continue cooking for ten minutes at 195 degrees, then remove the pot from the heat and place it in a large bowl partially filled with cold water. Again using a thermometer, bring the temperature of the milk down to 110 degrees. Now stir in 1 tablespoon plain yogurt containing active cultures. (Read the label on the yogurt container. It will say whether it contains live cultures.) Pour the milk into a warm quart jar and place the jar in a cooler with several jars or a small bucket of hot water. Close the lid on the cooler and allow the yogurt to ferment overnight, or up to 18 hours.

The reason for lowering the temperature of the milk after cooking is to create an environment in which the bacteria can thrive and multiply. The warm cooler also accelerates the fermentation process. The miracle result is a quart jar full of thick, luscious yogurt you can begin to enjoy immediately.

It seems that every family has its own way of making smoothies. Our recipe is as follows: In a blender jar, place 1 peeled banana, 2 heaping cups of cleaned and stemmed strawberries (about 1 pound), 1/2 cup plain yogurt, 1/2 cup orange juice and 1 1/2 tablespoons honey. Blend until thoroughly mixed. Then add about 1 cup ice cubes, cover and blend until completely smooth.

Even kids who don't normally eat yogurt love smoothies made with this distinctive dairy product.

Note: Children allergic to milk should not eat yogurt. However, people who are lactose intolerant may be able to enjoy yogurt, since the lactose in the milk has been consumed during the fermentation process.


Mark said...

Where do you get your yogurt culture?

Ed Bruske said...

Mark, the yogurt culture was simply a tablespoon of plain yogurt right out of a container purchased at the local Whole Foods. Just be sure the container says there are live cultures in the yogurt.

This kind of culture is like a daisy chain. It will go on forever if you just save some of the yogurt from each batch to make the next. Just like keeping a soughdough bread culture.

eweaston said...

Is there any benefit/reason to using whole milk (besides the obvious that fat tastes good)? Could one use skim or lowfat?

Thanks for the great work here too. I'm learning so much about what's possible.

Hope you're well. ee

Michelle said...

What's the texture of the homemade yogurt? I really like a thicker, Greek-style yogurt. Could I strain the homemade through a cheesecloth to make a thicker product?

Anonymous said...


I find whole milk easier to digest than skim milk or cream.


Charlotte said...

I made yogurt all winter from the delicious raw Jersey milk I was getting from a local rancher. We're on hiatus while the cows calve, and I'm hoarding the last of my yogurt -- it's so delicious, and either it's because of the milk, or because I use a lot of starter, but it gets really really thick. I hate to admit I'm jealous of a calf, but I'm looking forward to milk deliveries starting up again in the next month or so ...

Ed Bruske said...

EW, my resources all call for using whole milk. But if you look at the lables on commercially made yogurts, they do use low-fat milks, then add in more milk proteins. But I would not be able to tell the home cook how to do that.

Michelle, I like the Greek-style yogurt as well. It is much more like sour cream. I'm not sure how they accomplish that. Straining yogurt through cheese cloth is the method used to arrive at a Middle Eastern cheese product called labneh. But if you find out how they make that Greek yogurt, don't forget to let us know.

Emily, I notice on the Greek yogurt container that it is made with whole milk and cream. No other ingredients listed.

Charlotte, I envy you your raw milk yogurt. We acquired some raw milk butter recently, and it is not only delicious, but vibrant with color. Too much starter culture can result in a failed yogurt. Follow the recipe.

Riana Lagarde said...

great post ed, so wonderful that you are passing it on to the kids.

its so cheap to make yogurt and you can store it in big reused bottles. i add honey for sweetness and some people add powdered milk or agar or gelatin to make it thicker like greek style.

i always keep a baby food sized jar of yogurt in the freezer and use that as the started the next time, if i dont have any yogurt on hand.