As I sit here now, I am enjoying spoonful after spoonful of delicious homemade yogurt. Yes, that is correct, I said homemade. It turns out yogurt is not limited to the small plastic containers lining the dairy aisle at the local grocery store. Rather, yogurt is a miracle of fermentation and bacterial reproduction, and something so simple literally anyone can make it at home. I can sum up the yogurt-making process into one sentence. You stir a little starter into warm milk, let the mixture rest at a warm room temperature sit, and in a few hours the bacteria from the starter have multiplied a hundredfold and created a thickened product full of billions of healthful, tangy bacteria in every spoonful.
But the wizardry of yogurt making deserves a bit more than that sentence. Our interested started thanks to this great article by Harold McGee in The New York Times. Sam found it online, and we were immediately curious, so we experimented this weekend. It could not have been easier. Basically yogurt making is nothing more than giving a small colony of chosen bacteria an expansive home, and allowing them a bit of time to take it over. The bacteria is a special type of bacteria called lactic acid bacteria. As McGee explains, "The lactic acid bacteria are a group of microbes that share the ability to convert sugars into lactic acid, which suppresses the growth of their competitors. The lactic acid also causes the proteins and fat globules in milk to cluster into a continuous solid network, with the milk’s water trapped in its pores." Thus, the bacteria turn regular old milk to yogurt.
And when McGee says "continuous solid network" he is not kidding. After just four hours of fermentation our yogurt was a thick and solid, shiny mass that was more inclined to stick to itself than anything else. Before draining, we could poke our spoon into the culture and bring it back up clean, almost like putting a spoon into a block of jello. After 24 hours draining through cheesecloth in the fridge, it has become like a delicious dairy glue. The final product is very thick, very rich, and very, very sticky.
We made two types of yogurt, one 2% and one whole milk. The verdict is still out, but I think we prefer the 2%. We used a 99% fat free vanilla Yoplait as our starter, and the bacteria in it were champs. My only complaints is that there is a faint and lingering flavor of vanilla yoplait in our yogurt batch. I expected the quart of milk to dilute our two tablespoons of vanilla into nothing, but apparently the flavor is potent. You might consider searching for a plain yogurt for your starter. I think our next batch will be better, as the vanilla will begin to be diluted into infinity as we use leftover yogurt as a starter in future batches. Also, one quart reduced to about a pint of yogurt after draining. If you have a big family or eat a lot of yogurt, you might consider making this from a gallon of milk rather than just a quart.
Any way you make it, this yogurt is a marvel of science, flavor, and what feels like magic. I am so pleased we tried this at home, most importantly as a reminder than many good things in the grocery store have long lost humble beginnings in the home cook's kitchen.
All yogurts begin in the same way -- milk is heated and then cooled slightly. Active cultures, which can vary depending on the type of yogurt, are added, and the mixture ferments until it sets. Anyone, literally, ANYONE is capable of completing this amazing, inexpensive, rewarding science experiment at home, and reaping their reward for breakfast. I would love to make yogurt with children. I think it seems like a great learning experience.
One quart milk (whole or 2% preferred for flavor)
2 tablespoons starter (either remains from an old yogurt batch, or a commercial yogurt)
Heat the fresh milk to 180-190 degrees, or to the point that it’s steaming and beginning to form bubbles. Cool the milk to 115 to 120 degrees, Stir in two tablespoons of yogurt, either store-bought or from your last batch, thinning it first with a little of the milk. Pour warm milk/yogurt mixture in a an insulated, wide mouthed container and cover it. Keep the milk warm as its sets, which usually takes about four hours. When set, strain through cheesecloth if desired (its what I recommend), put in a sealed container and refrigerate.
To make a thick Greek-style yogurt, spoon your mixture into a fine-mesh strainer or colander lined with cheesecloth. Let the whey drain into a bowl for several hours. The longer the mixture drains, the thicker the final product.