Homemade Yogurt

        From the blog For Love of the Table

Before you begin, gather the following:

a quart of whole milk (I use local, organic)

a tablespoon (15 grams) of yogurt (a commercial brand with live and active cultures or your own from a previous batch—no older than five to seven days)

a 3-quart saucepan

a candy thermometer and/or an instant read thermometer

a heat-proof rubber spatula

a ladle

a clean 1-quart jar (or 2 pint jars)

a clean insulated cooler.

Fill the cooler with warm water (115° to 120°), cover and set aside.  Place the glass jar in a 215° oven (after 10 minutes, I shut the oven off and open the door slightly so that the jar will cool down before I fill it—it's nice if it's still warm, but if it's too hot, it can kill the yogurt culture).  Place the tablespoon of yogurt in a small bowl and set aside.

Pour the milk into the saucepan, clamp the candy thermometer on the side of the pan and set the pan over medium-high to high heat.  Heat, stirring occasionally, until the temperature reaches 180° F.  Turn off the heat and let cool to 110° F (stirring occasionally).  I should mention that I have an electric stove.  Consequently, when I turn the heat off, the temperature of the milk continues to rise as the burner cools—often reaching a temperature of 200°F.  I actually think this is a good thing.  I remember reading somewhere (I don't happen to remember where) that holding the milk at (or slightly over) 180° F for a few moments will help firm up the milk proteins, which will in turn help produce a thicker yogurt.  I have no idea if this is true or not, but allowing the milk to heat to 200°F (over the cooling burner) and then cool down more slowly than it would if I actually removed it from the burner has worked well for me—my yogurt is nice and thick.

When the milk has cooled down to 110° F, ladle a small amount into the bowl with the tablespoon of yogurt and stir with the rubber spatula until completely smooth.  Add more milk until the yogurt is of a pourable consistency.  Pour this mixture back into the warm milk (scraping with the spatula to get all of it) and stir well.  (I have learned since my last post that this is called inoculating the milk.) Pour the inoculated milk into the prepared jar and seal the jar (screw on the lid or put on the rubber ring and clamp the jar shut).  Place the jar in the cooler filled with warm water, adding or removing water so that the level of the water is even with the level of the inoculated milk in the jar.  (I actually always pour the water out that has been keeping the cooler warm and start with fresh warm water...simply because my cooler doesn't do a great job of keeping the water warm enough and I want to start the yogurt culturing process no lower than 115° to 120°--I use my instant read thermometer to check the temperature.)

Close the cooler and let the yogurt sit undisturbed for at least five hours.  At the five hour point you should have yogurt. It will be obviously set (tilt the jar slightly to check—but don't jostle it too much). The longer you allow it to stay in the warm water, the sharper the yogurt will taste. I prefer mine at about six hours, but you can let it go even longer. 

Remove the jar from the cooler.  Dry the outside of the jar with a towel, open the jars and wipe the condensation off the inside of the lid.  Place the yogurt in the refrigerator and let it cool with the lid off.  When thoroughly chilled, close/cover the jar.

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