Sunday, January 15, 2012

Sour Milk

Not far from my hometown is a small stream called the Sweet Milk Creek. I suspect that it was named such  --  or more likely the Zoete Melk Kill *  --  by early Dutch settlers in what is now Rensselaer County. The creek was perhaps so named because of the foam created when the water ran rapidly over the rocky creek bed. It is a popular trout stream, and a tributary of the Poestenkill, which empties into the Hudson River near Troy, New York.

The name of this creek conjures up bucolic scenes of cows grazing peacefully in grassy pastures. At the end of the day, they trudge slowly into the barn to be milked. But what happens if their sweet milk is left too long without refrigeration? If you have ever poured such milk into your morning coffee, you know exactly what has happened the moment your lips (or nose) get a sip or a whiff: it has turned sour.

What causes this "turning" of milk? It is a chemical reaction that occurs when the bacteria in milk consume the milk sugar (or lactose) and produce more bacteria. Over time, the resulting by-product is lactic acid, which gives the milk its sour taste. Pasteurization kills much, but not all of the bacteria. So if you keep your milk too long, even in the refrigerator, it will eventually turn sour.

Of course, in the early days before artificial refrigeration, milk had to be consumed promptly, otherwise it would turn sour more quickly than it does today in our fridges. What was one to do then, if it did go sour? Not to be wasteful, housewives developed recipes to use it up somehow, as in Minnie's recipe for Sour Milk Cake:

Minnie's Sour Milk Cake Recipe

Minnie got the recipe from her mother, Kittie Van Slyke ("Grandma Nan"), who also passed it along to my mother. As you can see from Mom's handwritten notes, she tried it out and adapted it as she saw fit:

Mom's recipe  -- from Grandma Nan

The ingredients are basically the same; since they do not include instructions, Mom figured out her own steps. Note how, similar to last week's Nut Cake recipe, the baking soda is dissolved in the milk, rather than being sifted into the flour. I don't know the rationale behind that technique, but it seems to work out.

If you need more detailed instructions, here is how I did it. I usually reduce the amount of sugar in a made-from-scratch cake recipe, and that turned out fine as well:

Sour Milk Cake

- 2 cups flour
- 1 teaspoon baking soda
- 1/4 teaspoon nutmeg
- 1/4 cup butter, margarine, or baking sticks
- 1/2 cup sugar
- 1 egg
- 1/2 teaspoon vanilla (optional)
- 1 cup sour milk

Pre-heat oven to  350 degrees Fahrenheit; pre-sift flour.
Grease and flour an 8 inch cake pan.
Sift together flour and nutmeg; dissolve baking powder in milk.
Cream butter and sugar; beat in egg.
Add milk and flour mixtures alternately, beat just until mixed.
Pour batter into cake pan and bake until toothpick comes out clean, approximately 20 minutes.

Although the cake's consistency is a bit denser than that of a cake from a mix, your guests will never guess that its ingredients include sour milk. The sourness is not evident, and the oven's heat kills the bacteria that soured the milk.

Sour Milk Cake - fresh out of the oven

And in case you're wondering: If you don't have any sour milk, what to do? You can turn sweet into sour by pouring a tablespoonful of vinegar or lemon juice into your measuring cup, adding enough milk to make one cup, and leaving the concoction at room temperature for about 15 minutes. This technique will produce the same chemical change as Mother Nature. 

* Note: "kill" is an archaic Dutch word for "creek"; there are many such named streams in the area of Upstate New York settled by the Dutch in the 17th century: Normanskill, Wynantskill, Poestenkill, Lisha Kill, Fishkill, Wallkill, Stony Kill, Sanders Kill, Peters Kill, Swarte Kill, Kleine Kill, Platte Kill, and believe it or not, Beer Kill. ( I suspect that this last one really means "Bear Creek," as the Dutch word for "bear" is spelled "beer.")

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