Buttermilk has always been my preferred liquid in baking, especially cupcakes and muffins. It is rich and creamy (but the fat content is actually lower than whole milk). It yields tender and moist cakes with a tangy edge.
Traditionally, buttermilk is the liquid left over after fermented cream is churned into butter. Traditional buttermilk is supposed to be a very delicious and refreshing drink (per Alton Brown’s podcast – Hugh Acheson episode, we’ll just have to take his words for it) with many health benefits. However, today commercially available buttermilk is low fat or nonfat milk that has been inoculated with a bacterial culture to simulate the naturally occurring bacteria in the traditional product. The bacteria convert lactose found in milk into lactic acid and increases the acidity of the milk, which lends buttermilk both its thickness and tartness. Some dairies add yellow flecks to cultured buttermilk to simulate butter flecks left over from the churning process. You may be able to see the yellow flecks in the pictures above and below. Culture buttermilk may not be very delicious to drink, but it sure makes some delicious cakes.
From the previous food facts posts, we know that baking is very much a science, and acidity plays quite an important role. Gluten protein is what gives baked goods their structure and acid can alter the quality of gluten. Acidity in the dough increases the number of amino acids along the protein chains. These amino acids are positively charged, which increases the repulsive forces between chains and weakens the gluten network (Harold McGee’s On Food and Cooking: The Science and Lore of the Kitchen). Thus, buttermilk plays a part in inhibiting gluten formation which then yields tender and moist crumbs in cakes and muffins.
Not only that, buttermilk also plays a role in leavening baked goods. Since it is acidic, baking soda is the leavening agent on choice in buttermilk batter. Baking soda and lactic acid react to produce carbon dioxide which helps buttermilk baked goods rise. More on how baking soda and baking powder works can be found here.
In a pinch, if you run out of buttermilk or just don’t have any on hand, you can make acidified buttermilk by mixing 1 tablespoon of lemon juice or vinegar with 1 cup of milk. Let it sit for about 10 minutes until it curdles. Milk of any fat level can be used, but whole milk is usually used for baking.
I know it’s a pain to have so much left over buttermilk when you only want to make a batch of muffin. But due to its acidity, buttermilk has good staying power and will last three to four weeks in the fridge. I’ve used buttermilk past its printed expiration date without any problems. However, please use common sense as with any food, check the texture and smell (may be more difficult to tell here), if it is grainy or clumpy, it is probably bad. When in doubt, toss it, better be safe than sorry.
Try some of my recipes using buttermilk here:
Happy Friday and have a good weekend, friends! And I am off to a Dodgers’ game tonight, fun times!