The Southern 1-Ingredient Upgrade for the Best Banana Bread

In my household, bananas are a staple. But as soon as their peels bruise, my family rejects them. That’s when I start baking, because the best bananas for banana bread are very ripe, with an intense, sweet flavor and a soft, mashable texture.

There’s another reason my banana bread is so moist and flavorful. I got this upgrade from an expert baker who inherited it from his Southern-born mom: buttermilk. It brings three superpowers to the job: tenderizing, leavening, and flavor. All are thanks to its acidity.

How Buttermilk Makes Banana Bread More Tender

“Growing up in the South, buttermilk was never questioned,” says my pal Ben Mims, author of Crumbs: Cookies and Sweets from Around the World. “It wasn’t until I tried making banana bread with regular milk that I understood that the acid in buttermilk is a tenderizer. Just as you would use it in marinade to tenderize meat, it creates a more tender crumb.”

Cultured buttermilk—the kind at the grocery store—is made by adding a bacterial culture to cream or milk. The culture ferments the milk, producing lactic acid, which breaks down proteins. The gluten in flour is a protein. When you add buttermilk to banana bread batter, it softens the gluten, tenderizing the crumb.

How Buttermilk Improves Banana Bread’s Taste

“I’ve tried making banana bread with regular milk, sour cream, and yogurt, but buttermilk produces the best flavor,” says Mims. Its tang contrasts deliciously with the sweetness of the fruit and sugar, yet it’s not as strong as sour cream or yogurt.

How Buttermilk Helps Banana Bread Rise

Baking soda is alkaline. If you use it in banana bread, you need its opposite. “Buttermilk is a source of acid,” explains Melanie Wanders, Research and Development Specialist at King Arthur Baking Company. “It reacts with baking soda to produce carbon dioxide.” The carbon dioxide yields a fluffy crumb and nice rise. I use 1/3 cup of buttermilk to 3/4 teaspoon baking soda.

Other leaveners work differently. Baking powder is a combo of baking soda and a leavening acid, so it has the reactivity built in. It doesn’t need buttermilk. Self-rising flour, which includes baking powder, is also lower in gluten than all-purpose flour, so it doesn’t absorb liquids as well. If you opt for it, use less buttermilk, or add a 1/4 teaspoon of baking soda to achieve a good rise.

Which Buttermilk To Use in Your Banana Bread

• Cultured, true, or homemade buttermilk? True buttermilk is the liquid leftover from churning cream into butter. It lacks the acid and body you want in banana bread. In “homemade” buttermilk—regular milk soured with vinegar or lemon juice—the citric or acetic acid is sharper than lactic acid, without its creamy flavor. Go with cultured buttermilk.
• Whole or low-fat buttermilk? Check the label. When you churn cream, the fat ends up in the butter, so true buttermilk is low-fat. Kate’s, the cultured buttermilk I like, is churned from cream, then inoculated, so it’s thick, preservative-free, and naturally low-fat. The fat in cultured whole buttermilk can yield a more tender bread, but whole buttermilk is harder to find, and many contain emulsifiers and fillers.
• Cold or room temp? Temperature won’t affect leavening or flavor, says Wanders, but if you’re using softened or melted butter, cold buttermilk can make it seize up, resulting in a grainy texture.