For all the dairy in the Midwest, one product gets a lot more love elsewhere.

The product is buttermilk, and the elsewhere is the South.

Buttermilk adds a wonderful tang, along with moistness and a fine, tender crumb, to cakes and other baked goods. It produces the fluffiest pancakes. It mellows out the fishy flavor in a fillet when used as poaching liquid.

It also makes creamy salad dressings, extraordinary ricotta cheese, refreshing smoothie-style drinks — and is a fine facial cleanser to boot.

Yet per capita annual consumption of buttermilk nationwide is only about 1 ½ pounds a year, or just under 3 cups, according to the Wisconsin Milk Marketing Board.

One reason, no doubt, is the name. “Buttermilk” gives the mistaken impression that it’s high in fat, like butter. In fact, it is low in fat. Originally, it was the low-fat milk left over after butter was churned from whole milk or cream. Today’s commercial buttermilk is made from skim milk.

Consumers in the South wouldn’t care either way.

Although the South is not a prime dairy region, small farmers everywhere made their own butter, said Debbie Moose, author of a new cookbook, “Buttermilk” (University of North Carolina Press, $18).

Back before refrigeration, because of the extreme heat, the resulting buttermilk fermented quickly. Frugal Southerners used the buttermilk anyway and came to favor its tart flavor.

“Regular milk, what my mother called ‘sweet milk,’ was predominantly used in the North,” where fermentation doesn’t take place so quickly, she said.

Add to that the fact that making yeast breads “was never hugely popular in the South.”

“Southerners are more likely to make biscuits and corn bread and quick breads,” Moose said. In the 1800s, when baking powder and baking soda were invented, they needed an acid, and buttermilk, with its acidic profile, found a new role.

Classic uses for buttermilk include such Southern staples as corn bread, biscuits, fried chicken and poundcake. Pancakes and waffles are also typical uses, as are certain layer cakes, including red velvet and German chocolate. Buttermilk in the batter helps with the rising and adds moistness.

“If you’ve ever taken a recipe for buttermilk pancakes and substituted regular milk, you’ll see the difference,” Moose said. “The recipe will work, but the regular milk pancakes will be a little flatter and a little drier.”

And not as flavorful.

A redefinition

One important point: What sells as buttermilk in stores now isn’t “true” buttermilk. The first change from the pure product occurred in the 19th century with the advent of centrifugal cream separators, author Harold McGee writes in his food science book “On Food and Cooking.”

“This produced sweet, unfermented buttermilk, which could be sold as such or cultured with lactic bacteria to develop the traditional flavor and consistency,” he writes.

After World War II, an imitation “cultured buttermilk” was invented, he writes, made from ordinary skim milk — the same pasteurized, homogenized milk you buy at the store — and fermented until acid and thick.

What’s the difference?

“True buttermilk is less acid, subtler and more complex in flavor,” McGee writes. And it’s rich in valuable emulsifiers like lecithin.

You’d have to churn your own butter to find out for yourself. But what you can find is powdered buttermilk made from true buttermilk.

For 30 years, Saco Foods in Middleton, Wis., has been purchasing buttermilk from butter manufacturers and turning it into powder. Because it’s less processed (the buttermilk does need to be pasteurized), the company says Saco’s nationally distributed Buttermilk Blend retains the natural emulsifiers that yield those fine-textured foods.

“Fluid buttermilk, too, will have an effect [on foods], different from straight milk,” said Saco general manager Amy Verheyden. “But if you make the same recipe with fluid buttermilk and then with powdered, there really is a difference.”

To use the powder in baking or other batters, just mix it in with the other dry ingredients, then add the appropriate amount of water to the liquid ingredients. (Four tablespoons of powder plus 1 cup water equals 1 cup buttermilk.)

However, you’ll want to use fluid buttermilk for cold salads, dressings and the like, “anything that relies on the thickness of the buttermilk,” Verheyden said. “Liquid buttermilk contains live cultures, which makes it thick. If you reconstitute powdered buttermilk, you won’t get that thickness.”

Once opened, the powder should be stored in the refrigerator, where it will keep for several years.

Buttermilk tips

• You can substitute buttermilk for regular milk in just about any baking recipe, cup for cup — but some experts advise making sure the recipe includes at least ½ teaspoon baking soda per cup of buttermilk. If the recipe calls for only baking powder, replace enough of the powder with baking soda to meet this requirement.

• A little buttermilk substituted for some of the liquid in the batter of a baked good will prevent the blue discoloration you often get around cherries and berries such as blueberries, raspberries, blackberries and strawberries.

• Always shake fluid buttermilk before using.

• Because buttermilk is cultured, like yogurt, it will keep longer in the refrigerator than regular milk. However, it does not freeze well.

• Because buttermilk is cultured and fermented, it curdles easily when heated, more so than milk or cream. Avoid stirring it directly into very hot dishes, such as hot soups.

• A little buttermilk added to pie crust makes it tender.