How we tested

In the test kitchen, we go through 30 to 40 pounds of unsalted butter a week as we bake cakes and cookies, make frostings and pancake batter, and cook pan sauces, roast chicken, and sautéed vegetables. We use unsalted butter almost exclusively because the sodium level of the salted stuff can vary and we prefer to control the seasoning of our food.

But which unsalted butter is best? A few years ago, we decided it was Plugrá, a high-fat product with a luscious texture. At almost $12 a pound, though, it's expensive. Although Plugrá is sometimes worth the splurge, we wanted a butter that was affordable and convenient for everyday use.

We assembled seven national top sellers, priced from $4.49 to $7.58 per pound. Two were cultured, which means that flavorful bacterial cultures were added during production, and one of these butters was imported from Europe. The rest were domestic “sweet cream” butters. All were purchased in the user-friendly format familiar in America: individually wrapped ¼-pound sticks, sold in packs of two or four. All but one product had measurement markings right on the sticks; the outlier had markings on the box. Tasters sampled the butters in three blind tastings: plain, in pound cake, and in sugar cookies.

Understanding a Complex Process

To better understand our lineup, we first looked at how butter is made. Although it can be churned by hand, our butters were all made using industrial equipment. According to Better Butter (2012), a technical manual by Robert Bradley of the University of Wisconsin's Center for Dairy Research, it looks something like this: A tanker truck of cream arrives at the factory. The cream is tested and pasteurized. It's then tempered, a complicated process of raising and lowering the temperature that alters the structure of the cream's fat globules so the cream can be churned more effectively. In the production of cultured butter, the bacterial cultures are added at this point.

Next, during churning, the cream crashes down on itself with enough force to burst the membranes that surround the fat globules and help keep them separate. The bits of fat begin to clump together, eventually forming a solid mass of butter. The liquid (now buttermilk) is drained, and then the butter is rinsed. At this point, additional ingredients may be added, including preservatives such as salt for salted butter and lactic acid for most unsalted butters. The butter is “worked,” or kneaded, to incorporate the salt or lactic acid and to remove moisture. Once it's cohesive and has the desired moisture level, it is portioned and packaged.

It's a Good Time for Butter

We were pleased with the quality of the butters in our lineup; in fact, we recommend every product we tasted. Marianne Smukowski, an expert on food safety and quality at the University of Wisconsin's Center for Dairy Research, attributed the good scores across the board to two factors. First, even though butters have different grades on their packaging, they're all made with good-quality cream. Second, modern churns work very well and produce very good, very consistent butters.

Some Are Tangy, Grassy, or Extra-Buttery

There were some noticeable flavor differences among the products, especially with the two cultured butters, which were complex, with “grassy,” “tangy,” “floral,” and even “cheesy” notes. The culturing adds distinctive aromas and flavors to the butters—much like the cultures used to make cheese. We also noticed a “movie theater popcorn” flavor that may indicate the presence of diacetyl, an aroma compound with an intensely nutty, buttery flavor. It exists naturally in sweet cream butter and can occur in high levels when cream is cultured.

The two cultured butters also stood out for their markedly darker colors, a possible indicator that the milk used to make them came from cows that grazed on lots of grass. The FDA recommends, but does not require, that butter labels state when food coloring has been added. Grass contains the yellow pigment and antioxidant beta-carotene, and if cows eat enough grass, beta-carotene makes it into their milk.

Why Packaging Matters

Packaging can also impact flavor, and all the experts we talked to agreed that the best way to prevent butter from picking up off-flavors is to wrap it in aluminum foil or special coated parchment paper. Four of the top five products in our lineup had this kind of packaging. Manufacturers wouldn't offer specifics on the parchment coatings, but they really seemed to work. The lower-ranked butters, on the other hand, had a slightly “stale,” “funky” flavor and hints of a “sour” aftertaste, indicating that their simple parchment paper wrappers were more permeable.

Our Favorite Unsalted Butter: Challenge Unsalted Butter

Chances are your supermarket carries several good-quality unsalted butters priced for everyday use. Although some of our panel loved the complex, tangy flavors of cultured butters, these products weren't our overall favorites. Instead, we preferred the simple, straightforward taste of sweet cream butter, with Challenge Unsalted Butter ($4.49 per lb) leading the pack. It had a “milky” “sweetness” and fresh dairy flavor. Its aluminum foil wrapper ensured that it tasted fresh and was free of off-flavors. For everyday cooking and baking, this convenient, affordable butter is our new top choice.

Methodology

We tasted seven top-selling unsalted butters, all sold in individually wrapped ¼-pound sticks, priced from $4.49 to $7.58 per pound. Panels of 21 tasters sampled them in three blind tastings: plain, in pound cake, and in sugar cookies. Information on wrappers, ingredients, and the cows' diets was obtained from manufacturers and/or product packaging. Fat is reported per 1-tablespoon serving. Prices were paid in Boston-area supermarkets. Scores from the tastings were averaged, and products appear below in order of preference.