Supermarket Frozen Yogurt
From Cook's Illustrated | July/August 2014
These days, supermarket frozen yogurts are flying off the shelves. Is that because they’re healthful and taste good—or because they simply sound that way?
Frozen yogurt has had its ups and downs since it debuted in the 1970s, but its recent comeback has been big. Sales of the low-fat ice cream alternative jumped 74 percent between 2011 and 2013 to rake in a total of $486 million. That’s a staggering increase compared with the numbers for ice cream, which, though it still outsells frozen yogurt by more than 12-fold, grew about 4 percent. But the growth isn’t hard to explain. By implying that their products have the indulgent taste of ice cream but still offer many of the same nutritional benefits as refrigerated yogurt, frozen yogurt manufacturers have convinced a growing population of health-conscious consumers that they’re not sacrificing that much by switching to the dessert—and might actually be doing themselves a favor by eating it. We wanted to judge for ourselves whether the huge popularity of this current generation of supermarket frozen yogurts is warranted, so we scooped up eight of the best-selling national products, both low-fat and nonfat versions, in the most… read more
Frozen yogurt has had its ups and downs since it debuted in the 1970s, but its recent comeback has been big. Sales of the low-fat ice cream alternative jumped 74 percent between 2011 and 2013 to rake in a total of $486 million. That’s a staggering increase compared with the numbers for ice cream, which, though it still outsells frozen yogurt by more than 12-fold, grew about 4 percent. But the growth isn’t hard to explain. By implying that their products have the indulgent taste of ice cream but still offer many of the same nutritional benefits as refrigerated yogurt, frozen yogurt manufacturers have convinced a growing population of health-conscious consumers that they’re not sacrificing that much by switching to the dessert—and might actually be doing themselves a favor by eating it. We wanted to judge for ourselves whether the huge popularity of this current generation of supermarket frozen yogurts is warranted, so we scooped up eight of the best-selling national products, both low-fat and nonfat versions, in the most straightforward flavor: vanilla. Whether a frozen yogurt had the flavor of traditional vanilla ice cream or the tartness of a refrigerated yogurt, we wanted it to deliver a rich, creamy texture and clean, not-too-sweet flavor.
Before we dug in, we did a little research into how much these frozen desserts have in common with refrigerated yogurt—and it turns out, that’s a very tricky question to answer. The U.S. Food and Drug Administration (FDA) has only a loose definition for refrigerated yogurt, and none whatsoever for frozen yogurt. In fact, the FDA doesn’t even regulate how many live and active cultures the refrigerated product should contain—and of course, the presumption that yogurt contains a significant dose (specifically of Lactobacillus bulgaricus and Streptococcus thermophilus) is the main reason it’s considered a health food in the first place.
We concluded that it’s best to take the label “yogurt” on frozen yogurt packaging with a grain of salt, along with mentions of live and active cultures on the ingredient list. Even if a frozen yogurt starts out with lots of bacteria, that doesn’t mean those bacteria will make it through the manufacturing process. For example, heat-treating the dairy after culturing (a practice used to prolong shelf life or reduce tartness) will kill off virtually all the bacteria—and since there are no regulations for frozen yogurt, manufacturers aren’t required to tell you what they’ve done. What’s more, even if a frozen yogurt hasn’t been heat-treated, the vast majority of bacteria that it contains before it’s frozen is likely to die off during freezing. According to Donald Schaffner, extension specialist in food science, director of the Center for Advanced Food Technology, and professor at Rutgers University, “It’s possible, or even likely, that the freezing process might kill off anywhere from 90 to 99 percent of bacteria.”
These aren’t the only reasons to doubt frozen yogurt’s value as a “healthy” dessert. While the product is generally much lower in fat compared with ice cream, it often contains nearly as much sugar. Most frozen yogurts are also loaded with a laundry list of additives and stabilizers that don’t make their way into high-quality refrigerated yogurt or ice cream.
Those considerations aside, there’s no denying the huge popularity of frozen yogurt, so we carried on with our tasting to see if any of the supermarket products offered at least good flavor and texture. But even the news on that front wasn’t great. With a few exceptions, the yogurts either tested our tolerance for sweetness or exhibited odd off-flavors. Even more damning were their textures—no surprise, since when you remove fat from a frozen dairy product, it becomes more difficult to attain an ultrasmooth consistency. We could tell just by looking that some products were rock hard, while others were fluffy like whipped cream cheese. The better brands achieved “smooth,” “light” creaminess thanks to a few key components. The first: corn syrup. Corn syrup inhibits iciness by restricting the movement of the water molecules so that they are less likely to link up and form large crystals. Corn syrup also depresses the freezing point of frozen yogurt, which makes it less vulnerable to the constant thawing and refreezing involved in transporting a frozen dessert.
Stabilizers also help stave off ice crystal formation and boost the perception of creaminess. In fact, their role is even more crucial in frozen yogurt than it is in ice cream, since frozen yogurt’s lower fat and higher moisture contents make it especially vulnerable to ice crystal formation. Some stabilizers, like carrageenan, are particularly effective. When combined with milk protein, this polysaccharide forms a custardy gel so strong that it replicates the texture of cream. The combination of carrageenan and corn syrup worked so well in one fat-free yogurt that the “soft,” “smooth” product earned our recommendation. (The “gritty” textures of the other two fat-free yogurts moved them to the bottom of the chart.) But without corn syrup, carrageenan was unable to save another product, which tasters found “sludgy.” It was also easy to spot the lone stabilizer-free frozen yogurt, a product that went from rock hard to soup in minutes.
The Importance of Air and Cream
Another core, but less obvious, component of the texture of frozen desserts is air. Manufacturers aerate their products to increase the overall volume and to produce a lighter texture. “Overrun” refers to the percentage increase in volume from aeration, and by law it can be as high as 100 percent in frozen desserts. If that sounds like a cheap way to get consumers to pay more, it is—and the overrun in some of the yogurts we tasted ran as high as 78 percent. Some overrun is a must in frozen desserts, particularly lean frozen yogurts; without air, they would be rock solid and virtually inedible.
Finally, cream might sound like an unlikely ingredient in a low-fat dessert like frozen yogurt, but even in small quantities it made a big difference. Besides adding richness, it introduced additional milk solids, which decreased moisture and minimized potential ice crystal formation. It also boosted vanilla flavor, since vanillin (the flavor compound in vanilla extract) is largely fat-soluble.
Not surprisingly, the two frozen yogurts that tasters favored most each contained a combination of corn syrup, carrageenan (among other stabilizers), and cream. Tasters enjoyed both the “straightforward vanilla” flavor of one brand and the recognizable yogurty “tang” of another.
But even these frozen yogurts didn’t elicit anything close to the rave reviews of a great ice cream—or a great fresh yogurt. Nevertheless, if you’re looking for a low-fat frozen dessert with decent texture and reasonably good flavor (that may or may not be full of healthy bacteria), any of our recommended yogurts will do.
Twenty-one America’s Test Kitchen staff members tasted eight top-selling supermarket vanilla frozen yogurts. We rated the products on flavor, texture, and overall appeal. Fat and sugar per 1/2-cup serving were taken from package labels. An independent laboratory calculated overrun, listed as a percentage increase over the original volume of the frozen yogurt base. Results were averaged and frozen yogurts appear below in order of preference.