And the Best Gluten-Free White Sandwich Bread is . .

Gluten-free bread may be a multi-billion-dollar industry, but are there any slices actually worth eating? The editors of Cook's Illustrated investigated.

When you're avoiding gluten, it's tough to give up toast and sandwiches. Enter gluten-free bread: a multi-billion-dollar industry that's rapidly expanding as the trend of avoiding gluten for dietary reasons continues to grow. Hoping to find a loaf that was a serviceable alternative to (not a sacrifice compared with) regular sandwich bread, we tasted eight national brands of gluten-free white sandwich bread both plain and toasted with butter.

Almost all of the breads were very unappealing straight out of the packaging. Toasting and buttering turned a few inedible samples palatable, but most were still subpar by our sandwich bread standards. The exception: our winning bread, whose "light wheatiness" and "yielding" chew were impressively close to that of regular white bread. So what was this manufacturer doing differently?

First we reviewed how gluten works in bread. When the proteins in wheat flour (and other grains like barley and rye) are combined with water and kneaded, they link into a network that strengthens dough. This linked structure helps baking bread trap gas as it rises, allowing the loaf to expand and achieve a lighter, springier crumb and satisfying chew.

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Replacing gluten is tricky because alternative flours don't contain these structure-building proteins. However, when we compared the nutrition labels on all eight loaves (to make even comparisons among samples with different serving sizes, we converted all nutrition values to base them on a 100-gram serving), we noticed that our winner contains far more protein than do competing breads -- as much as 72 percent more. Its source? Lots of protein-rich egg whites. Like gluten, egg whites build structure by trapping air in the baking bread. Our gluten-free winner also adds chemical leaveners and, of course, yeast, which contribute to more lift, and a goodly amount of salt (our favorite regular sandwich loaf contains 43 percent less sodium), which boosts flavor.

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We also looked into why gluten-free breads are sold from the freezer case. It turns out that most products are high in moisture (as much as 55 percent compared with roughly 36 percent for regular sandwich bread) and starch -- qualities that make them stale easily due to a process called retrogradation. The more water and starch in the bread the more susceptible its starch molecules are to moving around and crystallizing (trapping water inside the crystals), which renders the crumb dry. Freezing halts the staling process since the frozen starch molecules can't move around. (The lone product that wasn't frozen came vacuum-sealed with a sell-by date six months away.) What's more, gluten-free bread turnover in supermarkets is slow, so freezing makes sense.

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If you're looking for a gluten-free option, our winner has clean, yeasty flavor and a moderate amount of chew, making it the best -- and only worthwhile -- alternative to regular sandwich bread.

WHO WON? VIEW THE WINNING GLUTEN-FREE BREAD AND FULL RESULTS

This taste test was originally published in Cook's Illustrated magazine. Subscribe today and get a free gift. Our magazines are also available in mobile and tablet editions.