Nothing is quite as disappointing as unpacking your food bag and discovering good grub gone bad. Too much heat and hard time in an overstuffed pack can make crumbs out of your crackers, grow fuzz on your bagels, and transform a stick of salami into a bacteriological time bomb. But you don't have to suffer crushed or moldy food just because you're on a long hike.

So says Claudia Pearson, food-packing guru at the National Outdoor Leadership School (NOLS) and author of The NOLS Cookery. "The longest ration I've planned was 12 to 13 days, and it all came out edible." On those extended backcountry journeys, using good judgment (like not packing perishables in warm weather) is key to maintaining a healthy stash of food. Pearson adds these tips for keeping food edible.

These are good general tips, but I wanted to learn more: How would specific foods survive the rigors of the trail? To find out, I subjected 51 common backpacking foods to a week of packing in hot, humid weather (daily highs in the 90s). My mission: to determine which items would spoil, crumble, or melt fastest in typical summer conditions, and which would still be edible on day 8.

Breads

Take: Tortillas, bagels, pita, rye bread

Flour tortillas stayed mold-free longest. Bagels and pita breads held their shape better than sliced bread, but gradually became deformed.

Leave: Freshly baked white and wheat bread

These breads and English muffins broke into pieces; muffins spoiled first. Freshly baked baguettes turned soggy, then hard.

Cheese

Take: String cheese and Mini Babybel

Individually sealed packages were the clear winners, surviving 8 days without a spot of mold. Processed products tend to last longer than traditional cheeses due to their lack of animal-borne bacteria and microorganisms.

Leave: Shredded cheddar and farmer's cheese

An 8-ounce package of generic cheddar became a greasy orange disaster after 1 hot day. By midweek, the farmer's cheese had produced a toxic brown funk.

Meat

Take: Pepperoni sticks

Choose an unsliced stick over sliced pepperoni; it remained appealing until the end. Italian sausage and party bites were looking weathered by day 8, but remained mold-free and edible.

Leave: Bologna and salami

Maggots appeared on day 6. The salami, however, was the first to turn, becoming gray by the end of day 1.

Chocolate

Take: M&M's

Peanut, peanut butter, and baking M&M's looked as good on day 8 as they did on day 1. Plain M&M's got a bit sticky. Hershey's bars held up well despite being broken into chunks, and the bite-size Milky Ways were only slightly mangled (and still delicious) on day 8.

Leave: Chocolate chips

Chocolate morsels melted in the heat, then solidified into a crusty hunk.

Trail mix

Take: Dried fruits, nuts, and pretzels

These tasty old standards survived unscathed. Choose pretzel nuggets over thins-unless you like crumbs.

Leave: Granola and anything yogurt-covered

Granola's crunch was gone within 48 hours, and the yogurt coating on pretzels and raisins melted on day 2, after an hour of being left out in the heat. Double-bag and seal crispy snacks to keep crunch alive.

Cookies

Take: Animal crackers

Even after a week of jostling, zebras and giraffes remained recognizable. Mini Oreos leaked far less white frosting than anticipated, making them a great option as well.

Leave: Oatmeal raisin

Large, soft-baked cookies crumbled quickly. Small, dry cookies (like ginger snaps) stayed in one piece longer. Fig Newtons would have survived longer if I'd kept them in the original packaging.

Crackers

Take: Wheat Thins

These little munchies kept their crunch through day 8 with few broken pieces. Stoned Wheat Thins and Melba crackers also held strong.

Leave: Graham crackers

Forget about trying to make s'mores after 4 days. Fins and tails were all that were left of the Goldfish.