The best way to keep fresh food from spoiling on a backpacking trip is to wrap the perishables in plain brown paper bags or kraft paper. This allows air to circulate and kill the anaerobic bacteria responsible for the spoilage. Never wrap in plastic wrap, foil or zip locks, which should be reserved for dry foodstuffs. Be sure the veggies or meat is dry before wrapping. The paper can be used for scrubbing pots or starting fires after its role as packaging is finished.
It's important to consume perishables early and within a reasonable time frame on backpacking trips. Consider picking fresh food that take longer to spoil- like vacuum-sealed meats, dry, hard cheeses, root vegetables, and more. If you're in the frontcountry and have a car accessible, consider bringing a cooler with you to your campsite or storing food in a cooler in your car to prolong its freshness. If you're backpacking or camping in bear country, be very careful with how you store food, especially fresh food. When possible, keep it away from your campsite or your car, and consider storing it in bear bags, lockers, or canisters.
Tom Valone, Owner