If you have a good machine, such as our winning countertop model, the Nesco Deluxe Vacuum Sealer ($90), vacuum sealing food is quick and easy. Here’s how they work: Vacuum sealers typically come with a starter set of plastic bags, after which you buy more separately. You place the food you want to seal inside the bag, taking care to keep the top of the bag clean because food reside can prevent the bag from sealing tightly. Next, open the machine’s lid and position the bag. It goes over the seal bar and inside a small chamber ringed by a foam gasket. Shut the lid and press or lock it into place following the manufacturer’s directions. A port inside the machine pulls air from the bag and the seal bar heats up and melts a narrow strip across the top of the bag, sealing it shut. If you follow that basic method, plus our tips below, your food will last much longer than it will in conventional zipperlock bags or storage containers.