One major move you can make toward food preservation is making sure your refrigerator's temperature is between 34 and 39 degrees, says Jill Houk, a former chef for large food companies and currently a food consultant on consumer packaged goods.
Keeping your fridge within perfect temperature range preserves foods the longest, without freezing your buns or broccoli. Then, store all leftover food in a container that fits exactly, as extra air in a container increases the chances for spoilage, Houk says. For example, place a cup of leftover, cooked carrots into a 1-cup container.