Paleo Approved Canning Recipes: Canning Recipes That Can Help You Maximize Your Fresh Produce All Year Round Canning is a preservation technique that aims to maintain the flavor of the fruit or vegetable. It is a safe method of packing jars with food and placing them in high temperature to kill any bacteria and organism that can cause it to spoil. Air is also forced out of the jar and a vacuum seal is created once the preserve starts to cool. This vacuum protects the food from being contaminated by microorganisms.