If better tasting food and preventing food waste is important to you, a vacuum food sealer is one of the best kitcen investments one can make. Vacuum foodsavers work by eliminating air and oxidation. When exposed to air and heat, food oxidizes. Oxidation changes the chemical composition of food. It not only affects the taste and nutrional value of food, it can cause fats to go rancid. Not only does bottled oil go rancid, but it can go rancid in baked goods and nuts too. Last but not least, the ingestion of rancid fats may be connected to coronary heart disease and atherosclerosis. .