Often times, we open a bag of potato chips and, surprise, it’s half empty, even though it looked totally full because it was actually full of air. However, this strategy is not the fruit of marketing. It is actually somewhat more complicated and has to do with the preservation of the potato chips themselves.
Being half empty, the bags can be filled with air, but with a very special air, an atmosphere that protects the potato .
Light and oxygen
Potato chips and other similar snacks easily go rancid when exposed to light and oxygen. To avoid this, opaque bags are used that serve as a barrier to light.
In addition, inside there is a protective atmosphere: the air is replaced by a mixture of gases that protect the product, as explained by Miguel Ángel Lurueña in his book Que no te bundle con la comida :
In the specific case of French fries, nitrogen is normally used, which is a colorless, odorless, tasteless and inert gas, that is, it does not react with other compounds and is safe for health. To make this protective atmosphere effective, the ratio between the volume of gas and the volume of food must be equal to or greater than two, which explains why there is so much "air" in the bags and so few potatoes. By the way, this protects the product against breakage by impact or crushing, that is, it serves as an "airbag".