Nourish with science: Why do they sell bags of potatoes full of air?

By Paula Guerrero

No, the bags of chips are not full of air – the myth of the ‘chips fraud’

Resultado de imagen de bag of chips 100 air gif

The situation is more than recurring. The stomach roars, the hunger tightens, and you, starving, decide to go to the vending machine of work to catch some food. Among the nonsense foods that you see behind the glass, you decide to drop that insane bag of chips that has caught your attention. With it you intend to calm your voracious appetite. However, when you open it, the same feeling of anger that appeared the last time you bought those Cheetos Gang returns to seize you: approximately half of the bag is full of “air”. “What a scam!” You curse. It’s a deflating feeling: you open a bag of crisps, and the air rushes out, leaving a few underwhelming crumbs at the bottom of a huge packet.

Bags of crisps are filled, not with air, but with nitrogen to keep them fresh

Yes, we can say it is full of “air”  (air is composed of 78% nitrogen, 21% oxygen and 1% CO2) This method of preservation allows to prolong the useful life of the product until 4-6 months, avoiding also the use of additives that have such a bad reputation.

In most foods the main concern when preserving its qualities is centered on the possible growth of microorganisms capable of causing alterations or causing diseases (especially bacteria and molds). However, this is not a problem in French fries because they have low water activity, they do not have enough for microorganisms to develop. This is so if the product does not pick up moisture from the environment, in which case not only would its safety be compromised, but it would also adversely affect its flavor and, above all, its texture: “the potatoes would soften and stop being crispy” said Miguel Ángel Lurueña, a doctor in Food Science and Technology , on behalf of an article in El Mundo Today. Therefore, humidity is one of the elements that must be taken into consideration when preserving the product.

To prevent the humidity of the environment from altering the characteristics of the potato chips, what can be done is to use hermetic containers formed by materials that act as a barrier to water vapor, such as a plastic bag. However, this is not enough to keep the product intact because there are other elements that can also damage it. Among the most important are light and oxygen, which are responsible for causing the oxidation of fats, a phenomenon that causes the development of rancid odors and flavors and alterations in color, as well as the deterioration of certain nutrients ( polyunsaturated fatty acids and fat-soluble vitamins) and the formation of potentially toxic compounds. In other words, eating rancid potatoes is not only unpleasant because of its bad taste, it can also negatively affect our health.

The purpose of the container is to protect the food from deterioration with a protective atmosphere

“What we find inside different types of food products is a protective or modified atmosphere, whose gas composition varies according to the type of food in question,” explains food technologist and disseminator Mario Sánchez (aka Sefifood) “In the case of chips, a very high concentration of nitrogen is used, since oxygen causes the rancidity of fats and, therefore, worsens the organoleptic characteristics”, adds.

Therefore, to protect fried potatoes it is necessary to use a container made of a material that acts as a barrier against light, oxygen and humidity. But not only that. In addition, you must meet a series of mechanical skills (resist tearing and tensile forces, be able to close with the application of heat, etc.), commercial (must be suitable for printing, easy to open, attractive, etc.) and of another type (it must be economic, light, inert, etc.). As it is difficult for a single material to fulfill all these characteristics simultaneously, what is usually done is to use a structure formed by multiple layers with sheets of different materials, such as polypropylene and metallized polypropylene, which serve as protection against light and prevent diffusion of gases (water vapor, oxygen, etc.).

We must not forget that the moment we open a bag of chips packed in a protective atmosphere, the leakage and protection offered by the gases that were contained inside are lost, so the product is exposed to moisture, oxygen and, if we’re not careful, in light, which are the riders of the apocalypse of the potato chips.

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