Chips and Air: Why Your Favorite Snacks Are Always Half-Full

If you are a snack lover, you have probably been disappointed at least once when you open up your bag of delicious chips and see it is only half (or even a third) full.

But, despite the disappointment that many face, experts like Joe Schwarcz, a chemistry professor at McGill University, say there’s actually a good reason for this— and it is not because of inflation.

“There is actually a reason why the bag looks the way that it does and why as soon as you open it, you hear as the air comes out. Well, it isn’t actually air. It’s pure nitrogen,” Schwarcz said.

According to Fred Caporaso, professor of food science at Chapman University, companies choose nitrogen to fill their snack bags because the gas is inert, meaning it doesn’t react with anything else, whereas the oxygen that it’s in the air will react with the oil in the chips, thus causing them to go rancid quickly.

This is why unopened bags of chips are still fresh two to three months later, thanks to nitrogen, Caporaso added. 

Ok, but now, why do companies put so much nitrogen in the bags? 

According to Caporaso, companies do this to avoid crushing any chips in the bag-sealing process. 

“You don’t want to have any chips to sit in the seal, which wouldn’t seal correctly,” Caporaso said. “So you have what we call ‘head space’, which is space where there’s no chip, but there’s air in there.

In addition to shelf-life, Schwarcz says chips are full of air to protect them from all the transportation they go through before they hit the store and then, your mouth. 

“These poor potato chips go through a rough travel schedule as they make their way from the producing facility to the store,” Schwarcz said. “They are jostled about and we don’t want to end up with a bag full of powdered potato chips. So the nitrogen in there actually acts as a cushion.”

So next time you go grab your favorite snack, remember that chips are sold by weight. 

“If you look at the weight on the bag and you can get yourself a scale and weigh it, you’ll see that the chips weigh exactly what it says on the bag,” Schwarcz said. “There are a lot of food scams out there, but this is not one of them,” he concluded.