How active are the microorganisms in your yogurt? We created a new tool to study probiotic activity — and made it out of cardboard

Fermented foods can be a good source of probiotics. Yulia Naumenko/Moment via Getty Images

Humans have been fermenting food and drinks — everything from kimchi and yogurt to beer and kombucha — for more than 13,000 years.

Fermentation – a natural process that uses microorganisms to create alcohols and acids from carbohydrates – can preserve food so it lasts longer, and it can enhance the quality of a food by turning some components into more easily digestible forms.