The mysterious companies behind Costco's Kirkland Signature and Trader Joe's O's

Kirkland Signature. Two-Buck Chuck. Simple Truth. Cat & Jack. Great Value. Amazon Basics. Store brands have never been more popular.

They have become forces in their own right and make up around 21% of sales in the $1.7 trillion US grocery industry, according to IRI.

As prices surge, store brands -- also known as private labels, white labels or generic brands -- have become an even more attractive option for inflation-fatigued shoppers who are looking to switch from pricier name brands. Store brands can be anywhere from 10% to 50% cheaper.

But the origins of store brands remain largely secretive.

Retailers aren't typically forthcoming about the companies that make their brands. And manufacturers, likewise, have little incentive to reveal that they're creating similar products to their name brands under a different label sold on the cheap.

Many leading national brand manufacturers create private labels for multiple retailers. In the late 1990s more than half of brand manufacturers were estimated to make private goods as well.