PepsiCola has worked with flavor research firm Senomyx since 2010 to develop sweeteners and other flavorings.

Based in San Diego, Senomyx has been accused of using proteins derived from human embryonic kidney cells in its research, which has been used by many large food companies. An article in the Miami New Times summarizes those claims, notes the company’s denial of them — and also notes that in 2003, the company filed a patent for “recombinant methods for expressing a functional sweet taste receptor.”

That patent, for what is essentially an automated taste test, was granted in 2008. It mentions HEK 293, or Human Embryonic Kidney 293, a widely available cell line that was originally cultured in the early 1970s from a human embryo in the Netherlands.