Making chemicals kosher

In the world of processed foods, keeping kosher is a complicated process that can involve individually certifying as many as 100 chemical compounds just to make a single flavoring agent that meets kosher standards.

The problem is where the compounds come from. In the 1930s, Atlanta-area Rabbi Tobias Geffen was asked to help make Coca-Cola kosher. In the process, he realized that glycerin, a chemical additive used to disperse flavors evenly through the soda, was made from rendered animal fat—and there was no clear way to tell whether the fat came from a kosher animal. Geffen decided that even the molecules mattered. Coca-Cola made their kosher brew with cotton-seed oil glycerin instead, and other rabbis have followed Geffen's lead.

Today, you can spot kosher-for-Passover soda by the distinctive yellow cap. In this case, sucrose subs in as the sweetener, in place of corn syrup, as corn is a banned grain during the Passover holiday.