The Real Thing: How Coke Became Kosher

Detail from Coca-Cola ad, 1939. In 1935 Coke began using vegetable-derived glycerin in some of its soda in order to comply with kosher law. (Courtesy the Coca-Cola Company)

Detail from Coca-Cola ad, 1939. In 1935 Coke began using vegetable-derived glycerin in some of its soda in order to comply with kosher law. (Courtesy the Coca-Cola Company)

Separation Anxiety

Controversy erupted again in the 1950s when rabbis discovered that the vegetable-derived glycerin used to make kosher Coke traveled through the same piping system used by nonkosher glycerin in Procter and Gamble plants. Their concerns stemmed from an important kosher principle known as blios—literally, taste—that applies to the materials touched by food and food ingredients.

Blios generally refers to the residue—however minute—left by food on the surfaces it touches and how that “taste” could transfer to later batches of food that touch the same surface. The commonplace practice among observant Jews to maintain separate dishes, pots, and utensils at home for milk and meat meals stems from a concern about blios. The rabbis who were uneasy with Procter and Gamble’s glycerin-production methods applied the same principle to the containers, surfaces, pipes, and any other places that allowed for the transfer of nonkosher glycerin residues to kosher glycerin. By that standard the glycerin used in Coke was not kosher, even though it came from vegetable oils, because it had been contaminated by the glycerin derived from nonkosher animal fats.

Doubtless this subtlety in kosher law escaped the Procter and Gamble and Coca-Cola executives who were sincerely trying to observe kosher requirements. Indeed, the affidavits obtained by Rabbi Geffen were truthful since the glycerin had been made from cottonseed oil. Procter and Gamble probably never worried about the details: from a conventional manufacturing perspective the animal fats–derived glycerin in the pipes was the same chemical as that produced from cottonseed oil, and so there were no ill consequences. The companies, even if mystified by the concept of blios, nonetheless went along with the rabbis’ requirements. Procter and Gamble defused the controversy by spending $30,000 to construct a parallel piping system to separate the glycerin that was kosher from the glycerin that was not.

This final episode brought to a close Coke’s importance as a precedent in the creation of kosher food: it unmistakably established that all equipment coming into contact with kosher food must remain uncontaminated by nonkosher materials. Just as Geffen’s stand on ingredients imposed stringent requirements for what could be included in kosher processed food, so too did the rigorous application of blios establish a high standard for how firms would control and regulate the production of kosher-certified food.

Seal of Approval

The creation of kosher Coke—along with other efforts to make processed foods kosher—had an even more profound effect: Orthodox rabbis realized that they needed to learn chemistry if they were to effectively supervise the production of modern kosher food. Understanding 2,000 years of kosher law was not enough. By the late 1950s knowledge of chemistry and of food manufacturing was integral to the process of certifying kosher food.

This knowledge has since become incorporated into the certification of kosher food in various ways. It is now possible to speak not only about kosher chemistry but also about a new generation of kosher chemists. In many cases rabbis have learned chemistry specific to the areas of food that they certify, such as oils or wine. Certification organizations often employ chemists and food scientists as consultants to advise them on the certification process. In a few cases rabbis have themselves obtained advanced scientific degrees. The president of Star-K Kosher Certification, Avrom Pollack, has a rabbinic ordination and a doctorate in cell and molecular biology.