Kosher Glycerin

In the world of food ingredients, no ingredient is as versatile as glycerin. In the world of Kosher-sensitive food ingredients, none is more sensitive than glycerin. Glycerin's versatility is not limited to food-grade applications; glycerin is also widely used as a key ingredient in the pharmaceutical and cosmetics industries.

Glycerin is known as a humectant. This means glycerin helps retain moisture. Therefore, glycerin is a wonderful ingredient that keeps baked-goods products moist and gives them a longer shelf life. Glycerin is sweet and can serve as a substitute for liquid sugar. Glycerin is an excellent solvent and is used as a key ingredient in food coloring. These properties make glycerin an important ingredient in countless food applications.

In addition, glycerin's natural properties make it an essential element in pharmaceutical products and health-and-beauty aids. What is that sweet syrup base used in over-the-counter cough medicine? Glycerin. What is the basic ingredient in many mouthwashes and toothpastes? Glycerin. How about soap and shampoo? You guessed it... glycerin. In fact, there is an article listing more than 1,500 uses of glycerin!

In the Kosher/non-Kosher world, glycerin ranks first among sensitive substances. Glycerin can be produced naturally from plant or animal sources, or refined synthetically from petroleum. It can be produced as Kosher or Treif, and also as year-round Kosher or Kosher LePesach (for Passover).

What is glycerin? How is it derived or produced? What makes it so sensitive for Kosher?

Glycerin or glycerol is a term derived from the French word "glycerine," or from the Greek term "glykeros," meaning "sweet." Glycerin occurs naturally in the human body as well as in vegetables and animals. Glycerin is known as a lipid. A lipid is a fat found in humans, animals and vegetables, and glycerin is part of this lipid.

Believe it or not, in 1799, the pharmacist Carl Scheele discovered glycerin by chance. Scheele mixed olive oil and caustic soda at high temperature, and the result created a new material. The free fatty acids combined with sodium to form what is called "soap stock," the basic component of soap production. This soap-making process and its by-products are usually called saponification, the method used to produce soap. The by-product of this reaction is crude glycerin, which today is more of a main product than just a by-product.

Saponification is not limited to plant-based products such as olive oil, palm oil or coconut oil. It can also be achieved using lipids such as tallow or lard. Separating animal-based triglycerides with caustic soda has the same result, producing animal soap stock and animal-based glycerin.

Interestingly, in the oil-refining field, when crude olive oil or crude vegetable oil is required, the first stage of the refining process is called "neutralization." When caustic soda is mixed with unrefined oil, neutralization of acidity is achieved. In this case, the caustic soda can remove a very small amount of free fatty acids, thereby reducing acidity, while keeping the triglycerides and glycerin in the olive oil intact. Experts say the difference between saponification and neutralization depends on the amount of caustic used plus the heat applied to the oil. No heat plus caustic equals neutralization, and the oil remains intact. High temperature and a large amount of caustic cause saponification, where the glycerin molecule splits.

Another method used to produce glycerin is called transesterification, in which methanol and acetic acid are used as extractants to combine with lipids to form many components. Glycerin is one of the by-products. This process is usually called biodiesel extraction. Depending on the starting material, whether plant or animal, the result will be Kosher or non-Kosher biodiesel and Kosher and non-Kosher glycerin.

A few years ago, Kosher certifiers were concerned about one thing: even in vegetable transesterification, there was a major issue, because using waste vegetable oil from McDonald's (and other similar sources) as the starting material for biodiesel would produce non-Kosher vegetable biodiesel and non-Kosher glycerin. Clearly, if this method of producing biodiesel from waste oil became cost-effective, Kosher glycerin would sell at an ultra-high price, further complicating the Kosher glycerin market.

A third method used to produce crude glycerin is the synthetic method: using the petrochemical product propylene as the starting material. The propylene molecule is modified through chlorination and oxidation, thereby generating glycerin molecules. This method produces viable Kosher synthetic glycerin, but it is not cost-effective.

As we have seen, glycerin was discovered due to a mistake in 1799, and today glycerin can be produced through many chemical methods. Surprisingly, the end result is that, regardless of the method, the Kosher glycerin molecule is identical. This is an incredible gift from the Ribono Shel Olam (Master of the Universe). Just as we have learned of glycerin's incredible applications, we have also learned of glycerin's potential kashrus pitfalls. Therefore, kashrus bodies must be very vigilant to ensure that kashrus standards are followed at the production, transport and storage levels as well as the end-user level, because a spoonful of non-Kosher glycerin is not so pleasant, nor does it go down well.