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By Rabbi Dovid Cohen, Administrative Rabbinic Coordinator

Q. What is glycerin, and why is it kosher-sensitive?

All fats and oils – whether they come from animal, vegetable, or fruit – consist of two distinct parts.  One part is called “glycerin” which has three “arms” giving it a shape like the letter “E”, and the other part is three fatty acids, each of which is attached to one of the “arms” of the glycerin.  Glycerin is the same regardless of which fat or oil it comes from, and the difference between one fat and the next, or one oil and another, is the makeup of the fatty acids.  For example, the reason beef fat is solid at room temperature, while olive oil is not, is because of the types of fatty acids they each have.

If oil or fat is heated to very high temperatures (~700°F) under pressure in a huge device called a “splitter”, the glycerin and fatty acid will separate from one another.  The glycerin and fatty acids will each then go through (separate) distillation to purify them and separate the individual fatty acids from one another.  In the commercial world, all animal fat is non-kosher, and this means that glycerin made from animal fat is also not kosher.  Even vegetable-based glycerin can be non-kosher if the equipment used for “splitting” or purifying the glycerin had previously been used to do the same for animal-based products.  Additionally, glycerin is transported in bulk from place to place, and hashgachah ensures that the ship, railcar, tanker truck, or drum, used for that shipment is dedicated to kosher use or kashered before being used for kosher.

Glycerin is used in food products because it adds sweetness and helps them retain moisture.  It is also typically used in relatively large amounts, such that it is not batel in the food.  Therefore, if a food contains glycerin, that food is automatically kosher-sensitive and should only be eaten if it bears a reputable hashgachah.

Glycerin is also a significant component of liquid medicines, mouthwash, toothpaste, and vaping juice.  Generally, these items are not available with kosher certification, and that raises several questions: Which of these items are considered “edible”?  How likely is it that the company is particular to use (kosher) vegetable glycerin?  What alternatives are there, and does the person’s medical condition warrant consuming the product even if the glycerin might not be kosher?  These questions are beyond the scope of this presentation and should be addressed to one’s Rabbi.

This article first appeared in the Let’s Talk Kashrus column, Yated Ne’eman, July 21, 2023.