Rabbi Mordechai Stareshefsky
- Feb 27, 2023
- 3 min read

Biodiesel and Kosher Glycerin: An Important Fuel and Its Valuable Coproduct

Biodiesel producers who are using plant-based feedstock, or those who are willing to switch, can get certified kosher and capture more value from their glycerin coproduct.

About 350,000 tons of glycerin are produced in the United States each year. Kosher glycerin is harder to come by today than it was previously, in part because of decreased government subsidies and certain other economic factors. Along with using plant-based feedstock, certifying biodiesel refineries kosher under rabbinic supervision makes it possible to manufacture kosher glycerin and meet a growing demand.

One of the most exciting and innovative processes spawned by relatively recent technology advancements is that of biodiesel. Simply put, biodiesel is a replacement fuel for diesel engines. One fascinating and exciting use of biodiesel is in marine fuel. Many commercial shipping liners and other maritime companies have committed themselves to using marine biofuel, of which biodiesel fills a prominent role. While standard diesel fuel is made from petroleum, biodiesel, which is nontoxic and biodegradable, is made from what are known as biomass oils.

These biomass oils can be derived from plant oils, such as soybean, canola and corn oil, but this industry is so versatile that refineries can take waste products such as used cooking oil (UCO) and animal fats and turn them into biodiesel. Even algae is being investigated as a potential source of biodiesel feedstock.

Of particular relevance to the food world is the fact that a coproduct of biodiesel production is glycerin, an indispensable ingredient in a variety of foods, such as dried and canned vegetables or fruits, precooked vegetables, precooked pasta, rolled oats, breakfast cereals, rice or tapioca pudding, breading or batters, precooked rice products and baked goods. Glycerin helps to retain moisture, prevent sugar crystallization, and add bulk, smoothness, softness, sweetness and texture.

Many biodiesel refineries are now looking to attain kosher certification. This is for two reasons:

Biodiesel is not cost-effective to manufacture without heavy government subsidies. Congress has proven to be parsimonious and inconsistent with these subsidies, and producers are scrambling to develop ways to add value to their products, such as making the glycerin kosher by using kosher feedstock, for example.

Animal feedstock, which includes animal fats, is becoming increasingly expensive. While it is highly in demand because it meets various California environmental standards for renewable sources, it can’t be used to make a kosher product. In order to produce kosher glycerin, then, the biodiesel process must use strictly plant-based feedstock.

The Production and Kosherization Process

Biodiesel is produced by a process called transesterification, which converts fats and oils into biodiesel and glycerin, a coproduct commonly used in the manufacture of pharmaceuticals and cosmetics as well as many foods. The process of making biodiesel starts with feedstock being delivered to the facility by boat or by tanker truck and stored in terminals until it is treated. About 100 pounds of oil or fat are mixed with 10 pounds of methanol and a catalyst to form 100 pounds of biodiesel and 10 pounds of glycerin (or glycerol).

Orthodox Union Kosher rabbis not only thoroughly understand how to apply Jewish law to the products they supervise, but they also make it their business to learn exactly how these products are manufactured. This often includes mastering technical intricacies that require special advanced education and training. It also means the rabbis are skilled at pinpointing the best processes and adaptations to help a company take advantage of the value-added benefit of being able to market a product as kosher.

In addition, OU Kosher has, of course, vast experience in helping refineries transition from nonkosher to kosher. Although each refinery is unique, the basic plan takes two steps: the cleaning of the equipment and its kosherization. Although kosherization of tanks is typically done with boiling water, this is not feasible in a biodiesel refinery for two reasons:

Many tanks are not jacketed, that is, they don’t have the ability to heat themselves, and the water therefore will not reach a boil

The amount of water necessary to effect kosherization will wreak havoc with the plant’s utilities—boiling and disposing of up to 5 million gallons of water is quite a challenge

Accordingly, kosherization of refineries is done with steam. The plant will blow in live steam through the top of the tank, and the rabbi supervising the kosherization will measure the condensate exiting below. Once the condensate displays consistent readings of 200 degrees Fahrenheit and above, the tank has been effectively kosherized.