Is Propylene Glycol Made from Soy? Understanding Its Diverse Sources

December 3, 2025 •

4 min read

Historically derived from petroleum, a growing portion of modern propylene glycol is now sourced from renewable, plant-based materials like soybeans and corn. This shift highlights the availability of more sustainable alternatives to the traditional manufacturing process.

Quick Summary

Propylene glycol is produced from various raw materials, including petroleum-based propylene oxide and renewable plant-based sources like soybeans, corn, and glycerin. Its origin depends on the manufacturer and the desired product grade.

Key Points

Diverse Origins: Propylene glycol can be produced from petroleum, soybeans, corn, and glycerin, depending on the manufacturer and method used.
Renewable Source: Some manufacturers, like ADM, produce a renewable version of propylene glycol primarily derived from soybeans and canola.
Traditional Method: The conventional industrial process for creating propylene glycol uses propylene oxide, which is derived from petroleum.
Biodiesel Byproduct: Another bio-based route involves converting glycerin, a byproduct of biodiesel production, into propylene glycol.
Source vs. Grade: A product's grade (e.g., USP/food-grade) is a better indicator of its purity and safety for consumption than its raw material source.
Driving Factor: The shift towards plant-based sources is driven by consumer demand for sustainable products and the availability of advanced 'green chemistry' methods.

The Answer: Propylene Glycol Is Made from Diverse Sources

Propylene glycol (PG) is a versatile, synthetic organic compound used in thousands of products, from foods and cosmetics to industrial applications. While many consumers are concerned about its origin, particularly whether it is derived from fossil fuels, the truth is more nuanced. Propylene glycol is produced from multiple feedstocks, and its source largely depends on the manufacturing process used. It is a common misconception that all PG comes from petroleum; however, a significant and increasing amount is now produced from plant-based materials, including soy.

The Traditional Method: Petroleum-Based Propylene Glycol

For decades, the standard commercial method for producing propylene glycol has relied on petroleum. The process begins with the refining of petroleum to obtain propylene, a three-carbon hydrocarbon. Propylene is then converted into propylene oxide, which serves as the primary intermediate compound. Finally, the propylene oxide is hydrolyzed (reacted with water) at high temperatures and pressures to form a mixture containing propylene glycol and other related glycols. This method is highly efficient and is the source of the majority of industrial-grade propylene glycol.

The Renewable Approach: Propylene Glycol from Plant-Based Sources

Driven by a demand for more sustainable and bio-based products, chemical manufacturers have developed alternative processes for producing propylene glycol from renewable resources. The most prominent of these involves using vegetable oils, which can be derived from soybeans, corn, and canola. These plant-based methods are a testament to advancements in green chemistry and offer a non-petroleum alternative.

How Soybeans Are Used to Make Propylene Glycol

One of the leading methods for producing bio-based propylene glycol uses soybeans as a primary feedstock. This process is utilized by major companies, such as ADM, to produce kosher and plant-based versions of the chemical.

Extraction: Soybeans are processed to extract crude vegetable oil. This is a multi-step operation involving crushing, dehulling, and extraction.
Transesterification: The vegetable oil is further processed into a refined oil, which is then converted into crude biodiesel and crude glycerin through a transesterification process.
Refinement: The crude glycerin is purified through several distillation and evaporation steps to meet USP-grade specifications.
Conversion: The refined glycerin is then processed using proprietary technology to convert it into high-purity propylene glycol.

Other Bio-Based Sources

Besides soybeans, other plant-based materials are used to create propylene glycol, often through similar or related pathways.

Glycerin from Biodiesel: The production of biodiesel creates a surplus of crude glycerin. This glycerol byproduct can be catalytically hydrogenated to produce propylene glycol, which offers a cost-effective and environmentally friendly route for renewable production.
Corn: Some bio-based propylene glycol is produced from corn kernels. The process typically involves fermenting corn-derived sugar into lactic acid, which is then converted into propylene glycol using a copper-based catalyst.

Comparison Table: Sources of Propylene Glycol


Feature	Petroleum-Based Propylene Glycol	Plant-Based Propylene Glycol	Glycerin-Based Propylene Glycol
Raw Material	Propylene oxide from petroleum	Vegetable oils (soybeans, canola, corn)	Crude glycerin from biodiesel
Manufacturing Process	Hydrolysis of propylene oxide	Conversion of vegetable oil to glycerin, then to PG	Catalytic hydrogenolysis of glycerin
Typical Applications	Industrial, food-grade (USP), pharmaceuticals	Industrial, food-grade (USP), pharmaceuticals	Primarily industrial, though quality varies
Sustainability	Relies on non-renewable fossil fuels	Uses renewable, bio-based feedstocks	Uses a byproduct of biodiesel production
Environmental Impact	Higher carbon footprint from fossil fuel extraction and processing	Reduced carbon footprint compared to petroleum-based methods	Lower environmental impact through waste product valorization

Why the Source Matters: Grades and Purity

The source of propylene glycol is important because it often correlates with the product's grade and intended use. For instance, USP (United States Pharmacopeia) grade propylene glycol has a very high purity and is suitable for food, drug, and cosmetic applications, regardless of whether it originates from petroleum or plant matter. However, consumers and manufacturers seeking a renewable or non-petroleum option can choose the bio-based versions. For many industrial applications, where the cosmetic odor and taste of glycerin-derived PG is not a concern, this pathway offers a cost-effective solution.

The Future of Propylene Glycol Production

The trend towards sustainability and renewable resources is accelerating, and the production of propylene glycol from sources like soy and glycerin is a key part of this shift. Companies are continually investing in research and technology to improve the efficiency and reduce the environmental footprint of these bio-based processes. This offers consumers and industries a choice that aligns with growing environmental consciousness, without sacrificing the quality and safety of the final product. Understanding the different manufacturing routes and their feedstocks is crucial for making informed decisions about the products we use.

Conclusion

To answer the central question, yes, propylene glycol can be made from soy. However, it is not the only source. The chemical can also be produced from petroleum or from other plant-based materials like corn and glycerin. The origin is determined by the manufacturer and their chosen process, with both petroleum-based and renewable versions available on the market. Consumers and industries seeking a sustainable alternative have more options than ever before, with bio-based propylene glycol offering a high-quality, renewable option for a wide array of products. The shift towards plant-based feedstocks demonstrates a positive move towards more sustainable chemical manufacturing practices.

Outbound Link

For more information on how renewable propylene glycol is produced from soybeans and other plant sources, you can visit the product pages of manufacturers like ADM.

Frequently Asked Questions

No, not all propylene glycol is derived from petroleum. While the traditional method uses petroleum, manufacturers also produce bio-based versions from renewable plant sources like soybeans and corn.

Propylene glycol is made from soybeans through a multi-step process. First, vegetable oil is extracted and processed into crude glycerin. This glycerin is then purified and converted into propylene glycol using specialized technology.

The safety of propylene glycol is determined by its purity grade, not its raw material source. Both petroleum-derived and plant-based versions must meet the same strict purity standards (e.g., USP grade) for use in food and medicine.

Propanediol is a term often used for a vegetable-derived glycol, which is chemically similar to propylene glycol. While propylene glycol has been produced from both petroleum and renewable sources, propanediol is typically associated with the bio-based, corn-derived version.

An allergic reaction to propylene glycol is unrelated to whether it comes from soy. True allergic reactions to purified propylene glycol are very rare. The refining process removes allergenic components from the original feedstock, whether it is soy or petroleum.

Companies may use a plant-based source to appeal to consumers who prefer products made from renewable and sustainable ingredients. The manufacturing process for bio-based PG is also considered more environmentally friendly than petroleum-based methods.

Soy-based propylene glycol can be used in a wide array of products, especially those that benefit from a renewable or bio-based label. This includes many foods, cosmetics, and personal care products, as well as industrial applications.