Supercritical 101

Other Extraction Methods

Petrochemical Solvent Extraction

Over 95% of food-grade oils are extracted with hexane or similar solvents. These byproducts of petroleum refining have several drawbacks:

Hexane is classified as both a hazardous air pollutant and a toxic air contaminate by the United States EPA.
A suspected carcinogen, hexane can remain in trace amounts in the products exposed to it. This includes nearly all soybean meal, used for animal feed, and most of the food-grade vegetable oils sold in the United States.
Hexane is highly explosive and volatile, and is stored and used in large amounts at solvent extraction plants, where they are continuously at risk of being exposed to heat, sparks, and/or excess air conditions.
The numerous public concerns about hexane have made the permitting process for these plants is lengthy and difficult.

To date, the criticism from the consumer food side has not been severe, and many Americans are unaware of the potential risks of hexane in the food supply.

Mechanical Extraction

Mechanical extraction (typically performed with continuous screw presses or expellers) is a relatively old technology which has received increased attention in recent years, driven by demand for healthier cooking oils and safer, more environmentally-friendly extraction methods. However, the method is not as cost effective on a large scale compared with solvent extraction, and is typically used in smaller, less energy-efficient facilities.