HEXANE IN SEED OILS

Q. One thing about [your] “Short History of French Fries,” what about people using vegetable oil? . . . It is all processed with hexane. . . . Just wondering what you think about that. Patricia R., Denver.

A. Hexane, a hydrocarbon in liquid form, is often used as an extractive solvent in seed (soybean, canola, sunflower) oil production. The hexane is then evaporated, leaving only trace, if any, amounts. Nonetheless, some eaters express concern about hexane residue. (Hexane is toxic in gaseous form. The FDA does not regulate or monitor hexane in seed oils. In some way, therefore, it is difficult to ascertain what level of hexane, if any, is in conventional seed oils.)

Expeller-pressed (sometimes called “cold-pressed”) oils use pressure only, not chemicals, to extract oil. Some grapeseed or flaxseed oils are labeled as such. (Oils from fruit such as olives or avocados, or from nuts such as coconut, by and large are also extracted mechanically and, if no chemicals are used to further extraction, will be labeled “virgin,” “cold-pressed” or “expeller-pressed.”)

Other fats used in frying foods, such as beef tallow, duck fat or pork lard, don’t contain hexane or are not rendered using hexane. But because they are high in saturated fat, they pose other hazards for the diet according to some. (For some killer, Belgian-style, twice-fried French fries, try those cooked in duck fat at Satchel’s on 6th, in Denver.)

I do appreciate the perspective on hexane in seed oils (whether present or not) provided by Harvard University’s Medical School: “Regarding hexane, for example, the average person's intake of any possible residual traces of this chemical in oils and other foods is dwarfed by exposures from other sources, such as gasoline fumes.”