Introduction
Fats and vegetable oils are largely utilized for food and to produce renewable fuels. Conversion of oils to higher molecular weight species (polymerization) during frying or storage is detrimental to health and bio-refinery processes . One measure of edible oil deterioration is polymer concentration . Indeed, vegetable oils also used to synthesize polymers . Yet the molecular transformations and cross-links in the polymers are vague and controversial.
Biodiesel, produced from oils and fats of plants and animals, is a renewable and biodegradable alternative to fossil diesel. Worldwide fossil petroleum reserves are expected to run out this century. Industrial production relies on catalytic transesterification of virgin plant oils (palm, soy, canola) and recycled cooking oils to produce methyl esters and glycerol byproduct, Figure 1 . One biorefinery problem is oxidative polymerization reactions , during storage, handling, and conversion, that decrease productivity.