Molecular distillation (used for all of our fish oil products) removes environmental toxins like mercury and other heavy metals, dioxins, etc., saturated fats, and other undesirable organic compounds, leaving behind only the key beneficial components of the fish oil. It is a gentle distillation process with exceptionally low heat residence time, and is performed in a vacuum to further reduce the heat requirement. Flash distillation (used for our non-concentrated fish oils) accomplishes the same thing as molecular distillation, but utilizes steam rather than a vacuum.
All fish oil‚ regardless of the kind of manufacturing process used‚ needs to be processed in order to remove contaminants and pass minimum laws and standards (such as California's Proposition 65). This process always requires the use of heat. However, heat itself does not cause oxidative damage to the fish oil‚ it can only affect the rate of oxidation. Without the presence of free radicals or oxygen, there is no oxidation to speed up. This is also why nitrogen-flushed fish oils can handle being shipped, delivered, and stored in even the hottest climates and still taste great.
Third-party testing for TOTOX values will reliably show the total oxidation to which the oil has been exposed, and will thereby reliably assess the quality of any processing technique. (For more information on TOTOX values, see below.) Perhaps even more important is the absence of a fishy taste. It has been verified that the most significant and sensitive pieces of equipment that measure oxidation in oils are still not nearly as sensitive as the human palate [From the AOCS meeting 2007]. The aldehyde byproducts of oxidative damage to fish oils have a high vapor pressure (thus the fish burp) and the distinctly disagreeable taste and smell of rancid fish.