While it is true that heat processing destroys the nutritional value and natural structure of essential fatty acids, I was surprised to learn that most oils labeled “cold pressed” are not cold pressed at all.
As industry and government is yet to agree on a definition of the term “cold pressed” regarding the manufacturing of healthy oils, any company is free to invent one that suits their particular purpose.
When I contacted and asked a number of companies that use the term to provide their definition, each suggested that “no external heat was applied to the seeds while they where being pressed”. However, the fact is that no external heat is required during modern processing – the pressing itself produces heat due to pressure and frictional forces.
The term “cold pressed” in Germany has an historical meaning of no heat being applied to either seed or oil, that is, a completely fresh, natural product. In Switzerland, the term “cold pressed” means an oil has been processed in temperatures not exceeding 50 degrees C. The fact is, it’s impossible today to find a commercially pressed oil without some degree of heat processing.
Ideally, pressing temperatures need to be kept as low as possible. For every 10-degree C increase in temperature, the speed of chemical reactions more than doubles, meaning that more internal changes occur to the oil, destroying their biological and nutritional value. From what I’ve studied, as long as temperatures are kept below approx 70-degrees C during pressing, disruption to delicate chemical bonds with the fatty acid structures is minimal, as long as light and air are excluded from contact with the oil.
In terms of quality, it is more important that the oil is protected from light and oxygen during pressing, bottling, storage and shipping. Unfortunately very few manufacturing facilities provide this protection. If the oil you purchase is not sold in a sealed, opaque container that is kept in the refrigeration section of the store, then this food will most likely not contain the essential nutrients you require.
