The Science of Sunflower Oil - Cold Pressing versus Industrial Production

 

You may wonder, what does Cold Pressing really mean when it comes to producing Sunflower Oil?   Cold pressed oils are made without heat or chemicals at low (room) temperature  - the process is strictly mechanical.  Oil is slowly squeezed out of the seed – a slow speed is crucial as higher speeds create friction which causes the seed to heat up which in turn reduces the quality of the oil.    Cold pressing retains the flavour and colour of the seed as well – Cold Pressed Sunflower Oil tastes like taking a bite of fresh Sunflower Seeds.

Industrial production of oil can involve both solvents and heat to increase the amount of oil extracted from the seed.   However, the health qualities and flavour are lost in the process.

The most efficient process is "Solvent Extraction" which involves heat and chemical refining.  The seed is first crushed and washed in a solvent, typically hexane, to recover the oil inside.  The mixture is then heated to distill off the solvent from the oil before moving into the RBD (Refined, Bleached, and Deodorized) process. This process resulting in the extraction of up to 97% of the seed’s oil.  Chemically processed oils are not considered healthy for consumers as the refinement process strips most of the beneficial nutrients and antioxidants, resulting in an inferior healthful product.    They persist because of the high yield and production of a heat tolerant oil for frying in large food production facilities. 

The next most efficent is "Hot Pressing"  which involves subjecting the oil seed to higher heat to “soften” the seed while in the oil press which destroys many of the nutrients.   Heat is used to cook and dry the seed prior to pressing to allow for more efficient separation of the oil in the press. Once in the press, temperatues can exceed 200 degress F due to higher pressure and friction in the extraction process.  This method results in about 80-90% oil removal from the seed. 

Cold Pressing is by far the best choice if you are looking for a high quality cooking oil.  The process retains more of the oil’s natural properties such as purity, flavour, fragrance and nutritional value. Although introducing a heat source and chemicals to help extract the oil will yield a greater quantity, the quality of the oil extracted in this way is compromised as the process can damage the antioxidants, vitamins and minerals of the oil. It’s a case of quality versus quantity when it comes to oil extraction!