Enhancing the Shelf Life of Flaxseed Oil by Modifying Oil Manufacturing Processes

Sarah Frühwirth, Raphael Steinschaden, Larissa Woschitz

Department of Physiological Chemistry, Faculty of Chemistry, University of Vienna; Department of Physiological Chemistry, Faculty of Chemistry, University of Vienna; Department of Physiological Chemistry, Faculty of Chemistry, University of Vienna

Cold-pressed flaxseed oil is rich in omega-3 fatty acids but also highly vulnerable to lipid oxidation. Oil fortification with synthetic and natural antioxidants is a common strategy to overcome the limited shelf life of PUFA-rich flaxseed oil. However, adding antioxidative plant extracts or compounds lead to an increase of costs. Thus, it was aimed to enhance the oxidative stability of flaxseed oil by modifying the manufacturing process to allow efficient transfer of naturally occurring antioxidants from the seeds to the oil.
The effect of open and closed process, nitrogen atmosphere, roasting and oil-assisted extraction from press cake on the content of tocopherols and polyphenols in the flaxseed oil as well as on the peroxide value and the shelf life of the oil was evaluated by means of HPLC, LC-MS, titrimetry and Rancimat, respectively.

Pressing the seeds in a closed process led to a significant decline of the peroxide value by 76% but did not affect the polyphenol and tocopherol content in the flaxseed oil. Similarly, roasting at 100°C or higher hardly caused any changes with regard to the polyphenols and tocopherols, but a remarkable reduction of the peroxide value by 89.2%. Only oil-assisted extraction of polyphenols from press cake led to a 12-fold increase of the polyphenol concentration in the oil. The polyphenol-enriched flaxseed oil demonstrated to have longer shelf life compared to conventionally-produced flaxseed oils.

Low-cost changes of the manufacturing process of flaxseed oil led to an oil with increased amounts of polyphenols and higher oxidative stability.