The Content and Antioxidant Activity of Phenolic Compounds in Cold-pressed Plant Oils

Many nontraditional vegetable oils have been introduced to the market relatively recently, and therefore data on their antioxidant potential have not been reported. Such data are of importance for the evaluation of the nutritional and health impact of these oils. Antioxidant properties of the methanolic extracts of cold-pressed oils such as soybean, sunflower, rapeseed, corn, grapeseed, hemp, flax, rice bran and pumpkin were studied. The methanolic extracts were obtained by solid phase extraction and separation, and identification of phenolic acids was conducted by high-performance liquid chromatography. The obtained extracts were characterized by different scavenging activities of 2,2-diphenyl-1-picrylhydrazyl radicals. The best antioxidant properties were displayed by the extract from hemp, pumpkin and rapeseed oils. The highest content of total phenolic compounds was determined for the pumpkin and hemp oils – about 2.4 mg/100 g. Rapeseed oil was characterized by the highest content of phenolic acids, especially sinapic acid. To better understand the beneficial effects of antioxidant compounds in vegetable oils, it is important to investigate whether these bioactive compounds in oils differ in their reactions with free radicals. PRACTICAL APPLICATIONS Phenolic compounds have been reported to be present in all vegetable oils, which is very important for the oxidative stability of the polyunsaturated fatty acids of these oils. Additionally, edible oils rich in natural antioxidants 1 Corresponding author. TEL: +48-61-848-73-57; FAX: +48-61-848-73-52; EMAIL: [email protected] Journal of Food Lipids 15 (2008) 137–149. All Rights Reserved. © 2008, The Author(s) Journal compilation © 2008, Blackwell Publishing 137 may play a role in reducing the risk of chronic diseases. Thus, the oils examined may be used in different food applications to provide nutrition and health benefits.