Physicochemical and quality characteristics of cold-pressed flaxseed oils

Flaxseed oils currently sold on the worldwide market are not governed by specific standards or specifications. In this study, the physicochemical and quality characteristics of seven cold-pressed flaxseed oils sold in New Zealand have been analyzed. General regulations and specification for edible vegetable oils and cold-pressed oils were used as a guide. Fatty acid composition, tocopherol composition, moisture and volatile matter content, free fatty acids, chlorophyll pigments, total phenolic acids, total flavanoids, acid value, unsaponifiable matter, peroxide value, conjugated dienoic acids, p-anisidine value and specific extinction in the ultraviolet spectrum of the flaxseed oils were measured. Color and dielectric measurement of the flaxseed oils were also estimated using a spectrocolorimeter and a food oil sensor, respectively. The physicochemical characteristics of the flaxseed oils were found to be quite similar with only a few significant variations. Four out of the seven flaxseed oils passed all the quality tests conducted in this study. (c) 2006 Elsevier Inc. All rights reserved.