Physicochemical and quality characteristics of cold-pressed hemp, flax and canola seed oils

New Zealand cold-pressed hemp, flax and canola seed oils were analyzed for their fatty acid compositions, tocopherols, β-carotene, chlorophyll, total phenolics, flavonoids, color, quality, melting and crystallization characteristics. The dominant fatty acid of canola, hemp and flax seed oils was oleic (57.0 ± 0.0%), linoleic (55.7 ± 0.3%) and linolenic acids (58.7 ± 1.2%) respectively (p < 0.05). Hemp seed oil contained the highest tocopherol, flavonoid and phenolic acid contents. There was a significant difference in color for the oils (p < 0.05) due to the chlorophyll content in the oil. Melting and crystallization transitions and ΔH values varied for the three oils in the order canola > flax > hemp. All oils had low moisture and volatiles, unsaponifiable matter and free fatty acids. Peroxide value, p-anisidine, conjugated dienoic acid, acid value, specific extinction of cold-pressed oils at 232 and 270 nm were under the limits allowed in general regulations.