Canola (Brassica napus) oil from Australian cultivars shows promising levels of tocopherols and carotenoids, along with good oxidative stability

A total of 156 commercial canola seed samples were collected from two growing seasons and tested for oil and protein content, glucosinolate concentration and kernel weight. Extracted oil samples were tested for the bioactive compounds: beta-carotene (mean = 2.03 mg/kg), lutein (64.7), alpha-tocopherol (263), gamma-tocopherol (378) and delta-tocopherol (8.94). A subset of 52 oil samples were analyzed for fatty acid profile (FAP) and oxidative stability. Canola cultivar was found to be the dominant influence on many traits, particularly carotenoids and tocopherols, indicating potential breeding opportunities. Previously unreported significant correlations were discovered between the two major carotenoids, lutein and beta-carotene. Additionally, significant (p < 0.01) negative correlations existed between oil content and: beta-carotene (r = -0.33), lutein (r = -0.23), alpha-tocopherol (r = -0.49), gamma-tocopherol (r = -0.22), and delta-tocopherol (r = -0.30). Polyunsaturated fatty acid content was significantly (p < 0.01) positively correlated with carotenoid (r = 0.48) and tocopherol (r = 0.60) concentrations. Oxidative stability showed a weak negative correlation with total tocopherols (r = -0.38, p = 0.01) likely due to the overriding influence of fatty acid profile on oxidative stability, indicating tocopherols may be more influential from a nutritional perspective rather than oil functionality. (C) 2015 Elsevier Inc. All rights reserved.