Influence of Climate, Variety and Production Process on Tocopherols, Plastochromanol-8 and Pigments in Flaxseed Oil

Marko Obranović¹*, Dubravka Škevin¹, Klara Kraljić¹, Milan Pospišil², Sandra Neđeral¹, Monika Blekić¹ and Predrag Putnik¹*


¹Faculty of Food Technology and Biotechnology, University of Zagreb, Pierottijeva 6, HR-10000 Zagreb, Croatia
²Faculty of Agriculture, University of Zagreb, Svetošimunska cesta 25, HR-10000 Zagreb, Croatia




Article history:
Received May 12, 2015
Accepted June 2, 2015




Key words: 
flaxseed oil, variety, cold pressing, conditioning, tocopherols, plastochromanol-8, carotenoids, chlorophyll, climate




Summary:
The objective of this study is to compare the influence of genotype, environmental conditions and processing methods after maturation and harvesting of four varieties of flaxseed (Altess, Biltstar, Niagara and Oliwin) on the levels of tocochromanols, carotenoids and chlorophyll in flaxseed oil. Samples were produced by cold pressing of dry seeds and seeds heated for 30 min at 60 °C. Temperature, sunshine and rainfall were primary environmental conditions included. Grand mean of mass fraction of γ-tocopherol was (522±29), of plastochromanol-8 (305±2) and total tocochromanols (831±3) mg per kg of oil. The highest levels of these compounds and strongest antioxidant activity were found in cold-pressed oil of Biltstar variety. During seed maturation, levels of γ-tocopherol and plastochromanol-8 increased with average temperature and total sunshine and decreased with total rainfall. Fifth week after flowering was identified as the maturation period with best climate conditions to achieve optimal tocochromanol content. Grand mean of mass fraction of carotenoids expressed as β-carotene was (1.83±0.01) and of chlorophyll expressed as pheophytin a (0.43±0.10) mg per kg of oil. Altess variety had the highest levels of pigments. Antioxidant activity decreased with the increase of chlorophyll, while correlations with carotenoids were not determined. Generally, oil obtained by cold pressing had higher levels of tocochromanols and lower levels of pigments but similar antioxidant activity to the oil after seed conditioning. The results of this study contribute to identifying the flaxseed variety that is the best for oil production with the highest antioxidant activity and nutritive value, and provide better understanding of tocochromanol biosynthesis depending on different climate conditions.






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