Antioxidants (avenanthramides, tocopherols and tocotrienols) in different oat (Avena sativa) cultivars before and after malting

Detta är en Master-uppsats från SLU/Department of Molecular Sciences

Författare: Amanda Alvenäs; [2017]

Nyckelord: oats; oat cultivars; avenanthramides; tocols; malting;

Sammanfattning: Interest in oats has increased during recent years because of its health beneficial effects, mainly as foodstuff but also as a pharmaceutical. Oats contain unique phytochemicals, like the oat specific antioxidants called avenanthramides. Oats also contain high levels of unsaturated fatty acids which can lead to oxidation problems during processing. Antioxidants are currently added to oat products for this purpose. Malting of oat grains prior to processing might replace the added anti-oxidants since some studies have found that the avenanthramide amount has increased by the process. However, some other health beneficial compounds like tocols (Vitamin E) and β-glucan (fiber) might decrease by malting. In the present study, qualitative and quantitative properties of avenanthramides and tocols (to-copherols and tocotrienols) of 10 different oat cultivars were investigated, both before and after malting. Some of the oat groats (dehulled kernels) were malted before extraction but none of them germinated. Although, malting resulted in a significant avenanthramide increase by 238%, whereas tocol amount did not change significantly. This suggests that the food additives could be avoided by malting. Avenanthramide concentration varied a lot between cultivars. Amount increased most in the cultivars Belinda (+2943%) and SW151304 (+454%) but decreased in the cultivars Matilda (-71%) and Fatima (-63%). Belinda and SW151106 had the highest levels of avenanthramides after malting. However, large variations were observed for the malting duplicates of some cultivars regard-ing avenanthramide content. Generally, avenanthramide concentration was a bit lower than recorded by previous studies whereas tocol concentration was a bit higher. Antioxidant activity was higher after malting and largely it seemed to be attributed to the avenanthramides. In further studies, more cultivar analyses during controlled conditions are required and environmental and genotypic factors must be taken into consideration in order to assure cultivar variations. It is also of inter-est to analyse malting effects on β-glucan

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