Quality of flaxseed oil cake under different storage conditions

Flaxseed is well known for its nutritional/nutraceutical value and it is commonly cultivated for oil production. This process generates considerable amounts of by-products, such as oil cake. This study aimed at quantifying the nutrients and nutraceuticals content of cake and at checking their maintenance during storage in paper or polypropylene bags, at room temperature. Freshly-prepared cake was enriched in phenols (+250%), leading to increased antioxidant activity (+148%), while carotenoids and tocopherols underwent a remarkable reduction, as compared to seeds. During storage, the content of phenols, carotenoids, chlorophylls and tocopherols decreased, though alpha-tocopherol markedly increased (+86% and +99% after 3 months in paper and plastic, respectively), due to a possible conversion of gamma-tocopherol to the alpha-form. Cake maintained an excellent fatty acid composition, also during storage, with optimal omega-6/omega-3 ratios. After 3 months, a peak of conjugated dienes was observed, while peroxides and MDA decreased with storage. Thanks to the presence of antioxidant molecules, polyunsaturated fatty acids and proteins, this by-product could represent an interesting feed supplement, also in the form of stored product. Interestingly, no differences between paper- or plastic-stored cakes occurred, suggesting the preferential use of the eco-friendly material.