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Quality assessment of black currant, strawberry and cranberry seeds’ lipid fraction
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1  Department of Chemistry, Institute of Food Sciences, Warsaw University of Life Sciences (WULS – SGGW), 02-787 Warsaw, Poland
Academic Editor: Susana Casal

Abstract:

Proper management of waste generated during food production and processing is currently one of major and urgent challenges for the food industry. Berry seeds are believed to be a source of bioactive substances, that could be reused in food and cosmetic production, what is in agreement with the UE politics of circular economy and sustainable development. The aim of this study was to extract oils from black currant, strawberry and cranberry seeds and to determine the quality of the obtained oils. The following parameters were determined: fatty acid composition by gas chromatography, distribution of fatty acids between sn-2 and sn-1,3 positions of triacylglycerols by enzymatic hydrolysis, oxidative stability of fat by pressure differential scanning calorimetry and melting characteristics by differential scanning calorimetry. Oils were extracted with the yield of 5.71%, 11.62% and 22.74% in the case of black currant, strawberry and cranberry seeds, respectively. Based on the obtained results, it can be stated that studied oils were a rich source of polyunsaturated fatty acids, especially linoleic and alpha-linolenic acids. Linoleic acid was mainly present in the internal position of triacylglycerol molecules, whereas saturated fatty acids usually occupied the external positions of triacylglycerols. Black currant and strawberries seed oils were characterized by short oxidation induction times, which proves their low oxidative stability. Melting curves for black currant and strawberry seed oils were of similar shape characterized by one endothermic event, indicating the presence of low-melting triacylglycerol fractions containing polyunsaturated fatty acids. The shape of DSC curve for cranberry seed oil differed from the shape of the melting curves for blackcurrant and strawberry seed oils, and indicated two endothermic transitions proving the presence of low-melting fractions containing polyunsaturated fatty acids and medium-melting fractions rich in monounsaturated fatty acids. The shape of the curves corresponds to the analysis of the fatty acid composition. On the basis of the conducted analyzes, it can be concluded that cranberry seed oil is characterized by the highest quality parameters among the analyzed oils: it can be a source of both polyunsaturated and monounsaturated fatty acids; the distribution of fatty acids at the internal and external positions of the triacylglycerols is nutritionally favorable. This oil is also characterized by the highest resistance to oxidative processes.

Keywords: berry seeds; fatty acids composition; fatty acids distribution, oxidative stability, melting characteristics
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