Supercritical fluid extraction of bioactive compounds from berry seeds

Licentiate thesis, 2018

Industrial processing of berries into food and beverages generates seeds as a by-product. Most of these seeds are treated as waste even though they contain valuable biological compounds. An approach to adding value to the process is to extract these compounds from the seeds.
The aim of this study was to investigate the yield and chemical composition of oils obtained by supercritical fluid extraction (SFE) from cloudberry, black currant, and bilberry seeds. The extractions were carried out at different pressures (200–500 bar) and temperatures (40°–80°C). Hexane extraction was performed as a reference.
The berry seed matrices had significant impacts on the extraction efficiency. As black currant seeds have small cells, the milling step resulted in smaller particles with larger surface area, thereby favouring the extraction. The increase in pressure at the same temperature enhanced the supercritical carbon dioxide (SC-CO2) density, resulting in higher extraction yields. Increasing the temperature at 350 bar resulted in the higher levels of vitamin E and carotenoids in the recovered cloudberry and bilberry seed oils. The opposite effect was observed for black currants, due to differences in the seed matrix. The fatty acid composition of black currant seed oil, which includes stearidonic and γ-linolenic acid, suggests that this oil is a good source of polyunsaturated fatty acid. The low ω6/ω3 ratios (1.0–1.3) of cloudberry and black currant seed oils indicate that these oils could be interesting alternatives to fish oil supplements. In addition, the high levels of vitamin E seen in these oils suggest protection against lipid oxidation.