Influence of seed quality and storage time on the characteristics of cold-pressed sunflower oil: Impact on bioactive compounds and colour

Abstract

Response surface methodology (RSM) using a three-level Box-Behnken design was applied to investigate the impact of the seed storage time (0, 6, 12 months), organic impurities (0, 5, 10%) and hull (0, 16, 32%) contents in the material to press on the bioactive compounds and colour (as responses) of the cold-pressed sunflower oil. A strong, quadratic effect of the storage time was observed for total tocopherols, phenolics and carotenoids contents, as well as colour lightness (L*-value). Total phenolics content depended on the organic impurity content, while carotenoids and chlorophyll contents, as well as all factors significantly affected the lightness of oil. The hull content had the most significant impact on the lightness of oil. The chlorophyll content was significantly impacted by interactions between the storage time and organic impurities content as well as organic impurities and hull contents. The optimisation process carried out for the maximum values of all outputs (except chlorophyll) has shown that by pressing 8.1 months stored seeds with 6.04% of organic impurities and 5.49% of hull, the best oil quality was achieved to contain 540.22 mg/kg of total tocopherols, 15.30 mg/kg of total phenolics, 9.13 mg/kg of carotenoids, 0.19 mg/kg of chlorophylls and lightness of 23.32%; with providing golden yellow, transparent cold-pressed sunflower.