Influence of filtering of cold pressed berry seed oils on their antioxidant profile and quality characteristics

The quality, composition and colour of 11 oils from six different berries were evaluated before and after filtering of the cold-pressed oils. The filtering did not lead to significant compositional or quality differences, except a minor reduction in oxidative stability. Due to their high degree of unsaturation, the peroxide and p-anisidine values were high for all oils. However, the high level of tocopherols and tocotrienols appears to protect the oils during the oil stability test (significant correlation; r = 0.803; p = 0.003). Tocopherol contents between 138 mg/kg (kiwi seed oil, filtered) and 1639 mg/kg (blackberry seed oil, non-filtered) were found. Phenolic compounds, identified and quantified by HPLC, ranged from 90 mg/kg (blackberry seed oil, filtered) to 15,810 mg/kg (strawberry seed oil, filtered). No correlation was found between the quantified phenolic compounds and the oxidative stability of the oils, suggesting that in these oils the tocopherols were the main antioxidants protecting the lipids during storage.

Research highlights
► Six cold-pressed berry seed oils were evaluated before and after filtering.
► Due to the high degree of unsaturation, oxidation was relatively high for all oils.
► The main effect of filtering was a minor reduction in oxidative stability.
► Phenolics, identified and quantified by HPLC, did not correlate with stability.
► Higher stability correlated with higher levels of tocopherols and tocotrienols.