Enzymatic lipophilization of phenolic extract from rowanberry (Sorbus aucuparia) and evaluation of antioxidative activity in edible oil

Phenolic extracts from Sorbus aucuparia (L.) were lipophilized in the presence of Candida antarctica lipase using octadecanol as the alkyl donor. The antioxidant activity of the lipophilized extract was assessed in refined, bleached and deodorized rapeseed oil during accelerated storage at 65 °C and frying at 180 °C. Rapeseed oil fortified with lipophilized extract showed significantly higher storage stability with 43% decrease in peroxide value at the end of the 7-day storage compared to rapeseed control sample without extract; however, no significant difference was observed in the performance of lipophilized extract and the native extract. On the contrary, the lipophilized extract exhibited markedly better protection against thermo-oxidative degradation during frying, inhibiting polar component formation and polymerization of triacylglycerol by up to 48%, compared to 30% by the native extract. At the end of the frying, French fries prepared in the presence of lipophilized extract had 7 times more phenolic compounds compared to fries prepared in the native extract indicating better solubilization of the phenolic compounds in the frying medium. Thus, lipophilization of phenolic compounds enhanced their protective activity in frying oil and improved the functionality of the prepared food.