Addition of pumpkin peel extract obtained by supercritical fluid and subcritical water as an effective strategy to retard canola oil oxidation

Abstract

In the present study, the supercritical fluid extraction (SFE) and subcritical water extraction (SWE) methods were used to obtain the pumpkin peel extract. The obtained extracts were compared together. The results showed that total phenol content in the SFE extract (353.5 mg GA/100 g extract) was higher than the SWE extract (213.6 mg GA/100 g extract). However, carotenoid content was higher in the SWE extract (15.22 mg/100 g extract) compared to the SFE extract (11.48 mg/100 g extract). The extracts were added to canola oil at 400 ppm concentration separately and in combined form (SFE+SWE) and TBHQ was added at 100 ppm. The thermal stability of oil samples at the thermal condition of 180 °C was measured using the Rancimat test, conjugated diene and the polar value. The sample containing the combined SFE and SWE extract had the highest oxidative stability, consequently showing higher performance in preventing oil oxidation during the frying process compared to TBHQ. As a result, pumpkin peel extract can be used as a natural antioxidant in edible oils.