Effects of natural antioxidants in the improvement of corn oil quality: olive leaf vs. lemon balm

Commercially available corn oil was enriched in polyphenols by adding olive leaf and lemon balm extracts, respectively. First, dried and ground plants were extracted through homogeniser‐assisted extraction. Then, the dried extracts were partially dissolved into the corn oil by means of solid–liquid extraction method. Total phenolic content increased 9.5 and 2.5 times over the pure corn oil. The antioxidant activities of enriched oil by olive leaf and lemon balm extracts have been found almost 14 and 6 times higher than that of untreated oil, respectively. Olive leaf extract enhanced the quality better than lemon balm extract with respect to carotenoid (TCC) and chlorophyll contents. Addition of 0.12–0.15% natural antioxidants gave rise to increase in the stability of the oil (≈18%).