Effectiveness of natural versus synthetic antioxidants in a rice bran oil-based structured lipid

Antioxidants were evaluated for their ability to improve oxidative stability index (OSI) of enzymatically prepared rice bran oil-based structured lipid (RBOSL) containing caprylic acid. RBOSL was purified by short-path distillation. Vitamin E concentration decreased significantly in RBOSL after enzymatic modification. Total γ-oryzanol concentration after modification was not significantly different. OSI of RBOSL containing rosemary extract (RE), carnosic acid (CA), tertiary butyl hydroquinone (TBHQ), ethylenediamine tetraacetic acid (EDTA), and α-tocopherol (TOC), and 50:50 (w/w) combinations in concentrations of 200, 300, 400 and 500 ppm were determined. The OSI of unmodified rice bran oil (RBO) was 12.4 ± 0.2 h and significantly higher than RBOSL which was 11.4 ± 0.0. Mean peroxide and p-anisidine values for antioxidant treatments in RBOSL with the highest OSI values were determined after incubation at 60 °C for 21 days and sampled every 3 days. Mean peroxide and p-anisidine values for CA and CA/RE were comparable to TBHQ.