Oxidative stability of crude extract of red variety rice bran from Minahasa, north Sulawesi on lipid-based food products

Abstract

Rice bran is known to contain various phytochemical compounds, particularly, vitamin E in the form of tocopherol and tocotrienol that has antioxidant potential. The purpose of this research was to understand the antioxidant capabilities of the crude extract of red variety rice bran from North Sulawesi to inhibit the oxidation process in fortified mayonnaise. Fortified mayonnaise samples with fish oil were incorporated with red variety rice bran (RRB) extract and butylated hydroxy toluene (BHT). Butylated hydroxy toluene (BHT) was used as a synthetic antioxidant for comparison. The mayonnaise samples were stored for a period of 30 days and observed for the inhibition of oxidation characteristics. Observations were performed at day 0, 10, 20 and 30 of the storage. Among the analysis conducted during the observations were the formation of conjugated-diene-hydroperoxide, the detection of malonaldehyde (MDA) via TBARS method and the hydroperoxide formation via FTIR chromatogram. The results indicated that the mayonnaise with RRB extract (21.55±0.80 mmol/kg) had a higher inhibition of oxidation at the primary stages of storage compared to mayonnaise with BHT (21.84±1.48 mmol/kg) from the observation in the formation of conjugated-diene-hydroperoxide. While the formation of MDA of mayonnaise with BHT was less (0.23±0.01 mg/kg) compared to mayonnaise with RRB extract (0.24±0.03 mg/kg). The FTIR chromatogram results indicated that the control sample and pure fish oil had peaks beyond 3500 cm-1(3649 cm-1, 3673 cm-1, 3748 cm-1and 3838 cm-1) after 30 days of storage.