This research aimed to determine optimum extraction condition of black glutinous rice crude extract and
to determine its application as an antioxidant in fish oil enriched mayonnaise. Black glutinous rice flour
was extracted twice with 70:30 acetone-water mixture (v/v) at pH 2 and 6.8 for 2, 4 and 8 h of total
extraction times. Total phenolic content (TPC), total monomeric anthocyanin content (TMA) and antioxidant
activities as determined by ferric reducing antioxidant power (FRAP) and 2,2-diphenyl-1-
picrylhydrazyl (DPPH) free radical scavenging activity assays of the crude extracts were measured. The
extraction with pH 6.8 solvent for 4 h yielded the crude extract with significantly highest antioxidant
activities analyzed by both FRAP and DPPH tests (p 0.05) although its TPC and TMA were not greatest.
The freeze-dried extract from this condition was then added into fish oil enriched mayonnaise at
500 mg/kg and 1000 mg/kg (oil weight basis). Conjugated diene hydroperoxides (CDH), thiobarbituric
acid reactive substance (TBARs) and color in CIELAB system of the mayonnaise samples stored at 30 C
were determined up to 30 days. The samples contained 1000 mg/kg crude extract had lowest rate of CDH
and TBARs increase but had greatest extent of color deterioration, possibly due to anthocyanin degradation
and Maillard reaction.