The antioxidant activity of oleoresin from rosemary (Rosmarinus officinalis L.) (ROSM) and sage (Salvia
officinalis L.) (SAG) was evaluated using photochemiluminescent method (PCL assay), spectrophotometric
method based on 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay and Rancimat test. Using PCL assay, the
antioxidant content of lipid (ACL) soluble compound in the extracts was quantified (mol Trolox equivalents/
g extract). Rancimat test was used to evaluate the induction period (IP) of sunflower oil blended with
ROSM and SAG at 500 and 1000 mg/kg under elevated temperature (110 ◦C). The IP was used to determine
the oxidative stability index (OSI) and percentage antioxidant activity (%AA). In addition, the phenolic
characterization of extracts was performed using ultra performance liquid chromatography–tandem
mass spectrometry (UPLC–MS/MS) which suggested that phenolic diterpenes could be the major antioxidant
compounds. The EC50 value obtained from PCL and DPPH assays were significantly correlated
(r = 0.997, p < 0.01). The SAG showed significantly (p < 0.05) higher antioxidant activity than ROSM in
all the tested methods. The OSI and %AA of ROSM and SAG blended oil was significantly higher (p < 0.05)
than the control sunflower oil sample. In conclusion, the PCL and Rancimat test were successfully used
for direct and dependable monitoring of antioxidant activity and intended as the alternative to DPPH
assay for industrial application.