Conjugated diene value (CDV)
The AOCS official method (Ti 1a-64) was used to determine CDV (AOCS, 1990). In brief, approximately 10 mg oil samples were weighed in test tubes (Pyrex, 16 × 125 mm) and dissolved in 10 ml isooctane. The solution (1.0 ml) was transferred to another test tube and diluted with 9 ml isooctane. The solution was added in a quartz cuvette and the absorbance was measured with the same spectrophotometer used for PV at 233 nm. Three experimental replicates were analyzed in duplicate.