Abstract:
Antioxidant activity of sesame {Sesamum indicum L.) oil can be assessed by
determining its total phenolic content (TPC) using Folin-Ciocalteu reagent (FCR)
method. Objective of this study was to optimize V, volume of FCR, C, concentration
of sodium carbonate (SC) solution and t, incubation time, used for the
determination of TPC of sesame oil since a standard method is not available for the
said purpose. Methanol-water (80:20 v/v) extracts of freshly produced sekku-based
sesame oil was used. TPC procedure adopted was as follows: 1 ml of the said extract
was diluted with 5 ml of distilled water; V ml of FCR and 2 ml of C g/100 ml of SC
solution were added; mixture was diluted with 1.5 ml distilled water and vortexed
at 1600 rpm for 30 seconds; kept in dark for t h. Absorbance at 765 nm was measured
using a UV-VIS Spectrophotometer (DR 6000™, HACH). Optimization of the
parameters were carried out using a full factorial design of experiment with V = 0.5,
1.0 and 1.5 and C = 7.5, 10 and 20. Contour plot obtained with the resulting
regression model featured a saddle point in the area enclosed by V ^ 1.0 to 1.5 and C
^ 15 to 20 for all t studied, and therefore this area shall be avoided in the TPC
determination of sesame oil. Optimum values of V, C and t. suggested by the results
of this study are 0.5 ml, 20 g/100 ml, and 1.5 h.
