2.4.3. Total phenolic content (TPC)
Finely ground samples (0.5 g) were treated with 10 mL of an NaOH 4 N solution, under stirring and nitrogen flushing, at room temperature, for 4 h. The solutions were adjusted to pH 1.35 with HCl 6 N and then extracted with ethyl acetate. The organic layers were evaporated to dryness and the residue dissolved in 1 mL methanol. The extracts (30–100 lL according to the expected concentration) were added to 100 lL of Folin-Ciocalteu reagent and neutralised with 350 lL of sodium carbonate (5%), and distilled water was then added to a total volume of 2900 lL. After incubation at room temperature for 1 h, the absorbance was measured at 760 nm using a Kontron UVIKON 930 Spectrophotometer (Kontron Instruments, Milan, Italy). A solution containing all the reagents,but without the samples, was used as a blank. The results were expressed as ferulic acid equivalents (calibration curve linearity range: 10–90 lg; r = 0.9935).
2.4.3. Total phenolic content (TPC)Finely ground samples (0.5 g) were treated with 10 mL of an NaOH 4 N solution, under stirring and nitrogen flushing, at room temperature, for 4 h. The solutions were adjusted to pH 1.35 with HCl 6 N and then extracted with ethyl acetate. The organic layers were evaporated to dryness and the residue dissolved in 1 mL methanol. The extracts (30–100 lL according to the expected concentration) were added to 100 lL of Folin-Ciocalteu reagent and neutralised with 350 lL of sodium carbonate (5%), and distilled water was then added to a total volume of 2900 lL. After incubation at room temperature for 1 h, the absorbance was measured at 760 nm using a Kontron UVIKON 930 Spectrophotometer (Kontron Instruments, Milan, Italy). A solution containing all the reagents,but without the samples, was used as a blank. The results were expressed as ferulic acid equivalents (calibration curve linearity range: 10–90 lg; r = 0.9935).
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