2.6 Total phenolic content (TPC) and Total flavonoid content
(TFC)
2.6.1 Total phenolic content (TPC)
Using Ainsworth and Gillepsie’s (2007) Folin-Ciocalteu procedure, the
TPC of the flours and cookie extracts was evaluated. A solution of 10 µL
extract and 50 µL Folin-Ciocalteu phenol reagent (Sigma Aldrich,
Germany) was added to 500 µL of distilled water. After letting it stand
in the dark for three minutes, 200 µL of 20% (g/v)
Na2CO3 (Sigma Aldrich, Germany) was
added, followed by the addition of 245 µL of distilled water. The
mixture (300 µL) was precisely pipetted into a 96-well microplate,
covered with aluminum foil, and then incubated in darkness for 30 min.
The plate’s absorbance was then measured using a micro plate reader
(iMark, Biorad, South Africa) at 750 nm. The standard utilized was
garlic acid (Sigma Aldrich, Germany), and the results were reported as
mg GAE/g sample.
2.6.2 Total flavonoid content (TFC)
The TFC was determined using the method proposed by Ar-Farsi and Lee
(2008), involving the mixing of 30 µL of the extract with 20 µL of 36 mM
NaNO2. About 20 µL of 94 mM AlCl3 was
then added. A micro plate reader (iMark, Biorad, South Africa) was used
to measure the mixture’s absorbance at 450 nm. Using catechin (Sigma
Aldrich, Germany) as a reference, the results were reported as mg of
catechin equivalents per g of the sample (mg CE/g sample).