it is not very tough. just compare the absorbance of your extract with that of the standard curve of a phenolic compound e.g. gallic acid.
It just depends on which type of quantifying method you are using like HPLC or spectrophotometer.
If spectrophotometer then check your absorbance against standard curve like Gallic acid (GA) and data will be represented as gallic acid equivalent (GAE). If you need a protocol then please follow Ainsworth and Gillespie, 2007 article published in nature protocols.
Thanks
you can quantify the total phenolic content by spectrophotometric method using any phenolic compound as standard(Eg Ferulic or gailic acid)..
Reagents are 20% sodium carbonate and folin's reagent in water(1:2) .
Blueish products are formed which can be measured at A720nm.
Folin-Ciocalteu method using gallic acid or caffeic acid as a standard.
For a quick method see:
http://link.springer.com/article/10.2478%2Fs11535-012-0107-3
The total phenol is determined by the Folin–Ciocalteu method, the reaction mixture contained 200 μL of diluted extracts, 800 μL of freshly prepared diluted Folin Ciocalteu reagent and 2 mL of 7.5% sodium carbonate. The final mixture is diluted to 7 mL with deionized water and kept in the dark at ambient conditions for 2 h to complete the reaction. The absorbance at 765 nm is measured. Caffeic acid is used as standard, and the results were expressed as mg caffeic acid/g dried extract
(mg CAE/g DE).
Total phenolic
compounds were determined by the Folin-Ciocalteu method
(27) with simple modification and expressed as gallic
acid equivalent (GAE). A mass of 2 g of sample (lyophilized
fruit powder and marmalades) was dissolved in
20 mL of distilled water, centrifugated at 6000×g for 10
min and the supernatant was separated. A volume of 0.1
mL of the supernatant was mixed with 5 mL of distilled
water and 0.5 mL of commercial Folin-Ciocalteu reagent
(0.2 M based on sodium hydroxide titration). The content
was mixed well and kept at room temperature for 5
min followed by the addition of 2.0 mL of 10 % aqueous
sodium carbonate and incubation at room temperature
for 1 h. Absorbance of the developed blue colour was
read at 760 nm against a blank reagent. For calibration
curve, five standard gallic acid solutions (0-100 mg/L)
were prepared in distilled water and their absorbances
were read according to the same protocol.
You can search: Properties of Rose Hip Marmalades
Oktay Yildiz, and Mehmet Alpaslan, Food Technol. Biotechnol. 50 (1) 98–106 (2012)
phenolic content, absorbed to 730 nm, standard by tannic or catechin or gallic acid. coloremetric method is a simple method (pholin-Dien) or (pholin-coecaltueau). its very important if you need diultion, and very important separate blue solution to precipitate
Sample extracts or standard solutions were treated with Folin-Ciocalteu reagent for 6 min. Then the mixture was alka- linized with Na2CO3. The blue colour of the solution was developed for 90 min, and the absorbance was measured at 760 nm using a UV–VIS spectrophotometer. The measurement was compared to standard curve of gallic acid and expressed as mg of gallic acid equiv. (GAE)/100 g dry weight (DW).