The total phenolic
contents of the apple samples were measured using a modified
colorimetric Folin-Ciocalteu method (21). A volume of 0.5 mL of
deionized water and 0.125 mL of a known dilution of the extract were
added to a test tube. Folin-Ciocalteu reagent (0.125 mL) was added
to the solution and allowed to react for 6 min. Then, 1.25 mL of 7%
sodium carbonate solution was aliquoted into the test tubes, and the
mixture was diluted to 3 mL with deionized water. The color developed
for 90 min, and the absorbance was read at 760 nm using a MRX II
DYNEX spectrophotometer (DYNEX Technologies, Inc., Chantilly,
VA). The measurement was compared to a standard curve of prepared
gallic acid solutions and expressed as milligrams of gallic acid
equivalents per 100 g ( SD fresh apple component for the triplicate
extracts.