Determination of Total Polyphenols in Apple Vinegar Drink by Folin-Ciocalteu Method

The optimum condition on determining total polyphenols content in apple vinegar drink by Folin-Ciocalteu method was studied.The results indicated that the optimum conditions for total polyphenols determination by FolinCiocalteu were as follows: 2.5 mL of Folin-phenol reagent was added in 1.0 mL of sample,and then 4.0 mL of 12% sodium carbonate solution was added.After the coloration reaction was for 1.5 h at 45 ℃,the optical density was measured at 756 nm.Under the optimum conditions,the absorbance increased linearly with the concentration of gallic acid in the range of 0 to 6 μg/mL(y=0.1238x+0.0098,R2=0.9992).The average spiked recovery rate was 101.2% with the relative standard deviations of 2.8%(n=5).The method is highly precise and stable,and suitable for determining total polyphenol content in apple vinegar drink.