engleski

Monitoring the Total Polyphenols in Foods Using Enhanced Automatic Flow-Injection Analysis with Spectrophotometric Detection

An optimised flow-injection method for the determination of the total polyphenol content in foods based on the Folin-Ciocalteau reaction in 0.5 mol L-1 NaOH is proposed. The method allows different types of samples to be analysed automatically at a rate of 55 samples per hour by using gallic acid as standard. By applying the proposed method to real samples (white and red wines, green, indian, lime-tree, mentha and chamomile teas, and fruit juices of blackberry and cherry), their total polyphenol indices were determined with a higher reproducibility than that obtained by conventional method, whatever the dilution used.. By using optimized flow sheet diagram and the best selected values of chemical parameters involved in total polyphenols determination the flow injection method showed the most reliable results. Flow injection analysis with sectrophotometric detector is faster than the conventional batch method which requires 30 min per sample. The method is highly tolerant towards the most common interferences (SO2, reducing sugars and ascorbic acid) that occur with its batch counterpart. The results provided by the proposed method relatively agree with those obtained using the conventional Folin-Ciocalteau method.

flow-injection method; Folin-Ciocalteau reaction; total polyphenol index; interferences

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