Development of Spectrophotometric Quantification Method of Iron-Polyphenol Complex in Iron-Fortified Black Tea at Relevant pH Levels

Abstract

The formation of iron complexes with phenolic compounds in foods causes discoloration and reduces iron bioavailability. Black tea is a beverage of particular interest because of its high polyphenol content and widespread consumption. A simple spectrophotometric method for the quantification of iron-polyphenol complexes was developed and used to compare complex formation of iron with black tea polyphenols and gallic acid, a monomeric polyphenol. The amount of iron-polyphenol complex formation was quantified with a variety of iron sources (ferrous sulphate, ferrous fumarate, and ferric sodium EDTA) at pH levels relevant to brewed tea and iron absorption into the body. The results confirm the potential usefulness of ferric sodium EDTA in the fortification of high polyphenol content foods, particularly in black tea. This method has the potential to assist in the development of an optimal formulation of iron-fortified black tea and may also be easily adapted for use with other polyphenol containing foods.