| The fortification of black tea with iron has the potential to reduce the prevalence of iron deficiency in the developing world. Tea is an ideal vehicle for food fortification because it is centrally processed, is the most consumed beverage globally, aside from water, and is consumed in regular quantities by those of all socioeconomic strata in many regions. Unfortunately polyphenolic compounds present in tea, which are responsible for colour and flavour, form complexes with iron which reduce the bioavailability of both compounds and cause strong unattractive colour development. The objective of this study was to develop a technique for the fortification of tea with iron such that these complexes do not form. A spectrophotometric method was developed and validated for the quantification of iron-polyphenol complex formation. Iron-polyphenol complex formation was further investigated with a variety of iron sources, temperatures, and polyphenol concentrations using a gallic acid model system and tea extract. Analysis and modeling of iron-polyphenol complex formation prompted the investigation of predicted inhibitors, specifically reducing and chelating agents. Reducing agents were able to hinder iron complex formation at pH 5 (the pH of brewed tea) but not at pH 7 (an approximation of the small intestine's pH). Chelating agents were successful at preventing iron-polyphenol complex formation at both pH 5 and pH 7. Due to its superior performance, disodium ethylenediaminetetraacetate (EDTA) was optimized for use in black tea. In summary, a technique has been developed for producing iron fortified tea based on a comprehensive framework for understanding the formation and inhibition of iron-polyphenol complexes in the presence of black tea polyphenols. This tea maintains its visual acceptability while providing iron in a bioavailable form. A process for effective iron fortification based on our laboratory technique is ready for in-vivo evaluation of its effectiveness and pilot scale testing. |
