Improvement and Validation of Phytate Determination in Edible Seeds and Derived Products,as Mineral Complexing Activity

The analysis of phytates, as antinutrients that naturally occur in edible seeds, is important due to its interaction with certain minerals (Ca, Mg, Zn, Fe) essential for health, especially for children or other groups at risk of deficiency diseases. Although several analytical methods for phytates use complex techniques, complexometric methods are recently applied since they provide the knowledge of real mineral complexing activity of different phytates in foods, which is of great relevance for nutritional studies. A reliable method for phytate quantification in terms of cation binding activity has been optimized, based on previous complexometric methods, with the improvement of quantification through calibration with standards instead of estimation through equations. The methodology was optimized for different matrices of seeds and seed-derived food products, including infant foods, and it was validated according to AOAC standards to assess reliability. Due to the presence of different phytate forms in foods, and the different ability of complexation of each one, the expression of results of phytates as phytic acid equivalents (PAE) is proposed. With this methodology, phytates were found in all the samples analyzed, showing a higher amount in seeds (4029 mg PAE/100 g in dehulled hemp seed) than in infant foods (231 mg PAE/100 g in rice formula). From the validation protocol, the method showed good linearity, accuracy, and precision for food samples over 80 mg PAE/100 g, not requiring high-cost equipment, and providing high reliability and practical applicability for routine laboratories, with the purpose of monitoring of food quality.