New methods for the determination of isoflavones from soy and derived foods

In this Doctoral Thesis several aspects of soy isoflavones determination were assessed for the development of new methods for the extraction, clean-up/concentration and hydrolysis, as well as new analysis methods by high performance chromatography methods. Previously, the stability of soy isoflavones extracts and standard solutions was evaluated. Thereafter, new extraction methods were developed using the latest techniques and materials available. It was evaluated the use of ultrasounds, pressurized liquids, microwaves and solid phase extraction for the extraction of soy isoflavones from several types of samples. The developed methods are fast, reliable and highly reproducible. New materials were also evaluated, like solid phase extraction polymeric cartridges and the monolithic columns for liquid chromatography. These materials were used for the determination of isoflavones from several soy juices samples with excellent results. Globally, the information provided allows increasing the speed, precision, reproducibility, flexibility and decreasing operational costs of the determination of isoflavones not only from soybeans, but also other matrices, since the developed methods can be potentially used for different types of samples.324 p