Investigation of soy based botanical supplements by FT-IR spectroscopy for a fast and non-destructive quality control

Nutritional preparations of soy (Glycine max (L.) Merr.) have gained interest in western countries as an alternative to hormonal therapy in the treatment of menopausal problems such as hot flushes. The active compounds responsible for this are the present isoflavones, mainly genistin, daidzin and glycitin which show a weak estrogenic activity and are therefore called phytoestrogens.

In the present study, FTIR-ATR spectroscopy has been applied for the characterization and identification of the main isoflavones in soy based nutritional preparations available in German pharmacies. Informations about the functional groups and the chemical composition could be obtained which makes FTIR analysis expedient for a simple and non-destructive quality control.

Moreover, using the partial least square (PLS) analysis multivariate calibration models were employed. This made estimations about the amount of the individual isoflavones and the total isoflavone content possible. The results of these infrared spectroscopy studies in combination with multivariate calibration showed the potential for production monitoring by pharmaceutical manufacturers and public supervisory authorities.