Flavonoids: precipitation kinetics and interaction with surfactant micelles

Polyphenolic substances, such as flavonoids, attract considerable interest due to their ability to act as antioxidants. The vast majority of studies published deal with the nutritional, biochemical, or chemical structure aspects of these substances while few reports exist on the physico-chemical properties as well as solution behavior of the substances. In this article we report on the precipitation kinetics of naringenin, quercetin, and rutin in pure water as well as in micellar solutions of Tween 80. The methods used are dynamic and static light scattering in conjunction with cryo transmission electron microscopy. The results show that the substances precipitate rapidly in pure water. In the presence of Tween 80 micelles, however, the flavonoids can become solubilized in the micelles, which can result in solutions which are stable for days. The results suggest that the extent of solubilization is related to the chemical structure of the flavonoids. This study illustrates that precipitation kinetics and the distribution of polyphenolic substances in solutions and dispersions are factors of importance, which should be taken into account when designing investigations and interpreting results.