Green tea encapsulation by means of high pressure antisolvent coprecipitation

MARÍA VALENTINA SOSA; FACUNDO MATTEA; MARÍA JOSÉ COCERO; MARTÍN CISMONDI

Natal

Congreso; II Iberoamerican Conference on Supercritical Fluids; 2010

Green tea catechins account for approximately a fifth of the dry weight of the leaves. These polyphenols report health benefits, such as antioxidant and antimutagenic activities, among others. To overcome the problem of the short half-life of tea catechins in plasma after their intake, it is indispensable to design an effective controlled delivery system in order to obtain prolonged-delayed release for the active principles with high- water solubility, besides their protection against degradation. In this work, green tea extracted with an organic solvent was coprecipitated together with a polymer by using the semi continuous supercritical anti solvent process (SAS). Carbon dioxide (CO2) was used as anti solvent in addition to be a dispersing agent. Poly(ε-caprolactone) (PCL) (25000) was the selected biodegradable polymer since it finds applications in the medical and pharmaceutical industry and acetone was used as solvent for the tea and polymer solutions. The extracts from the commercial green tea were obtained by microwaved assisted extraction (MAE) technique. The influence of different process parameters, including the operating pressure (8-12 MPa) and temperature (283-307 K), the polymer/solutes concentration (w/w) ratio (4-58), and the CO2 / solution mass flow rate ratio (4-10) have been studied experimentally. Scanning Electron Microscopy (SEM) and Differential Scanning Calorimetry (DSC) were used to analyze the precipitates. Composite particles were successfully obtained (3-5 μm) with a high degree of agglomeration. The SEM images of the products show that a good encapsulation of the green tea compounds was achieved, while information from the DCS patterns of the products reveals that the semicrystalline properties of the polymer remains very similar to the original polymer material. Also HPLC analysis was performed to prove the presence of some of the antioxidant materials extracted from the tea in the coprecipitated particles.