Supercritical adsorption process to obtain concentrated natural antioxidants

FACUNDO MATTEA; DAMIÁN A. CARDARELLI; MIGUEL A. MATTEA

Rio de Janeiro

Congreso; 2nd Mercosur Congress on Chemical Engineering, 4th Mercosur Congress on Process Systems Engineering; 2005

An important quantity of active chemical compounds with antioxidant properties have been identified in spice extracts and herbs, particularly in labiates family such as rosemary, sage and thyme. The recoveries of such compounds require the use of gentle techniques due to their thermolabile nature. In this work, an adsorption-desorption process using CO2 under supercritical conditions (SCO2) was used to concentrate natural antioxidants from rosemary (Rosmarinus officinalis) leaves. The leaves were first extracted with steam to separate the essential oil. Subsequently, the solid residue was extracted with isopropyl alcohol to obtain a dark, viscous and odorous oleoresin. The resulting oleoresin was kept overnight in contact with an adsorbent (silica gel), at room temperature, to favor the adsorption of its components. Afterwards, supercritical carbon dioxide was used as solvent to selectively extract the adsorbed compounds from the adsorbent. Different extraction temperatures (40 - 80°C) and pressure levels (20-40MPa) were tested in order to recover and concentrate extracts with high antioxidant activity, low color and odor. The antioxidant power of extracts was determined by measuring the oxidative stability of crude soybean oil added with well known extracts quantities (