Screw press extraction and ultrafiltration of flavonoids from kalanchoe leaves and stems

Kalanchoe leaves and stems contain flavonoids known to have anti-inflammatory, anti-microbial and anti-allergenic properties of interest for use in cosmetics and pharmaceuticals. The present study investigates the aqueous extraction of flavonoids from the leaves and stems of kalanchoe hybrids. The extraction process consisted of screw pressing followed by aqueous batch extraction, microfiltration using tubular 0.2 μm polypropylene membranes, 20 kDa polyethersulfone flat sheet membranes and 1 kDa composite fluoropolymer membranes. The experiments showed that the screw press efficiently separated the kalanchoe leaves and stems into a solid fraction with a dry matter content of 14 % and a liquid fraction with a dry matter content of 2.4 %. Approximately two thirds of the flavonoids were in the liquid phase after the initial pressing. The batch extraction time was found to be 3 hours to achieve maximum flavonoid concentration. The combination of microfiltration and ultrafiltration could produce a liquid fraction rich in flavonoids. However, the proposed combination of membranes and cleaning procedures are not optimal and needs further development.