Optimizing quercetin and kaempferol extraction from Moringa oleifera leaves via ultrasonic assisted extraction: Kinetic modeling and process optimization

Abstract

Flavonols, such as quercetin and kaempferol, are pigments found in Moringa oleifera leaves (M. oleifera), which show potential medical values that can be extracted using various extraction methods. This study employed direct probe ultrasound-assisted extraction (UAE) to extract quercetin and kaempferol compounds from M. oleifera leaves. We used the one-factor-at-a-time (OFAT) method to investigate five operating parameters: solvent concentration, extraction temperature, extraction time, amplitude, duty of cycle, and solid-to-solvent ratio, in order to identify the most important extraction parameters. The OFAT experiment's results prompted the development of a Box-Behnken Design (BBD) for processing parameter optimization. According to the BBD results, the solvent concentration had little influence on the yields, however the extraction duration had a considerable impact on all of them. After a few runs, the measured yields acquired under predicted processing parameters matched the results that were expected. The findings showed that the highest amounts of quercetin and kaempferol were obtained when 60 % ethanol was used, the extraction process of 14 minutes, the temperature of 48 °C, and the ratio of liquid to solid (L/S) of 45:1 ml/g. The structural surface of M. oleifera leaves changed after exposure to the UAE process and maceration extraction, as revealed by scanning electron microscopy (SEM). These results imply that the UAE has the potential to extract the phenolic compound from M. oleifera leaves at optimal processing parameters with optimal yields.