Materials, Methods & Technologies, Volume 15, 2021

Abstract: Rheum ribes L. (rhubarb), which belongs to the family of Polygonaceae, is one of the most important medicinal Mediterranean plants. Its aqueous decoctions have become a common practice among patients suffering from diabetes, hypertension, obesity, and diarrhea. Therefore, it is worth using techniques capable of increasing the extraction of valuable compounds while providing effective microbiological decontamination of the raw material. Instant Controlled Pressure-Drop (DIC) is a high temperature-short time treatment (HTST) followed by an abrupt pressure-drop (ΔP/Δt>500 kPa s-1) towards a vacuum (about 5 kPa). It allows a controlled expansion to ensure better diffusivity and higher availability of the active molecules. Indeed, DIC treatment has already shown its potential in improving the conventional extraction of active molecules and essential oils from plants. Rheum ribes L. rhizomes were collected from Chouf, Lebanon, dried from 1.33±0.28 to 0.16±0.02 g H2O/g dry-basis, ground, and sieved into small particles of 0.4-2 mm. DIC treatment was used with a saturated steam pressure ranged from 200 to 600 kPa for 10 to 40 s. The antiradical characteristics (DPPH· test) of aqueous extracts of DIC-treated samples were determined. At low levels of saturated steam-pressure, DIC treatment showed a significant impact on the scavenging capacity of the rhizomes. Thus, at 260 kPa, it recorded the lowest IC50 value (54.56±0.19 μg/mL) versus 71.29±0.499 μg/mL for the untreated rhizomes (RM for raw material) used as a control. DIC processing parameters will be optimized in our future work to obtain the highest yield of phytochemicals while assessing the antimicrobial, cytotoxic, and bioactive properties of the aqueous extracts of R. ribes L. rhizomes.