Life cycle assessment of green pilot-scale extraction processes to obtain potent antioxidants from rosemary leaves

In this work, the water extraction and particle formation on-line (WEPO) process has been used to obtain dry antioxidant powder from rosemary leaves. This process includes pressurized hot water extraction (PHWE) and on-line drying of the extracts in one step. Based on previous works, water extraction at 200 °C was selected to achieve the maximum antioxidant activity while water flow rate was studied to determine its influence on powder formation. Other parameters influencing the drying process, such as scCO2 pressure (80 bar) and flow rate (2.5 mL/min) and N2 flow rate (0.6 mL/min) were settled to obtain a fine and constant spray. Powders obtained were evaluated in terms of particle size and morphology by scanning electron microscopy (SEM) as well as antioxidant capacity by an in vitro DPPH antioxidant assay. In order to assess the environmental performance of the WEPO process, this has been compared in terms of Life Cycle Assessment (LCA) to other green processes typically used for antioxidant extraction from rosemary leaves, such as supercritical fluid extraction (SFE) and a static pressurized hot water extraction, PHWE, carried out with a commercial equipment, both followed by a conventional drying step. The WEPO process, carried out in one step, giving dry bioactive extracts from rosemary, results in lower environmental impacts and energy consumption than the other green processes studied. The sensitivity assessment demonstrated the importance of primary energy sources in the production of electricity used, especially when green processes are being implemented.