Multi-Criteria Optimization Including Environmental Impacts of Ultrasound-Assisted Extraction of Phenolic Antioxidants from Blackcurrant Pomace By-Product

Ultrasound-assisted extraction of antioxidant compounds from blackcurrant pomace was studied. The obtained results showed that this pomace is rich enough in phenolic antioxidants and suggested a potential way to valorize this by-product. Ultrasound assistance greatly enhanced the extraction efficiency (yields more than twice higher than the obtained without ultrasound). Extraction process was optimized using a recently developed original multi-criteria optimization tool which was respectively adapted to the concrete case of this study. This hybrid model, based on kinetic equations, experimental design and Life Cycle Assessment, enabled to estimate simultaneously the antioxidant activity of the extracts, the extraction yields of anthocyanins and polyphenols, the energy consumption, and the environmental impacts of extraction process at each experimental condition. All of these criteria were expressed as functions of the studied operating parameters (extraction time, liquid/solid ratio, solvent composition, and ultrasound power). Maximal yields of polyphenols and maximal antioxidant activity were obtained at 120 min, while the maximal yield of anthocyanins was obtained at 28 min only. Simultaneous consideration of several criteria and detailed analysis using this model enables to find conditions to decrease considerably environmental impacts and energy consumption without a significant decrease of productivity criteria (extraction yields and antioxidant activity of extracts).