Towards a green and sustainable recovery of phenolic compounds form food by-products

Food wastes or food by-products have long been matter of concern due to their environmental, economic, etical and social impact. However, nowadays the approach towards these mate-rial is changing since they are considered as a cheap source of valuable component. Among food by-products, grape pomace (skins and seeds) and germ and bran of wheat represent a rich source of polyphenols, fatty acid, oil, vitamins, and fiber that could be extracted and further used as functional additives in food, cosmetic or pharmaceutic products. In this work, the influence of pulsed electric field (PEF) pre-treatment of grape skin and seeds as well as of germ and bran of wheat on extraction yield of polyphenolic compounds during the subsequent extraction with solvent was investigated. PEF treatments were carried out at 1, 3, and 5 kV/cm with a con-stant energy input of 10 kJ/kg. Kinetics and concentrations of total polyphenols extracted were evaluated in different green solvents (water, aqueous-ethanol and natural oil) for up to 24 h and optimum parameters were defined. The composition of phenolic extracts obtained under the optimum processing conditions were determined by metabolomics analyses (UHPLC­MS/MS, GC/MS/MS, UPLC­Q­TOF­MS­ORBITRAP). The results demonstrate that PEF assisted extraction has the potential to increase the extraction rates and yield of phe-nolic compounds from both grape and flour by-products. Moreover, this eco friendly or “green” process (due to modali-ties of PEF with low energy consumptions and utilization of eco-solvents) is expected to allow the reduction of the steps in extracts purification following PEF treatments.