1 Affordable production of antioxidant aqueous 2 solutions by hydrodynamic cavitation processing of 3 silver fir ( Abies Alba Mill . ) needles 4

Extracts from parts of coniferous trees have received increased interest due to their 20 valuable bioactive compounds and properties, useful for plenty of experimental and consolidated 21 applications, in fields comprising nutraceutics, cosmetics, pharmacology, food preservation, and 22 stimulation of plant growth. However, the variability of the bioactive properties, the complexity of 23 the extraction methods, and the use of potentially harmful synthetic chemicals, still represent an 24 obstacle to the spreading of such valuable natural compounds. Hydrodynamic cavitation is 25 emerging as a promising innovative technique for the extraction of precious food components and 26 by-products from waste raw material of the agro-food production chain, which can improve 27 processing efficiency, reduce resource consumption, and produce healthy, high-quality products. 28 In this study, a process based on controlled hydrodynamic cavitation was applied for the first time 29 to the production of aqueous solutions of silver fir (Abies Alba Mill.) needles with enhanced 30 antioxidant activity. The observed levels of the in vitro antioxidant activity, comparable or higher 31 than those found for reference substances, pure extracts, and other water extracts and beverages, 32 highlight the very good potential of the HC process for the creation of solvent-free, aqueous 33 solutions endowed with bioactive compounds extracted from silver fir needles. 34