Valorization of <i>Prunus cerasus</i> var. Marasca Pomace Derived From Industrial Processing: Recovery, Characterization, and Bioactivity Assessment of Secondary Metabolites

The phytochemical composition of Prunus cerasus var. marasca pomace produced as industrial byproduct was investigated. Its antioxidant and anti-tyrosinase properties were also assessed to evaluate a possible reuse as a bioactive food ingredient. Secondary metabolites were extracted from pomace using an optimized ultrasound-assisted maceration in ethanol/water. Total phenols (26.2 mg GAE/g), flavonoids (2.5 mg RE/g), and anthocyanins (82.5 µg CE/g) in the extract were determined spectrophotometrically. Seventy metabolites were identified by UHPLC-QToF-MS, and several are here reported in marasca cherries for the first time. The extract exerts valuable free-radical scavenging, metal-reducing, and metal-chelating activities that underlie its antioxidant properties. Also, it inhibits tyrosinase with an effect equaling 39 mg kojic acid/g of extract. However, temperatures >4°C during 6-month storage significantly affected the phenolic content and bioactivity of extract. Pomace of P. cerasus var. marasca cherries can be reused as a source of bioactive secondary metabolites, which can be easily recovered by sustainable ultrasound-assisted maceration. The extract can potentially be used as an additive to increase the oxidative stability of food products and control enzymatic browning, and improve their nutraceutical properties. However, storage time and temperature should be carefully evaluated in order to preserve extract's properties. Alternatively, appropriate stabilization strategies need to be developed further.