Valorization of Strawberry (Fragaria × ananassa Duch) cv. ‘Malwina’ by-products: A Source of Phenolics and Antioxidants for Sustainable Applications

The leaves, stems, and roots of strawberries (Fragaria × ananassa Duch.) are typically discarded, together with the pomace residues generated during industrial processing. This study evaluated the distribution of phenolic compounds, flavonoids, and anthocyanins in different plant parts and pomace to assess antioxidant activity and potential circular economy applications. Fully ripe strawberry (Fragaria x ananassa Duch.) cv. ‘Malwina’ fruits were harvested in August from Joniskis region, Lithuania. Calyces were separated and juice was pressed. The remaining agronomic waste (leaves, stems, crowns, rhizomes and roots) and pomace from juice extraction were freeze dried. Total phenolic content (TPC), total flavonoid content (TFC), and total anthocyanin content (TAC) were determined using spectrophotometric methods, while antioxidant activity was assessed using DPPH· and ABTS+- assays. Statistical analyses were performed using one-way analysis of variance (ANOVA). Fisher‘s test was applied to assess significant differences (p<0.05) between the samples. The relationship between parameters was assessed by Pearson’s linear correlation test at a p < 0.05 significance level. The results revealed that the total phenolic content (TPC) was relatively high in all parts of the strawberry (Fragaria x ananassa Duch.) plant (41–51 mg GAE g-¹ D.W.), with the leaves exhibiting the highest flavonoid content (5.1–5.3 mg QE g^-1 D.W.) and the pomace showing moderate anthocyanin levels (0.32–0.36 mg Cy3G g^-1 D.W.). Strong positive correlations were notably observed between TPC and DPPH· radical scavenging activity across most plant parts, indicating that phenolic compounds largely contribute to the antioxidant potential. Although low in flavonoids and anthocyanins, roots, crowns and rhizomes still contributed to the overall phenolic content and antioxidant capacity, indicating a source of bioactive compounds. The findings indicate that strawberry by-products are rich in phenolics and antioxidants, highlighting their potential for valorization in food, nutraceutical, and cosmetic applications within a circular economy framework.