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Introduction: Blueberry (Vaccinium spp.) waste, a by-product of industrial fruit processing, represents a rich source of polyphenolic compounds, particularly anthocyanins, which may contribute to the antioxidant potential. Ultrasound-assisted ethanolic extraction is an efficient and eco-friendly approach for obtaining bioactive extracts from this raw material.1 The aim of this study was to optimize the extraction conditions for blueberry waste and evaluate the in vitro antioxidant potential of three obtained extracts.
Methodology: Ultrasound-assisted extraction was performed using ethanol concentrations of 40% and 60%, temperatures of 45 °C and 55 °C, and extraction times of 20–60 min. Antioxidant activity was determined by DPPH and ABTS assays (IC50, µg/mL), while total phenolic content (TPC) was determined by the Folin–Ciocalteu method (mg GAE/g DE).
Results: Extract E1 (60% EtOH, 55 °C, 30 min) exhibited the highest TPC (93.14 mg GAE/g DE), strongest ABTS activity (IC50 = 24.19 µg/mL), and favorable DPPH activity (IC50 = 304.85 µg/mL). Extracts E2 (40% EtOH, 55°C, 60 min) and E3 (60% EtOH, 45°C, 20 min) showed slightly lower but comparable antioxidant activity (DPPH IC50 = 308.65 and 322.00 µg/mL; ABTS IC50 = 40.47 and 33.60 µg/mL) and phenolic content (85.43 and 80.00 mg GAE/g DE).
Conclusion: E1 showed the most favorable overall antioxidant profile, indicating that higher ethanol concentration and temperature favored phenolic recovery and antioxidant activity within a short extraction time. E2 and E3 also demonstrated considerable antioxidant activity and phenolic content, supporting ultrasound-assisted extraction as an effective approach for blueberry waste valorization.
Keywords: Blueberry, fruit waste, ethanolic extraction, ultrasound, polyphenols.