Enhanced extraction of antioxidant phenolics: Quercetin, Kaempferol, Gallic Acid, Syringic Acid, and Epicatechin from fresh berries and their waste using Ultra-Turrax and Ultrasonication

This study aimed to improve extraction of antioxidant phenolics from fresh berries and berries waste. A combination of Ultra-Turrax milling and ultrasonication, both efficient and eco-friendly techniques widely used in the extraction of bioactive compounds, produced the best extraction of quercetin, kaempferol, gallic acid, syringic acid and epicatechin. These methods, which rely on mechanical disruption and ultrasonic waves to enhance cell wall breakdown, allow for greater release of phenolic compounds while minimizing heat damage. Ultra-Turrax 14,000 r/min, 5 min combined with 1 h ultrasonication led to total phenolics and total flavonoids concentration of 42.29 mgGAE g⁻¹dw, 21.85 mgRE g⁻¹ for blueberry, 97.68 mgGAE g⁻¹dw, 27.62 mgRE g⁻¹ for raspberry and 44.28 mgGAE g⁻¹dw, 16.5 mgRE g⁻¹ for blackberry. In waste, 72.01 mgGAE g⁻¹dw, 41.61 mgRE g⁻¹ from blueberry, 101.18 mgGAE g⁻¹dw, 19.76 mgRE g⁻¹ from raspberry and 96.60 mgGAE g⁻¹dw, 28.90 mgRE g⁻¹ from blackberry were obtained. Syringic acid and epicatechin were the main recovered compounds with 1945 mg g⁻¹dw and 2028 mg g⁻¹dw from fresh raspberry and 884 mg g⁻¹dw and 966 mg g⁻¹dw from blackberry waste. Extracts from blueberry, raspberry and blackberry had antioxidant activities of 832.87, 2757.64 and 583.32 µM TE g⁻¹ dw correspondingly. This study highlights an efficient extraction method that can support more sustainable practices in the food industry by maximizing the recovery of valuable phenolic compounds from both fresh berries and their processing waste.