Evaluation of the Effect of Ultrasonic Vibration on the Physicochemical and Bioactive Properties in Non-Marketable Blackberry (Rubus sp.)

Abstract

Nowadays, global attention has increasingly focused on environmentally friendly technologies and the valorization of non-marketable food materials. In blackberry production, approximately 30% of the harvested fruit may be lost due to damage during harvesting and postharvest handling, highlighting the need for sustainable strategies to recover valuable compounds and promote the circular economy. Therefore, this study evaluated the effect of ultrasound on the physicochemical properties and bioactive compounds of non-marketable blackberries. The high-power ultrasound was applied for 0 to 60 min at a frequency of 20 kHz and 100% amplitude, using water as the extraction medium at a 2:1 water-to-sample ratio. Ultrasound significantly increased total soluble solids (12.57 ± 0.82 °Brix), soluble dietary fiber (11.79 ± 0.36 g/100 g DW), total phenolic compounds (235.54 ± 3.47 mg GAE/100 g FW) and antioxidant activity measured by ABTS (8569.61 ± 221.34 mmol TE/100 g FW) and FRAP (32,408.41 ± 310.57 mmol TE/100 g FW). In contrast, anthocyanin content decreased with increasing treatment time, reaching 39.15 ± 1.82 mg of CGE/100 g FW. Overall, high-power ultrasound promoted the recovery of certain bioactive compounds from non-marketable blackberries, demonstrating potential for fruit valorization, functional ingredient development, waste reduction, and environmentally friendly processing within a circular economy framework.