Processing of Strawberry Juice Using High-Power Ultra-Sound (HPU) and Pulsed Electric Field (PEF): Synergistic Effects on Quality, Color and Anthocyanins Revealed by Chemometrics.

Minimally processed, non-thermal technologies are increasingly used to preserve fruit juice quality and safety while extending shelf life. This study evaluated high-power ultrasound (HPU; 25% amplitude, 50% pulse, 2.5-7.5 min) combined with pulsed electric field (PEF; 30 kV cm-1, 100 Hz, 1.5-4.5 min), applied in the HPU → PEF sequence, as a hurdle strategy for strawberry juice stored for 7 days at 4 °C. The aim was to assess effects on anthocyanin content, color, and physicochemical properties (conductivity, browning index, dissolved oxygen, HMF) and to identify optimal processing conditions using a chemometric approach. Storage significantly affected all parameters (p ≤ 0.01), increasing conductivity, browning index, and total color difference while reducing anthocyanin, oxygen, and HMF levels. Among HPU-PEF combinations, the mildest treatment (HPU 2.5 min + PEF) preserved the highest anthocyanin content (19.48 ± 0.05 mg 100 mL-1), lowest conductivity, browning index, and HMF, while more intensive treatments caused progressive degradation. Optimization identified HPU 2.5 min + PEF 1.5 min (no storage) as maximizing anthocyanin retention (20.07 mg 100 mL-1), while minimal HMF (4.29 mg L-1) required HPU 3.5 min + PEF 1.5 min. Short-duration HPU-PEF combinations thus provide an effective mild-intensity hurdle strategy for maintaining fresh-like strawberry juice quality.