Radio frequency blanching facilitates enhanced release of bioactive phytochemicals and boosts antioxidant capacity in...

Apple juice extraction generates substantial amounts of pomace rich in phenolic compounds, many of which are poorly recovered due to polysaccharide-phenolic interactions and limited mass transfer. Here, radio frequency (RF) blanching was applied to comminuted apple solid-liquid mixtures to enhance bioactive phytochemical release and antioxidant capacity in pressed juice, compared with water-bath (WB) blanching. Under the RF-9 treatment condition (9 cm electrode gap), the mixture heated from 27 to 70 °C in 8 min (WB: 25 min). RF-9 increased total phenolics and flavonoids to 29.35 mg GAE/100 mL (+90.5%) and 21.75 mg RE/100 mL (+222.2%), with ∼50% higher DPPH/ABTS activity. Browning was suppressed (L* 47.35, +37%). GC-MS showed better retention of fruity esters/alcohols and reduced aldehyde off-notes, supported by SEM-observed cell wall disruption. Overall, RF blanching shows potential as a rapid pretreatment to improve pressed apple juice quality and enhance the transfer of bioactive compounds into the juice phase.