Development and optimization of dry-peeling method for plums (Prunus domestica) using infrared radiation heating technology

This study explores the feasibility and optimization of infrared (IR) dry-peeling for plums (Prunus domestica) as a sustainable alternative to conventional lye peeling, aiming to enhance product quality and minimize environmental impact. A laboratory-scale system equipped with a ceramic IR emitter and rotating fruit rollers for loosening peels and a novel rubber-tube peel removal device was designed. The effects of IR emitter power (350–1000 W), heating time (90–150 s), and emitter distance (20–70 mm) on physicochemical properties and peeling performance were evaluated using Response Surface Methodology (RSM). The results showed that optimal conditions (797.48 W, 70 mm, 107 s) achieved 90 % peelability, 4.5 peeling easiness (1–5 scale), 0.30 % moisture loss, 0.12 mm peel thickness, 40 °C surface temperature, 13.5 ΔE color change, and 14 mg/100 g ascorbic acid retention. Hot lye peeling (10 % NaOH, 85 °C, 100 s) was used as a control treatment, and the findings indicated that IR has the potential for significantly reduced moisture loss (0.30 % vs. 9.56 %), preserved bright yellow hue (Hue angle 82 vs. 55°), and enhanced ascorbic acid retention (14 vs. 10.5 mg/100 g), while eliminating chemical wastewater. The rubber-tube device, with 76.67 % peelability under optimal IR conditions, performed comparably to lye pretreatment and showed potential for replacing manual peeling and enhancing process hygiene.