Valorization of potato waste via pretreatments and drying: enhancement of bioactive compounds, antioxidant activity, and stability for sustainable applications

The valorization of agro-industrial residues through process intensification strategies offers a sustainable route for generating functional ingredients. This study evaluated the effects of different pretreatments (sodium carbonate solution (SCP), ethanol (ETP), blanching (BP), and ultrasound (USP)) on drying (70 °C), nutritional composition, phenolic profile, and bioactive stability of potato peel powder. As a value-added product, the resulting powder can be applied in food formulations as a natural antioxidant source and fiber-rich ingredient. In terms of processing, USP and ETP significantly reduced drying time compared to the control (270 min), reaching 210 min (USP) and 240 min (ETP). These treatments also increased the drying rate (USP = 0.408 g·g⁻¹·min⁻¹; ETP = 0.451 g·g⁻¹·min⁻¹) and the effective moisture diffusivity (USP = 4.12×10⁻¹⁰ m²·s⁻¹; ETP = 3.35×10⁻¹⁰ m²·s⁻¹), values up to six times higher than the control (7.22×10⁻¹¹ m²·s⁻¹). From a compositional perspective, the powder retained relevant levels of proteins (14.53-15.20%), lipids (0.90-1.56%), and minerals (8.02–9.20%), highlighting their nutritional potential. HPLC analysis identified 21 phenolic compounds, with emphasis on catechin, epicatechin gallate, p-coumaric acid, and caffeic acid. DSC analysis confirmed greater thermal stability of the samples treated with USP (ΔH = 28.09 J/g) and SCP (ΔH = 25.11 J/g), suggesting greater applicability of the powder in processes involving heating. During 180 days of storage at 20 °C and 85% relative humidity, the pretreatments significantly reduced losses of bioactive compounds (≈12-15%) compared to the control (-34.5%). Overall, the results confirm that USP not only improved drying efficiency but also increased the retention of phenolic compounds and storage stability. The study demonstrates that integrating pretreatments with the drying route is a promising process intensification strategy to transform potato residues into stable, high-value-added functional ingredients. • Pretreatments efficiently intensified drying, reducing time and thermal exposure • USP and ETP improved moisture removal rates and mass transfer efficiency • Potato peel powder retained proteins, lipids, minerals, and nutritional quality • USP enhanced catechins, phenolic acids, and flavonoid content • All pretreatments improved bioactive stability during storage