EFFECT OF FORCED CONVECTIVE DRYING ON PHENOLIC COMPOUNDS, ANTIOXIDANT CAPACITY AND TECHNO-FUNCTIONAL PROPERTIES OF NATIVE POTATO BY-PRODUCTS

Andean native purple potatoes are a natural source of bioactive compounds, and their agro-industrial processing generates large amounts of by-products, mainly tuber portions discarded during the slicing process. To enable their valorization, these by-products must be stabilized, with forced convective drying being one of the most widely used preservation methods. However, the thermal impact of this process on the bioactive compounds and techno-functional properties of these by-products remains insufficiently studied. This study investigated the effect of forced convective drying on the total phenolic content (TPC), monomeric anthocyanin content (MAC), antioxidant capacity (DPPH and ABTS assays), and techno-functional properties, including water absorption index (WAI), water solubility index (WSI), and oil holding capacity (OHC), of by-products derived from the Andean native potato cultivar Cacho de Toro (Solanum tuberosum L.). Drying temperature exerted a significant effect (p < 0.05) on all evaluated responses. Increasing the drying temperature from 50 to 80 °C progressively reduced the TPC, which decreased from 3339.11 ± 24.40 to 1482.54 ± 12.20 mg GAE kg⁻¹ (dry basis), representing a 55.6% reduction. Likewise, the MAC decreased from 673.08 ± 5.14 to 345.51 ± 3.74 mg cyanidin-3-glucoside equivalents kg⁻¹. Antioxidant capacity decreased by 50.7% in the DPPH assay (12.77 ± 0.13 to 6.30 ± 0.20 µmol TE g⁻¹) and by 32.2% in the ABTS assay (19.56 ± 0.08 to 13.26 ± 0.34 µmol TE g⁻¹). Techno-functional properties were also affected by drying temperature, with WAI (5.56–6.10 g·g⁻¹), WSI (7.95–9.83%), and OHC (0.80–0.89 g·g⁻¹) reflecting structural modifications associated with starch gelatinization and protein denaturation. Overall, drying at 50 °C provided the best balance between moisture reduction, bioactive compound retention, and techno-functional performance, supporting the valorization of these by-products as functional food ingredients within circular bioeconomy frameworks.