Effects of drying methods on physicochemical properties and bioactive compounds of wild fruits native to the Gümüşhane flora of NE Türkiye

Wild fruits are valuable natural sources of bioactive compounds with significant nutritional and functional properties. This study comparatively evaluated the effects of freeze-drying (FD), oven drying (OD), and open-air drying (AD) on the physicochemical properties, total phenolic content (TPC), vitamin C content, and antioxidant properties of five wild fruit species naturally growing in the Gümüşhane region of Türkiye: wild pear (Pyrus elaegrifolia Pall.), hawthorn (Crataegus orientalis), rosehip (Rosa canina L.), cornelian cherry (Cornus mas L.), and barberry (Berberis vulgaris). Drying method markedly affected both physicochemical characteristics and bioactive compounds. Oven drying produced the lowest water activity values (0.10–0.34), indicating enhanced microbiological stability, whereas freeze-dried samples generally showed superior preservation of phenolic compounds and antioxidant activity. The highest TPC was observed in air-dried cornelian cherry (935.59 mg GAE/kg), while freeze- dried rosehip exhibited the highest TPC among freeze-dried samples (907.63 mg GAE/kg). Vitamin C was highly sensitive to thermal processing, and most oven-dried samples showed values below the detection limit (<0.30 mg/kg). In contrast, freeze-dried rosehip retained the highest vitamin C content (1594 mg/kg). Freeze-dried cornelian cherry exhibited the highest DPPH radical scavenging activity (93.45%), whereas oven-dried rosehip showed the highest total antioxidant content (33.38 mg/g). The relatively high antioxidant values observed in some oven-dried samples may also be partially associated with the formation of Maillard reaction products exhibiting antioxidant properties under thermal processing conditions. Correlation and hierarchical cluster analyses revealed statistically significant (p < 0.05) fruit-specific differences in antioxidant behavior and clustering patterns, indicating that the responses to drying treatments were more strongly influenced by fruit matrix composition than by drying method alone. The findings demonstrate that the effects of drying treatments are strongly fruit matrix-dependent and that no single drying method is universally optimal for preserving all quality attributes of wild fruits.