Evaluation of antioxidant activity and polyphenol preservation in rosehip (Rosa spp.) during storage and convective drying

Rosehip (Rosa spp.) is a nutritionally rich fruit valued for its bioactive compounds, particularly polyphenols and other antioxidants, making it essential for the food and nutraceutical industries. This study evaluates the effects of storage and convective drying on its physicochemical properties, focusing on polyphenols, antioxidant activity, color, and shrinkage. A factorial 2² experimental design was employed for storage (temperatures: −20 °C and 24 °C; durations: 5 and 15 days) and drying (temperatures: 30 °C and 50 °C; airflow: 0.6 m/s and 1.0 m/s). Storage at −20 °C preserved polyphenols (1767.62 ± 57.35 mg GAE/100 gDW) and antioxidant activity better than 4 °C, with DPPH ARP and ABTS values of 484.23 ± 35.34 μmol/gDW and 10882.76 ± 190.24 mg TE/100 gDW, respectively. Drying kinetics revealed faster moisture removal at higher temperatures, while polyphenol retention peaked at 50 °C and 0.6 m/s (4321.16 ± 43.18 mg GAE/100 gDW), whereas antioxidant activity was highest at 30°C, with either 0.6 or 1.0 m/s depending on the method: ARP = 317.70 ± 16.19 μmol/gDW (1.0 m/s); ABTS = 14535.83 ± 309.55 mg TE/100 g DW (0.6 m/s). Intermediate conditions (30 °C, 1.0 m/s) balanced color preservation and structural integrity. Combining −20 °C storage with 30 °C, 1.0 m/s drying is a potential strategy to preserve antioxidant activity, polyphenols, and physical properties, enhancing the commercial and nutritional value of rosehip for food and nutraceutical applications.