Physicochemical Properties, Antioxidant Capacity and Sensory Acceptability of Instant Rosehip Teas Prepared by Spray-Drying and Freeze-Drying Methods

In this study, the physicochemical properties, antioxidant capacity, sensory properties, and phenolic and mineral profiles of instant rosehip teas prepared using spray-drying (SD) and freeze-drying (FD) were compared. The yield of instant tea produced using FD and SD was 23.75 and 21.25 g/100 g, respectively. The total color difference between the FD and SD tea was 50.74, with the SD sample exhibiting higher redness and yellowness. The FD tea was richer in ascorbic acid than SD tea (67.2 and 59.4 mg/100 g dry weight, DW, respectively). The mineral content ranged from 0.20 mg/kg DW (copper) to 2,837 mg/kg DW (potassium) in SD tea, and from 0.31 mg/kg DW (copper) to 3,083 mg/kg DW (potassium) in FD samples. The total phenolic content was 1,315 and 1,495 mg GAE/100 g DW of SD and FD samples, respectively. The antioxidant capacity of instant rosehip teas was determined as total antioxidant capacity, ferric reducing antioxidant power and DPPH radical scavenging activity. In all these assays, FD tea was found to have a higher antioxidant capacity. In the phenolic profile determined by liquid chromatography-tandem mass spectrometry (LC-MS/MS) technique, protocatechuic acid dominated in instant rosehip teas prepared using both methods. The main flavonoids identified were quercetin, quercitrin, hyperoside and luteolin 7-glucoside. Following the sensory analysis, the panelists have generally preferred the FD tea in terms of aroma and flavor, while opting for the SD tea in terms of appearance and color. In conclusion, although freeze-drying allowed obtaining a product with a higher antioxidant capacity and antioxidant content than spray-drying, both drying methods may be considered suitable for the production of instant rosehip teas and ensure obtaining a functional food product.