Impact of Drying on Phytonutritional Compounds, In Vitro Antioxidant Activity and Cytotoxicity of Spiny Saltbush (Rhagodia spinescens).

The Spiny saltbush (Rhagodia spinscens) is a halophyte species with the potential to provide natural ingredients used in food and pharmaceutical industries. In food and pharmaceutical applications, drying is necessary to maintain shelf-life, which reduces phytonutrient content. In this study, changes in the nutritional composition, phenolic and carotenoid profiles of radical antioxidant scavenging activity [(2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)(ABTS)], antioxidant power [ferric reducing antioxidant ability assay (FRAP)], and cytotoxicity of freeze- and oven-dried (55 °C for 24 h) spiny saltbush were determined. Sodium (4.72 g/100 g dry weight (DW), potassium (6.86 g/100 g DW), calcium (4.06 g/100 g DW), zinc (372 mg/kg DW) and protein content were higher in oven-dried samples than freeze-dried samples. Ultra-performance liquid chromatography-mass spectrometry analysis detected 18 metabolites in saltbush extracts. Partial Least-Squares Discriminant Analysis, Hierarchical Cluster Analysis, and Variable Importance in Projection discriminated between freeze-dried and oven-dried samples. Freeze-dried samples retained more individual metabolites than oven-dried samples, while oven-dried samples had higher antioxidant activity (ABTS and FRAP), lutein, trans-β carotene, and cis-β-carotene. Correlation analysis identified potential antioxidant candidates between phenolic and carotenoid compounds. Neither freeze-dried nor oven-dried spiny saltbush samples showed cytotoxicity. The study uncovered changes in phytonutritional compounds after the oven and freeze-drying spiny saltbush, a potential salt alternative and functional ingredient for the food industry.