Comprehensive Triterpenoid Saponin Profiling of Beta vulgaris L. Root Extracts and Their Functional Application in Cleansing Gels

Plant-derived bioactive ingredients are increasingly valued in cosmetic formulations due to their multifunctionality and natural origin. This study evaluated beetroot (Beta vulgaris L.) extracts as plant-derived surfactant-supporting ingredients in cleansing gels, with DPPH radical-scavenging response assessed as a secondary formulation-level endpoint. Three cultivars—Dark Red Round (red), Boldor (yellow), and Snow Ball (white)—were characterized for triterpenoid saponin composition and functional performance. Unlike previous studies focused primarily on the phytochemical characterization of beetroot saponins, the present work integrates cultivar-dependent chemical profiling with comparative evaluation of the corresponding extracts in the same cleansing formulation. UHPLC–CAD–QTOF–HRMS/MS analysis tentatively annotated 30 triterpenoid saponins and revealed cultivar-dependent differences. Semi-quantitatively estimated total saponin concentrations were 17.5, 15.1, and 11.6 g/kg dry extract for Dark Red Round, Boldor, and Snow Ball, respectively, with oleanolic acid-based saponins predominating. Cleansing gels containing 1% (w/w) beetroot extract were evaluated for physicochemical, rheological, and functional properties. Extract-enriched gels showed increased foamability, cultivar-dependent foam stability, and pseudoplastic shear-thinning behavior. Surface tension remained substantially lower than that of water but increased moderately after incorporation of the extracts, indicating modification rather than further surface-tension lowering of the existing surfactant system. DPPH screening showed cultivar-dependent radical-scavenging responses, with the highest inhibition observed for the red beetroot formulation (8.94%). Overall, triterpenoid saponin-containing beetroot extracts modified the functional performance of the cleansing formulations, particularly their foaming and oil-emulsification properties. These findings support their potential as sustainable, plant-derived surfactant-supporting ingredients in multifunctional cleansing formulations.