Andean Tuber Ulluco (Ullucus tuberosus): Phenolic Profiling by UV-Vis Spectrophotometry and UHPLC-ESI-MS/MS

<i>Ullucus tuberosus</i> is an underutilized Andean tuber of South America, representing a highly nutritious food source valuable in bioactive compounds and used in traditional medicine by the local population. Despite its potential as a functional food, limited information is available regarding the phenolic composition of its diverse varieties, hindering its revalorization and potential biotechnological applications. In this study, the total phenolic content (TPC), antioxidant activity (AA), and thirteen individual phenolic compounds were investigated in five ulluco varieties using UV-Vis spectrophotometry and ultra-high-performance liquid chromatography, coupled with electrospray ionization and a triple quadrupole mass spectrometer (UHPLC-ESI-MS/MS). Statistical analyses revealed significant differences (<i>p</i> < 0.05) among the varieties in TPC, AA, and the concentration of the four quantified flavonoids. The major flavonoids found were rutin, quercetin-3-glucoside, kaempferol-3-rutinoside, and isorhamnetin-3-rutinoside, using solid-phase extraction (SPE-C8) as a cleanup step for ultrasound-assisted extracts, achieving satisfactory precision and recovery. Principal Component Analysis (PCA) effectively discriminated the samples based on their phenolic profiles, AA, and TPC. These findings contribute to the revalorization of ulluco varieties by providing new insights into their phenolic composition and demonstrating their potential as a source of health-promoting bioactive compounds.