Physicochemical Characterization and Optimized Ultrasound-Assisted Extraction of Bioactive Compounds from Teff (Eragrostis tef): Phenolic Profile, Antioxidant Activity, Prebiotic Potential, and Phytic Acid Degradation

Teff (Eragrostis tef) is a gluten-free cereal and a valuable source for functional food. This study evaluated the physicochemical characteristics of teff flours and optimized ultrasound-assisted extraction of bioactive compounds. Ultrasonic-assisted extraction (UAE) was optimized using a Box–Behnken design (BBD), and the best extraction conditions were 50% ethanol, 60 °C, and 45 min, yielding 49.6 ± 0.028 mg gallic acid equivalents (GAE)/100 g dry weight (DW). High-performance liquid chromatography (HPLC) analysis revealed an abundant phenolic profile with compounds including epigallocatechin (2960.30 µg/g), epicatechin (113.55 µg/g), hesperidin (163.64 µg/g), and ferulic acid (41.79 µg/g). Prebiotic potential testing with Lactobacillus plantarum MIUG BL21 at 4 °C over 21 days indicated a concentration-dependent decrease in viability: at 5 mg/mL, mean counts decreased from 4.721 ± 0.049 to 2.349 ± 0.048 log colony-forming units (CFU)/mL; at 2.5 mg/mL, from 3.396 ± 0.095 to 0.500 ± 0.198 log CFU/mL; and at 1 mg/mL, counts became undetectable. Phytic acid degradation in teff extracts followed first-order kinetics, with half-lives of 1504.55, 752.30, and 300.91 min at 50, 70, and 90 °C, respectively. The activation energy of 39.07 kJ/mol confirmed the temperature dependence of the process and indicated an effective reduction in phytic acid. In conclusion, teff extracts may represent promising functional ingredients with antioxidant potential, support for probiotic viability, and reduced antinutritional factors.