Ultrasound-Assisted Extraction of Hydroxytyrosol from Lactiplantibacillus plantarum Fermented Olive Leaves: Process Optimization and Bioactivity Assessment

Olive leaves are important by-products for the recovery of phenolic compounds and extracts with high content using lactic acid bacteria during fermentation. Lactiplantibacillus plantarum (L. plantarum) strains as glucosidase-positive starter cultures used to control fermentation process. The main objective present work is determine most effective strain biodegradation oleuropein hydroxytyrosol two L. olive leaves. Box–Behnken experimental design was applied optimum ultrasound-assisted extraction (UAE) conditions obtain hydroxytyrosol-rich extract brine fermented ATCC 14917 (hydroxytyrosol; 126.89 ± 1.59 mg/L) showed higher oleuropeinolytic activity than ATCC-BAA 793 (85.93 0.70 in leaf brine. When UAE method applied, it seen that concentration samples were inoculated (362.29 2.31 compared (248.79 4.14) increased. determined 30% amplitude-5 min-30% ethanol 45% amplitude-9 min-10% BAA strain. This study brines can be considered added value products.