The effect of processing methods on total phenolic content, antioxidant capacity and bioavailability of table olives

Olive tree (Olea europea, L.) is one of the oldest known fruit tree in the World. The olive trees have been symbollized many Mediterranean civilizations, and served as a basis of all the civilizations that were established in this region throughout history. Olive provides important benefits to human health with high nutritional value. In this thesis, olive samples obtained from different regions of Bursa province (e.g., Mudanya, Gemlik, Orhangazi, Iznik) and processed by different production methods were analyzed in terms of total phenolic substance, antioxidant capacity, bioavailability and some physicochemical properties. In the analyses, brined black olives, brined green olives and sele (dry-salted) olives were used. Bioavailability of the samples were determined using the vitro enzymatic extraction method that mimicks gastrointestinal system conditions. For this purpose, an artificial environment corresponding to the human digestive system was prepared for the olive samples and the levels of the components passed into the structure were measured. Total phenolic content and antioxidant capacity were determined by Folin-Ciocalteu method and CUPRAC, ABTS, FRAP and DPPH methods, respectively. Antioxidant capacity (ABTS, CUPRAC, FRAP and DPPH) and total phenolic content of the samples were determined separately in the extractable and hydrolysable portions. According to the analysis results, the total phenolic content of extractable compounds ranged from 185 to1410 mg GAE/100 g, and the total phenol content of hydrolyzable compounds ranged from 257 to 1578 mg GAE/100 g. The antioxidant capacity of the samples varied based on the analysis method chosen. ABTS and DPPH methods showed higher results than FRAP and CUPRAC methods.