An investigation of antioxidant effects of phenolic extracts obtained from Sarı Ulak Tarsus olive and black tea

ABSTRACTMSc THESISAN INVESTIGATION OF ANTIOXIDANT EFFECTS OF PHENOLICEXTRACTS OBTAINED FROM SARI ULAK TARSUS OLIVEAND BLACK TEAEsra TURANDEPARTMENT OF FOOD ENGINEERINGINSTITUTE OF NATURAL AND APPLIED SCIENCESUNIVERSITY OF CUKUROVASupervisor : Yrd. Doç. Dr. Türkan KEÇELYıl : 2005, Sayfa:48Jury : Yrd. Doç. Dr. Türkan KEÇELProf. Dr. Ali ALTANDoç Dr. Bilgehan GÜZELIn this research, natural phenolic extracts which was obtained from black tea that wasproduced by Oba Çay and Sarı Ulak Tarsus variety and grown in Tarsus in Mersin werecompared with BHT which was a synthetic antioxidant and the antioxidant effects of naturalphenolic extracts were investigated. Extraction of phenolic compounds from black tea andolive samples and following analyses were done in Cukurova University Food EngineeringLabs.Total phenolic contents of black tea and olive samples were found as 286 mg/100g forolive and 5649 mg/100 g for black teas as CAE (Caffeic Acid Equivalent).When the antioxidant effects of phenolic extracts which was obtained from black teaand olive samples were compared with BHT; antioxidant effects were found as follows blacktea > olive ≥ BHT for 30., 60. minutes and in final time. When the DPPH free radicalscavenging capacity of phenolic extracts which was obtained from black tea and olivesamples were compared with BHT; it was found that black tea samples had higher radicalscavenging capacity than BHT which was known with its strong antioxidant properties andolive samples had equal radical scavenging capacity compared to BHT. In addition, it wasfound that DPPH free radical scavenging capacity of BHT was increasing with concentrationand time as phenolic extracts which were obtained from black tea and olive samples.Antioxidant activities of phenolic extracts which were obtained from black tea andolive samples and BHT were evaluated in sunflower oil and olive oil. The oxidation insunflower oil was occurred more rapidly than the oxidation in olive oil as a substrate with/without added phenolic extracts and BHT during experiments.Key Words: Olive, Black Tea, BHT, Phenolic Compounds, Antioxidants