Phenolic profile and antioxidant activity of olive fruits of the Turkish variety “Sarıulak” from different locations

Abstract

The phenolic compounds, radical scavenging effect and antioxidant capacity of olive fruits from the “Sarıulak” variety were studied from four different locations: Alanya, Ceyhan, Silifke and Karaman in the Mediterranean region of Turkey. They were collected on three different harvest dates (HDs) and in two consecutive crop years. The levels of most of the phenolic compounds in the fruits of the Alanya location were remarkably high among the values (mg/kg) obtained for all location samples mainly on the first HDs, for instance hydroxytyrosol rose to 3596.4, luteolin rose to 269.5, vanillic acid rose to 159.8 and caffeic acid rose to 62.1. The olive fruits from Alanya, which had the highest average rainfall compared to the other locations, showed the highest phenolic content. The olive fruits from Silifke, which had a dramatic decrease in rainfall between the two crop years, showed a reduction in total phenolic content in the following crop year. The highest oleuropein contents (mg/kg) were detected for the fruit samples grown in Silifke (963.5-2981.8) and for Karaman (835.2-655.6). All of the locations showed similar changes in antioxidant activity pointing to an increase with later HDs. The effect of HD on the phenolic compounds such as 4-hydroxyphenyl acetic acid, caffeic acid, syringic acid and hidroxytyrosol, luteolin, chlorogenic acid and 3,4-dihydroxybenzoic acid were more dependent on the location factor.