The chlorophyll and oleuropein content of local olive varieties

Abstract

Local olive oil production has been on the increase since the last few years. In spite of its importance, another olive tree product which is not yet fully exploited is the olive leaf. The leaf has been used in the past as a form of herbal tea, particularly in the Mediterranean region. The main aim of this study was primarily to determine the phytochemical potential of the olive leaf. The parameters studied were chlorophyll and oleuropein contents. These two parameters were observed for four olive tree varieties namely Bella di Spagnia, Noccelara Messinese, Girasole and Carolea. The study was conducted over a seven-week period, i.e. up to fruit maturation. Fresh leaves were extracted with acetone and methanol for the quantitative determination of chlorophyll content and the qualitative analysis of oleuropein, respectively. Acetone extracts were subjected to UV spectrophotometry and the content of total chlorophyll, chlorophyll A and chlorophyll B were determined at two wavelengths, 646 nm and 663 nm. The oleuropein content was determined by Thin-Layer Chromatography, and the retention factor for this compound was established for each methanolic extract. It was observed that all four varieties exhibited an increase content of chlorophyll and oleuropein over the seven-week period, suggesting that the process of photosynthesis is essential throughout the development of the fruit, up to maturation. In fact, in the final olive oil, the green colour attributed to a metabolite of the chlorophyll features well. The oleuropein content confirms the anti-oxidant activity of the olive leaf and hence the olive oil. However, further studies on the quantity of oleuropein present within these varieties have to be conducted.