Use of an enzyme-assisted method to improve protein extraction from olive leaves

The improvement of protein extraction from olive leaves using an enzyme-assisted protocol has been investigated. Using a cellulase enzyme (Celluclast® 1.5L), different parameters that affect the extraction process, such as the influence and amount of organic solvent, enzyme amount, pH and extraction temperature and time, were optimised. The influence of these factors was examined using the standard Bradford assay and the extracted proteins were characterised by sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS–PAGE). The optimum extraction parameters were: 30% acetonitrile, 5% (v/v) Celluclast® 1.5L at pH 5.0 and 55 °C for 15 min. Under these conditions, several protein extracts from olive leaves of different genetic variety (with a total protein amount comprised between 1.87 and 6.64 mg g−1) were analysed and compared by SDS–PAGE, showing differences in their electrophoretic protein profiles. The developed enzyme-assisted extraction method has shown a faster extraction, higher recovery and reduced solvent usage with respect to the use of the non-enzymatic methods described in literature.