Optimisation of microwave-assisted extraction of triterpenoic acids from olive mill waste using response surface methodology

Maslinic acid (MA) and oleanolic acid (OA) are pentacyclic triterpenic phytochemicals found in the olive fruit and leaves as well as wastes. Dried olive pomace is a good source of both triterpenic acids. This study aimed to investigate the potential of microwave-assisted extraction (MAE) to obtain MA and OA from olive pomace and to optimise the MAE process temperature and time by response surface methodology (RSM). The model produced for each compound showed high adequacy to predict the experimental results, hence, the conditions for each triterpenic acid were optimised. The optimal condition for MA extraction was 40 °C for 10 min, whilst OA had optimal extraction at 40 °C for 2.93 min. Compared to conventional Soxhlet extraction, MAE is a promising method to produce MA and OA rich extracts from olive pomace. Also, RSM is a relevant and accurate tool to optimise the MAE parameters.