Development and evaluation of a microwave‐assisted continuous system for olive pomace oil extraction and in‐line esterification/transesterification

Abstract

This study developed and evaluated a preliminary continuous microwave‐assisted system integrating oil extraction from olive pomace and subsequent conversion into fatty acid ethyl esters (FAEEs) in a single processing unit. A conventional microwave oven was adapted for continuous operation by incorporating magnetron power adjustment and a proportional–integral–derivative (PID) temperature‐control system. Extraction and integrated extraction/reaction experiments were conducted at 50 and 70 °C using ethanol as both the extraction medium and reagent. Additional experiments involved continuous catalyst feeding. At 70 °C, microwave‐assisted extraction yielded 12.05 ± 2.65 wt% oil, corresponding to a recovery of 99.42%. When the reactor was coupled to the extractor, FAEE formation was limited without a catalyst, whereas continuous catalyst feeding increased the FAEE concentration to 58.24 wt% at 70 °C and 39.12 wt% at 50 °C. The integrated configuration demonstrated the feasibility of simultaneous lipid extraction and conversion directly from olive pomace. Pressure buildup and associated limitations in temperature measurement were identified as engineering challenges. Further development should focus on pressure‐resistant fittings, improved temperature sensing, and optimization of the alcohol‐to‐oil ratio to improve process stability and overall performance.