Influence of experimental conditions on the extraction of phenolic compounds from parsley (Petroselinum crispum) flakes using a pressurized liquid extractor

The influence of six pressurized liquid extraction parameters (temperature, pressure, particle size, flush volume, static time, and solid-to-solvent ratio) on the extraction of phenolic compounds from parsley flakes was examined. Parsley extracts were analyzed for their phenolic content by high performance liquid chromatography and Folin–Ciocalteu assay. The two major phenolic compounds extracted from parsley flakes were identified as apiin and malonyl-apiin. Particle size, solid-to-solvent ratio, and temperature influenced the amount of phenolic compounds extracted from parsley flakes. Higher extraction yields of phenolic compounds were obtained when extractions were performed with the smallest particle size (<0.425 mm) fraction. Temperature also showed a significant impact on the phenolic profile of the parsley extracts. The yield of malonyl-apiin decreased, while the amount of acetyl-apiin improved with the increase in extraction temperature. The latter compound (acetyl-apiin) is formed by decarboxylation of malonyl-apiin. The yield of the phenolic compounds did not increase proportionately with the increase in sample size, thereby suggesting that it is essential to have optimum solid-to-solvent ratio for accurate estimation of bioactive phytochemicals in foods. Flush volume did not show any major influence on phenolic yields, but it can be manipulated to reduce usage of extraction solvents, which in turn decreases solvent waste disposal costs generated after extraction. Similarly, changes in the static time (extraction time per cycle) and pressure did not result in any significant change in the yield of phenolic compounds extracted from parsley samples. However, sample throughput can be increased significantly by reducing static time.