Revalorization of Olive Stones from Olive Pomace: Phenolic Compounds Obtained by Microwave-Assisted Extraction
2025
Alicia Castillo-Rivas | Paloma Álvarez-Mateos | Juan Francisco García-Martín
Olive stones (OS) are a by-product of great interest from olive oil mills and the table olive industry due to their high content of phenolic compounds. In this work, the extraction of phenolic compounds from OS via microwave-assisted extraction (MAE) with aqueous acetone was assayed. A central composite design of experiments was used to determine the optimal extraction conditions, with the independent variables being temperature, process time, and aqueous acetone (v/v). The dependent variables were the total content of phenolic compounds (TPC) measured by the Folin&ndash:Ciocalteu method and the main phenolic compounds identified and quantified by UPLC. Under optimal conditions (75 °:C, 20 min, and 60% acetone), 3.32 mg TPC was extracted from 100 g of dry matter (DM) OS. The most suitable extraction conditions were different for each polyphenol. Therefore, 292.11 &mu:g vanillin/g DM: 10.94 &mu:g oleuropein/g DM: and 10.11 protocatechuic acid &mu:g/g DM were obtained under conditions of 60 °:C, 15 min, and 100% acetone: 43.8 °:C, 10.45 min, and 61.3% acetone: and 64.8 °:C, 16.58 min, and 97.8% acetone, respectively. Finally, MAE was compared with the traditional Soxhlet method under the same conditions. As a result, MAE was proven to be an enhanced and more feasible method for polyphenol extraction from OS.
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