Optimization of microwave-assisted extraction of ergosterol from Agaricus bisporus L. by-products using response surface methodology

This work intends to valorise by-products of the industrial processing of mushrooms to obtain ergosterol as a value-added compound. Agaricus bisporus L. is the world’s most consumed mushroom and one of the richest sources of ergosterol. Microwave-assisted extraction was used to replace conventional techniques that are time-consuming and need large amounts of solvent. Time (3-20 min), temperature (60-210 ºC) and solid-liquid ratio (1-20 g/L) were found the relevant variables to analyze the extraction process. To maximize the ergosterol extraction yield, response surface methodology was used to optimize the process. The global optimal extraction conditions were determined and comprise: 19.4±2.9 min, 132.8±12.4 ºC and 1.6±0.5 g/L, yielding 556.1±26.2 mg of ergosterol per 100 g of mushroom by-products. In the MAE optimal conditions, it was possible to obtain ergosterol in a similar value to the one obtained in other works when using the Soxhlet extraction method with a significant decrease in the time of extraction. The results show the potential of using the by-products of an agroindustry, mushrooms processing industry, as productive sources of ergosterol.The authors acknowledge FCT (Portugal) for financial support to CIMO (PEst-OE/AGUI/0690/2014), Sandrina A. Heleno (SFRH/BPD/101413/2014) and L. Barros (SFRH/BPD/107855/2015), to FCT/MEC and FEDER under Programme PT2020 for financial support to LSRE (Project UID/EQU/50020/2013), and to QREN, ON2 and FEDER (Projects NORTE-07-0124-FEDER-000014 and NORTE-07-0162-FEDER-000050). The authors also acknowledge Xunta de Galicia for financial support of the post-doctoral researcher M.A. Prieto, and to Patrícia Diz for some support in MAE experiments