One-step coextraction method for flavouring soybean oil with the dried stipe of Lentinus edodes (Berk.) sing by supercritical CO2 fluid extraction

Dried Lentinus edodes (Berk.) sing stipe (LES) is mostly discarded owing to its high fibre content and bad palatability, causing significant waste of resources. The aim of this study is to sustainably use LES for the production of flavour soybean oil using the supercritical CO2 fluid extraction (SFE) method. The quality properties of the obtained soybean oil flavoured by LES (OFLS) were evaluated in this study. Profiles obtained with an electronic nose and gas chromatography results obtained by quadrupole time-of-flight mass spectrometry and with a mass-selective detector indicated that mushroom-like aroma compounds were mainly concentrated into the OFLSs from separation kettle A (9 MPa). Interestingly, off-flavour compounds from soybean oil, such as o-xylene and trans-2-nonenal, were mostly distilled into separation kettle B (4 MPa). More importantly, the developed SFE method effectively improved the colour quality of the OFLSs. Additionally, the decrease of the viscosity of the OFLSs indicated that the thermal stability of the edible oil could be improved. In summary, the OFLSs prepared by the green and sustainable SFE method significantly improved the quality of the edible oil.