Hydrothermal extraction and micronization in a one-step process for enhancement of β–glucan concentrate at subcritical water conditions

As one of the green techniques to fractionate the plant biomass components, here, the utilization of subcritical water as an extraction medium to obtain β–glucan compounds from Ganoderma lucidum (G. lucidum) and barley grain (Hordeum vulgare L.) was discussed. Using a semi-batch process, the extraction was performed at temperatures of 100 to 190 °C with ∼180 min extraction time. Through thermal softening, the liquid water allows to remove and dissolve these plant biomass substances. The spectra of UV–vis and FTIR indicated that the β–glucan compounds were successfully extracted at this extraction temperature range. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI–TOF MS) indicated that the substance in the collected solution products had molecular weight around 500–2900 m/z with 162 m/z peak–to–peak mass difference, consistent with the repeating β–glucan compound unit. When carbon dioxide was introduced in the extraction system as a catalyst, at the equal extraction conditions, the level of β–glucan compounds in the collected solution products increased clearly (around 3.5%). Next, the collected solution products were directly atomized to generate the fine particles with <5 μm size diameters, and the level of β–glucan compounds in these generated fine particles could approach 45%.