Deproteinization of water-soluble ß-glucan during acid extraction from fruiting bodies of Pleurotus ostreatus mushrooms

• ß-1,3-ß-1,6- ß-1,4-glucan was extracted from Pleurotus ostreatus.
• A method for the simultaneous extraction and deproteinization was developed.
• Response surface methodology was used to optimize the extraction method.
• ß-glucans without covalently linked proteins were obtained.

Some ß-glucans can be easily extracted from Basidiomycete mushrooms but commonly used extraction procedures are not satisfactory. A simultaneous method for acid extraction and deproteinization in the case of Pleurotus ostreatus was developed using response surface methodology. The optimized extraction conditions proposed here (30 °C, 3.8% HCl, 300 min, stirring) allow for the simultaneous extraction and deproteinization of polysaccharides. Additionally, the acid extraction yield was 7 times greater than that of hot water extraction. The combined enzymatic digestion with lyticase, ß-glucanase, exo-1,3-ß-d-glucanase, and ß-glucosidase results elucidated that an extract containing ß-1,3-ß-1,6-ß-1,4-glucan. The gel permeation chromatography (GPC) results showed that the two glucan fractions obtained do not contain linked proteins. The weight average molecular weight of the first fraction (Mw = 1137 kDa) was 60 times higher than that of the second fraction (Mw = 19 kDa).