Ethanol precipitation will cause low beta-glucans to be removed and therefore wont be measured. We cannot provide the information about molecular weight cut off point, as we have not measured it.
Alternatively, borohydride reduction be used instead of ethanol precipitation. This method can be found where K-BGLU appears on the Megazyme website under the "Documentation" tab. Please see the link below.
Please note that the borohydride reduction method will also underestimate the oligosaccharide content. This underestimation is due to the reduction of terminal reducing sugars in the oligosaccharides to sugar alcohols (sorbitol), which are not measured in the current assay. The underestimation will depend on the degree of hydrolysis of the original beta-glucan.