The fact
might relate to protein content in the powders. Assuming the protein
solubility, at a fixed sample/extractant ratio, was mainly depended
on the protein content in the powder as observed in
various industrial extractions. The higher the protein content in
the test powder, the higher the protein concentration in extract
was. The protein contents of cap powders (16.71–18.29 g/100 g)
were much higher than that of stipe powders