Compositional analysis
Theprocedureusedindeterminingthetotalproteincontentwas adapted from the Bradford method (Bradford 1976). One hundredμLofsamplesolution(1mg/mL)wasmixedwith5mLof Bradford Protein Assay kit solution. After shaking and incubating in room temperature, the absorbance was measured at 595 nm, and the protein content was calculated with bovine serumalbumin(BSA)asstandardprotein.Phenol–sulfuricacid method (Dubois et al. 1956) was employed for the measurementoftotalsugarcontentwithglucoseasthestandard.Uronic acidcontentwasdeterminedbycarbazole-sulfuricacidmethod (Bitter and Muir 1962) with D-galactose as standard. Total phenolics content was detected using gallic acid as standard according to our previous study (Chen et al. 2012).