Transparent thermoreversible gels of β-(1 → 6)-branched β-(1 → 3)-glucan derived from the cauliflower mushroom Sparassis crispa

Sparassis crispa is an edible mushroom and its purée forms a thermoreversible cold-setting gel. In the present study, the gel component was extracted and was analyzed by NMR. The gel component had the same primary structure as reported for the β-glucan of schizophyllan or scleroglucan, with β-(1 → 3)-linked glucose as the main chain and every three residues containing a β-(1 → 6)-linked glucose. Large deformation test of this β-glucan gel at 4 °C showed fracture at a strain of approximately 60% in the concentration range from 1.8 to 2.0 wt %. The β-glucan above a critical molecular weight appears to be required for gel formation.