Structural Changes in Mushroom-Derived β-Glucan During Hydrogel Formation

Abstract

The hydrogel formed by lentinan, a β-glucan extracted from the edible waste portion of shiitake mushrooms (Lentinula edodes), was investigated using dynamic viscoelastic measurements to determine whether it is a true gel. Furthermore, we analyzed the structural changes in the lentinan associated with gelation using NMR. Results from dynamic viscoelastic measurements suggested that structural changes in the lentinan occurred around 6°C during cooling, and that a true gel formed at temperatures below 6°C. This gel was similar to the hydrogels of scleroglucan, a β-(1,6)-branched β-(1,3)-glucan, and β-glucan derived from Sparassis crispa that we previously reported. Based on NMR results, the lentinan in this study was considered to have two β-(1→6)-linked glucose side chains for every five glucose units in the main chain. The NOESY measurement results suggested changes in side-chain orientation, indicating that the gel formed through the partial association of triple helices with reduced steric hindrance in the side chains.

graphical abstract