Functionality of cellulose

Cellulose has many uses as an anticaking agent, emulsifier, stabilizer, dispersing agent, thickener and gelling agent, but these are generally subsidiary to its most important use of holding water. Dry amorphous cellulose absorbs water becoming soft and flexible. Some of this water is non-freezing but most is  simply trapped. Less water is bound by direct hydrogen bonding if the cellulose has high crystallinity but some fibrous cellulose products can hold on to considerable water in pores and its  typically straw-like cavities. As such water is supercoolable, this effect may protect against ice damage. Cellulose can give improved volume and texture, particularly as a fat replacer in sauces and dressings but its insolubility means that all products will be cloudy. 

Swelled bacterial cellulose (eg. Acetobacter xylinum) exhibits pseudoplastic viscosity, like xanthan gels but this viscosity is not lost at high temperatures and low shear rates as the cellulose can retain its structure. Where individual cellulose strands are surrounded by water, they are flexible and do not present contiguous hydrophobic surfaces.