Water Sorption and Glass Transition Behavior of Polyalditol (PD30), a New Nonreactive Malto-Oligosaccharide Cryo- and Drying-Protectant

Polyalditols are a new family of nonreactive polyols whose reducing power is reduced to <1% dextrose equivalent (DE) by catalytic hydrogenation of malto-oligosaccharides. This work investigated water sorption property and glass transition behavior of PD30, a polyalditol with an average molecular weight of ∼1000 Daltons and a DE value of <0.5. Properties of PD30 are compared with those of maltodextrin M180 (precursor of PD30), which has a DE of 16.5 to 19.5 and is used to make PD30. Water sorption properties were investigated by isothermal sorption and desorption methods. Sorption study showed that PD30 adsorbs less water than M180 at 22°C at relative humidity (RH) below 45%, but adsorbs more water at higher RH. The analysis with Guggenheim-Anderson-de Boer (GAB) model estimates the same monolayer hydration (∼0.05 g/g) for both M180 and PD30, but PD30 could adsorb more weakly bound water. Thermal desorption study showed that PD30 binds significantly less water than M180 at temperatures above 45°C. Glass tr...