Moderate moisture evaporation strengthens the network structure and practical features of konjac glucomannan/soy protein isolate system during drying process

The effect of thermal radiation drying (TR) and thermal convection drying (TC) methods on drying kinetics and physicochemical properties of konjac glucomannan/soybean protein isolate (KGM/SPI) gels was comparatively evaluated. Upon heating, the shortened molecular distance and the restricted molecular movement ability promoted hydrogen bonding between components and buried hydrophobic groups on SPI, increasing hydrogen bonds and reducing hydrophobic interactions. Compared with TC drying process, the relative moderate drying rates (reflected by smaller drying rate and effective moisture diffusivity D eff ) during TR drying favored stronger hydrogen bonding and occurrence of smaller SPI aggregates with concentrated size distribution. These contributed to the formation of a denser and more compact network structure, thus improved mechanical properties and increased their water barrier properties (decreased water vapor permeability and increased water contact angle). They help understanding the drying process of polysaccharide/protein assembly and provide a reference for the rational choosing of drying methods.