The control of ice crystal growth and effect on porous structure of konjac glucomannan-based aerogels

•Three potential factors were investigated to control ice crystal growth during aerogel formation.•Low temperature polarizing microscopy and scanning electron microscopy were used to view the ice crystal and pore structures.•Size distribution figures of ice crystals and aerogel pores were drawn and could be used to support the discussions. Konjac glucomannan (KGM)-based aerogels were prepared using a combination of sol-gel and freeze-drying methods. Preparation conditions were chosen to control ice crystal growth and aerogel structure formation. The ice crystals formed during pre-freezing were observed by low temperature polarizing microscopy, and images of aerogel pores were obtained by scanning electron microscopy. The size of ice crystals were calculated and size distribution maps were drawn, and similarly for aerogel pores. Results showed that ice crystal growth and aerogel pore sizes may be controlled by varying pre-freezing temperatures, KGM concentration and glyceryl monostearate concentration. The impact of pre-freezing temperatures on ice crystal growth was explained as combining ice crystal growth rate with nucleation rate, while the impacts of KGM and glyceryl monostearate concentration on ice crystal growth were interpreted based on their influences on sol network structure.