Preparation and Adsorption Properties of Sodium Trimetaphosphate Crosslinked Porous Corn Starch

The crosslinked porous corn starch was prepared by two steps: the native corn starch was hydrolyzed by α-amylase and glucoamylase, then the porous corn was crosslinked by sodium trimetaphosphate (STMP). The morphology and size of granules, spherulites, crystal type, molecular structure, swelling properties, thermal stability and adsorption properties of the crosslinked porous starch were investigated. The results indicated that a lot of holes formed in the porous starch, and the particle size of starch granules decreased. Under the cross-linking action of STMP, the porous starch particles are cross-linked and agglomerated together. The crystalline form of porous starch presents A + V type, and crystallinity increased after crosslinking. The crosslinked porous starches have higher short-range ordering comparing to the porous without crosslinked porous starch. The crosslinking degree, melting enthalpy and melting peak of starch increased with the increase of STMP content. The bulk density and the vibrated density of the porous starch increased after crosslinking. With the increase of the content of STMP, the water and oil absorption of porous starch increased and then decreased. The MB adsorption capacity of crosslinked porous starch has the maximum value with the STMP 20 wt% content. MB adsorption behavior of porous starch is more consistent with the pseudo-second-order kinetic model, and the equilibrium adsorption increased after crosslinking.