Modification of potato starch by critical melting pretreatment combined with freeze-thawing: Preparation, morphology, structure, and functionality.

Critical melting pretreatment for granular swelling and soluble starch release was performed before freeze-thawing (FT) to enhance the effect of FT treatment on structure modification of potato starch. The critical melting temperature applied was based on the onset melting temperature (T o) of the native potato starch. After pretreatment, the effect of multiple FT cycles on the morphology, structure, and functionality was investigated. The pretreatment effectively induced granular swelling and partial disruption of the crystalline structure by increasing the volume of water molecules inside the granules. The pasting pattern changed obviously after treatments with the significantly increased final viscosity (up to 5000 from 2900 mPa s) and decreased breakdown (1/5th of native starch). Soluble starch released due to the both critical melting and FT treatments had a strong tendency to reassociate outside the granules, which effectively raised the thermal stability of starch granules. Moreover, increased water (∼109–∼164%) and oil (∼56–∼64%) absorption of starch at room temperature were observed. The synergistic effect of the combination of critical melting pretreatment and mechanical force of ice crystals effectively modified the properties of potato starch, suggesting a useful clean-label method for starch modification. [Display omitted] • Pretreatment enhanced modification effect of freeze-thawing on potato starch (PS). • Critical melting pretreatment applied is based on onset melting temperature of PS. • The combined treatment changed the morphology, structure, and functionality of PS. • Thermal stability of PS granules raised significantly after the combined treatment. • Partial disruption of chain arrangement and soluble starch release plays a key role. [ABSTRACT FROM AUTHOR]