Freeze‐Thaw Stability and Refrigerated‐Storage Retrogradation of Starches

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Abstract
A method for the evaluation of freeze‐thaw stability of starch gels is described and compared with refrigerated‐storage retrogradation. Differential scanning calorimetry (DSC) is used to estimate the energy required to break down recrystallized starch molecules after 10 cycles of freezing‐thawing or after storage at 4°C for 1 week. Different DSC properties were observed for different starches. Chemical modification decreased all DSC values for gelatinization except the gelatinization range of all modified starches examined. Rice and wheat starches displayed the lowest energies of gelatinization compared with other native starches studied. Most chemical modifications completely inhibited the recrystallization of starches during storage at 4°C or after 10 cycles of freeze‐thaw. Mira‐Cleer 340® (modified regular maize starch; hydroxypropyl distarch phosphate) had a slight recrystallization value. DSC endotherms for both recrystallization studies occured at considerably lower temperatures than those of the original gelatinization.