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Method for Determining the Rate and Extent of Accelerated Starch Retrogradation¹

¹Contribution 15344 of the Agricultural Research Programs, Purdue University. ²Nestlé Research & Development Center-Connecticut, New Milford, CT 06776-5528. ³Whistler Center for Carbohydrate Research, 1160 Smith Hall, Purdue University, West Lafayette, IN 47907-1160. ⁴Corresponding author. E-mail: bemiller@foodsci.purdue.edu

A method to accelerate and quantitate retrogradation of starch pastes using a freeze-thaw cycle (FTC) process and turbidometric analysis has been developed. Using this method and differential scanning calorimetry (DSC), it was determined that the rate of retrogradation in 2.5% waxy maize pastes was inversely correlated to the rate of freezing, and that the thawing temperature affected perfection of the crystallites in retrograded amylopectin. DSC and X-ray diffraction were used to determine whether the crystallites formed during the FTC process were the same as those formed in starch pastes held isothermally at 4°C. Analysis of retrogradation of pastes of starches from various botanical sources indicated that the method reflects retrogradation in higher concentration pastes. Retrogradation rates were reduced by the addition of sodium dodecyl sulfate. Microstructures of freeze-thaw processed waxy maize and common corn starch pastes were examined.