Retrogradation kinetics of chestnut starches cultivated in three regions of Korea.

Retrogradation kinetics of chestnut starches from three different regions of Korea were investigated during storage at 4 °C. The retrogradation properties were determined using four DSC characteristics: glass transition temperature ( T g ' ), ice melting enthalpy (ΔHi), amylopectin melting enthalpy (∆Hr) and degree of retrogradation (DR). The Gongju (GJ) starch showed the highest gelatinization enthalpy (∆Hg) value, followed by Gwangyang (GY) and Hadong (HD). T g ' of all samples gradually increased with increasing storage time, while ∆Hi decreased as the storage time increased. ∆Hr of all samples significantly increased after 2 days of storage. DR, calculated based on ∆Hg and ∆Hr, showed a similar tendency with ∆Hr. The retrogradation rates of three chestnut starches were analyzed using the Avrami equation, and the time constants (1/k) were obtained. GY, GJ and HD showed the fastest retrogradation rate in T g ' , ∆Hi, and ∆Hr, respectively suggesting that each sample experienced different retrogradation kinetics in different region.