Effects of freezing treatments on viscoelastic and structural behavior of frozen sweet dough

Fresh and frozen (−20 °C, −30 °C, −40 °C and immersion in liquid nitrogen) sweet doughs were evaluated for structural and rheologic properties explored by different and complementary methods: Fourier transform infrared (FTIR), rheologic measurements and differential scanning calorimetry (DSC).The results revealed the effect of low freezing rates on the frozen sweet dough rheologic properties, resulting in elasticity reduction of 8.6% and 12% for freezing at −30 °C and −40 °C, respectively. This can be attributed to dehydration of the dough network, and the starch retrogradation phenomenon.FTIR results revealed the protein aggregation of dough frozen slowly that is manifested by a decrease in the amount of α-helix connected to the increased content of β-sheet fraction extended.This present study also showed that freezing rate is not the only parameter responsible for rheologic changes that occur during freezing. External freezing temperature could be explain the changes taking place at slow freezing rates.

► Freezing rate had a significant effect on rheologic parameters for frozen sweet doughs.
► Linear correlation exists between local freezing rate and radial position for all freezing rates.
► α-Helix and β-sheets and starch of FTIR data proved protein aggregation and starch retrogradation by slow freezing.
► The immersion cryogenic freezing (fast freezing rate) provided overall best results.