Effect of freezing rate and frozen storage on the rheological properties and protein structure of non-fermented doughs

Abstract The objective of this study was to investigate the effects of the freezing rate and frozen storage duration on the rheological properties and protein structure of the non-fermented dough. The samples were frozen at −40 (0.149 °C/min), −30 (0.086 °C/min) and −20 °C (0.039 °C/min), and stored at −18 °C for 30 days. Freezing at −40 and −30 °C led to minimal changes in the rheological properties of the non-fermented dough. Additionally, −40 °C freezing resulted in higher maximum creep compliance (Jmax) and lower zero shear viscosity (η0). The content of glutenin macro-polymers (GMP) decreased gradually throughout the storage period, while that of free thiol groups (-SH) increased significantly, especially for samples frozen at −20 °C. Fourier transform infrared (FTIR) spectroscopy showed that slower freezing rate and prolonged storage led to a significant decrease in the proportion of α-helices, and a notable increase in that of β-sheets and random coils. The gluten network was severely deteriorated by a slower freezing rate but was relatively intact in the −40 and −30 °C frozen dough samples.