Effects of Freeze–Thaw Cycles on the Quality of a Novel Mixed Grain Composite Dough and Its Product (Potato-Oat Yu): Hybridization of Potatoes and Oats

To provide a theoretical basis for the frozen storage of potato-oat composite dough and its products, this investigation examines changes in the quality of potato-oat composite dough and its resulting product during freeze–thaw cycles. The study measured key aspects such as moisture content, dynamic rheological properties, water state, protein secondary structure, color, and sensory assessment. The influence of these factors on the product’s quality is analyzed. The findings revealed that the freeze–thaw treatment caused a reduction in water content, freezable water, and deeply bound water, as well as an increase in weakly bound water, β-sheet, random coil, and α-helix, and a decreased β-turn of the potato-oat composite dough. Additionally, the dough treated by freeze–thaw cycles resulted in darker color, and the sensory properties of the product were affected significantly after exceeding three freeze–thaw cycles. Moreover, an increase in the number of freeze–thaw cycles resulted in an upward trend of moisture content for the composite dough, whereas G′ initially increased and then decreased. The G″ of the composite dough peaked after the third freeze–thaw cycle. Overall, the composite dough quality significantly deteriorated at the fourth freeze–thaw cycle. There was a significant increase in the freezable water content, the largest modulus of elasticity, and the smallest tan δ. Therefore, the usage of the potato-oat composite dough should not exceed three cycles.