Insights into the delaying mechanism of taro-based yogurt on the retrogradation of the frozen part-baked bread: Starting with strain screening

The co-fermentation effect of adding taro-based yogurt strengthened the gluten network of frozen part-baked bread (FPBB). The underlying mechanisms were systematically investigated in terms of strain screening, dough stability, gluten structure and starch retrogradation behavior. Among the five lactic acid bacteria evaluated, taro-based yogurt fermented by Lactobacillus bulgaricus (LBF) was identified as the optimal improver, because it could provide higher fermentation intensity, acidification effect and water-holding capacity for the dough. LBF addition promoted the transformation of α-helix and β-sheet structures into β-turns, which softened the dough, increasing its extensibility and gas retention capacity, particularly at 10% LBF supplementation. The strong gluten network provided FPBB with excellent freezing performance, as confirmed by changes in microstructure, protein secondary structure, and starch short-range order after freezing for 28 days. LBF significantly reduced the enthalpy ( ΔH ) by 20.94% ∼ 26.99%. The water migration rate decreased from 11.84 to 6.58 days, and the crystallization rate was only 0.06 days.