Effect of allulose on the quality characteristics of sugar-free bread

As a C-3 epimer of D-fructose, D-allulose does not increase blood glucose and insulin levels. As awareness of healthy eating grows, there is a growing demand for sugar-free options, especially in baked goods. Due to its low calories, allulose (Alu) can reduce the free sugar in bread. However, compared with sucrose bread, allulose bread required a longer fermentation time to reach a similar volume. At the same fermentation time, the baking loss rate of allulose bread was reduced by approximately 21 %, while the specific volume decreased by 48.5 %. Meanwhile, the allulose bread fermented for 1 h (Alu-55-1) had high hardness and a weak Maillard reaction. The browning index (BI) of allulose bread is also very low, far less than that of sucrose bread. Extending the fermentation duration for allulose samples to 3 h (Alu-55-3) resulted in improvements across nearly all evaluated parameters of the bread, including specific volume, texture and stomatal distribution. The addition of Alu also affected the rheological properties of the dough. At high frequencies, the fluid properties of allulose dough were enhanced, and the dough was soft and viscous. In the allulose environment, the yeast grew slowly, and there was no obvious exponential phase, indicating that the yeast was inhibited by allulose. This also explained the small size and high hardness of allulose bread.