# Possibility of Replacing Sugar with Apple Puree in Muffins
## 3 Results
### The Effect of Replacing Sucrose in Muffins with Apple Puree on the Viscoelastic Properties of Dough  
Figure 2 shows the effect of replacing sucrose in different percentages with apple puree on the flow curves of muffin doughs. A typical shear-thinning behavior was observed in all doughs (Figure 2), with the doughs being less viscous when sucrose was substituted with apple puree. This behavior is very likely related to the moisture content of the apple puree, which would have led to a decrease in the viscosities of the doughs in which sucrose was partially substituted for total sugar. Apparent viscosity decreased significantly (\(p<0.05\)) with increasing percentage of sucrose substituted with apple puree. Other authors also obtained a decrease in viscosity by substituting sucrose in muffin batter with agave syrup [44] by replacing sucrose with grape, mulberry, or apricot molasses [75]. The results showed that the values for the elastic modulus G\({}^{\prime}\) were higher than those for the viscous modulus G\({}^{\prime\prime}\) in the temperature range of 20-90 \({}^{\circ}\)C (Figures 3 and 4). Figure 3: Effect of sucrose substitution in muffin dough on storage modulus (G\({}^{\prime}\)) with temperature. Figure 2: The impact of sucrose replacement by apple puree on the flow curves of the muffin dough. The viscoelastic properties were evaluated in accordance with the temperature, from 20 \({}^{\circ}\)C to 90 \({}^{\circ}\)C, to observe the structural changes in the muffin doughs by simulating the behavior of the dough in the oven. The final structure and texture of the muffins are directly influenced by the structural changes that occur in the dough during baking. Sucrose increases the gelatinization temperature of starch, its role being crucial during dough heating. This allows for the correct formation of water vapor and CO\({}_{2}\) and sufficient expansion of the air bubbles before the dough sets. Thus, sucrose contributes to the development of the fluffy structure of the muffins, ensuring an airy and uniform texture [74]. The effects of temperature on the storage modulus (G\({}^{\prime}\)) and loss modulus (G\({}^{\prime\prime}\)) during dough heating are shown in Figures 3 and 4. The results showed that, in the temperature range of 20-90 \({}^{\circ}\)C, the values for the storage modulus G\({}^{\prime}\) were higher than those for the loss modulus G\({}^{\prime\prime}\). The values for G\({}^{\prime}\) and G\({}^{\prime\prime}\) decreased with increasing temperature, probably due to the denaturation of the proteins, which lose their ability to retain water in the dough system. Subsequently, as the temperature continues to rise, the released water begins to be absorbed by the starch granules, which hydrate and subsequently gelatinize, leading to increased G\({}^{\prime}\) and G\({}^{\prime\prime}\) values. Regarding the behavior of the doughs, samples P10-P60 showed values close to those of the control sample for G\({}^{\prime}\) and G\({}^{\prime\prime}\). Therefore, the behavior was similar, unlike the other samples that showed significantly higher values than the control sample. Similar results were obtained by [PERSON] et al. (2020) by substituting sucrose in muffin dough with agave syrup [44]. Also, viscoelastic properties were studied as a function of frequency, which varied between 0.1 and 10 Hz at a constant temperature. Figures 5 and 6 show the frequency dependence of the different doughs on the storage modulus (G\({}^{\prime}\)) and the loss modulus (G\({}^{\prime\prime}\)). Doughs with 40%, 70%, 80%, 90%, and 100% apple puree showed higher values for the modulus of elasticity compared to the control sample, compared to doughs with 10%, 20%, 30%, and 50% apple puree that presented lower values for the storage modulus compared to the control sample (Figures 5 and 6). The sample with 60% apple puree showed the same values for the storage modulus versus frequency as the control sample. Figure 4: Effect of sucrose substitution in muffin dough on loss modulus (G\({}^{\prime\prime}\)) with temperature.