## 3 Results and Discussion
### Flow Curves of Tested Film-Forming Solutions
#### 3.1.3 Sodium Alginate Solutions with Pumpkin Puree  
Figure 1C shows the flow curves of composite solutions with sodium alginate concentrations of 1 (SA_1), 1.5 (SA_1.5), and 2% (SA_2) and pumpkin puree added. Based on the course of the flow curves of the composite solutions of sodium alginate with the addition of puree, it was also found in this case, similarly to those described above, that the tested solutions belong to the group of shear-thinning liquids with no yield point. Based on the R\({}^{2}\) parameter (Table 2), the Ostwald [PERSON] model (1) was again used to describe the flow curves of composite solutions of sodium alginate with the addition of pumpkin puree. In this case, the tendency obtained for the sodium alginate solutions without the addition of pumpkin puree, tested by [PERSON] et al. [27], was not confirmed in this case for which the Newtonian model was used (Equation (1)) in the study by [PERSON] et al. [27].  
The flow index \(n\) for composite sodium alginate solutions with the addition of pumpkin puree was not characterized by any trend (Table 2). For a solution with a concentration of 1.5% sodium alginate (SA_1.5) with the addition of pumpkin puree, the parameter \(n\) was lower (0.6951) than for a solution with a concentration of 1% with the addition of pumpkin puree (0.7718). On the other hand, for a solution with a concentration of 2% sodium alginate SA_2) with the addition of pumpkin puree, the parameter \(n\) increases, but the obtained value of the parameter was not higher than the value obtained for a solution with a concentration of 1% sodium alginate (SA_1) with the addition of pumpkin puree.  
The apparent viscosity of composite solutions of sodium alginate with the addition of pumpkin puree increases with increasing concentration and ranges from 0.1866 Pa-s to 0.4522 Pa-s (Table 2). Compared to sodium alginate solutions without the addition of pumpkin puree [27], the viscosity is one order of magnitude higher, which also confirms the trends described for composite solutions of gelatine and soy protein isolate of various concentrations and with the addition of pumpkin puree. The smallest difference was between the solutions with a concentration of 2% sodium alginate--the viscosity of the sodium alginate solution with the addition of pumpkin puree (0.4522 Pa-s) was more than five times higher compared to the solution of sodium alginate without the addition of pumpkin puree (0.0884 Pa-s) obtained in previous research [27].  
[PERSON] et al. [31] studied the rheological properties of sodium alginate solutions with the addition of pullulan. Sodium alginate solution (0.2% \(w/w\)) was prepared, and then pullulan was added to give 60:40 and 40:60 sodium alginate to pullulan weight ratios. The viscosity test was carried out at 20 \({}^{\circ}\)C. The [PERSON] model (Equation (1)) was used to describe the flow curves, as in this study. In the case of the solution with a higher content of sodium alginate, the rheological parameters \(k\) and \(n\) had the values of 0.977 Pa-s and 0.916, respectively, while in the case of the solution with the ratio of sodium alginate to pullulan was 40:60, the rheological parameters \(k\) and \(n\) had the values of 0.199 Pa-s and 0.974, respectively. The results obtained by [PERSON] et al. [31] indicate that the viscosity decreases with the increase in the addition of pullulan. It can also be seen that the values of parameter \(n\) are closer to 1 than in this study. This means that a Newtonian model would probably be a better model to describe the flow curves obtained by [PERSON] et al. [31].