# Chemical Composition and Palatability of Nutraceuticaltical Dog Snacks
## 3 Results
### Texture of Snacks  
Scanning electron microscopy images of the extruded and baked snacks are shown in Figures 2-5.  
The SEM analysis determined that the surface and cross-section of the extruded snacks (S1, S2) was relatively smooth but not homogenous. The pores were slightly visible, meaning a lack of expansion of the snacks (Figures 2a,b and 3a,b). Additionally, deeply embedded starch granules were visible on the cross-section of the samples. It may be concluded that the addition of banded cricket protein into the starch caused the increase of the protein network around the starch granules, which resulted in a decrease of the extruded snack expansion. Moreover, little cracks were visible on the surface of both samples (Figures 2a and 3a). Analyzing the cross-section of the S1 and S2 snacks (Figures 2b and 3b), it was concluded that the S1 sample was compact. Contrary to S1, the S2 sample consisted of two visible layers that were not compact and homogenous. Starch granules were visible as well as the protein network. Comparing the S1 and S2 surface (Figures 2a and 3b), it should be noticed that the differences between starch particles size were higher for the S1 snack than for the S2 snack.  
The SEM analysis demonstrated that the surface of the baked snacks (S3, S4) was smooth, dense and compact with swollen and gelatinized starch granules (Figures 4a,b and 5a,b). It was indicated that the starch granules were embedded in a protein matrix. Moreover, little cracks were visible on the surface of both samples. Additionally, the differences between the granules size were noticed meaning that their swelling was insufficient. It should be underlined (Figures 4b and 5b) that air bubbles (holes) were visible on the cross-section of S3 and S4 snacks, confirming the expansion of the baked snacks. The structure of the S4 cross-section was less compact than the S3 structure. It should be mentioned that the S4 sample was similar to closed-cell foam in which gas formed little pockets surrounded by the protein network containing starch granules.  
In summary, the SEM analysis demonstrated that all the snacks were a heterogeneous system. Additionally, the SEM images revealed that baked snacks contained large-sized starch granules with slightly visible spaces between starch granules and protein, suggesting the dominance of starch over the protein network. Additionally, air bubbles were observed on the cross-section of the S3 and S4 samples confirming a higher expansion of the baked snacks compared to the extruded samples.  
\begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline
**Item** & **Cu** & **Fe** & **Mn** & **Zn** & **Co** & **Cd** & **Pb** & **Mo** & **Cr** & **Ni** \\ \hline S1 & 0.485 & 3.218 & 1.443 & 2.265 & nd & nd & nd & 0.136 & nd & nd \\ \hline S2 & 0.533 & 3.703 & 1.299 & 2.334 & nd & nd & nd & 0.120 & nd & nd \\ \hline Mean & **0.51 a** & **3.46 a** & **1.37 a** & **2.30 a** & **nd** & **nd** & **nd** & **0.13 a** & **nd** \\ \hline SD & 0.034 & 0.343 & 0.102 & 0.049 & - & - & - & 0.011 & - & - \\ \hline S3 & 0.558 & 4.875 & 1.564 & 2.420 & nd & nd & nd & 0.130 & nd & nd \\ \hline S4 & 0.679 & 6.115 & 1.481 & 2.594 & nd & nd & nd & 0.105 & nd & nd \\ \hline Mean & **0.62 b** & **5.50 b** & **1.52 b** & **2.51 b** & **nd** & **nd** & **nd** & **0.12 a** & **nd** \\ \hline SD & 0.086 & 0.877 & 0.059 & 0.123 & - & - & - & 0.018 & - & - \\ \hline \hline \end{tabular}  
Means with the same letter in the superscript (a, b) did not differ statistically at \(p=0.05\) (for all columns separately); SD, standard deviation; nd, not detected.  
\end{table}
Table 5: Trace elements (mg/100 g DM) content of extruded (S1, S2) and baked (S3, S4) dog snacks.  
Figure 2: (**a**) The surface of the snack S1; (**b**) the cross-section of the snack S1.  
Figure 3: **(a)** The surface of the snack S2; **(b)** the cross-section of the snack S2.  
Figure 4: **(a)** The surface of the snack S3; **(b)** the cross-section of the snack S3.