# Snack Texture Estimation System Using a Simple Equipment and Neural Network Model +
## 3 Experiment  
Rice crackers, potato chips, cookies, biscuits, and corn snacks purchased from a local supermarket were the food specimens evaluated by the system (Figure 4). Table 1 shows the number of samples and texture information of each food specimen after the experiment. Specifically, 200 rice crackers, 200 potato chips, 200 cookies, 200 biscuits, and 200 corn snacks were sampled. Table 2 enumerates the conditions for the load and sound evaluation of the food samples. Figure 5a shows the image of three stacked potato chips being crushed by the equipment; this was carried out 200 times, leading to 200 data for the potato chips samples. The experiment of each sample was conducted 200 times, for a total of 200 data. The samples are numbered accordingly, as illustrated in Table 1. Figure 6 displays graphs of five specimens of the experiment. The graph at the top illustrates the curve of the load (red line) and the sound (blue line), as shown in Figure 6a, which indicates that as the probe touched the sample, the load increased and a loud sound occurred. The middle graph in Figure 6a shows automatically extracted signals for 2.0 s; the extraction method is explained in the following paragraph. By focusing on the 2.0 s period while the snack is being pressed, we do not have to consider the noise influence except at the 2.0 s period. The bottom graph in Figure 6a shows the FFT (Fast Fourier Transform) results of the extracted 2.0 s sound data. Likewise, the results for the potato chips, cookie, biscuit, and corn snack samples are displayed in Figure 6b-e, respectively. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline  & **Rice Crackers** & **Potato Chips** & **Cookies** & **Biscuits** & **Corn Snacks** \\ \hline Number of Samples & 200 & 200 & 200 & 200 & 200 \\ Sample Number & No.1–200 & No.201–400 & No.401–600 & No.601–800 & No.801–1000 \\ Crunchiness & 0.9 & 0.2 & 0.7 & 0.5 & 0.4 \\ Crispness & 0.8 & 0.9 & 0.7 & 0.7 & 0.8 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Number and texture information of the snack samples. Figure 4: Food specimens: (**a**) A popular rice cracker in Japan; (**b**) smaller sized potato chip compared with ordinary merchandise; (**c**) a butter cookie; (**d**) small sized biscuit and; (**e**) a corn snack. Figure 5: Images of stacked potato chips under equipment evaluation: (**a**) Three stacked potato chips prior to evaluation and; (**b**) potato chips being crushed. Figure 6: Graphs of texture examination of all sorts of samples: (**a**) Rice cracker; (**b**) potato chips; (**c**) cookie; (**d**) biscuit and; (**e**) corn snack. The signal data for 2.0 s were extracted from the entire 10 s data as shown in Figure 7a. 1. The maximum load point (1) was determined. 2. Point, at 1.0 % of maximum load, was identified. 3. Finally, signals for 2.0 s from point (2) were extracted. The load curve of the extracted 2.0 s signals was divided into five sections, as shown in Figure 7b. Subsequently, parameters W1-W5 in the load were calculated as follows:  
1. W1 is the average of the load between 0.0 s and 0.4 s.
2. W2 is the average between 0.4 s and 0.8 s.
3. W3 is the average between 0.8 s and 1.2 s.
4. W4 is the average between 1.2 s and 1.6 s.
5. W5 is the average between 1.6 s and 2.0 s.  
The extracted 2.0 s sound signal data were converted by FFT, resulting in a frequency range of 1-10 kHz, which was also divided into five sections, as shown in Figure 7c. F1-F5 in the sound were calculated as follows:  
1. F1 is the integration of FFT result between 1 Hz and 2 kHz. 2. F2 is the integration of results between 2 kHz and 4 kHz. 3. F3 is the integration of results between 4 kHz and 6 kHz. 4. F4 is the integration of results between 6 kHz and 8 kHz. 5. F5 is the integration of results between 8 kHz and 10 kHz. Figure 8 shows the average values and standard deviations (STDs) of the parameters W1-W5 for (a) rice cracker, (b) potato chips, (c) cookie, (d) biscuit, and (e) corn snack, respectively. As observed, averages of W were different depending on each specimen.