# Preparation and Characterization of Flavored Sauces from Chinese Mitten Crab Processing By-Products
## 3 Results and Discussion
### E-Nose Analysis  
The conductivity graphs of the six samples used in this experiment are displayed in Figure 3. Due to the various kinetic properties of the sensor, the data resulting from the interaction of the volatiles on the detecting element are transformed into an odor fingerprint. Principal component analysis (PCA) and linear discriminant analysis (LDA) are widely used in E-nose data analysis. Figure 4 displays the E-nose analysis's findings. During the use of reduced dimensionality, the PCA analysis first evaluated the similarity between the clusters before visualizing all the data in the dataset [22]. The PCA value of the CBs was 96.07%, of which PC1 and PC2 accounted for 70.84% and 25.23%, respectively. The PCA value of the CLs was 98.83%, with PC1 and PC2 accounting for 97.71% and 1.12%. Indicating that both types of volatile chemicals accounted for the majority of the samples, the PCA of the crab legs and bodies was higher than 85%. The distance between the sample points demonstrated that they were far apart and highly different, and the primary two scent component types and quantities varied noticeably between the samples. \begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline \multicolumn{1}{c}{**Taste Attribution**} & \multicolumn{1}{c}{\multirow{2}{*}{
\begin{tabular}{c} **C1** \\ **(mg/mL)** \\ \end{tabular} }} & \multicolumn{6}{c}{**Free Amino Acid**} \\ \cline{4-10}  & & \multicolumn{3}{c}{**CL**} & \multicolumn{6}{c}{**CB**} \\ \hline  & & **HO** & **EHS** & **MRS** & **The** & **HO** & **EHS** & **MRS** & **The** \\  & & **(mg/mL)** & **(mg/mL)** & **(mg/mL)** & **Inceasing** & **(mg/mL)** & **(mg/mL)** & **(mg/mL)** & **Inceasing** \\  & & & & & & & & & & \\  & & & & & & & & & & \\ \hline Proline & Sweet/bitter (+) & 0.03 & 0.05 & 0.04 & 25.00 & 0.01 & 0.03 & 0.03 & 66.67 \\ Aspartic acid & Umaami (+) & 0.00 & 0.04 & 0.02 & 100.00 & 0.00 & 0.04 & 0.02 & 100.00 \\ Threonine * & Sweet (+) & 0.00 & 0.05 & 0.02 & 100.00 & 0.00 & 0.03 & 0.01 & 100.00 \\ Serine & Sweet (+) & 0.00 & 0.07 & 0.03 & 100.00 & 0.00 & 0.04 & 0.01 & 100.00 \\ Glutamic acid & Umaami (+) & 0.00 & 0.09 & 0.04 & 100.00 & 0.01 & 0.09 & 0.04 & 75.00 \\ Glycine & Sweet (+) & 0.04 & 0.10 & 0.05 & 20.00 & 0.05 & 0.08 & 0.03 & \(-66.67\) \\ Alanine & Sweet (+) & 0.05 & 0.18 & 0.11 & 54.55 & 0.05 & 0.09 & 0.05 & 0.00 \\ Cysteine & Bitter/sweet (-) & 0.00 & 0.00 & 0.02 & 100.00 & 0.00 & 0.02 & 0.01 & 100.00 \\ Valine * & Sweet/bitter (-) & 0.00 & 0.09 & 0.07 & 100.00 & 0.00 & 0.05 & 0.03 & 100.00 \\ Methionine * & Bitter/sweet (-) & 0.00 & 0.04 & 0.02 & 100.00 & 0.00 & 0.02 & 0.01 & 100.00 \\ Isoleucine * & Bitter (-) & 0.00 & 0.06 & 0.05 & 100.00 & 0.00 & 0.04 & 0.02 & 100.00 \\ Leucine * & Bitter (-) & 0.00 & 0.13 & 0.09 & 100.00 & 0.00 & 0.07 & 0.04 & 100.00 \\ Tyrosine & Bitter (-) & 0.00 & 0.07 & 0.04 & 100.00 & 0.00 & 0.03 & 0.02 & 100.00 \\ Phenylalanine * & Bitter (-) & 0.00 & 0.09 & 0.05 & 100.00 & 0.00 & 0.04 & 0.02 & 100.00 \\ Histidine * & Bitter (-) & 0.00 & 0.05 & 0.09 & 100.00 & 0.01 & 0.03 & 0.07 & 85.71 \\ Lysine * & Sweet/bitter (-) & 0.00 & 0.12 & 0.06 & 100.00 & 0.01 & 0.08 & 0.04 & 75.00 \\ Arginine & Sweet/bitter (+) & 0.04 & 0.17 & 0.09 & 55.56 & 0.05 & 0.08 & 0.03 & \(-66.67\) \\ EAA/NEAA & - & 0.00 & 53.85 & 53.45 & – & 5.56 & 33.72 & 17.44 & – \\ EAA/TAA & - & 0.00 & 35.00 & 34.83 & – & 5.26 & 66.28 & 38.37 & – \\ Total & – & 0.16 & 1.40 & 0.89 & – & 0.19 & 0.86 & 0.48 & – \\ Umaami & – & 0.00 & 0.13 & 0.06 & – & 0.01 & 0.13 & 0.06 & – \\ Sweet & – & 0.16 & 0.87 & 0.51 & – & 0.17 & 0.52 & 0.25 & – \\ Bitter & – & 0.07 & 0.87 & 0.55 & – & 0.08 & 0.49 & 0.32 & – \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Proportion of hydrolyzed amino acid composition, the concentration, and the increasing ratio of free amino acids. Figure 4: E-nose patterns: (**a**) PCA of crab legs, (**b**) LDA of crab legs, (**c**) PCA of crab bodies, and (**d**) LDA of the crab bodies.