## 3 Results and Discussion
### Changes in Taste Compounds in Cooked Marinated Pork Knuckle During Processing
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Traits**} & & \multicolumn{4}{c}{**Content (mg/100 g)**} \\ \cline{3-6}  & & **T1** & **T2** & **T3** & **T4** \\ \hline Umami taste & Asp & 0.26 \(\pm\) 0.01 \({}^{\text{c}}\) & 2.47 \(\pm\) 0.01 \({}^{\text{b}}\) & 44.79 \(\pm\) 0.91 \({}^{\text{a}}\) & 2.46 \(\pm\) 0.30 \({}^{\text{b}}\) \\ FAAs & Glu & 5.03 \(\pm\) 0.07 \({}^{\text{c}}\) & 24.37 \(\pm\) 0.25 \({}^{\text{b}}\) & 301.73 \(\pm\) 1.24 \({}^{\text{b}}\) & 19.53 \(\pm\) 2.89 \({}^{\text{a}}\) \\ \hline \multirow{4}{*}{Sweet taste FAAs} & Ser & 0.71 \(\pm\) 0.25 \({}^{\text{c}}\) & 5.23 \(\pm\) 0.08 \({}^{\text{b}}\) & 40.64 \(\pm\) 0.67 \({}^{\text{a}}\) & 3.85 \(\pm\) 0.53 \({}^{\text{b}}\) \\  & Ala & 11.30 \(\pm\) 0.07 \({}^{\text{b}}\) & 10.60 \(\pm\) 0.28 \({}^{\text{b}}\) & 50.08 \(\pm\) 0.66 \({}^{\text{a}}\) & 8.92 \(\pm\) 1.37 \({}^{\text{b}}\) \\  & Gly & 4.80 \(\pm\) 0.06 \({}^{\text{b}}\) & 7.05 \(\pm\) 0.24 \({}^{\text{b}}\) & 29.48 \(\pm\) 1.20 \({}^{\text{a}}\) & 4.70 \(\pm\) 0.66 \({}^{\text{b}}\) \\  & Thr * & 12.12 \(\pm\) 0.54 \({}^{\text{b}}\) & 9.50 \(\pm\) 0.09 \({}^{\text{c}}\) & 54.86 \(\pm\) 0.12 \({}^{\text{a}}\) & 4.50 \(\pm\) 0.68 \({}^{\text{d}}\) \\ \hline \multirow{4}{*}{Bitter taste FAAs} & His & 6.12 \(\pm\) 0.19 \({}^{\text{b}}\) & 2.07 \(\pm\) 0.08 \({}^{\text{c}}\) & 10.89 \(\pm\) 0.23 \({}^{\text{a}}\) & 1.08 \(\pm\) 0.18 \({}^{\text{d}}\) \\  & Ile * & 2.30 \(\pm\) 0.01 \({}^{\text{c}}\) & 8.50 \(\pm\) 0.22 \({}^{\text{b}}\) & 74.92 \(\pm\) 0.78 \({}^{\text{a}}\) & 6.83 \(\pm\) 0.97 \({}^{\text{b}}\) \\  & [PERSON] * & 5.29 \(\pm\) 0.01 \({}^{\text{c}}\) & 15.78 \(\pm\) 0.31 \({}^{\text{b}}\) & 124.64 \(\pm\) 1.64 \({}^{\text{a}}\) & 12.10 \(\pm\) 1.76 \({}^{\text{b}}\) \\  & [PERSON] * & 3.59 \(\pm\) 1.21 \({}^{\text{c}}\) & 10.02 \(\pm\) 0.18 \({}^{\text{b}}\) & 65.82 \(\pm\) 0.48 \({}^{\text{a}}\) & 8.36 \(\pm\) 1.17 \({}^{\text{b}}\) \\  & Tyr & 0.99 \(\pm\) 0.01 \({}^{\text{b}}\) & 0.07 \(\pm\) 0.01 \({}^{\text{b}}\) & 23.13 \(\pm\) 0.93 \({}^{\text{a}}\) & 0.16 \(\pm\) 0.05 \({}^{\text{b}}\) \\ \hline \multirow{4}{*}{Bitter/sweet taste} & Pro & 4.36 \(\pm\) 0.05 \({}^{\text{c}}\) & 10.65 \(\pm\) 0.42 \({}^{\text{b}}\) & 100.00 \(\pm\) 1.38 \({}^{\text{a}}\) & 7.90 \(\pm\) 0.70 \({}^{\text{b}}\) \\  & Arg & 4.04 \(\pm\) 0.42 \({}^{\text{b}}\) & 3.62 \(\pm\) 0.12 \({}^{\text{b}}\) & 14.10 \(\pm\) 0.05 \({}^{\text{a}}\) & 3.06 \(\pm\) 0.54 \({}^{\text{b}}\) \\  & Val * & 4.21 \(\pm\) 0.07 \({}^{\text{c}}\) & 12.10 \(\pm\) 0.16 \({}^{\text{b}}\) & 105.39 \(\pm\) 0.31 \({}^{\text{a}}\) & 9.81 \(\pm\) 1.39 \({}^{\text{b}}\) \\  & Lys * & 5.16 \(\pm\) 1.10 \({}^{\text{c}}\) & 10.03 \(\pm\) 0.17 \({}^{\text{b}}\) & 67.10 \(\pm\) 0.59 \({}^{\text{a}}\) & 8.08 \(\pm\) 1.17 \({}^{\text{b}}\) \\  & Met * & 1.65 \(\pm\) 0.01 \({}^{\text{c}}\) & 3.03 \(\pm\) 0.20 \({}^{\text{b}}\) & 16.40 \(\pm\) 0.16 \({}^{\text{a}}\) & 2.06 \(\pm\) 0.09 \({}^{\text{c}}\) \\ \hline \multirow{2}{*}{Sour taste FAA} & Cys & 0.68 \(\pm\) 0.02 \({}^{\text{b}}\) & 0.81 \(\pm\) 0.30 \({}^{\text{b}}\) & 11.58 \(\pm\) 1.31 \({}^{\text{a}}\) & 1.05 \(\pm\) 0.54 \({}^{\text{b}}\) \\ \hline Total FAAs & & 72.60 \(\pm\) 4.08 \({}^{\text{c}}\) & 135.89 \(\pm\) 3.10 \({}^{\text{b}}\) & 1135.54 \(\pm\) 12.66 \({}^{\text{b}}\) & 104.46 \(\pm\) 15.07 \({}^{\text{b}}\) \\ \hline \multirow{2}{*}{EAAs} & 34.32 \(\pm\) 2.95 \({}^{\text{c}}\) & 68.95 \(\pm\) 1.33 \({}^{\text{b}}\) & 509.13 \(\pm\) 4.08 \({}^{\text{a}}\) & 50.76 \(\pm\) 8.65 \({}^{\text{b}}\) \\ \hline \end{tabular} Values in the same column with different letters were significantly different (\(p<0.05\)). The mark * denotes essential amino acids (EAAs). Treatments: T1: raw meat stage; T2: marinade stage; T3: simmer in brine soup stage; T4: finished product stage.  
\end{table} 
Table 2: Changes in free amino acid (FAA) of cooked marinated pork knuckle during processing. The essential taste-active compounds in meat production involve amino acids and nucleotides.