# The Effect of the Improvement Technology on the Quality of Midu Pork Roll
## 3 Results and Discussion
### Evaluation of the TAV of FAAs  
FAAs are one of the main base flavor substances in food. According to the taste characteristics of FAAs, they can be divided into four categories: umami amino acids, sweet amino acids, bitter amino acids and aromatic amino acids [43].  
This study evaluated the TAV of FAAs before and after the improved process. TAV was introduced to determine the taste contributions of FAAs because FAAs with taste activity contribute to the taste of fermented food. A substance with TAV > 1 was considered an active component affecting the taste perception of the sample [44]. Consistent with a previous study, among all the FAAs, Glu contributed to the overall taste of MPR [45]. These FAAs are an important part of the formation of flavor substances in fermented MPR, which means they can be used as flavoring agents and nutritional supplements.  
The results are shown in Table 5. By the comparison of taste amino acids, the content of umami amino acids and bitter amino acids is higher than the others. As shown in Table 4, the umami amino acids of T1 and T2 were significantly higher than those of C. Among them, the TAV value of Glu was the highest (C: 2.56, T1: 4.97, T2: 5.10). Research by [PERSON] et al. [46] found that Glu and Asp were the basic components of umami taste. Glu had the strongest umami taste, with a taste threshold of 0.3 mg/mL.  
There was no significant difference in the TAV value of sweet amino acids between the three groups. Sweet amino acids can mask bitterness and astringency. Furthermore, they have a synergistic effect with umami amino acids to enhance flavor and freshness [47].  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Taste** & **FAAs** & **Threshold** & \multicolumn{3}{c}{**TAV**} & **Sig.** \\ \cline{4-7}
**Characteristics** & **FAAs** & **(mg/g)** & **C** & **T1** & **T2** & **Sig.** \\ \hline \multirow{3}{*}{Umami Amino Acids} & Glu & 0.3 & 2.47 \(\pm\) 0.03 c & 4.97 \(\pm\) 0.06 b & 5.53 \(\pm\) 0.19 a & **+** \\  & Asp & 1 & 0.09 \(\pm\) 0.01 c & 0.13 \(\pm\) 0.01 b & 0.15 \(\pm\) 0.01 a & **+** \\  & Total & — & 2.56 \(\pm\) 0.02 c & 5.10 \(\pm\) 0.06 b & 5.68 \(\pm\) 0.09 a & **+** \\  & Ala & 0.6 & 0.02 \(\pm\) 0.01 c & 0.05 \(\pm\) 0.01 a & 0.03 \(\pm\) 0.03 b & **+** \\  & Gly & 1.3 & 0.05 \(\pm\) 0.02 a & 0.03 \(\pm\) 0.01 b & 0.05 \(\pm\) 0.01 a & **+** \\  & Ser & 1.5 & 0.08 \(\pm\) 0.01 a & 0.02 \(\pm\) 0.03 c & 0.05 \(\pm\) 0.01 b & **+** \\  & Thr & 2.6 & 0.05 \(\pm\) 0.01 a & 0.01 \(\pm\) 0.02 c & 0.03 \(\pm\) 0.01 b & **+** \\  & Total & — & 0.2 \(\pm\) 0.01 a & 0.11 \(\pm\) 0.02 c & 0.17 \(\pm\) 0.02 b & **+** \\ \hline \multirow{3}{*}{Bitter amino acid} & Arg & 0.5 & 0.28 \(\pm\) 0.01 a & 0.10 \(\pm\) 0.03 c & 0.16 \(\pm\) 0.01 b & **+** \\  & Ile & 0.9 & 0.09 \(\pm\) 0.01 a & 0.03 \(\pm\) 0.02 b & 0.04 \(\pm\) 0.02 b & **+** \\  & Leu & 1.9 & 0.04 \(\pm\) 0.02 a & 0.02 \(\pm\) 0.01 b & 0.02 \(\pm\) 0.01 b & **+** \\  & Met & 0.3 & 0.37 \(\pm\) 0.01 a & 0.20 \(\pm\) 0.01 b & 0.20 \(\pm\) 0.01 b & **+** \\  & Phe & 0.9 & 0.14 \(\pm\) 0.02 a & 0.06 \(\pm\) 0.01 b & 0.12 \(\pm\) 0.01 a & **+** \\  & Val & 0.4 & 0.30 \(\pm\) 0.02 a & 0.20 \(\pm\) 0.01 b & 0.20 \(\pm\) 0.01 b & **+** \\  & Total & — & 1.22 \(\pm\) 0.02 a & 0.61 \(\pm\) 0.01 c & 0.74 \(\pm\) 0.02 b & **+** \\  & Lys & 0.5 & 0.04 \(\pm\) 0.03 c & 0.16 \(\pm\) 0.02 b & 0.32 \(\pm\) 0.01 a & **+** \\  & Pro & 3 & 0.02 \(\pm\) 0.01 a & 0.02 \(\pm\) 0.02 a & 0.02 \(\pm\) 0.01 a & ns \\  & Total & — & 0.06 \(\pm\) 0.02 c & 0.18 \(\pm\) 0.02 b & 0.34 \(\pm\) 0.01 a & **+** \\ \hline \hline \end{tabular}
\end{table}
Table 5: The FAAs TAV of MPR with different process conditions.  
The TAV of Met in bitter amino acids was the highest. Its taste-presenting effect was that T1 and T2 were lower than C.