*3.6. Amino Acids Profile*

Amino acids have many health benefits. For example, lysine can enhance immunity and improve the central nervous function of the human body [49]. Moreover, glutamic and aspartic are umami amino acids that could contribute to the enhancement of the flavor of meat products [50]. Therefore, the amino acid content is another key factor of the meat products' nutrients [51]. As shown in Table 5, the addition of the PO enhanced the contents of all the essential amino acids and non-essential amino acids compared with the control group (*p* < 0.05). It could be seen that the essential amino acids of the control sausage were mainly lysine, leucine, and valine; the non-essential amino acids were mainly glutamic, aspartic, and arginine. Comparing PO40 with the control group, the contents of lysine, leucine, valine, glutamic, aspartic, and arginine in sausage increased by 39.26%, 40.00%, 35.53%, 34.65%, 32.26%, and 40.00%, respectively. All of these increases might be contributed by the abundance of amino acids in PO [27].


**Table 5.** Amino acid profile (%) of *Pleurotus ostreatus* (PO) sausages during storage.

a–e Means within the same row with different letters differ significantly among the treatments (*p* < 0.05). Values are given as mean ± standard deviations. Control, PO10, PO20, PO30, and PO40 were 0 wt.%, 10 wt.%, 20 wt.%, 30 wt.%, and 40 wt.% addition of PO puree, respectively.

### *3.7. Sensory Evaluation*

The sensory evaluation results of each group are shown in Figure 1. The appearance of all groups had excellent performance (>8). In the PO10 and PO20 groups, an appropriate increase in brightness of the sausages might be more loved by the group members. For the PO30 and PO40 groups, the decrease in the redness might reduce group acceptance of the sausages in appearance. In terms of aroma and flavor, all scores exceeded eight and PO20 had the best aroma and flavor. This might be because PO was rich in free amino acids, especially glutamic and aspartic, which were conducive to enhance the aroma and flavor of the sausage. The texture of the sausages decreased with the increase in PO content. This result might be caused by the soft texture of the sausage and more gaps inside the sausages (Section 3.2.) which were disliked by the group member. Although a difference was found between each group, all of these samples were judged as acceptable (>7), suggesting that PO had an opportunity to in sausages. From what has been discussed above, PO20 can be regarded as the best group in sensory evaluation through comprehensive consideration.

**Figure 1.** Sensory evaluations of each group of sausages.
