*2.3. Contents of Free Amino Acids in OPs*

Table 3 shows the free amino acid content and composition of OPs. The contents of total free amino acids in OPs were 15.80 g/100 g, indicating OPs contained abundant free amino acids. Among these free amino acids, Pro (2.49 g/100 g), Glu (2.12 g/100 g), Tyr (1.51 g/100 g), Lys (1.43 g/100 g), Gly (1.38 g/100 g), and Val (0.91 g/100 g) were highly detected in OPs. The essential free amino acids accounted for 33.73% of the free total amino acids, and free hydrophobic amino acids accounted for 38.86%.


**Table 3.** Contents of free amino acids in OPs.

Note: \* Essential free amino acids. # Hydrophobic free amino acids; ND: not detected.
