HPLC efficiently separates peptides from protein hydrolysates, and
also provides some indication on their hydrophobicity and hydrophilicity.
Several researchers have employed this technique in studying tryptic
hydrolysate from bovine β-lactoglobulin [35] or crude protease
extract hydrolysates from zebra blenny [13].
The RP-HPLC elution profiles of TRMHs are presented in Fig. 2. By
comparison with the undigested protein, TRMHs showed a several
peaks confirming the hydrolysis of the muscle protein and the generation
of several peptides. Two aromatic amino acids, tyrosine and tryptophan,
were run separately and their retention times (13.3 min and
26.03 min, respectively) were used to divide the area under the chromatograms
into three zones. Zone 1 consisted of peptides eluted before
tyrosine (hydrophilic peptides). Zone 2 comprised of peptides eluted
between tyrosine and tryptophan (low hydrophobic peptides), while
zone 3 comprised of those eluted after tryptophan (high hydrophobic
peptides). The hydrolysates have a high content of hydrophobic peptides
than hydrophilic and lowhydrophobic ones. TRMH-Crude showed
the highest content of hydrophilic peptides. However, TRMH-A26 and
TRMH-Alcalase showed the highest content of low hydrophobic peptides,
while TRMH-Neutrase showed the highest content of high hydrophobic
peptides. Rao et al. [29] reported that Neutrase is characterized
by its high affinity for hydrophobic amino acids, hence, the differences
in RP-HPLC profiles of TRMHs could be essentially due to the difference
in the specificity of enzymes used during hydrolysis.