For estimation of tryptophan, the
samples were hydrolysed using 4.2 M NaOH at 110
◦
C (Allred and
MacDonald, 1988). The hydrolysates were dissolved in methanol
and loaded into Ultra-HPLC Dionex RSLC (Dionex Corporation,
USA). Detection was done at 263 nm and 338 nm (Meussen et al.,
2014).