2.6. Amino acid analysisFreeze-drie

2.6. Amino acid analysis
Freeze-dried clam portions were hydrolysed with 4.0 M
methanesulphonic acid under reduced pressure at 110 C for 22 h
to prevent the oxidation of tryptophan. The hydrolysates were
neutralised with 3.5 M NaOH and diluted with 0.2 M citrate buffer
(pH 2.2). An aliquot of 100 ll was applied to an amino acid analyser
(JLC-500/V AminoTac™, JEOL Inc., USA). Amino acid contents
were expressed as mg/g dry sample.