Effect of hydrolysis time on the determination of amino acids in samples of soybean products with ion-exchange chromatography or precolumn derivatization with phenyl isothiocyanate.
Accurate determination of amino acid levels in soy products facilitates optimum diet formulation and amino acid supplementation. A study was carried out to investigate the effect of hydrolysis time and method of amino acid measurement on amino acid levels. Correction factors to standardize amino acid levels to 24 h of hydrolysis were also determined. Six different soybean products were evaluated. Hydrolysis was carried out for 10 different periods of time. Amino acids were analyzed by both ion-exchange chromatography and precolumn derivatization with phenyl isothiocyanate. Both hydrolysis time and measurement method affected (P < 0.05) amino acid levels. Standard hydrolysis conditions (hydrolysis in 6 M HCl at 110 degrees C for 24 h) rarely provide the maximal amino acid values. Therefore, sequential hydrolyses curves were very useful and should be used.
Albin
D M
DM
Department of Animal Sciences, University of Illinois at Urbana-Champaign, 1207 West Gregory Drive, Urbana, Illinois 61801, USA. albin@uiuc.edu
Wubben
J E
JE
Gabert
V M
VM
D000596:Amino Acids / Q000032:analysis*; D002852:Chromatography, Ion Exchange / Q000379:methods*; D006868:Hydrolysis; D007202:Indicators and Reagents; D017879:Isothiocyanates; D007700:Kinetics; D013025:Glycine max / Q000737:chemistry*; D013861:Thiocyanates / Q000737:chemistry*
D000596:Amino Acids; D007202:Indicators and Reagents; D017879:Isothiocyanates; D013861:Thiocyanates; C005441:phenylisothiocyanate