Precolumn Phenylisothiocyanate Derivatization and Liquid Chromatography of Amino Acids in Food

Abstract

A precolumn phenylisothiocyanate derivatization method is described for the determination of amino acids in protein hydrolysates from a wide variety of complex food matrixes, with and without performic acid oxidation pretreatment. Analysis of samples that were not pretreated with performic acid was necessary since this pretreatment destroyed an average of 25% of the histidine and 87% of the tyrosine present in the food samples. This method is rapid and reproducible; coefficients of variation between duplicate analyses of the same food item were less than 5% for a majority of the amino acids. Occasionally, variation between duplicate analyses for histidine and tyrosine was greater than 10%. Recoveries of amino acids added to samples were in the 100% range.

Attractability and palatability of liquid protein hydrolysates for Nile tilapia juveniles

“…The amino acid composition of both protein hydrolysates was performed according to the method MA-009 (Hagen, Frost, & Augustin, 1989;White, Hart, & Fry, 1986) in a commercial laboratory (CBO Análises Laboratoriais Ltda. ; Table 3).…”

HPLC Method for Cyst(e)ine and Methionine in Infant Formulas

“…Method (oxidation+hydrolysis+derivatization). The method we used to check the accuracy of hydrolysis and oxidation was similar to that of Hagen et al (1989). The content of amino acids in a protein, ␤-casein (representative of the matrix studied) was measured in triplicate.…”

“…Although HPLC has been used in the study of amino acids, a review of published studies revealed that most of them have focused on the application of hydrolysis and previous treatment to protect CYS and MET in foods such as fish meal, maize corn meal, mixed feed, soybean meal, meat meal, whey powder, egg white and beef, etc.) (Sarwar et al, 1983;Elkin, 1984;Spindler et al, 1984;Gehrke et al, 1985;MacDonald et al, 1985;Elkin and Wasynczuk, 1987;Iwaki et al, 1987;Hagen et al, 1989;Cubedo Fernández-Trapiella, 1990;Van Der Meer, 1990) or pure proteins such as casein, ␤-lactoglobulin, lysozyme, etc.) (Sarwar et al, 1983;Bidlingmeyer et al, 1984;Cohen et al, 1984Cohen et al, , 1986Gehrke et al, 1985;MacDonald et al, 1985;Hagen et al, 1989).…”

“…(Sarwar et al, 1983;Elkin, 1984;Spindler et al, 1984;Gehrke et al, 1985;MacDonald et al, 1985;Elkin and Wasynczuk, 1987;Iwaki et al, 1987;Hagen et al, 1989;Cubedo Fernández-Trapiella, 1990;Van Der Meer, 1990) or pure proteins such as casein, ␤-lactoglobulin, lysozyme, etc.) (Sarwar et al, 1983;Bidlingmeyer et al, 1984;Cohen et al, 1984Cohen et al, , 1986Gehrke et al, 1985;MacDonald et al, 1985;Hagen et al, 1989). Very few studies have been reported on milk (Hanning et al, 1992) and infant formula (Sarwar et al, 1988(Sarwar et al, , 1989Astephen and Wheat, 1993).…”

“…Since automatic systems previously described Cohen et al, 1984;Elkin and Wasynczuk, 1987;Hagen et al, 1989) for this kind of determination (the Waters PicoTag), were not available the usefulness and efficiency of a manual system of evaporation, allowing simultaneous treatment of 12 samples, was evaluated.…”