The purpose of this study was to determine protein amino acid contents of some Korean foods by gas-liquid chromatography, and to evaluate this technique as a procedure for the quantitative determination of amino acids in foods. The crude protein content of foods was also estimated from the nitrogen content.
1. Nitrogen content of each food sample was determined previously to adjust the amount of sample for GLC analysis
2. In the analysis of 17 known amino acids, a linear relationship was found between the weight of 13 amino acids of 17 amino acids, the internal standard as well as the injection volume of a mixture and the detector responses for the derivatives of the amino acids. No response for arginine, cystein, histidine, and tyrosine was observed.
3. The relative molar response (RMR) values for the 13 amino acids of standard solution relative to glutamic acid as $quot;1.00$quot; were obtained under normal operating conditions with a hydrogen flame ionization detector.
4. The recovery of amino acids from their mixtures with natural food materials was carried out. The recoveries were essentially quantitative except threonine and serine. An overall mean recovery of 11 amino acids was 101.4±8.4 per cent before hydrolysis and 98.1±8.7 per cent after hydrolysis of samples.
5. The comparative analysis of the acid hydrolysates of two food samples by gas-liquid and ion-exchange chromatographic analysis were carried out. In white-bait pemmican, only threonine and asparagine amounts by GLC analysis had similar values to those obtained by ion-exchange chromatography. The other seven amino acids gave higher values as measured by GLC than by ion-exchange. With the food sample, soybean, alanine, valine, asparagine, and glutamic acid were in good agreement in two analysis, while leucine, proline, threonine, phenylalanine, and lysine were found in slightly higher concentrations in the GLC analysis.
6. Grant variations of amino acid content were found among samples analyzed. The amino acid contents of each sample were compared with the values found in the literature.
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