Quantitative determination of pumpkin seed amino acids by gas-liquid chromatography

The objectives of this study were to determine whether pumpkin seed (Cucurbita pepo var. Lady Godiva) grown in Tennessee differs in amino acid composition from that grown in Minnesota and to develop a simple, quick and inexpensive routine laboratory technique for the quantitation of amino acids.

Defatted pumpkin seed was hydrolyzed with 6N HC1 at 145° C for 4 h. Ion exchange was carried out for the clean-up of the amino acids. Prepurified amino acids were derivatized, first by esterification with isobutanol-3N HC1 at 120° C for 30 minutes and then acylation with heptafluorobutyric anhydride at 150° C for 10 minutes. Mixtures were quantitated by gas-liquid chromatography through a column packed with 3% SE 30 on 100-120 mesh Chromosorb W, HP using pipecolinic acid as the internal standard.

Data gathered in this study indicated that the percentage of five amino acids, glutamic acid, aspartic acid, glycine, lysine and proline, was higher than literature values. The other amino acids were lower in concentration.