ARS | Publication request: FREE AMINO ACID AND CYSTEINE SULFOXIDE COMPOSTION OF 11 GARLIC (ALLIUM SATIVUM L.) CULTIVARS BY GAS CHROMATOGRAPHY WITH FLAME IONIZATION AND MASS SELECTIVE DETECTION

Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 1, 2005
Publication Date: October 19, 2005
Citation: Lee, J., Harnly, J.M. 2005. Free amino acid and cysteine sulfoxide compostion of 11 garlic (allium sativum l.) cultivars by gas chromatography with flame ionization and mass selective detection. Journal of Agricultural and Food Chemistry. 53:9100-9104.

Interpretive Summary: In this study, we examined the free amino acid content of 1 1 cultivars of garlic (Allium sativum). Allium, the chemical compound that gives garlic its distinctive aroma and taste is derived from a non-coded amino acid (an amino acid that is not genetically coded for incorporation into proteins) upon crushing. Both coded and non-coded amino acids were determined in this study. Samples were analyzed using a commercially available kit that allowed rapid extraction and derivatization of the free amino acids for analysis by gas chromatography with flame ionization detection (GC-FID) and gas chromatography with mass spectrometric detection (GC-MS). The total free amino acid content ofthe 11 garlic samples ranged from 1 1 22 to 3 1 06 mg/g (fresh weight); a factor of three. The major free amino acid, in all but one sample, was glutamic acid. Aspartic acid was the highest concentrated amino acid in the odd sample. The alliin concentration varied by a factor of 5 in the 1 1 garlic cultivars. These results establish the variation of coded and non-coded amino acids in garlic and illustrate the utility of this rapid analytical method for the determination of amino acids.

Technical Abstract: Two garlic subspecies (n=11), Allium sativum L. var. opioscorodon (hardneck) and Allium sativum L. var. sativum (softneck), were evaluated for their free amino acid composition. The free amino acid content of garlic samples analyzed ranged from 1122 to 3106. mg/100g of fresh weight (mean 2130.7 + 681.5mg/100g). Hardneck garlic had greater methiin, alliin, and total free amino acids compared to softneck garlic. The major free amino acid present in all but one subspecies was glutamic acid (Mother of Pearl had aspartic acid as the major free amino acid). ‘Music pink garlic (a rocambole hardneck variety) contained the most methiin, alliim. and total free amino acid. The solid phase extraction, alkylchloroformate derivatization, GC-FID, and GC-MS methods used in this study were simple and rapid, allowing 8 free amino acids in garlic to be separated within 10 min.