Determination of Gamma-aminobutyric Acid (GABA) Content in Grains and Cruciferous Vegetable Seeds

Gamma aminobutyric acid (GABA) has great physiological functions, mainly as a major inhibitory neurotransmitter in the brain, which makes it important for the development of functional foods. This study detected GABA in grains and cruciferous vegetable seeds by using HPLC after pre-column on-line derivatization with diode array detection (DAD) and fluorescence detection (FLD). The limit of quantitation was 2.94 and 2.86 µg/mL with DAD and FLD, respectively. GABA recoveries ranged from 98.8 to 111.2% on both detectors. Intra and inter-day precision showed relative standard deviations, generally, less than 10% for both DAD and FLD. GABA was determined in different grains (flaxseeds, white quinoa seeds, and buckwheat) and cruciferous vegetable seeds (broccoli, kale, daikon radish, mustard, cabbage, and brussels sprouts). Organic broccoli seeds contained the highest amount and mustard seeds the least amount of GABA in the Brassica family with none being detected in organic white quinoa and flaxseeds. A statistically significant difference (p < 0.05) exists between the various lots of the broccoli seeds. GABA is important as a natural source in functional foods.