Amino Acid, Amino Acid Metabolite, and GABA Content of Three Domestic Tomato Varieties

To determine the nutritional value of domestic tomatoes, the levels of amino acids, amino acid metabolites, and the bioactive compound γ-aminobutyric-acid (GABA) were analyzed in three domestic tomato varieties (Rafito, Momotaro, and Medison). Eighteen free amino acids were found, and total free amino acid content was 3,810.21～4,594.56 mg/100 g (dry weight). L-glutamic acid (L-Glu) was the most abundant amino acid, ranging from 1,866.60 mg/100 g for Momotaro to 2,417.45 mg/100 g for Medison. The next most abundant amino acids were L-glutamine (L-Gln) and L-aspartic acid (L-Asp). The three tomato varieties had a good balance of all the essential amino acids except tryptophan. Total essential amino acid content was 274.26～472.71 mg/100 g (dry weight). The following amino acid metabolites were found: L-carnitine (L-Car), hydroxylysine (Hyl), o-phosphoethanolamine (o-Pea), phosphoserine (p-Ser), β-alanine (β-Ala), N-methyl-histidine (Me-His), ethanolamine (EtNH2),and L-citrulline(L-Cit). Large quantities of GABA were found in all three varieties: 666.95-868.48 mg/100g (dry weight). These results support the use of these tomato varieties as nutritious food materials.