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Kinetics of free protein amino acids, free non-protein amino acids and trigonelline in soybean (Glycine max L.) and lupin (Lupinus angustifolius L.) sprouts

Abstract:

A contribution for a better nutritional knowledge of lupin (Lupinus angustifolius L. var. zapaton) and soybean (Glycine max L. var. merit and var. jutro) sprouts about free protein amino acids (FPAA), free non-protein amino acids (FNPAA such as β-N-oxalyl-l-α,β-diaminopropionic acid (β-ODAP), α-aminoadipic acid, γ-aminobutyric acid (GABA) and β-alanine) and trigonelline content has been carried out. Seeds were germinated at 20 °C and darkness during several days in order to obtain good appearance sprouts. The content of FPAA and FNPAA varied among species and varieties. FPAA increased dramatically during germination and the lowest concentrations were found for G. max L. var. jutro. Cys was not detected as FPAA in seeds and seedlings of both legumes. Asn was present in the highest amounts in soybean and lupin seedlings. The α-aminoadipic acid gliotoxin, which was not present in raw soybean seeds, appeared in low amounts during germination. Later stages of germination caused significant increases of β-alanine and GABA, amino acids with beneficial properties. Germination also affected the content of the multifunctional plant hormone trigonelline and slight changes were observed. Highest levels of FPAA, beneficial FNPAA and trigonelline were found at 4, 6 and 9 days of germination for G. max L. var. jutro, G. max L. var. merit and L. angustifolius L. var. zapaton, respectively. Furthermore, these selected germination conditions showed low levels of the gliotoxic α-aminoadipic acid ensuring nutritional safety of the studied seedlings. © Springer-Verlag 2006.