Dynamics of gamma-aminobutyric acid in wheat flour bread making

作者：Lamberts Lieve^*; Joye Iris J; Belien Tim; Delcour Jan A

来源：Food Chemistry, 2012, 130(4): 896-901.

DOI：10.1016/j.foodchem.2011.08.004

• Bread making
• gamma-Aminobutyric acid
• Glutamic acid decarboxylase
• Wheat flour
• Yeast

The dynamics of the health-improving non-protein amino acid gamma-aminobutyric acid (GABA) during bread making were studied. Wheat flour contains trace levels of GABA (<15 ppm) and ca. 160-175 ppm of its precursor, glutamic acid (GA). During dough mixing, the levels of both GA and GABA largely increased. While wheat flour endogenous glutamic acid decarboxylase (GAD) performs some minor conversion of GA into GABA, yeast is the main contributor to GABA formation. Comparison of amino acid levels of dough samples, without or with yeast, indicated that yeast favours both GA and GABA formation already during mixing. Fermentation decreased both GA and GABA contents, due to amino acid consumption by the yeast, which used more GA than GABA. Proofing and baking resulted in large GABA losses, the latter probably in Maillard browning reactions during baking. Thermal loss of GA was less pronounced than that of GABA. Breads contained only trace levels of GABA and ca. 90-130 ppm of its precursor. Exogenous supplementation of recombinantly produced GAD of Yersinia intermedia decreased GA levels in mixed and fermented dough and increased GABA levels. The highest GAD dosage used resulted in fermented doughs with ca. 300 ppm of GABA, i.e. three times higher than the level present in the reference sample (no GAD added). After baking, a significant GABA level was left in the bread samples (ca. 115 ppm) and GABA-enriched breads were obtained. Addition of sodium glutamate (100-380 ppm) to a bread recipe containing no added GAD clearly indicated that its precursor was not the limiting factor for GABA conversion during bread making since the resulting breads contained no GABA, or only trace levels (ca. 20 ppm).

• 出版日期2012-2-15