Title: Dynamics of gamma-aminobutyric acid in wheat flour bread making
Authors: Lamberts, Lieve ×
Joye, Iris
Beliën, Tim
Delcour, Jan #
Issue Date: 2012
Publisher: Applied Science Publishers
Series Title: Food Chemistry vol:130 issue:4 pages:896-901
Abstract: The dynamics of the health-improving non-protein amino acid c-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 GABAenriched
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).
ISSN: 0308-8146
Publication status: published
KU Leuven publication type: IT
Appears in Collections:Centre for Food and Microbial Technology
× corresponding author
# (joint) last author

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