In situ production of γ-aminobutyric acid in breakfast cereals

Breakfast cereals are an important part of an equilibrated diet in the Western world, making them extremely suited for carrying health benefits. Intake of γ-aminobutyric acid (GABA), a major inhibitory neurotransmitter of the nervous system, has been related to blood pressure lowering in hypertensive individuals. In vivo, GABA is formed from glutamic acid (GA) by glutamic acid decarboxylase (GAD), a widely distributed enzyme in prokaryotic and eukaryotic species. We here enriched breakfast cereals with GABA by recipe and process optimisation. The dynamics of GA and GABA were monitored throughout the production process. Addition of exogenous recombinantly produced GAD of Yersinia intermedia increased GABA levels by 2- to 5-fold. As only trace levels of GABA (<15 ppm) and relatively low levels of its precursor (GA, <100 ppm) are present in the wheat and rice flour used, a well-thought ingredient choice (inclusion of quinoa flour (ca. 90 ppm GABA and 700 ppm GA) or bran enrichment (ca. 66 ppm GABA and 500 ppm GA)) also significantly increases the GABA content in the final flakes. Finally, a strict control of the heating steps during the production process reduces GA and GABA losses. Consumption of one portion (30 g) of the here produced enriched breakfast cereals can even meet up to 55% of the daily intake earlier reported to lower blood pressure (ca. 10 mg).