AUTHOR=Tsapou Evangelia A. , Ntourtoglou George , Drosou Fotini , Tataridis Panagiotis , Dourtoglou Thalia , Lalas Stavros , Dourtoglou Vassilis 

TITLE=In situ Creation of the Natural Phenolic Aromas of Beer: A Pulsed Electric Field Applied to Wort-Enriched Flax Seeds

JOURNAL=Frontiers in Bioengineering and Biotechnology

VOLUME=8

YEAR=2020

URL=https://www.frontiersin.org/journals/bioengineering-and-biotechnology/articles/10.3389/fbioe.2020.583617

DOI=10.3389/fbioe.2020.583617

ISSN=2296-4185

ABSTRACT=<p>To fine tune the production of phenolic aromas in beer, a pulsed electric field (PEF) was applied to beer wort, which was enriched with flax seeds. The choice of flax seeds as a source of FA is based on its high content of ferulic precursors and their intrinsic nutritional value. PEF was applied to ground flax seeds, with and without beta glycosidase. Fermentation was carried out with <italic>Saccharomyces</italic> and non-<italic>Saccharomyces</italic> yeast strains. Moreover, 4-vinylguaiacol (4-VG), a flavor highly active derived from volatile phenol, was produced by decarboxylation of ferulic acid (FA), or its precursor and flavor-inactive (4-hydroxy-3-methoxycinnamic acid). All yeast strains could metabolize FA into 4-VG, using the pure compound in the synthetic medium or in flax seeds, with the best quantity produced by <italic>Saccharomyces cerevisiae</italic> as a precursor. The method yields 4-VG production efficiencies up to 120% (mgL<sup>−1</sup>). Experimental treatment conditions were conducted with E= 1 kV/cm, total time treatment 15 min (peak time t<sub>i</sub> = 1 μs, pause time t<sub>p</sub> = 1 ms, Total pulses 900<sup>3</sup>). Treatment efficacy is independent of the fermentation yeast.</p>