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

Abstract

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 Saccharomyces and non-Saccharomyces 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 Saccharomyces cerevisiae as a precursor. The method yields 4-VG production efficiencies up to 120% (mgL −1). Experimental treatment conditions were conducted with E= 1 kV/cm, total time treatment 15 min (peak time t i = 1 µs, pause time t p = 1 ms, Total pulses 900 3). Treatment efficacy is independent of the fermentation yeast.

Evaluation of Pulsed Electric Field Polyphenol Extraction from Vitis vinifera, Sideritis scardica and Crocus sativus

“…PEF of 7 kV/cm proved to be effective, using water as extraction medium for a total extraction time of 40 min. Ntourtoglou et al (2020) [28] also reached a 20% increase in the extraction rate of the alpha acids of bitter hop using a pulsed electric field of 1.15 to 2.5 kV/cm as the primary extraction method, while Tsapou et al (2020) [29] achieved phenolic flavor enhancement in beer with a production efficiency in 4-vinylguaiacol (target compound) up to 120% (mg L −1 ) by applying PEF extraction of 1 kV/cm during a 15 min treatment.…”

Enhancement of Polyphenols Recovery from Rosa canina, Calendula officinalis and Castanea sativa Using Pulsed Electric Field

“…Ntourtoglou et al [51] achieved an increase of 20% in the extraction rate of the alpha acids of bitter hop using PEF. Tsapou et al [52] applied a Pulsed Electric Field (PEF) to beer wort, enriched with flax seeds, to reach phenolic flavor enhancement in beer, succeeding in 4-vinylguaiacol (target compound) production efficiency up to 120% (mg L −1 ). Finally, Lakka et al [41] successfully extracted polyphenols from the aerial parts of Sideritis scardica, tepals of Crocus sativus, and fruits of Vitis vinifera using a PEF of 1.2-1.4 kV cm −1 .…”

Pulsed electric field: A “green” extraction technology for biomolecular products from glycerol with fermentation of non-Saccharomyces yeasts

“…Pulsed electric field (PEF) is a technique that has been usedfor extractions due to its capability to cause disorganization of plant or microbial cells by disrupting membranes and releasing cell metabolites from the inner to outer part of the cell ( Tsapou et al, 2020 ). The disruption of the cell membrane due to electroporation is caused by high intensity PEF and leads to complex phenomena ranging from cell restructuring to cell death ( Delsart et al, 2012 ; Ntourtoglou et al, 2020 ).…”

“…Electro-permeabilization of cells must be irreversible to cause inactivation of microorganisms. Electroporation was previously used as nonthermal treatment of liquid foods to inactivate microorganisms ( Alvarez et al, 2003 ; Ntourtoglou et al, 2020 ; Tsapou et al, 2020 ).…”