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 900³). Treatment efficacy is independent of the fermentation yeast.

Greek grape marc spirits, although being traditional products, have lately attracted increasing attention as a revisited spirit product category. A headspace solid-phase microextraction coupled to the gas chromatography-mass spectrometry method was optimized in order to determine the volatile composition of 39 samples of grape marc spirits from eight major geographical regions of Greece and 4 protected designations of origin (PDOs). This untargeted analysis approach yielded the identification and quantification of 200 volatiles characterizing those products. Principal component analysis and partial least-squares-discriminant analysis (PLS-DA) combined with the volatile matrix were further employed to identify terroir denomination. Initial results showed a clear separation of the PDO products from Tyrnavos from the rest. Variable importance in projection data pretreatment was further adopted, and with 31 volatiles subsequently used with PLS-DA, products were correctly classified according to region of origin at 76.92% and for 3 out of 4 PDO denominations at 100%.

Glycerol is the main organic by-product of the biodiesel industry and it can be a source of carbon for fermentations or a substrate for biotransformations. This work investigates a process that uses pulsed electric field (PEF) to enhance polyol and propanediols extraction from a glycerol/glucose fermentation broth. Three different commercial, non-Saccharomyces strains, Torulaspora delbrueckii Prelude (Hansen), Torulaspora delbrueckii Biodiva 291 (Lallemand) and Metschnikowia pulcherrima (Lallemand) were studied. The results revealed that PEF had a positive impact on the extraction of polyols ranging from 12 to 191%, independently of fermentation conditions. Torulaspora delbrueckii Biodiva 291 (Lallemand) was found to be more efficient at pH 7.1. An optimized chromatography-based method for the qualitative and quantitative determination of the formed products evaluated. The experiments were carried out either in flasks or in a bioreactor.