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

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.

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

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 ti = 1 µs, pause time tp = 1 ms, Total pulses 9003). Treatment efficacy is independent of the fermentation yeast.

Addition of yogurt to wort for the production of spirits: Evaluation of the spirit aroma over a two-year period.

Triggered by the development of lactic acid bacteria (LAB) during the production of Scotch whisky, this study examined the influence of yeast and LAB inoculation on whisky flavor. Four new spirits were produced using the same process. LAB were added as a form of a Greek yogurt's live culture. In each category (barley and rye), one sample was fermented with Greek yogurt while the other was fermented without it. The spirits were matured and analyzed at five different points. Results from gas chromatography-mass spectrometry (GC-MS) analysis showed basic volatile compounds, along with some important extra compounds with yogurt culture. The most obvious differences were observed in the concentration of butanoic acid, a characteristic acid in spirits undergoing lactic acid fermentation: to identify esters such as ethyl butanoate, ethyl isobutanoate, isoamyl butanoate, and 2-phenylethyl butanoate, they are not typical compounds in whisky.