The interest of wood chips in non-alcoholic beer

Details

Supervisors

Collin, Sonia ; Simon, Margaux

Faculty

Faculté des sciences

Degree label

Master [120] en biochimie et biologie moléculaire et cellulaire, à finalité spécialisée: biotechnologie

Abstract

Non-alcoholic beers have many defects, the main ones being the accumulation of "stale odorants", the lack of fermentation products and the lack of antioxidant power mainly due to the lack of ethanol. Indeed, ethanol is a good scavenger of reactive oxygen species (ROS) and hydroxyl radicals (HO°) which prevent early oxidation.The purpose of this master thesis is to improve the antioxidant power and to bring specific aromas to non-alcoholic beers produced in the laboratory using different microorganisms and different types of wood chips. Actually, some non-Saccharomyces microorganisms such as Pichia kluyveri are known to produce large amounts of fermentation esters while producing low amounts of ethanol, which makes them very interesting to produce alcohol-free beers. This yeast was compared to the yeast Saccharomyces cerevisiae var. chevalieri, widely used to produce non-alcoholic beers. On the other hand, the wood contains many polyphenols such as tannins which have great antioxidant power. Wood is also a source of aromas such as vanillin (vanilla), furfural (almonds), eugenol (spices), syringaldehyde (vanilla) or cis and trans oak-lactones (woody taste). The use of chips made it possible to create antioxidant power in the different alcohol-free beers, but their use also generated artefacts in the spectrometric analysis of bitterness because of the many polyphenols they contain. The different wood chips used (oak, acacia, beech, mulberry) showed different flavor profiles. Acidic beers have also been produced using various lactic bacteria (Lactobacillus plantarum, Levilactobacillus brevis, Lactobacillus helveticus) to assess their aromatic profile and to extract the interesting compounds from the different woods by acidolysis. Indeed, NABs do not contain ethanol, which is the main extractor of these compounds. However, for a concentration of 6 g/L of wood chips and maturation time of 45 days, the concentration of most of the extractable compounds from the wood was below their perception threshold, including cis oak-lactone. We therefore tested a concentration of 20 g/L. In our productions with P. kluyveri, we have unfortunately confirmed an excess of phenylacetaldehyde, recently identified as a major aromatic defect in NABLABs. Nevertheless, this yeast made it possible to produce larger quantities of acetate esters compared to Saccharomyces, especially isoamyl acetate whose concentrations exceeded its perception threshold. The bacterium Lactobacillus helveticus also made it possible to obtain higher concentrations of various odorous molecules such as ethyl lactate or γ-nonalactone.

Citations

• APA

Vandescure, A. (2023). The interest of wood chips in non-alcoholic beer. https://dial-mem.test.bib.ucl.ac.be/handle/2078.2/31489