A review of methods of low alcohol and alcohol-free beer production

Exploring the flavor life cycle of beers with varying alcohol content

Decreasing alcohol in beer and increasing the pleasure of lower alcohol beers is a potential way to limit total alcohol consumption. Consumers’ willingness to drink alcohol‐reduced beers is mainly limited by unfavorable flavor characteristics that arise during consumption. To investigate the temporal flavor dominance during consumption, we analyzed the five most dominant beer flavors from nine different beers among three types of beer with varying alcohol content to assess the Flavor Life Cycle. Results show that beers with different alcohol content displayed similar flavor dominance (e.g., bitterness) and displayed differences in worty‐off flavor, malty flavor, and astringency. In alcohol‐free beers, worty‐off flavor was most pronounced in dominating between 5 and 30 s and malty flavor increased after swallowing. For bitterness and astringency, higher alcohol content resulted in higher flavor dominance, especially prior to swallowing (≤40 sec). Based on these findings, we provide some brief advice to minimize unfavorable flavor experience during consumption of beer with lower alcohol. For now, consumers who want to enjoy beers with lower alcohol should consider flavor changes and focus on the favored and defocus on the less favored flavors.

Aroma Characterization and Safety Assessment of a Beverage Fermented by Trametes versicolor

A cereal-based beverage was developed by fermentation of wort with the basidiomycete Trametes versicolor. The beverage possessed a fruity, fresh, and slightly floral aroma. The volatiles of the beverage were isolated by liquid-liquid extraction (LLE) and additionally by headspace solid phase microextraction (HS-SPME). The aroma compounds were analyzed by a gas chromatography system equipped with a tandem mass spectrometer and an olfactory detection port (GC-MS/MS-O) followed by aroma (extract) dilution analysis. Thirty-four different odor impressions were perceived, and 27 corresponding compounds were identified. Fifteen key odorants with flavor dilution (FD) factors ranging from 8 to 128 were quantitated, and their respective odor activity values (OAVs) were calculated. Six key odorants were synthesized de novo by T. versicolor. Furthermore, quantitative changes during the fermentation process were analyzed. To prepare for the market introduction of the beverage, a comprehensive safety assessment was performed.

Mass spectrometry-based metabolomics approach to determine differential metabolites between regular and non-alcohol beers

Non-alcohol beers show taste deficiencies in relation to regular (alcohol) beers as shown by consumer evaluation. In this study, multivariate statistical analysis of data obtained by ultra-performance liquid chromatography-mass spectrometry (UPLC-MS) measurements was applied to determining differential metabolites between two regular (R1 and R2) and their related low- and non-alcohol beers (F1 and F2, respectively) from a Spanish manufacturer, as well as between F1 and F2 and two non-alcohol beers (F3 and F4) from a non-Spanish producer. Principal component analysis (PCA) of data from UPLC-MS measurements with electrospray ionization in negative mode was able to separate the six beers. Sugar content was 6-fold and 2-fold higher in F2 and F1 than in R2 and R1, respectively. Isoxanthohumol and hop acid contents decreased in F2 as compared with R2 but kept in F1 similar to R1. Results are discussed in relation to valued taste characteristics of each beer type.

Yeast: the soul of beer's aroma--a review of flavour-active esters and higher alcohols produced by the brewing yeast

Among the most important factors influencing beer quality is the presence of well-adjusted amounts of higher alcohols and esters. Thus, a heavy body of literature focuses on these substances and on the parameters influencing their production by the brewing yeast. Additionally, the complex metabolic pathways involved in their synthesis require special attention. More than a century of data, mainly in genetic and proteomic fields, has built up enough information to describe in detail each step in the pathway for the synthesis of higher alcohols and their esters, but there is still place for more. Higher alcohols are formed either by anabolism or catabolism (Ehrlich pathway) of amino acids. Esters are formed by enzymatic condensation of organic acids and alcohols. The current paper reviews the up-to-date knowledge in the pathways involving the synthesis of higher alcohols and esters by brewing yeasts. Fermentation parameters affecting yeast response during biosynthesis of these aromatic substances are also fully reviewed.

Physiological tests for yeast brewery cells immobilized on modified chamotte carrier

In this study yeast cell physiological activity was assessed on the basis of the in situ activity of two important enzymes, succinate dehydrogenase and pyruvate decarboxylase. FUN1 dye bioconversion and cellular ATP content were also taken as important indicators of yeast cell activity. The study was conducted on six brewing yeast strains, which were either free cells or immobilized on a chamotte carrier. The experimental data obtained indicate clearly that, in most cases, the immobilized cells showed lower enzyme activity than free cells from analogous cultures. Pyruvate decarboxylase activity in immobilized cells was higher than in planktonic cell populations only in the case of the Saccharomyces pastorianus 680 strain. However, in a comparative assessment of the fermentation process, conducted with the use of free and immobilized cells, much more favorable dynamics and carbon dioxide productivity were observed in immobilized cells, especially in the case of brewing lager yeast strains. This may explain the higher total cell density per volume unit of the fermented medium and the improved resistance of immobilized cells to environmental changes.