Elucidating the odor-active aroma compounds in alcohol-free beer and their contribution to the worty flavor

Alcohol-free beers (AFB) brewed by cold-contact fermentation exhibit a flavor reminiscent of wort which affects consumer acceptability. The aims of this study were to identify the odor-active compounds in AFB and elucidate the contribution of these to the overall aroma and worty character of the beer. Using a sensomics approach, 27 odor-active aroma compounds were identified and quantitated using GC-MS. The most odor-active compound was methional (boiled potato-like aroma), followed by 3-methylbutanal (cocoa-like), (E)-β-damascenone (apple, jam-like), 5-ethyl-3-hydroxy-4-methyl-2(5H)-furanone (curry, spicy-like), and phenylacetaldehyde (floral, honey-like). The important contribution of these flavor compounds to the worty and honey aroma of AFB was determined by sensory assessment of the recombinate in a beer-like matrix with omission tests. The role of 5-ethyl-3-hydroxy-4-methyl-2(5H)-furanone in AFB aroma was reported for the first time. The outcomes from this study are of relevance for the brewing industry to design strategies for the reduction of the wortiness of AFB

Impact of Labeled Glasses in a Bar Laboratory Setting: No Effect on Ad Libitum Alcohol Consumption.

AIMS: Information provided on glass labels may be an effective method to reduce alcohol consumption. The aim of this study was to assess the impact of glass labels conveying unit information and a health warning in reducing ad libitum alcohol consumption. METHODS: A cluster-randomized experimental study was conducted to measure the efficacy of a labeled glass in reducing alcohol consumption in a semi naturalistic bar laboratory setting, in a sample of 81 pairs (n = 162) of UK young adult drinkers. Pairs were randomized to receive two 340-ml glasses of beer or wine: labeled or plain (control). Alcohol consumption was assessed in an ad libitum drinking period, and urge to drink was measured at baseline and postdrinking period. Focus groups (n = 2) were conducted, and thematic analysis was used to gain an insight into the acceptability and the perceived effectiveness of the glasses. RESULTS: Mean unit consumption was 1.62 (SD ± 0.83) units in the labeled glass condition and 1.69 (SD ± 0.82) units in the non labeled glass condition. There were no significant effects of the labeled glasses on ad libitum alcohol consumption (95% CI -0.25 to 0.37, p = 0.35), despite participants (85%) noticing the information. Qualitative analysis of focus groups indicated that although participants perceived the glasses as a useful tool for increasing awareness of units and guidelines, they were viewed as limited in their potential to change drinking behavior due to the unappealing design of the glass and a view that unit guidelines were not relevant to drinking patterns or contexts. CONCLUSIONS: Labeled glasses did not change alcohol consumption in the current study, potentially due to ineffectiveness of this type of message in a young adult population. The information on the glasses was attended to, highlighting that glasses could be a feasible tool for providing information

Brewers' spent grains: Drying kinetics and biodiesel production

Enormous amounts of brewers' spent grains (BSGs) per year are generated to produce bear worldwide. BSGs can be used as a carbon source, biofuel to generate energy and as a source of biogas. Typically, BSGs contain >60 mass% of water and, therefore, drying kinetics is a paramount for the development of any of these valorisation processes. In this work, we reveal the main parameters and mechanism of drying kinetics of BSGs at isothermal conditions (60 °C–90 °C), measured by thermogravimetric analysis. Diffusion coefficients ranged from 1.42 × 10−9 m2 s−1 to 2.67 × 10−9 m2 s−1 while the activation energy was 26.6 kJ mol−1. Furthermore, for the first time, biodiesel production from BSGs is reported. We employed acid catalysed in situ transesterification process, at different catalyst concentrations, methanol to BSGs ratios, reaction time and temperature. The outcomes of our study show promise for alternative valorisation of brewers' spent grains, an abundant waste spread around the world