Alcohol-free and low-alcohol beers: aroma chemistry and sensory characteristics

Alcohol-free beers have gained popularity in the last few decades because they provide a healthier alternative to alcoholic beers and can be more widely consumed. Consumers are becoming more aware of the benefits of reducing their alcohol consumption, and this has increased the sales of non-alcoholic alternatives. However, there are still many challenges for the brewing industry to produce an alcohol-free beer that resembles the pleasant fruity flavor and overall sensory experience of regular beers. The aim of this review is to give a comprehensive overview of alcohol-free beer focusing on aroma chemistry. The formation of the most important aroma compounds, such as Strecker aldehydes, higher alcohols and esters, is reviewed, aiming to outline the gaps in current knowledge. The role of ethanol as a direct and indirect flavor-active compound is examined separately. In parallel, the influence of the most common methods to reduce alcohol content, such as physical (dealcoholization) or biological, on the organoleptic characteristics and consumer perception of the final product, is discussed

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

Orthonasal and retronasal detection thresholds of 26 aroma compounds in a model alcohol-free beer: effect of threshold calculation method

Detection thresholds are used routinely to determine the odour-active compounds in foods. The composition of a food matrix, such as hydrophobicity or solids content, has an impact on the release of flavour compounds, and thus on thresholds. In the case of beer, thresholds determined in alcoholic beer may not be the same for alcohol-free beer (AFB). Therefore, the aim of this study was to determine detection thresholds for aroma compounds typically found in beer within a model AFB. The model was designed to match the sugar concentration and pH of an AFB brewed by a cold contact process. Thresholds were measured using a 3-AFC procedure and calculated using either Best Estimate Threshold (BET) method or by logistic regression. Moreover, an algorithm for the removal of false positives was applied to adjust the assessors’ raw responses. Retronasal thresholds were generally lower than orthonasal. Those calculated by BET were significantly higher (p < 0.05) than those from logistic regression, and removal of false positives also produced significantly higher thresholds than those from raw data. The use of logistic regression has the advantage of providing the mathematical model describing the behaviour of the group. The results from this study can be used to better understand the role of flavour compounds in AFB and the effect of the calculation method to prevent under- or overestimated results

Sensory character on relation to composition of Greek red wines

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Quantification of odour active compounds and calculation of their orthonasal and retronasal detection thresholds in alcohol-free beer

International audienceThe low alcohol content in alcohol-free beers (AFB), i.e. below 0.05% v/v ethanol in EU countries, is not the only difference when compared to Lager beers. The pleasant fruity flavour of these beers is one of the most appreciated features, whereas AFBs brewed by cold contact fermentation (CCF) process exhibit a flavour reminiscent of wort and high amount of non-fermented sugars. These differences could alter the release properties of an AFB compared to alcoholic beers, thus affecting their perception threshold. In a previous part of this study, 24 odour regions were identified in SAFE and HS-SPME extracts. Thus, the aim of this study was to determine orthonasal and retronasal detection thresholds of these compounds in a model AFB-CCF and obtain their odour activity values (OAV) in a reference AFB-CCF. The model AFB-CCF was composed of a mixture of mono-, di-, and trisaccharides in carbonated water. Six concentrations of each compound in ascending order were sniffed and tasted by 12 or 24 panellists. The thresholds were calculated by either the standard BET method or logistic regression, and an algorithm for the removal of false positives was also utilised. The results showed significant differences between detection thresholds calculated by using the different methods, thresholds from BET method being always higher than those from logistic regression. The removal of false positives increased the threshold values as well as improved the goodness of fit of the data to the logistic function. Thresholds calculated by logistic regression with the false positives removed were used for the calculation of OAVs. Once the 24 aroma compounds were quantified by a range of analytical techniques, the OAVs showed that the most odour active compound was methional (concentration=85 μg/L, orthonasal detection threshold=0.47 μg/L, OAV=181), followed by 3-methylbutanal (38 μg/L, 0.61 μg/L, 62), phenylacetaldehyde (160 μg/L, 5.4 μg/L, 30), acetaldehyde (1,200 μg/L, 46 μg/L, 26), 2-phenylethanol (20,700 μg/L, 1,880 μg/L, 11), methylpropanal (24 μg/L, 4.3 μg/L, 5.6), and Z-4-heptenal (0.063 μg/L, 0.016 μg/L, 3.9). For the first time, the contribution of flavour compounds to the overall aroma of AFB-CCF has been decoded. The outcomes from this study may be of great relevance for the brewing industry for the reduction of the wortiness of AFBs

Quantification of odour active compounds and calculation of their orthonasal and retronasal detection thresholds in alcohol-free beer

International audienceThe low alcohol content in alcohol-free beers (AFB), i.e. below 0.05% v/v ethanol in EU countries, is not the only difference when compared to Lager beers. The pleasant fruity flavour of these beers is one of the most appreciated features, whereas AFBs brewed by cold contact fermentation (CCF) process exhibit a flavour reminiscent of wort and high amount of non-fermented sugars. These differences could alter the release properties of an AFB compared to alcoholic beers, thus affecting their perception threshold. In a previous part of this study, 24 odour regions were identified in SAFE and HS-SPME extracts. Thus, the aim of this study was to determine orthonasal and retronasal detection thresholds of these compounds in a model AFB-CCF and obtain their odour activity values (OAV) in a reference AFB-CCF. The model AFB-CCF was composed of a mixture of mono-, di-, and trisaccharides in carbonated water. Six concentrations of each compound in ascending order were sniffed and tasted by 12 or 24 panellists. The thresholds were calculated by either the standard BET method or logistic regression, and an algorithm for the removal of false positives was also utilised. The results showed significant differences between detection thresholds calculated by using the different methods, thresholds from BET method being always higher than those from logistic regression. The removal of false positives increased the threshold values as well as improved the goodness of fit of the data to the logistic function. Thresholds calculated by logistic regression with the false positives removed were used for the calculation of OAVs. Once the 24 aroma compounds were quantified by a range of analytical techniques, the OAVs showed that the most odour active compound was methional (concentration=85 μg/L, orthonasal detection threshold=0.47 μg/L, OAV=181), followed by 3-methylbutanal (38 μg/L, 0.61 μg/L, 62), phenylacetaldehyde (160 μg/L, 5.4 μg/L, 30), acetaldehyde (1,200 μg/L, 46 μg/L, 26), 2-phenylethanol (20,700 μg/L, 1,880 μg/L, 11), methylpropanal (24 μg/L, 4.3 μg/L, 5.6), and Z-4-heptenal (0.063 μg/L, 0.016 μg/L, 3.9). For the first time, the contribution of flavour compounds to the overall aroma of AFB-CCF has been decoded. The outcomes from this study may be of great relevance for the brewing industry for the reduction of the wortiness of AFBs

Characterisation of the key aroma compounds in alcohol free beer base by aroma extract dilution analysis

International audienceThe pleasant fruity flavour of lager beers is one of the most appreciated fea-tures of these beverages, whereas alcohol-free beers (AFB) also exhibit a flavour reminiscent of wort. Even though several studies have been carried out to charac-terise the key odorants in different alcoholic beers, there are no similar works for AFB. Hence, the aim of this research is to identify the compounds contributing to the characteristic aroma of AFB. In this work, the volatile fraction of an AFB-base (without added flavourings) was isolated using solvent assisted flavour evapora-tion (SAFE) and analysed by GC-MS and GC-Olfactometry. Twenty-three odour regions showed odour activity in GC-O experiments, amongst which the most po-tent were methional, phenylacetaldehyde, 2-methoxyphenol, β-damascenone, 2-phenylacetic acid, 2-phenylethanol, and 5-ethyl-3-hydroxy-4-methyl-2(5H)-furanone. The presence of these compounds plays a crucial role in AFB aroma

Characterisation of the key aroma compounds in alcohol free beer base by aroma extract dilution analysis

International audienceThe pleasant fruity flavour of lager beers is one of the most appreciated fea-tures of these beverages, whereas alcohol-free beers (AFB) also exhibit a flavour reminiscent of wort. Even though several studies have been carried out to charac-terise the key odorants in different alcoholic beers, there are no similar works for AFB. Hence, the aim of this research is to identify the compounds contributing to the characteristic aroma of AFB. In this work, the volatile fraction of an AFB-base (without added flavourings) was isolated using solvent assisted flavour evapora-tion (SAFE) and analysed by GC-MS and GC-Olfactometry. Twenty-three odour regions showed odour activity in GC-O experiments, amongst which the most po-tent were methional, phenylacetaldehyde, 2-methoxyphenol, β-damascenone, 2-phenylacetic acid, 2-phenylethanol, and 5-ethyl-3-hydroxy-4-methyl-2(5H)-furanone. The presence of these compounds plays a crucial role in AFB aroma

Multi-response kinetic modelling of the formation of five Strecker aldehydes during kilning of barley malt

International audienceStrecker aldehydes are responsible for the characteristic aroma of malts, but also important aroma compounds in beer. In malt, they are formed during the curing stage of kilning. The formation of five Strecker aldehydes (2-methylpropanal, 2-methylbutanal, 3-methybutanal, phenylacetaldehyde and methional) during this process was studied at pilot scale. Green malts were dried and cured at different temperatures (65, 78 and 90 °C) isothermally for 8.4 h. Multi-response kinetic modelling was used to develop a mathematical model based on precursors concentration, Amadori rearrangement products (ARP), Strecker aldehydes, temperature and time. This model demonstrated that the formation of Strecker aldehydes in malt was controlled from the formation of two intermediates: ARP and short chain dicarbonyls (SCDC). The kinetic model proposed in this study will help maltsters and researchers understand and manipulate the formation of these compounds in malt and the organoleptic quality of the beers brewed from them

Efecto del método de cálculo y de la presencia de falsos positivos en los umbrales de percepción

International audienceEl objetivo de este trabajo ha sido demostrar que, a la hora de calcular umbrales de percepción, el método de cálculo elegido y las respuestas que son falso positivo (es decir, aquéllas en las que la respuesta positiva no corresponde a la detección real del aroma sino al azar al elegir la respuesta), tienen un efecto significativo sobre el valor de umbral calculado