Comparison of odorants in beef and chicken broth – focus on thiazoles and thiazolines

The shift in consumer landscape towards vegan, vegetarian and flexitarian diets has created an unprecedented challenge in creating meat aroma from plant-based alternatives. The search for potential vegan solutions has thus led to a renewed interest in authentic meat flavour profiles. To gain a better understanding of the qualitative odour differences between boiled beef and boiled chicken, aroma extracts were isolated using Likens-Nickerson simultaneous distillation-extraction (SDE), selected expressly because the in-situ heating of the sample facilitates the cap-ture of aroma intermediates during the cooking process, thereby mimicking the cooking of meat in stocks and stews. The extracts were then analysed by Gas Chromatography-Mass Spectrome-try (GC-MS) and GC-Olfactometry (GC-O). Most of the volatiles identified in this study were sul-fur-containing compounds, such as sulfides, thiols, mercaptoaldehydes and mercaptoketones, which are derived from the Maillard reaction. Meanwhile, lipid oxidation results in the for-mation of unsaturated aldehydes, such as alkenals and alkadienals. Families of thiazoles and 3-thiazolines were found in the extracts. Two novel 3-thiazolines (5-ethyl-2,4-dimethyl-3-thiazoline and 2-ethyl-4,5-dimethyl-3-thiazoline) which may also contribute to the meaty aroma were identified in this work and synthesised from their respective aldehyde and mercapto-ketone precursors

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

Modelling the generation of flavour in meat like systems

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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

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

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

Kinetic model for the formation of acrylamide during the finish-frying of commercial French fries

Acrylamide is formed from reducing sugars and asparagine during the preparation of French fries. The commercial preparation of French fries is a multistage process involving the preparation of frozen, par-fried potato strips for distribution to catering outlets, where they are finish-fried. The initial blanching, treatment in glucose solution, and par-frying steps are crucial because they determine the levels of precursors present at the beginning of the finish-frying process. To minimize the quantities of acrylamide in cooked fries, it is important to understand the impact of each stage on the formation of acrylamide. Acrylamide, amino acids, sugars, moisture, fat, and color were monitored at time intervals during the frying of potato strips that had been dipped in various concentrations of glucose and fructose during a typical pretreatment. A mathematical model based on the fundamental chemical reaction pathways of the finish-frying was developed, incorporating moisture and temperature gradients in the fries. This showed the contribution of both glucose and fructose to the generation of acrylamide and accurately predicted the acrylamide content of the final fries