Non-enzymatic degradation of aliphatic Brassicaceae isothiocyanates during aqueous heat treatment.

Glucosinolate-derived isothiocyanates are valuable for human health as they exert health promoting effects. As thermal food processing could affect their levels in a structure dependent way, the stability and reactivity of 12 Brassicaceae isothiocyanates during aqueous heating at 100 °C and pH 5-8 were investigated. The formation of their corresponding amines and N,N'-dialk(en)yl thioureas was quantified. Further, the potential to form odor active compounds was investigated by HRGC-MS-olfactometry. A strong structure-reactivity relationship was found and shorter side chains and electron withdrawing groups increase the reactivity of isothiocyanates. 3-(Methylsulfonyl)-propyl isothiocyanate was least stable. The main products are the corresponding amines (up to 69% recovery) and formation of N,N'-dialk(en)yl thioureas is only relevant at neutral to basic pH values. Apart from allyl isothiocyanate also 3-(methylthio)propyl isothiocyanate is precursor to many sulfur-containing odor active compounds. Thus, the isothiocyanate-structure affects their levels but also contributes to the flavor of boiled Brassicaceae vegetables.

Acrylamide increases and furanoic compounds decrease in plant-based meat alternatives during pan-frying.

Plant-based meat alternatives are gaining popularity as protein sources. However, pan-frying may lead to the formation of potentially harmful food contaminants. We investigated the formation of acrylamide and furanoic compounds in four different plant-based meat alternatives and two meat burger patties during pan-frying at 160 and 200 °C. The highest acrylamide contents (72. ± 7.7 and 69.2 ± 9.5 µg/kg, respectively) were found in soy flour- and sunflower-protein based patties fried at 200 °C. Unprepared pea and soy protein-based burger patties contained the highest furfural amounts (2832.8 ± 576.2 and 2683.0 ± 868.5 µg/kg, respectively). Furfuryl alcohol content was highest in soy flour-based patties and increased temperature-dependently up to 1120.9 ± 383.4 µg/kg. Based on the tolerable intake calculated by the EFSA Scientific Panel on Contaminants in the Food Chain, these amounts do not pose a health risk. Nevertheless, since plant-based novel food are being increasingly consumed, further investigations into the formation of food contaminants in novel processed foods are warranted.

Heat-Introduced Formation of Acrylamide in Table Olives: Analysis of Acrylamide, Free Asparagine, and 3-Aminopropionamide.

Acrylamide was detected in considerable amounts in black table olives. In this study, besides black, also green and naturally black table olives were investigated for their acrylamide, free asparagine, and 3-aminopropionamide contents before and after heat treatment. Acrylamide amount was 208-773 µg/kg in black table olives and did not change due to heat treatment. In green and naturally black table olives acrylamide was ≤24 µg/kg before heat treatment and rose to 1200 µg/kg afterward. Asparagine content was 0.35-35 mg/kg in all samples before heat treatment and after heat treatment with no considerable change in the range. 3-Aminopropionamide showed amounts of ≤56 µg/kg in the unheated samples and increased up to 131 µg/kg due to heat impact. However, quantified asparagine and 3-aminopropionamide amounts were insufficient in almost all samples to explain the acrylamide quantities formed due to heat treatment based on the formation via the Maillard reaction.

Resilience of Chemistry: An Introduction to the Agricultural and Food Chemistry Technical Program at the 262nd American Chemical Society National Hybrid Meeting & Exposition, Both Online and in Atlanta, Georgia.

This is the third special issue of the Journal of Agricultural and Food Chemistry (JAFC) based on the Agricultural and Food Chemistry Division (AGFD) technical program, at the 262nd American Chemical Society National Meeting. This was the first national meeting held in a hybrid format, both virtually and in-person in Atlanta, Georgia, U.S.A., on August 22-26, 2021. The AGFD proudly hosted 12 symposia, including three award symposia. There were 34 sessions held in total, with 143 oral presentations and 49 poster presentations. This meeting was highly successful in terms of attendance, and technology issues experienced at the previous virtual meetings were successfully resolved.

Flavor of tea (Camellia sinensis): A review on odorants and analytical techniques.

Tea is among the most consumed nonalcoholic beverages worldwide. Understanding tea flavor, in terms of both sensory aspects and chemical properties, is essential for manufacturers and consumers to maintain high quality of tea products and to correctly distinguish acceptable or unacceptable products. This article gives a comprehensive review on the aroma and off-flavor characteristics associated with 184 odorants. Although many efforts have been made toward the characterization of flavor compounds in different types of tea, modern flavor analytical techniques that affect the results of flavor analysis have not been compared and summarized systematically up to now. Thus, the overview mainly provides the instrumental flavor analytical techniques for both aroma and taste of tea (i.e., extraction and enrichment, qualitative, quantitative, and chemometric approaches) as well as descriptive sensory analytical methodologies for tea, which is helpful for tea flavor researchers. Flavor developments of tea evolved toward time-saving, portability, real-time monitoring, and visualization are also prospected to get a deeper insight into the influences of different processing techniques on the formation and changes of flavor compounds, especially desired flavor compounds and off-flavor substances present at (ultra)trace amounts in tea and tea products.

Effect of Wort Boiling on Volatiles Formation and Sensory Properties of Mead.

Mead is an alcoholic beverage based on bee honey, which can be prepared in different variations such as modified honey-water compositions, the addition of spices, and the use of different yeast strains. Moreover, the technological process of mead production such as the step of wort preparation (with or without boiling of wort before fermentation) can be modified. All these factors might have a significant impact on the formation of aroma-active compounds, and therefore, sensory acceptance by consumers. High vacuum distillation, using the so-called solvent assisted flavor evaporation (SAFE) technique, or headspace-solid phase microextraction (HS-SPME) were applied for the isolation of the odorants. A sensory profile was used to monitor the changes in the aroma of the mead samples. Twenty-eight aroma-active compounds were detected during aroma extract dilution analysis (AEDA) based on gas chromatography-olfactometry (GC-O) and were finally identified by gas chromatography-mass spectrometry (GC-MS) using authentic reference compounds, including methyl propanoate, methyl 3-(methylthio)propanoate, and methional, all of them were identified for the first time in mead. Compounds with high flavor dilution (FD) factors were quantitated via stable isotope dilution analysis (SIDA) and revealed ethyl acetate (16.4 mg/L) to be the most abundant volatile compound, increasing to 57 mg/L after wort boiling, followed by ethyl hexanoate (both 1.2 mg/L). Furthermore, key aroma compounds were esters such as ethyl hexanoate, ethyl octanoate, and ethyl 3-methylbutanoate. The sensory panel evaluated ethanolic, honey-like, clove-like, sweet, and fruity notes as the main aroma descriptors of mead. The significant change in sensory evaluation was noted in the sweet odor of the heat-treated mead.

Characterization of Thermally Induced Flavor Compounds from the Glucosinolate Progoitrin in Different Matrices via GC-TOF-MS.

As important flavor precursors, glucosinolates are ubiquitous in the plant family of Brassicaceae. Glucosinolate degradation products are the major volatile flavor compounds of rapeseed oil, accounting for up to 80% of the total volatiles. However, up to now, little attention has been paid to the volatile flavor products of the nonenzymatic thermal degradation of glucosinolates. One of the most important factors that determine the flavor of hot-pressed rapeseed oil is the roasting process, where the thermal degradation of glucosinolates mainly occurs. The thermal degradation behavior and volatile products of progoitrin (the main glucosinolate of rapeseed) in different matrices (phosphate buffer at a pH value of 5.0, 7.0, or 9.0, sea sand, and rapeseed powder) at different temperatures (150-200 °C) and times (0-60 min) were studied using HPLC and GC-TOF-MS. Thereby, the degradation rate of progoitrin decreased in the following order: pH 9.0 > sea sand > rapeseed powder > pH 7.0 > pH 5.0. Further, a higher degradation was observed with increasing temperature and time. Under the applied conditions in this study, 2,4-pentadienenitrile was the major nitrile and thiophenes were the major sulfur-containing volatile compounds formed. Possible formation pathways of main sulfur-containing and nitrogen-containing volatiles were proposed.

Characterization of Key Aroma-Active Compounds in Rough and Moderate Fire Rougui Wuyi Rock Tea (Camellia sinensis) by Sensory-Directed Flavor Analysis and Elucidation of the Influences of Roasting on Aroma.

Rougui Wuyi rock tea (WRT) with the premium aroma is a subcategory of oolong tea. Roasting is a unique process that provides a comprehensive aroma to WRT. The key aroma-active compounds of rough Rougui WRT (RR) and Rougui WRT with moderate fire (RM) were characterized by sensory-directed flavor analysis. A total of 80 aroma-active compounds were identified by gas chromatography-olfactometry-time-of-flight-mass spectrometry (GC-O-TOF-MS) and two-dimensional comprehensive gas chromatography-olfactometry-mass spectrometry (GC × GC-O-MS), and 42 of them revealing high flavor dilution (FD) factors (16-4096) during aroma extract dilution analysis were quantitated. Finally, the aroma recombination and omission experiments confirmed 26 odorants as key aroma-active compounds in Rougui WRT. Roasting enhanced the aroma of roasted, woody, burnt/smoky, and cinnamon-like odor impressions in RM evoked by 2- and 3-methylbutanal, furaneol, 3-methylbutanoic acid, propanoic acid, methional, ß-myrcene, 2-pentylfuran, 5- and 6-methyl-2-ethylpyrazine, and furfural. In contrast, hexanal, linalool, (Z)-3-hexen-1-ol, (Z)-4-heptenal, (E)-2-heptenal, geraniol, pentanal, and ß-nerolidol were responsible for the more intense floral, fruity, and grassy/fresh leaf-like aroma attributes in RR.

Characterization of the Key Odorants Causing the Musty and Fusty/Muddy Sediment Off-Flavors in Olive Oils.

Microbial spoilage of olive fruits is among the most frequent reasons for two types of off-flavors in olive oils, assigned as musty and fusty/muddy sediment. To characterize both off-flavors on a molecular level by means of the sensomics approach, the key aroma compounds in a premium extra virgin olive oil (PreOO1) eliciting the typical sensory properties were compared to those identified in two off-flavor olive oils obtained from the International Olive Council (IOC). A comparative aroma extract dilution analysis (cAEDA) followed by identification experiments revealed 53 odorants in the musty reference olive oil (MusOO1) and 48 odorants in the fusty/muddy sediment one (FusOO1). Odorants, differing in flavor dilution (FD) factors or showing a high FD factor in at least one of the olive oils, were quantitated by stable isotope dilution analysis (SIDA), followed by the calculation of odor activity values (OAVs; ratio of concentration of an odorant to the respective odor threshold in odorless refined sunflower oil). Aroma recombination and omission experiments revealed 13 key aroma compounds in MusOO1 and 12 in FusOO1. To demonstrate the importance of volatile phenols, 10 phenolic smelling odorants were quantitated in further 13 extra virgin olive oils, in 3 musty and in 13 fusty/muddy sediment defective olive oils, and in 8 olive oils with other off-flavors. Both sensory defects could successfully be discriminated from extra virgin olive oils by applying either a principal component analysis or a hierarchical cluster analysis. Considering possible reaction pathways and all results obtained including Pearson coefficients between the odorant concentrations and the intensities of the defects, specifically 2-methoxyphenol and 4-ethylphenol were proposed as marker compounds for the quality assignment of both types of off-flavors induced by microbial spoilage among the identified key aroma compounds.

Investigations into the Ability to Reduce Cinnamic Acid as Undesired Precursor of Toxicologically Relevant Styrene in Wort by Different Barley to Wheat Ratios (Grain Bill) during Mashing.

Styrene is a food-borne toxicant in wheat beer and due to its classification as possibly carcinogenic to humans by the International Agency for Research on Cancer in 2002, mitigation strategies had to be developed. Aiming at understanding the impact of the barley to wheat malt ratio (grain bill) during mashing on the contents of soluble and free (i) cinnamic, (ii) p-coumaric, and (iii) ferulic acid, precursors of (i) styrene and the desired vinyl aromatics (ii) 4-vinylphenol and (iii) 2-methoxy-4-vinylphenol in wheat beer, wort was prepared at four different barley to wheat malt ratios of 100:0, 25:75, 50:50, and 0:100 (w/w). Additionally, the malts were produced at different germination temperatures and aeration rates (12/32, 18/35, 18/25, 24/18, and 26/25 (°C; L/min)) to consider these two further parameters as well. Thereby, soluble and free phenolic acid contents in wort showed linear correlations to the percentage of wheat in the grain bill, highlighting the absence of synergistic effects when mixing barley and wheat malts. In contrast, the results described the phenolic acid contents as a function of the concentrations in the respective barley and wheat wort, multiplied by their percentage in the grain bill. However, a clear recommendation for favorable barley to wheat malt ratios leading to a decrease of soluble and free cinnamic acid in wort could not be made, as the contents in the present study proved to be highly dependent on the barley and wheat varieties used during mashing and the parameters applied during malting. This was not the case for p-coumaric acid for which a clear decrease of the soluble and free forms was found with increasing wheat malt contents. Differently, the soluble form of ferulic acid increased with an increasing percentage of wheat malt, while the free form decreased. The malting parameters clearly recommended high germination temperatures and low aeration rates when aiming at a reduction of undesired cinnamic acid in wort. Fortunately, soluble and free p-coumaric and ferulic acid contents were only slightly affected, indicating that the formation of the characteristic wheat beer aroma might not suffer when applying these favorable conditions for styrene reduction.

Occurrence of 3-monochloropropane-1,2-diol (3-MCPD) esters and glycidyl esters in infant formulas from Germany.

Fatty acid esters of 3-monochloropropane-1,2-diol (3-MCPD), 2-monochloropropanediol-1,3-diol (2-MCPD), and glycidol are heat-induced processing contaminants formed during the deodorisation step of edible oil refining. Because these compounds are potentially carcinogenic and/or genotoxic, their presence in refined oils and fats and foods containing these oils/fats poses possible health concerns. In particular, formula-fed infants may be exposed to these compounds due to their presence in commercial infant formulas. For this reason, in 2018, the European Union established maximum limits for glycidyl esters in oils/fats and infant formulas and recently, as of January 2021, implemented regulations for the sum of free 3-MCPD and 3-MCPD fatty acid esters as well. This work involved the analysis of 3-MCPD and glycidyl ester contents in 45 infant formula products purchased from German supermarkets in 2019. The data produced in this study showed that average contaminant concentrations across all manufacturers were exceptionally low, with 100% of the products analysed falling below the current EU regulation for glycidyl esters in powdered formulas and 96% of the products analysed meeting the recently implemented regulation for the sum of free and bound 3-MCPD. In addition, a comparison of the 2019 data set to occurrence data collected for German formulas purchased in 2015 showed that average bound 3-MCPD and glycidol concentrations have decreased (from 0.094 to 0.054 µg g-1 and from 0.010 to 0.006 µg g-1, respectively), likely indicating that additional/improved mitigation measures for reducing contaminant concentrations in infant formulas have been implemented over the 4-year period. The data collected in this occurrence study are suitable for estimating levels of exposure to these compounds for German infants.Abbreviations: 2-MCPD: 2-monochloropropane-1,3-diol; 3-MCPD: 3-monochloropropane-1,2-diol; ARA: arachidonic acid; CE: collision energy; CXP: collision cell exit potential; DHA: docosahexaenoic acid; DP: declustering potential; EP: entrance potential; EPA: eicosapentaenoic acid; EtOAc: ethyl acetate; IPA: isopropanol; LC-MS/MS: liquid chromatography-tandem mass spectrometry; MeOH: methanol; MTBE: methyl tert-butyl ether; SPE: solid-phase extraction.

Flavor of rapeseed oil: An overview of odorants, analytical techniques, and impact of treatment.

As one of the three major vegetable oils in the world, rapeseed oil is appreciated for its high nutritional value and characteristic flavor. Flavor is an essential attribute, determining rapeseed oil quality and consumer acceptance. The present manuscript provides a systematic literature review of recent advances and knowledge on the flavor of rapeseed oil, which focuses on aroma-active as well as off-flavor compounds, flavor analysis techniques (i.e., extraction, qualitative, quantitative, sensory, and chemometric methods), and effects of treatments (storage, dehulling, roasting, microwave, flavoring with herbs, refining, and oil heating) on flavor from sensory and molecular perspectives. One hundred thirty-seven odorants found in rapeseed oil from literature are listed and possible formation pathways of some key aroma-active compounds are also proposed. Future flavor analysis techniques will evolve toward time-saving, portability, real-time monitoring, and visualization, which aims to obtain a "complete" flavor profile of rapeseed oil. The changes of volatile compounds in rapeseed oil under different treatments are summarized in this view. Studies to elucidate the influence of different treatments on the formation of aroma-active compounds are needed to get a deeper understanding of factors leading to the variations of rapeseed oil flavor.

Proteomic Analyses of 3-Monochloropropanediol 1-Monooleate and 1-Monostearate Induced Testicular Toxicity in a 90 Day Sprague-Dawley Rats' Study.

3-Monochloropropane 1,2-diol (3-MCPD) esters are toxicants formed during food thermal processing, and their testicular toxicities were widely reported. In this 90 day in vivo study, Sprague-Dawley rats were treated with 3-MCPD 1-monooleate at 10 and 100 mg/kg body weight (bw)/day or 1-monostearate at 15 and 150 mg/kg bw/day. Histological results indicated that testicular impairment was observed, and the level of serum testosterone was decreased dose dependently, while the levels of serum transforming growth factor beta and interferon-γ in rats' serum were increased dose dependently. To address the molecular mechanisms leading to testicular toxicities of 3-MCPD esters, testes samples were investigated with a mass spectrometry proteomic approach. The deregulated proteins affected by 3-MCPD esters include many enzymes related with the inflammatory necrosis pathways. While verifying the results in cellular level, 3-MCPD 1-monooleate and 3-MCPD 1-monostearate showed almost similar testicular cytotoxicity, and they could activate RIPK1 and MLKL pathways at the cellular level. All of these results showed the possible mechanisms about the toxicity of 3-MCPD esters in rats' testes and play a vital role in understanding the toxic effects of 3-MCPD esters both in vivo and in vitro.

Differences of characteristic aroma compounds in Rougui tea leaves with different roasting temperatures analyzed by switchable GC-O-MS and GC × GC-O-MS and sensory evaluation.

Roasting, an important process to refine Wuyi Rock tea, could impart different types of aroma to the final products. This study focuses on the differences in aroma characteristics among three kinds of refined teas, named light fire (LF), moderate fire (MF), and high fire (HF). A combination of solid phase microextraction (SPME) and a switchable system between GC-O-MS and GC × GC-O-MS was utilized to identify the odorants. In total, 97 aroma-active compounds could be smelled at the sniffing port, comprising alcohols, aldehydes, ketones, esters, heterocycles, and terpenes. However, only 52 obtained r-OAV >1. Significant differences were uncovered by the application of principal component analysis (PCA) and partial least squares regression (PLSR). Thereby, MF and HF had a more similar aroma profile, while in LF samples, alcohols, aliphatic aldehydes and some ketones were responsible for the aroma profile, such as (E,E)-2,4-hexadienal, octanal, hexanal, (E,Z)-2,6-nonadienal, (E)-ß-ionone, 3-octen-2-one etc. Strecker aldehydes had a great impact on the aroma of MF, including 2-methylpropanal, 2-methylbutanal, 3-methylbutanal etc. Some N-heterocyclic compounds also affected the overall aroma, for instance, 6-methyl-2-ethylpyrazine. In HF, the majority of aroma compounds increased with increasing roasting temperature, especially N-heterocyclic compounds as well as furfural and 5-methyl-2-furancarboxaldehyde, which are all closely related to the Maillard reaction. Besides, 5-methyl-2-(1-methylethenyl)-4-hexen-1-ol, trans-linalooloxide and 2-nonanone also remarkably influenced the aroma of HF. In addition, it was supposed that most amino acids that participated in the Maillard reaction during roasting were decomposed from the compounds that combined with tea polyphenols and amino acids.

The Role of Endogenous Enzymes during Malting of Barley and Wheat Varieties in the Mitigation of Styrene in Wheat Beer.

Knowledge of the biochemical processes responsible for the release of phenolic acids (precursors of vinyl aromatics) during malting is important to find mitigation strategies for the toxicologically relevant styrene (formed from cinnamic acid) in wheat beer. Therefore, grain and malts of four barley and three wheat varieties were screened for the activities of various enzymes and the amounts of nonstarch polysaccharides (to which the phenolic acids are bound to a certain extent). During malting, a very strong degradation of ß-glucan, synonymous to a depletion of the cell walls, was found, suggesting that a partial degradation of cell walls cannot have an effect on the release of phenolic acids. In barley malts, water-extractable arabinoxylan contents were between 0.59 and 0.79 g/100 g dm and in wheat malts between 0.93 and 1.51 g/100 g dm. Additionally, higher soluble ferulic acid contents in wheat wort compared to barley wort indicated that the degradation of nonstarch polysaccharides has an impact on the release of phenolic acids. For the feruloyl esterase, higher activities were found in malts of the barley varieties. However, this fact was not reflected by the free phenolic acid contents in those malts. Correlation coefficients between the protease activity and the feruloyl esterase, α- and ß-amylase, and ß-glucanase activities were proven to be insignificant, highlighting that the protease activity had no effect on the activities of these other enzymes.

Studies on the Impact of Malting and Mashing on the Free, Soluble Ester-Bound, and Insoluble Ester-Bound Forms of Desired and Undesired Phenolic Acids Aiming at Styrene Mitigation during Wheat Beer Brewing.

Mitigation studies on styrene in wheat beer found no correlation between the free phenolic acid contents in the processing steps and the final concentrations of the toxicologically relevant styrene and the desired aroma-active vinyl aromatics in beer, which can be explained by the presence of phenolic acid releasing enzymes that are still active after kiln-drying and by the yeast's own feruloyl esterase activity. The present study contributed to a better understanding of the coherence between the free, soluble ester-bound, and insoluble ester-bound forms of cinnamic, p-coumaric, and ferulic acid during malting and mashing of barley and wheat varieties. Concentration differences in malt by factors of up to 1700 were found between the total cinnamic acid contents (an undesired precursor of the toxicologically relevant styrene) and the total contents of p-coumaric and ferulic acid (both desired precursors of the aroma-active compounds 4-vinylphenol and 2-methoxy-4-vinylphenol). In grain and malt, cinnamic acid occurred predominantly in a soluble form, whereas the desired precursors were mainly insoluble ester-bound. This had a direct effect on the transfer rates from malt into wort, which were found to be >100% for cinnamic acid, revealing that a complete transfer was accompanied by an additional biosynthesis, but only <8% for the desired phenolic acids. Interestingly, in the wort, cinnamic and p-coumaric acid contents were dominated by the free form, while ferulic acid was mostly still soluble ester-bound. Overall, the use of barley malts led to an introduction of cinnamic, p-coumaric, and ferulic acid into the wort in a ratio of 2:14:84, and the use of wheat malt in a ratio of 1:2:97.

Determination of mono- and diacylglycerols from E 471 food emulsifiers in aerosol whipping cream by high-performance thin-layer chromatography-fluorescence detection.

Mono- and diacylglycerol (MAG and DAG) emulsifiers (E 471) are widely applied to regulate techno-functional properties in different food categories, for example, in dairy products. A method for the determination of MAG and DAG in aerosol whipping cream by high-performance thin-layer chromatography with fluorescence detection (HPTLC-FLD) after derivatization with primuline was developed. For sample preparation, aerosol whipping cream was mixed with ethanol, followed by the addition of water and liquid-liquid extraction with tert-butyl methyl ether. The sample extracts were analyzed by HPTLC-FLD on silica gel LiChrospher plates with n-pentane/n-hexane/diethyl ether (22.5:22.5:55, v/v/v) as mobile phase, when interfering matrix like cholesterol and triacylglycerols were successfully separated from the E 471 food additives. For quantitation, an emulsifier with known composition was used as calibration standard and the fluorescent MAG and DAG were scanned at 366/> 400 nm. Limits of detection and quantitation of 4 and 11 mg/100 g aerosol whipping cream were obtained for both monostearin and 1,2-distearin, respectively, and allowed the reliable quantitation of MAG and DAG from E 471 far below commonly applied emulsifier amounts. Recoveries from model aerosol whipping cream with 400 mg E 471/100 g were determined in a calibration range of 200-600 mg E 471/100 g sample and ranged between 86 and 105% with relative standard deviations below 7%. In aerosol whipping creams from the German market, E 471 amounts ranged between 384 and 610 mg/100 g.

Dry-Hopping to Modify the Aroma of Alcohol-Free Beer on a Molecular Level-Loss and Transfer of Odor-Active Compounds.

There are mainly two options for the dealcoholization of beer: evaporation of ethanol by heat treatment, whereby desired aroma-active compounds are also removed, and stopped fermentation that leads to beers still containing high amounts of unfermented sugar in parallel with lower amounts of aroma-active fermentation products. Thus, dry-hopping could be an opportunity to compensate for these aroma deficiencies. Therefore, following the sensomics approach, odorants were characterized in dry-hopped (Hallertauer Mandarina Bavaria, Hallertauer Cascade, or Hallertauer Mittelfrüh) top- and bottom-fermented alcohol-free beers either after thermal dealcoholization or stopped fermentation. Twenty-three odorants were quantitated via stable isotope dilution analysis, and odor activity values (OAVs; ratio of concentration to odor threshold) were calculated. Thermally dealcoholized samples showed high losses (up to 100%) of key odorants like 3-methyl-1-butanol or 3-methylbutyl acetate. During stopped fermentation, aroma compounds like ethyl butanoate or 2-phenylethanol were formed in relevant concentrations, leading to OAVs ≥ 1, but the amounts were significantly lower compared to beers with normal alcohol contents. For hop-derived odorants (linalool, geraniol, myrcene, and esters), transfer rates between 20 and 90% were found, leading to OAVs ≥ 1 in beer. Furthermore, hop addition apparently induced the formation of ethyl esters of hop-derived monocarboxylic acids.