Calculation Of Odor Activity Values Research Articles

Influence of Milk Pasteurization on the Key Aroma Compounds in a 30 Weeks Ripened Pilot-Scale Gouda Cheese Elucidated by the Sensomics Approach.

Gouda cheese was produced from pasteurized milk and ripened for 30 weeks (PM-G). By application of gas chromatography/olfactometry and an aroma extract dilution analysis on the volatiles isolated by extraction/SAFE distillation, 25 odor-active compounds in the flavor dilution (FD) factor range from 16 to 4096 were identified. Butanoic acid, 2- and 3-methylbutanoic acid, and acetic acid showed the highest FD factors, and 2-phenylethanol, δ-decalactone, and δ-dodecalactone were most odor-active in the neutral-basic fraction. Quantitations by stable isotope dilution assays followed by a calculation of odor activity values (OAVs) revealed acetic acid, 3-methylbutanoic acid, butanoic acid, and butane-2,3-dione with the highest OAVs. Finally, an aroma recombinate prepared based on the quantitative data well agreed with the aroma profile of the PM-G. In Gouda cheese produced from raw (nonpasteurized) milk (RM-G), qualitatively the same set of odor-active compounds was identified. However, higher OAVs of butanoic acid, hexanoic acid, and their corresponding ethyl esters were found. On the other hand, in the PM-G, higher OAVs for 3-methylbutanoic acid, 3-methylbutanol, 3-methylbutanal, and butane-2,3-dione were determined. The different rankings of these key aroma compounds clearly reflect the aroma differences of the two Gouda-type cheeses. A higher activity of lipase in the RM-G and higher amounts of free l-leucine in PM-G on the other side were responsible for the differences in the concentrations of some key aroma compounds.

Characterization of odor-active compounds in Liuzhou River snail rice noodles soup by sensory-directed flavor analysis

Liuzhou River snails rice noodles, a special snack of Liuzhou City in the Guangxi Zhuang Autonomous Region, China, possess a unique flavor of spicy, refreshing, fresh, sour, and hot. The present study aimed to characterize the composition of volatile compounds and key odor-active compounds in river snails rice noodles soup (RSRNS) through aroma extract dilution analysis and odor activity value calculation using solid-phase microextraction (SPME) combined with comprehensive two-dimensional gas chromatography–olfactometry–mass spectrometry (GC×GC–O–MS) and gas chromatography–olfactometry–mass spectrometry (GC–O–MS). A total of 71 volatile compounds were identified by GC–O–MS, of which 49 were odor-active. Meanwhile, 125 volatile compounds were identified by GC×GC–O–MS, of which 68 were odor-active. These results indicated that 3-methylbutanal, linalool, 1,8-cineole, myrcene, 2-acetylpyrazine, 4-allylanisole, 2-acetylthiazole, 1-octen-3-ol, hexanal, and eugenol were the main odor-active compounds of RSRNS.

Analysis of Floral Fragrance Components in Different Parts of Iris typhifolia

Floral fragrance, as one of the evaluation indicators for ornamental plants, influences people’s perception of these plants. To explore the volatile compounds and their application value in different parts of Iris typhifolia and to investigate the contributions of each part to the floral aroma, an AIRSENSE electronic nose, principal component analysis (PCA), linear discriminant analysis (LDA), and loading analysis (Loading) are employed to study the differences in floral components among the various parts. Samples from the stamen, pistil, flag petal, and pendant petal are qualitatively and quantitatively analyzed using solid-phase microextraction (SPME) and gas chromatography–mass spectrometry (GC-MS) techniques, combined with spectral library retrieval, cluster analysis, and Odor Activity Value (OAV) calculation. The results show that the electronic nose significantly distinguished the aromas from different parts, and there are significant differences in aroma composition. Through cluster analysis and OAV calculation, it is found that the pistil makes the primary contribution to the floral profile of Iris typhifolia, due to the presence of caproaldehyde, 2-methoxy-3-sec-butylpyrazine, and abundant terpenes. This research provides a valuable reference for reconstructing the floral aroma profile, extracting bioactive substances, and exploring aromatherapy with Iris typhifolia.

Assessment of Volatile Characteristics of Okinawan Pineapple Breeding Lines by Gas-Chromatography–Mass-Spectrometry-Based Electronic Nose Profiling and Odor Activity Value Calculation

The recent increase in demand for Okinawan pineapples has necessitated the development of new varieties with attractive aromas. This study aimed to evaluate the volatile characteristics of five Okinawan pineapple breeding lines, i.e., ‘No. 22’, ‘No. 25’, ‘No. 26’, ‘No. 27’, and ‘No. 28’. The total volatiles in the cryopulverized fruit flesh were examined using headspace gas-chromatography–mass-spectrometry-based electronic nose analysis. The total ion masses of the volatiles were visualized using principal component analysis, and three replicates of each line with comparable volatile characteristics were selected. Furthermore, the composition of the volatile components in these replicates was assessed, and the odor activity values (OAVs) were calculated. The breeding lines varied in the quantity and composition of their volatile compounds, which were predominantly esters, ketones, terpenes, and alcohols. The ‘No. 22’ fruit contained a greater content of volatiles than the other lines. Moreover, 14 volatiles with OAV > 1 were accounted as aroma-active compounds, and their variations were distinguished as follows: the highest OAV (786.96) was recorded for methyl 2-methylbutanoate of the ‘No. 26’ line; 2,5-dimethyl-4-methoxy-3(2H)-furanone was superior in the ‘No. 26’ and ‘No. 27’ lines; and δ-decalactone was only present in the ‘No. 22’ and ‘No. 27’ fruits, suggesting different potent practical uses for these new breeding lines.

Aroma characteristics of flaxseed milk via GC–MS-O and odor activity value calculation: Imparts and selection of different flaxseed varieties

Currently, the effect of varieties on the flavor and stability of flaxseed milk remains unknown. Therefore, this study was conducted to investigate the effects of different varieties on the stability, sensory, and aromas of flaxseed milk. 51 volatile compounds were identified in flaxseed milk using Stir Bar Sorptive Extraction-Gas Chromatography-Olfactometry-Mass Spectrometry (SBSE-GC-O-MS). Among them, 1-octen-3-ol, 2-methoxy-4-vinylphenol, and 2,3,5-trimethylpyrazine contributed higher relative odor active values (ROAV), resulted in the fruity, roasted, sweet, and cucumber in flaxseed milk. Isovaleraldehyde (green notes) was not detected in XHZM. However, other compounds such as 1-nonanol (floral), γ-nonanolactone and γ-octanoic lactone (coconut milk) had higher concentrations, causing a better sensory evaluation. Additionally, its stability was relatively good. The orthogonal partial least-squares regression (OPLS) model and VIP values showed that eight compounds were responsible for the sensory differences from different varietals. The study provided references to selection and understanding flavor composition basis of flaxseed milk.

GC–MS, GC–O, and sensomics analysis reveals the key odorants underlying the improvement of yellow tea aroma after optimized yellowing

An optimized yellowing process for yellow tea (YT) was recently developed. The study found that the optimized yellowing process caused a significant increase in sweet and floral aromas by 31.3% and 24.0%, respectively. A total of 21 aroma-active compounds were identified using gas chromatography-mass spectrometry (GC–MS) and gas chromatography–olfactometry (GC-O) combined with sensomics analysis. Quantification of the 15 aroma-active compounds and calculation of odor activity values (OAVs) showed that the OAVs of sweet and floral aroma compounds increased significantly by 986.2% and 46.4%, respectively, after the optimized yellowing process. Sensory-directed aroma reconstitution and omission experiments confirmed that dimethyl sulfide, 3-methylbutanal, β-ionone, β-damascenone, geraniol, phenylacetaldehyde, and linalool were the key odorants in YT after the optimized yellowing process. Odorant addition tests further demonstrated that β-damascenone (OAV 590.4) was the main odorant for YT sweet aroma enhancement, while β-ionone (OAV 884.6) was the main odorant for YT floral aroma enhancement.

Characterization of the key odorants in fresh Amomum tsao-ko Crevost et Lemaire fruit by gas chromatography-olfactometry, quantitative analysis and aroma reconstitution

To decode key odorants (KOs) in fresh Amomum tsao-ko Crevost et Lemaire fruit (FAF) and investigate the effect of isolation methods on KOs and enantiomer ratios, volatiles were isolated using both direct solvent extraction combined with solvent-assisted flavor evaporation (DSE-SAFE) and hydrodistillation (HD) and analyzed by gas chromatography‒mass spectrometry/olfactometry. In total, 55 odor-active compounds with flavor dilution factors between 1 and 8192 were identified, of which 36 and 39 odorants were detected in the SAFE and HD isolates, respectively. By quantitative analysis and odor activity value calculation, 22 odorants in the SAFE isolate and 25 odorants in the HD isolate were determined to be FAF KOs. The differences in the concentrations and the number of KOs caused the two isolates to have different odor characteristics. The recombination experiment further confirmed the results. Among the three studied chiral odorants, including linalool, 4-terpenol, and α-terpineol, the (S)-(−)-enantiomer was dominant, and the (S)-(−)-enantiomer inverted into the (R)-(−)-enantiomer during HD.

Characterization of the odor‐active compounds responsible for atypical aroma notes in cocoa (Theobroma cacao L.)

Cocoa is the key raw material in chocolate manufacturing. The quality of cocoa is crucial for the pleasant aroma of the final confectionery products. Ideally, cocoa shows a rich aroma with floral, sour, malty, earthy, and fruity notes. However, chocolate manufacturing companies occasionally report the presence of off‐flavors in fermented cocoa at the level of the incoming goods inspection. Among them, moldy‐musty and coconut‐like notes are frequently observed. It is hard to establish the presence of off‐flavors on the base of sensory data only, as it has mainly been done so far, because this type of assessment is very subjective. Therefore, there is a strong need for an objective method based on analytical data to affirm whether a cocoa batch is suitable or not for further manufacturing. To clarify the molecular background of the moldy‐musty and the coconut‐like notes, the volatiles were isolated from fermented cocoa samples tainted with off‐flavors by solvent extraction and solvent‐assisted flavor evaporation (SAFE). The odor‐active compounds were determined by comparative aroma extract dilution analyses (cAEDA), using flawless cocoa samples as reference.The first part of the investigation was focused on cocoa samples with a moldy‐musty off‐flavor. Application of cAEDA revealed (‐)‐geosmin, 4‐methoxy‐2,5‐dimethylfuran‐3(2W)‐one, 1W‐indole, and 3‐methyl‐1W‐indole as potential off‐flavor compounds. This compound selection was based on their odor quality and higher flavor dilution factors in the off‐flavor cocoa than in the reference sample. Quantitation of the four compounds in nine off‐flavor cocoa samples and calculation of odor activity values (OAVs; ratios of the concentrations to the odor threshold values) suggested crucial roles of (‐)‐ geosmin and 3‐methyl‐1W‐indole for the off‐flavor. In the chocolate industry, their quantitation can be used to objectively assess the moldy‐musty off‐flavor at the level of the incoming goods inspection. Because both compounds are inhomogeneously distributed between testa and embryo, separate quantitation in the two parts of the seeds is required.The second part of the investigation was focused on cocoa samples with a coconut‐like note. Application of cAEDA revealed coconut‐like smelling compounds δ‐octalactone, δ‐2‐octenolactone, γ‐ nonalactone, γ‐decalactone, δ‐decalactone and δ‐2‐decenolactones as potential causative odorants. Quantitation of these six compounds and calculation of OAVs suggested δ‐2‐decenolactone as the crucial compound. Chiral analysis showed the presence of pure (R)‐δ‐2‐decenolactone, commonly referred to as massoia lactone. Its key role for the coconut note was finally demonstrated in a spiking experiment: the addition of (R)‐δ‐2‐decenolactone to the reference cocoa in an amount corresponding to the concentration difference between the two samples was able to provoke a coconut note in an intensity comparable to the one in the atypically smelling cocoa. To avoid an undesired coconut note caused by (R)‐δ‐2‐decenolactone in the final products, the chocolate industry may consider its odor threshold value, that is 100 μg/kg, as a potential limit for the acceptance of fermented cocoa in the incoming goods inspection.Caterina's thesis is publication‐based and includes the following three papers:

The Combined Effect of Lactic Acid Bacteria and Galactomyces geotrichum Fermentation on the Aroma Composition of Sour Whey.

The increase in demand for food flavorings due to the shortening and simplification of food production technology also entails an increase in the demand for new technologies for their production. The biotechnological production of aromas is a solution characterized by a high efficiency, an independence from environmental factors and a relatively low cost. In this study, the influence of the implementation of lactic acid bacteria pre-fermentation into the production of aroma compounds by Galactomyces geotrichum on a sour whey medium on the intensity of the obtained aroma composition was analyzed. The monitoring of the culture in terms of biomass buildup, the concentration of selected compounds, and the pH resulted in the confirmation of interactions between the analyzed microorganisms. The post-fermentation product underwent a comprehensive sensomic analysis for the identification and quantification of the aroma-active compounds. The use of gas chromatography-olfactometry (GC-O) analysis and the calculation of odor activity values (OAVs) allowed 12 key odorants to be identified in the post-fermentation product. The highest OAV was found for phenylacetaldehyde with a honey odor (1815). The following compounds with the highest OAVs were 2,3-butanedione with a buttery aroma (233), phenylacetic acid with a honey aroma (197), 2,3-butanediol with a buttery aroma (103), 2-phenylethanol with a rosy aroma (39), ethyl octanoate with a fruity aroma (15), and ethyl hexanoate with a fruity aroma (14).

Volatomics-assisted characterization of aroma and off-flavor contributors in fresh and thermally treated kiwifruit juice

The distinctive aroma profile of kiwifruit juice was significantly changed during thermal treatment, however, the theoretical basis for clarifying and controlling the changes was deficient. In this study, we applied volatomics techniques to investigate the contributors of off-flavors in thermally treated kiwifruit juice. Sixteen aroma compounds were identified to be responsible for the typical “fruity”, “grassy”, and “cucumber-like” flavors of fresh kiwifruit by two different fused silica capillary columns coupled with chromatography-olfactometry/detection frequency (GC-O/DF) analysis and calculation of odor activity value (OAV). Thirty-one odor-active compounds were determined as important contributors to the sensory profile of thermally treated kiwifruit juice, 14 of which were common to all varieties investigated. The key aroma compounds on fresh kiwifruit significantly decreased after thermal treatment, while decanal, (E)-2-decenal, methional, β-damascenone, 1-octen-3-one, DMHF, and dimethyl sulfide which presented undesirable cooked cabbage/potato, roasted fruit, and sulfurous odors, were accumulated in a large amount. By applying PLSR analysis, (E)-2-decenal, methional, β-damascenone, DMHF, and dimethyl sulfide were further verified to have great contributions to the formation of the cooked off-flavor during thermal treatment. Moreover, XX was found to be more thermal-sensitive and more prone to forming cooked off-flavors after thermal treatment. This study could provide theoretical guidance for the regulation of thermal-induced off-flavors during the manufacturing of kiwifruit juice.

Key odorant identification and odor treatment technology evaluation during the chemical synthesis process of typical pesticide

Odor pollution has become one of the important environmental problems in China. In this study, Gas Chromatography Ion Mobility Spectrometry (GC-IMS), Gas Chromatography Mass Spectrometer (GC-MS) and Flame Ionization Detector (FID) were combined to obtain comprehensive information of the odor produced during the production of Captan, a common pesticide, and to evaluate the efficiency of the odorant treatment techniques utilized by the manufacturer studied. Based on our findings, refining, an important phase during the production process of Captan, was found to be the most important factor in determining the type and the concentration of the odorant produced. Of the odorants found during the production process, perchloromethylmercaptan (CCl3SCl) and other chlorine-containing compounds are the key odorants during the production process based on the calculation of odor activity value (OAV). The current odorant treatment utilized by the manufacturer studied showed about 40 % removal rate. However, the odorant treatment produced a new odorant, dimethyl disulfide. Therefore, a much more targeted odorant treatment technique without the production of new odorants is desired and should be utilized.

Comparative Profiling of Hot and Cold Brew Coffee Flavor Using Chromatographic and Sensory Approaches.

Coffee brewing is a complex process from roasted coffee bean to beverage, playing an important role in coffee flavor quality. In this study, the effects of hot and cold brewing on the flavor profile of coffee were comprehensively investigated on the basis of chromatographic and sensory approaches. By applying gas chromatography–mass spectrometry and odor activity value calculation, most pyrazines showed higher contribution to the aroma profile of cold brew coffee over hot brew coffee. Using liquid chromatography, 18 differential non-volatiles were identified, most of which possessed lower levels in cold brew coffee than hot brew coffee. The sensory evaluation found higher fruitiness and lower bitterness and astringent notes in cold brew coffee than hot brew coffee, which was attributed by linalool, furfural acetate, and quercetin-3-O-(6″-O-p-coumaroyl) galactoside. This work suggested coffee brewing significantly affected its flavor profile and sensory properties.

Effect of thermal treatment on the flavor quality of Chinese spicy cabbage

The sensory properties and quality of Chinese spicy cabbage (CSC) are constantly changing, because of the ongoing fermentation in the process of packaging, storage, and marketing. Thermal treatment of CSC could inhibit microbial activities and prolong the shelf life. However, the research concerning the influence of different temperature treatments on CSC flavor quality is limited. In this study, the lactic acid bacteria (LAB) counts, physicochemical characteristics, odor profiles and sensory evaluations of CSCs treated with 80 °C (80P), 100 °C (100P) and 200 °C (200P) were determined. It was shown that thermal treatment could effectively reduce the LAB counts, and also showed significant influence on physicochemical properties and sensory of CSC. Principal component analysis, heatmap analysis, and calculation of odor activity values (OAVs) were used to distinguish CSC with different thermal treatments. A total of 54 volatile compounds (VCs) were detected in all samples, and 23 VCs were considered as key aroma compounds. Sulfides possessed high OAVs and were recognized as the most important key aroma compounds to CSC imparted cabbage, garlic, and onion odors. After thermal treatment, the sulfides content in 80P, 100P, and 200P groups decreased by 9.52%, 25.07%, and 81.10%, respectively. Thermal treatment at 80 °C does not increase or generate new key aroma compounds. When the temperature reached 100 °C, the contents of most aldehydes, ketones, acids, esters, terpenes, nitriles, and furans increased significantly, so increased the complexity of the overall aroma. The reduction of most VCs after thermal treatment at 200 °C resulted in the faint flavor of 200P. In addition, new compounds linalool and decanal were detected in the 100P and 200P groups, contributing to sweet, fruity, floral, fat and waxy odors. (E)-2-Decenal, (E)-2-octen-1-ol and 1-octen-3-ol were also identified as the potential aroma markers responsible for the aroma differences in CSCs thermally treated at different temperatures.

Simple and Rapid Method for the Quantitation of Trace-Level 3-Alkyl-2-methoxypyrazines in Fragrant Vegetable Oils by Gas Chromatography–Tandem Mass Spectrometry

3-Alkyl-2-methoxypyrazines (MPs) are characteristic aroma compounds found in fragrant vegetable oils, a type of specially processed oils with enhanced flavor. MP contents in these oils are usually at trace level, which makes their quantification a big challenge. In this work, we describe an optimized approach with a double-step acid/alkali extraction for the analysis of such compounds, namely, 3-isopropyl-2-methoxypyrazine, 3-isobutyl-2-methoxypyrazine, and 3-sec-butyl-2-methoxypyrazine, in those fragrant oils using gas chromatography-tandem mass spectrometry (GC-MS/MS). The sample preparation conditions including selections and percentages of acids, alkalis, and extraction solvents, as well as the stability of MPs, were optimized and examined. Method validation was conducted with a good linearity (r2 > 0.999), and average recoveries between 93.9 and 109.3% were achieved. The limit of detection ranged from 0.2 to 0.4 μg/kg, and the relative standard deviations varied from 0.4 to 12.2% for samples spiked with the MPs at different concentrations. Overall, the method satisfactorily meets the requirements for the measurement of trace-level MPs in the fragrant vegetable oils via odor activity value calculation, and the results indicate that the improved acid/alkali extraction method is suitable for the routine analysis of MPs in those vegetable oils.

Molecular characterisation of an atypical coconut-like odour in cocoa

Parallel application of an aroma extract dilution analysis (AEDA) to the volatiles isolated from a sample of fermented cocoa with an atypically pronounced coconut note and to the volatiles isolated from a reference cocoa sample revealed coconut-like smelling compounds δ-octalactone, δ-2-octenolactone, γ-nonalactone, γ-decalactone, δ-decalactone, and δ-2-decenolactone as potential causative odorants. Quantitation of these six compounds and calculation of odour activity values as ratios of the concentrations to the odour threshold values suggested δ-2-decenolactone as the crucial compound. Chiral analysis showed the presence of pure (R)-δ-2-decenolactone, commonly referred to as massoia lactone. Its key role for the coconut note was finally demonstrated in a spiking experiment: the addition of (R)-δ-2-decenolactone to the reference cocoa in an amount corresponding to the concentration difference between the two samples was able to provoke a coconut note in an intensity comparable to the one in the atypically smelling cocoa. To avoid an undesired coconut note caused by (R)-δ-2-decenolactone in the final products, the chocolate industry may consider its odour threshold value, that is 100 µg/kg, as a potential limit for the acceptance of fermented cocoa in the incoming goods inspection.

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.

Impact of Chilling Rate on the Evolution of Volatile and Non-Volatile Compounds in Raw Lamb Meat during Refrigeration.

The aim of this study was to investigate the effect of chilling rate (1.44, 22.2, and 32.4 °C/h) on the evolution of volatile and non-volatile compounds in raw lamb meat during refrigeration (1, 24, 72, and 120 h). Through orthogonal projection to latent structure-discriminant analysis, the calculation of odor activity values (OAV > 1) and taste activity values (TAV > 1) analysis, 1-octen-3-ol, (E, E)-2,4-decadienal, nonanal, hexanal, nona-3,5-dien-2-one, 2,3-octanedione, hexanoic acid, 1-nonen-4-ol, aspartate (Asp), Glutamic Acid (Glu), 5′-GMP, 5′-IMP, and 5′-AMP were regarded as differential flavor or taste compounds for raw meat undergone different chilling rates. With a rapid chilling rate at 24 h after slaughter, the contribution of 1-octen-3-ol decreased, but (E, E)-2,4-decadienal increased. Moreover, at 24 h post-mortem, the equivalent umami concentration of Asp, Glu, 5′-GMP, 5′-IMP and 5′-AMP in raw meat were significantly lower at a chilling rate of 1.44 °C/h than 32.4 °C/h (p < 0.05). Conclusively, under the rapid chilling rate, more fatty odor and umami compounds accumulated in 24 h aged meat.

Impact of Malt Extract Addition on Odorants in Wheat Bread Crust and Crumb.

Application of gas chromatography-olfactometry and aroma extract dilution analysis to the volatiles isolated from (1) crust and (2) crumb of a wheat bread made with the addition of a dark liquid malt extract (LME) to the dough and (3) crust and (4) crumb of a reference bread made without addition resulted in the identification of 23 major odorants. Their quantitation followed by the calculation of odor activity values (OAV = ratio of concentration to odor threshold value) suggested that LME addition influenced the aroma of the bread predominantly by increasing seasoning-like smelling sotolon in crust and crumb, and caramel-like smelling compounds maltol and 4-hydroxy-2,5-dimethylfuran-3(2H)-one (HDMF) in the crumb. The increase in sotolon and maltol was explainable by direct transfer from the LME to the bread, whereas HDMF must have been formed from LME-derived precursors. This difference needs to be considered in the targeted optimization of LMEs for bread making.

Analysis of the Ability to Produce Pleasant Aromas on Sour Whey and Buttermilk By-Products by Mold Galactomyces geotrichum: Identification of Key Odorants.

Currently, there is a growing demand for flavorings, especially of natural origin. It is worth paying attention to the biotechnological processes of flavor production, characterized by simplicity, high efficiency and relatively low cost. In this study, we analyzed the ability of the Galac tomyces geotrichum mold to transform by-products of the dairy industry: sour whey and buttermilk to complex flavour mixtures with pleasant, honey-rose aroma. Furthermore, the aroma complexity of the fermentation product has been carefully identified applying a sensomic approach involving the use of gas chromatography-olfactometry (GC-O), gas chromatography-mass spectrometry (GC-MS) and stable isotope dilution assay (SIDA) to identify and quantify aroma compounds. Based on the calculation of odor activity value (OAV), 13 key aroma compounds were present in both tested variants. The highest OAVs were found for phenylacetaldehyde (honey-like) in the buttermilk variant (912) and 2-phenylethanol (rose-like) in the sour whey variant (524). High values of this indicator were also recorded for phenylacetaldehyde (319) and 3-methyl-1-butanol with a fruity aroma (149) in the sour whey culture. The other compounds identified are 3-methylbutanal (malty), 2,3-butanedione (cheesy), isovaleric acid (cheesy), 3-(methylthio)-propanal (boiled potato), butanoic acid (vinegar), (E)-2-nonenal (fatty), ethyl furaneol (burnt sugar), dimethyl trisulfide (cabbage), and acetic acid (vinegar).

Molecular Insights into the Contribution of Specialty Barley Malts to the Aroma of Bottom-Fermented Lager Beers.

Specialty barley malts provide unique aroma characteristics to beer; however, the transfer of specialty malt odorants to beer has not yet been systematically studied. Therefore, three beers were brewed: (1) exclusively with kilned base barley malt, (2) with the addition of a caramel barley malt, and (3) with the addition of a roasted barley malt. Major odorants in the beers were identified by aroma extract dilution analysis followed by quantitation and calculation of odor activity values (OAVs). The caramel malt beer was characterized by outstandingly high OAVs for odorants such as (E)-β-damascenone, 2-acetyl-1-pyrroline, methionol, 2-ethyl-3,5-dimethylpyrazine, and 4-hydroxy-2,5-dimethylfuran-3(2H)-one, whereas the highest OAV for 2-methoxyphenol was obtained in the roasted malt beer. Quantifying odorants in the malts revealed that the direct transfer from malt to beer played only a minor role in the amount of malt odorants in the beers, suggesting a substantial formation from precursors and/or a release of encapsulated odorants during brewing.