Odor-active Compounds Research Articles

Variation of Aroma Components of Pasteurized Yogurt with Different Process Combination before and after Aging by DHS/GC-O-MS

Pasteurized yogurt is a healthy yogurt that can be stored in ambient temperature conditions. Dynamic headspace sampling (DHS) combined with gas chromatography-olfactory mass spectrometry (GC-O-MS), sensory evaluation, electronic nose (E-nose), and partial least squares discriminant analysis (PLS-DA) were used to analyze the flavor changes of pasteurized yogurt with different process combinations before and after aging. The results of odor profiles showed that the sensory descriptors of fermented, sweet, and sour were greatly affected by different process combinations. The results of odor-active compounds and relative odor activity value (r-OAV) showed that the combination of the production process affected the overall odor profile of pasteurized yogurt, which was consistent with the sensory evaluation results. A total of 15 odor-active compounds of 38 volatile compounds were detected in pasteurized yogurt samples. r-OAV results revealed that hexanal, (E)-2-octenal, 2-heptanone, and butanoic acid may be important odor-active compounds responsible for off-odor in aged, pasteurized yogurt samples. PLS-DA and variable importance of projection (VIP) results showed that butanoic acid, hexanal, acetoin, decanoic acid, 1-pentanol, 1-nonanal, and hexanoic acid were differential compounds that distinguish pasteurized yogurt before and after aging.

Characterization of meat quality traits, fatty acids and volatile compounds in Hu and Tan sheep.

Sheep breed has a major influence on characteristics of meat quality and intramuscular fat (IMF), however, studies into the relationship between sheep breed and meat quality traits rarely consider the large variation in IMF within breed. In this study, groups of 176 Hu and 76 Tan male sheep were established, weaned at 56 days old, with similar weights, and representative samples were selected based on the distribution of IMF in each population, to investigate variations in meat quality, IMF and volatile compound profiles between breeds. Significant differences were observed in drip loss, shear force, cooking loss, and color coordinates between Hu and Tan sheep (p < 0.01). The IMF content and the predominate unsaturated fatty acids, oleic and cis, cis-linoleic acids, were similar. Eighteen out of 53 volatile compounds were identified as important odor contributors. Of these 18 odor-active volatile compounds, no significant concentration differences were detected between breeds. In another 35 volatile compounds, γ-nonalactone was lower in Tan sheep relative to Hu sheep (p < 0.05). In summary, Tan sheep exhibited lower drip loss, higher shear force values, and redder color, had less saturated fatty acids, and contained less γ-nonalactone against Hu sheep. These findings improve understanding of aroma differences between Hu and Tan sheep meat. Graphical Abstract.

Characterization of key odor-active compounds in Chinese Dornfelder wine and its regional variations by application of molecular sensory science approaches

In this study, aroma characteristics and odor-active compounds in Dornfelder wines from three main production regions of China were comprehensively investigated for the first time. The leading features of Chinese Dornfelder wines were black fruit, violet, acacia/lilac, red fruit, spice, dried plum, honey, and hay based on check-all-that-apply. Wines from the Northern Foothills of Tianshan Mountains and Eastern Foothills of Helan Mountains were dominated by floral and fruity aromas, while wines from the Jiaodong Peninsula were characterized by mushroom/earth, hay, and medicinal material notes. Aroma profiles of Dornfelder wines in three regions were successfully reconstructed with 61 volatiles determined by AEDA-GC-O/MS and OAV. Through aroma reconstitution, omission tests, and descriptive analysis, terpenoids could be regarded as varietal characteristic compounds directly contributing to floral perception in Dornfelder wines. Guaiacol, eugenol, and isoeugenol were further revealed to have a synergistic effect with linalool and geraniol on violet, acacia/lilac, spice, and black fruit.

Characterization of the key odorants and investigation of the effects of drying methods on the aroma, taste, color and volatile profiles of the fruit of Clausena anisum-olens (Blanco) Merr.

With a distinctive aroma, Shanhuangpi (SHP), the fruit of the plant Clausena anisum-olens (Blanco) Merr., has been newly developed as a commercial fruit resource. The fresh fruit deteriorates rapidly due to its high respiration and metabolism. Therefore, an effective drying process is urgently needed for its preservation. The influence of two commonly used drying methods for plant materials, i.e., vacuum freeze-drying (VFD) and hot air drying (HAD) was evaluated on the aroma, taste, color, and volatile profiles of this fruit. The results indicated that the VFD process well retained the color and volatile composition of the fresh fruit but produced extra graininess and sticky mouthfeel. Alternatively, the HAD process offered a shorter drying time, kept a more palatable sour/sweet ratio, but created a darker brown color and shrinking texture of the fruit. The volatile components were enriched by the micro-chamber/thermal extractor (μ-CTE) and 38 compounds were identified with gas chromatography-mass spectrometry. Sixteen odor-active compounds (detection frequency ≥4) were detected by gas chromatography–olfactometry. Results obtained in this study can be served as a reference for the evaluation and further development of SHP.

Role of Microorganisms in the Development of Quality during the Fermentation of Salted White Herring (Ilisha elongata).

Salted white herring (Ilisha elongata) is a popular fish product in the coastal region of China. The complex endogenous enzymes and microbial action determine the quality of a traditionally salted herring. In order to investigate the role of microorganisms in the quality formation of salted herring, three groups for different salting processes were established: traditional salted (TS), non-starter salted (NS), and starter culture salted (SS). The predominant microorganism in each processing group was Staphylococcus spp., as inferred by next-generation sequencing data. Different physicochemical parameters were obtained in each of the three processing groups (TCA-soluble peptide (trichloroacetic acid-soluble peptide), TVB-N (Total volatile basic nitrogen), and TBA values (thiobarbituric acid-reactive substance)). The TS group had the maximum level of total biogenic amines, while the SS group had the lowest. A strong positive correlation was found between Staphylococcus and 14 aromatic compounds, of which 5 were odor-active compounds that created fishy, grassy, fatty, and fruity flavors. Shewanella may produce trimethylamine, which is responsible for the salted herrings' fishy, salty, and deteriorating flavor. The findings demonstrated that autochthonous strains of Staphylococcus&amp;nbsp;saprophyticus M90-61 were useful in improving product quality because they adapted quickly to the high osmotic environment.

Characterization of key odor-active compounds in high quality high-salt liquid-state soy sauce

Solid-phase microextraction and liquid–liquid extraction with gas chromatography– olfactometry–mass spectrometry (GC–O–MS) were used to analyze four award-winning high-salt liquid-state soy sauces (HLS). In this study, 110 volatile odor compounds were detected using GC–O–MS. Twenty key odor-active compounds with a flavor dilution factor ≥ 1024 were identified through aroma extract dilution analysis(AEDA), of which 11 compounds had odor activity values > 1; these were methional, 4-hydroxy-2,5-dimethyl-3(2H)-furanone (HDMF), guaiacol, 4-hydroxy-2(or 5)-methyl-5(or 2)-ethyl-3(2 H)-furanone (HEMF), 1-hydroxy-2-propanone, 3-hydroxy-4,5-dimethyl-2(5H)-furanone, 2-ethyl-6-methylpyrazine, 3-methyl-1-butanol, 2,6-dimethylpyrazine, ethyl benzoate, and 4-ethylguaiacol. Sensory evaluation showed that roasted, cooked potato-like, seasoning-like, and smoky odors were the main odor characteristics in the award-winning HLS. Electronic nose analysis indicated that the odor characteristics of the four samples were significantly different and could be distinguished from each other. This study helps to understand and explore the odor characteristics and key odor components of the award-winning HLS.

Scent-Triggered Cerebral Activity: How Retronasal Olfaction Influences the Food-Reward Feedback System

The flavour of foods and drinks is influenced by perceptual interactions between genuine taste and odour active compounds that are sensed retronasally. Interdisciplinary teams of plant and sensory experts have identified specific flavour changes that influence overall favour profiles. Currently, it is unknown how retronasal sensations might vary with measures of taste phenotype and taste function, and how such differences might influence liking and intake of certain foods and drinks over others. Given that neural response depends not only on the type of stimuli, but also in large part on the cognitive context, focus and state of the individual, a conclusive determination of the food reward response triggered by retronasal olfaction is warranted.

Variations in physicochemical characteristics, antioxidant activity, phenolic and volatile profiles, and sensory attributes of tea-flavored Chardonnay wine during bottle aging.

A novel Chardonnay wine flavored with either green tea or black tea was subjected to bottle aging for 9 months, and the physicochemical properties, antioxidant capacity, total phenolic content, volatile content and sensory properties were monitored. There were 272 phenolic and non-phenolic compounds characterized in the aged Chardonnay wines, including newly formed 9, 1, 3 and 8 phenolic compounds and 10, 6, 1 and 6 non-phenolic compounds after aging for 1, 3, 6 and 9 months, respectively. For all the aged wines, catechin was determined as the most abundant phenolic compound, and epigallocatechin mainly contributed toward the antioxidant power. A total of 54 volatile compounds were identified in the aged Chardonnay wines, including 17 odor-active compounds. The aging process diminished floral and fruity odors, but intensified green odor. The consumer study revealed the highest consumer liking for 1% (w/v) black tea infused wine. This study revealed the quality and bioactivity of this novel flavored wine type during aging which is critical to understand the shelf-life and functionality of the product.

Sensory acceptability of antioxidant-based formulations dedicated to mitigate heterocyclic aromatic amines in cooked meat

In a previous work, we studied the inhibition of heterocyclic aromatic amine formation by natural ingredients rich in antioxidants: caper, oregano, wine and green tea. This present work aimed to assess the sensory impact of the addition of these ingredients in ground beef patties. The best liked formulations were determined by a hedonic scoring. Caper and oregano were not significantly different from the standard, the most appreciated, due to their congruency with cooked meat. Direct dissimilarity assessment was performed to evaluate the overall, gustative and odor differences between formulations. Olfactive differences were evidenced as key drivers of these differences. Standard and caper were close while oregano was found significantly different from them. A fast sensory profiling permitted to evidence that aromatic plant note was discriminant for oregano formulation. Gas chromatography-mass spectrometry/multibooth olfactometry identified the distinctive odor-active compounds of the formulations as pyrazines and sulfide for oregano formulation and ester for caper formulation.

Characterization and modelling of odor-active compounds release behavior from Fu-brick tea during boiling-water extraction by molecular sensory science approach

The odor-active compounds in Fu-brick tea and their release behaviors during boiling-water were studied. Fifty-one odor-active compounds were identified, and their release behaviors were identified by continuously recovering 16 sections of condensed water combined with sensory, instrumental, and nonlinear curve fitting analysis. The odor intensities of condensed water and the concentrations of odor-active compounds could be significantly fitted (p < 0.01) to power-function type curves. Hydrocarbons showed the fastest release rate, while organic acids showed the slowest. The release rates had very little correlation with their concentrations, molecular weights, and boiling points. Most odor-active compounds (≥70 %) released need to evaporate more than 24 % of the added water during boiling-water extraction. Meanwhile, on the basis of odor activity value (OAV) calculation, the aroma recombination experiments were performed to explore the odor-active compounds that made major contributions to the formation of the aroma profile of each condensed water.

Derivatization Strategies in Flavor Analysis: An Overview over the Wine and Beer Scenario

Wine and beer are the most appreciated and consumed beverages in the world. This success is mainly due to their characteristic taste, smell, and aroma, which can delight consumer’s palates. These olfactory characteristics are produced from specific classes of volatile compounds called “volatile odor-active compounds” linked to different factors such as age and production. Given the vast market of drinking beverages, the characterization of these odor compounds is increasingly important. However, the chemical complexity of these beverages has led the scientific community to develop several analytical techniques for extracting and quantifying these molecules. Even though the recent “green-oriented” trend is directed towards direct preparation-free procedures, for some class of analytes a conventional step like derivatization is unavoidable. This review is a snapshot of the most used derivatization strategies developed in the last 15 years for VOAs’ determination in wine and beer, the most consumed fermented beverages worldwide and among the most complex ones. A comprehensive overview is provided for every method, whereas pros and cons are critically analyzed and discussed. Emphasis was given to miniaturized methods which are more consistent with the principles of “green analytical chemistry”.

Where has all the aroma gone? Identification of aroma compounds in fresh and dried leaves of Melissa officinalis

Melissa officinalis is a popular aromatic plant, renowned for its lemon-like smell and pharmaceutical effects. Drying of Melissa officinalis is important for long-term storage and commercial purposes but can impact the sensory quality of the final product. Here, we aimed to characterize drying-related changes in aroma quality. In a first step, aroma profiles of fresh and dried leaves of Melissa officinalis were established by a trained sensory panel. In a second step, one- and two-dimensional gas chromatography-mass spectrometry/olfactometry (GC-MS/O) was performed to identify odor-active substances from fresh and dried leaves. A hay-like, straw-like and algae-like/fishy off-flavor was evident in dried leaves. GC-MS/O analyses led to the identification of known odor-active substances from Melissa officinalis like neral, geranial, geraniol in both fresh and dried leaves and additionally demonstrated the generation of further odor-active compounds due to drying, amongst others (Z)-4-heptenal and (E,Z)-2,6-nonadienal. Based on these results, further experiments can be designed to further investigate drying-related aroma changes, for instance with regard to quantitative determination of the aroma compounds in the leaves of Melissa officinalis.

Origins of volatile compounds and identification of odour-active compounds in air-classified fractions of faba bean (Vicia faba L. minor)

Faba bean (Vicia faba L. minor) has many interests but is characterised by off-notes (negative odours/aromas) due to volatile compounds that are promoted during seed processing. Little is known about the volatile compounds of faba bean and their contribution to its odour. The purpose of this study was to determine the volatile compound origins of air-classified fractions (flour (F), starch (S) and protein (P)) from 3 faba bean cultivars and identify the odour-active compounds. Firstly, the volatile content of the fractions was extracted by solvent-assisted flavour evaporation (SAFE) and analysed by gas chromatography-mass spectrometry (GC–MS). A total of 147 volatile compounds were detected and categorised into 12 chemical classes. The P fractions had many volatile compounds from free fatty acid (FFA) oxidation and a higher lipoxygenase (LOX) activity. The volatile content suggested that cultivar 1 (C1) was confronted with a biotic stress at field whereas cultivar 2 (C2), richer in molecules from amino acid (AA) degradation, was contaminated by microorganisms in the field. Secondly, 35 odour-active compounds (OACs) were identified by GC-olfactometry (GC-O) and 12 odour-classes were used to describe the faba bean odours. The P fractions had higher detection frequency (DF) than the S and F fractions. P2 had a more complex odour profile due to important FFA and AA degradation. This work provides a better understanding of the impact of cultivar and processing steps on the faba bean volatile content. Selection of pulse-based ingredients with low volatile compounds could improve their flavour and increase their consumption.

Flavor production in fermented chayote inoculated with lactic acid bacteria strains: Genomics and metabolomics based analysis

In this study, genomics and metabolomics were combined to reveal possible bio-synthetic pathways of core flavor compounds in pickled chayote via lactic acid bacteria (LAB) fermentation. The Lactiplantibacillus plantarum, Levilactobacillus brevis, and Lacticaseibacillus paracasei were selected as core LAB strains with better flavor-producing ability for chayote fermentation. The genomic results showed L. plantarum contained the largest number of metabolism annotated genes, while L. brevis had the fewest. Besides, the largest number of volatile compounds was detected in chayote fermented by L. plantarum, followed by L. brevis and L. paracasei. Some unique odor-active compounds (aldehydes, esters, and alcohols) and taste-active compounds (amino acids and dipeptides) were produced by different LAB strains. Accordingly, phenylalanine metabolic pathway (M00360), amino acid metabolic decomposition pathway (the Ehrlich pathway) and the anabolic pathway (the Harris pathway), and fatty acid biosynthesis pathway (M00061) were the main biosynthesis pathway involved in the flavor formation via LAB fermentation.

Increase the Content of Ester Compounds in Blueberry Wine Fermentation with the Ester-Producing Yeast: Candida glabrata, Pichia anomala, and Wickerhamomyces anomalus.

The co-fermentation of Saccharomyces cerevisiae and ester-producing yeasts is considered to be an effective way to improve the flavor and quality of fruit wine. In this study, three kinds of ester-producing yeasts (Candida glabrata NCUF308.1, Pichia anomala NCUF306.1, and Wickerhamomyces anomalus NCUF307.1) and S. cerevisiae NCUF309.2 were used to simulate blueberry wine co-fermentation at different ratios. The results showed that, compared with S. cerevisiae NCUF309.2 fermentation (S), the population of S. cerevisiae NCUF309.2 in co-fermentation samples decreased to varying degrees, and the content of ethanol also decreased. The results also showed that the co-fermentation of C. glabrata NCUF308.1 and S. cerevisiae NCUF309.2 at the ratio of 1:1 (CS1), co-fermentation of P. anomala NCUF306.1 and S. cerevisiae NCUF309.2 at the ratio of 5:1 (PS5), and co-fermentation of W. anomalus NCUF307.1 and S. cerevisiae NCUF309.2 at the ratio of 5:1 (WS5) could significantly increase the content of ester compounds (p &lt; 0.05), which was 3.29, 4.75, and 3.04 times that of the S sample, respectively. Among them, the sample of CS1 was characterized by phenethyl acetate and isoamyl acetate, while the samples of CS5 and PS5 were characterized by propyl octanoate and ethyl decanoate, and the sample of WS5 was characterized by 3-methylbutyl hexanoate. However, the contents of odor active compounds were higher in the CS1 sample. Therefore, the samples of CS1 had the potential to create the distinctive flavor of blueberry wine.

Characterization of Odor-active Compounds in Moutai-flavor Daqu Using Aroma Extract Dilution Analysis

Characterization of Odor-active Compounds in Moutai-flavor Daqu Using Aroma Extract Dilution Analysis

Changes in odorants and flavor profile of heat-processed beef flavor during storage.

Flavor quality changes of heat-processed beef flavor (HPBF) upon storage are greatly affected by storage conditions. Flavor characterization of HPBF stored for 168 days resulted in 17 key odor-active compounds having flavor dilution factors log3 FD ≥ 3 and odor activity values >1. Based on the concentration changes of these key odorants, a total of 13 HPBF samples were divided into four groups by hierarchical cluster analysis. Combined with flavor profile analysis, the overall flavor of HPBF gradually changed from a characteristic beef aroma to burnt and fermented soybean paste-like notes. Some of the 17 key odorants, such as 2-methyl-3-furanthiol, 2-furfurylthiol, methyl furfuryl disulfide, and difurfuryl disulfide, contributed to the characteristic beef aroma of the freshly prepared product and in the early stage of storage. On the other hand, the odor-active compounds 2-methylbutanal, dimethyl disulfide, dimethyl trisulfide, and 2-ethyl-3,5-dimethylpyrazine were associated with the later stage of storage showing a positive correlation with the intensity of burnt and fermented soybean paste-like notes. A molecular understanding of flavor profile changes of HPBF during storage will provide the basis for developing characteristic beef aroma notes and maintaining the keeping quality of beef products upon storage. PRACTICAL APPLICATION: The relationship between sensory quality and changes in odorant concentration of heat-processed beef flavor during storage will provide the molecular basis for developing high-quality thermal reaction meat flavorings.

Characterization of Key Odor-Active Off-Flavor Compounds in Aged Pasteurized Yogurt by Sensory-Directed Flavor Analysis

The purpose of this study was to determine the key odor-active compounds contributing to the off-flavor of aged pasteurized yogurt (APY) using sensory-directed flavor analysis. Additionally, different extraction methods were compared to determine their effects on the volatile compounds, including dynamic headspace sampling (DHS), solid-phase microextraction, and stir bar sorptive extraction, and DHS was found to be suitable for this study. The results showed that comprehensive two-dimensional gas chromatography-olfactometry-mass spectrometry analysis (GC × GC-O-MS) had more advantages in separating and identifying the volatile compounds than the traditional GC-O-MS. A total of 17 odor-active compounds were determined in the fresh pasteurized yogurt and APY samples by DHS coupled with GC × GC-O-MS. The dynamic headspace dilution analysis demonstrated that 2-heptanone and hexanal were the most vital components in APY with the highest flavor dilution factor. Furthermore, the spiking and omission experimental results revealed that the odor-active compounds, such as 2-heptanone, butanoic acid, pentanoic acid, hexanal, and (E)-2-heptenal, were the key odor-active off-flavor contributors in APY. Therefore, these compounds could be used as potential indicators to determine the freshness of pasteurized yogurt.

Novel Insight into the Formation of Odour-Active Compounds in Sea Buckthorn Wine and Distilled Liquor Based on GC-MS and E-Nose Analysis.

Sea buckthorn wine (SW) and distilled liquor (DL) are fruit wines with beneficial health effects. However, their unpleasant flavour limits their development and widespread acceptance. Therefore, it is necessary to analyse their flavour composition and changes. In this study, differential metabolites of sea buckthorn DL during processing were analysed, and the relationships between E–nose sensor values and key volatile organic compounds (VOCs) were established. The results show that 133 VOCs were identified, with 22 aroma–contributing components. Fermentation significantly increased the content of VOCs, especially esters. A total of seven and 51 VOCs were significantly upregulated after fermentation and distillation, respectively. Meanwhile, seven sensors were positively correlated with the increased level of alcohols and esters, and reflected the increasing trends of 10 key VOCs.

Solvent-assisted stir bar sorptive extraction and gas chromatography–mass spectrometry with simultaneous olfactometry for the characterization of aroma compounds in Japanese Yamahai-brewed sake

Yamahai-brewed sake, a Japanese alcoholic beverage brewed from rice and produced via natural lactic acid fermentation, has a complex and rich flavor compared with Sokujo-brewed sake, brewed with a general method using pure lactic acid. This study aimed to characterize the aroma compounds in Yamahai-brewed sake using solvent-assisted stir bar sorptive extraction (SA-SBSE) with gas chromatography–olfactometry/mass spectrometry (GC-O/MS) and to confirm the enhanced sensitivity of GC-O/MS with SA-SBSE compared with SBSE alone. SA-SBSE with GC-O/MS increased the number of detected odor-active compounds and improved the FD factor sensitivity of Yamahai-brewed sake. SA-SBSE-GC–MS analysis of three pairs of Yamahai-brewed and Sokujo-brewed sake showed higher polar aroma compound content in Yamahai-brewed sake with a low rice polishing ratio. Quantification of 11 characteristic aroma compounds with a wide range of log Kow values revealed that several compounds, including ethyl mandelate, ethyl 2-hydroxy-4-methylvalerate, and the newly identified γ-6-(Z)-dodecenolactone, were more abundant in Yamahai-brewed sake.