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In this study, E-nose and SPME-GC/MS were applied to compare the odour patterns and volatile compounds of two truffle species harvested in different areas of Campania (Southern Italy). In total, 107 Tuber mesentericum (black truffle) and 60 Tuber borchii (bianchetto truffle) truffles were sampled in areas of Avellino, Salerno, Benevento, and Caserta. The E-nose correctly discriminated between Tuber mesentericum and Tuber borchii truffles. The GC/MS analysis revealed qualitative-quantitative differences between Tuber mesentericum and Tuber borchii, with a prevalence of volatile phenols and aromatic compounds for the black truffle, which are responsible for smoky and floral aromas, and ketones, alcohols, aldehydes, and thiophene derivatives for the bianchetto truffle, mostly responsible for earthy mushroom- and garlic-like aromas. The discriminant analysis performed on the E-nose data pattern provided an average correct classification between 55 and 60% for the same species collected in different sites. Tuber borchii truffles were better discriminated based on the harvesting altitude (hilly and coastal areas). GC/MS revealed quantitative differences in the volatile compounds of truffles of the same species collected in different areas, with variations in abundance based on the harvesting site. The distinctive profile of volatile compounds could represent a useful chemical marker to be investigated to authenticate the truffle harvesting area. [ABSTRACT FROM AUTHOR]

Aroma components in foxtail millet are one of the key factors in origin traceability and quality control, and they are associated with consumer acceptance and the corresponding processing suitability. However, the volatile differences based on the foxtail millet varieties have not been studied further. The present study was undertaken to develop the characteristic volatile fingerprint and analyze the differences in volatile compounds of 20 foxtail millet varieties by electronic nose (E-Nose), headspace-gas chromatography-ion mobility spectrometry (HS-GC-IMS), and headspace solid-phase microextraction/gas chromatography-mass spectrometry (HS-SPME/GC-MS). A total of 43 volatile compounds were tentatively identified in foxtail millet samples, 34 and 18 by GC-IMS and GC-MS, respectively. Aldehydes, alcohols, and ketones were the major volatile compounds, and the hexanal content was the highest. The characteristic volatile fingerprint of foxtail millet was successfully constructed. A total of 39 common volatile compounds were found in all varieties. The content of hexanal, heptanal, 1-pentanol, acetophenone, 2-heptanone, and nonanal were explored to explain the aroma characteristics among the different varieties, and different varieties can be separated based on these components. The results demonstrate that the combination of E-Nose, GC-IMS, and GC-MS can be a fast and accurate method to identify the general aroma peculiarities of different foxtail millet varieties. [ABSTRACT FROM AUTHOR]

In this study, E-nose and SPME-GC/MS were applied to compare the odour patterns and volatile compounds of two truffle species harvested in different areas of Campania (Southern Italy). In total, 107 Tuber mesentericum (black truffle) and 60 Tuber borchii (bianchetto truffle) truffles were sampled in areas of Avellino, Salerno, Benevento, and Caserta. The E-nose correctly discriminated between Tuber mesentericum and Tuber borchii truffles. The GC/MS analysis revealed qualitative-quantitative differences between Tuber mesentericum and Tuber borchii, with a prevalence of volatile phenols and aromatic compounds for the black truffle, which are responsible for smoky and floral aromas, and ketones, alcohols, aldehydes, and thiophene derivatives for the bianchetto truffle, mostly responsible for earthy mushroom- and garlic-like aromas. The discriminant analysis performed on the E-nose data pattern provided an average correct classification between 55 and 60% for the same species collected in different sites. Tuber borchii truffles were better discriminated based on the harvesting altitude (hilly and coastal areas). GC/MS revealed quantitative differences in the volatile compounds of truffles of the same species collected in different areas, with variations in abundance based on the harvesting site. The distinctive profile of volatile compounds could represent a useful chemical marker to be investigated to authenticate the truffle harvesting area.

Aroma components in foxtail millet are one of the key factors in origin traceability and quality control, and they are associated with consumer acceptance and the corresponding processing suitability. However, the volatile differences based on the foxtail millet varieties have not been studied further. The present study was undertaken to develop the characteristic volatile fingerprint and analyze the differences in volatile compounds of 20 foxtail millet varieties by electronic nose (E-Nose), headspace-gas chromatography-ion mobility spectrometry (HS-GC-IMS), and headspace solid-phase microextraction/gas chromatography-mass spectrometry (HS-SPME/GC-MS). A total of 43 volatile compounds were tentatively identified in foxtail millet samples, 34 and 18 by GC-IMS and GC-MS, respectively. Aldehydes, alcohols, and ketones were the major volatile compounds, and the hexanal content was the highest. The characteristic volatile fingerprint of foxtail millet was successfully constructed. A total of 39 common volatile compounds were found in all varieties. The content of hexanal, heptanal, 1-pentanol, acetophenone, 2-heptanone, and nonanal were explored to explain the aroma characteristics among the different varieties, and different varieties can be separated based on these components. The results demonstrate that the combination of E-Nose, GC-IMS, and GC-MS can be a fast and accurate method to identify the general aroma peculiarities of different foxtail millet varieties.

The volatilomic fingerprint of nine different whiskeys was established using a rapid and sensitive analytical approach based on dispersive liquid–liquid microextraction (DLLμE) followed by gas chromatography mass spectrometry detection (GC-MS) and gas chromatography with flame ionization detection (GC-FID). The influence of the extractor solvent on the extraction efficiency of volatile compounds (VOCs) was evaluated by DLLμE/GC-MS. The highest amounts of VOCs were obtained using 5 mL of sample, dichloromethane as the extractor solvent, and acetone as the disperser solvent. The proposed method showed no matrix effect, good linearity (R2 ≥ 0.993) in the assessed concentration range, recovery (ranging from 70 to 99%, precision (RSD ≤ 15%) and sensitivity (low limits of detection and quantification). A total of 37 VOCs belonging to different biosynthetic pathways including alcohols, esters, acids, carbonyl compounds, furanic compounds and volatile phenols were identified and quantified using DLLμE/GC-MS and DLLμE/GC-FID, respectively. Alcohols (3-methylbutan-1-ol, propan-1-ol), esters (ethyl decanoate, ethyl octanoate, ethyl hexanoate), and acids (decanoic acid, octanoic acid, hexanoic acid) were the most abundant chemical families. The multivariate statistical analysis allowed for the discrimination of whiskeys based on their volatilomic fingerprint, namely octanoic acid, 2-furfural, ethyl octanoate, ethyl hexanoate, acetic acid, ethyl dodecanoate, butan-1-ol, and ethyl decanoate. [ABSTRACT FROM AUTHOR]

Coffee is one of the most popular beverages worldwide, whose production and consumption result in large amounts of waste, namely spent coffee grounds, constituting an important source of compounds for several industrial applications. This work focused on the establishment of the volatile fingerprint of five spent coffee grounds from different geographical origins using headspace solid-phase microextraction coupled with gas chromatography-mass spectrometry (HS-SPME/GC-MS), as a strategy to identify volatile organic metabolites (VOMs) with potential application in the food industry as antioxidant, anti-inflammatory, and antiproliferative agents. One hundred eleven VOMs belonging to different chemical families were identified, of which 60 were found in all spent coffee grounds analyzed. Furanic compounds (34%), nitrogen compounds (30%), and esters (19%) contributed significant to the total volatile fingerprint. The data obtained suggest that spent coffee grounds have great potential to be used as raw material for different approaches in the food industry towards the development of new food ingredients or products for human consumption, in addition to pharmaceutical and cosmetic applications, namely as antioxidant (e.g., limonene, carvacrol), antimicrobial (e.g., pyrrole-2-carboxaldehyde, β-myrcene) and anti-inflammatory (e.g., furfural, 2-furanmethanol) agents, promoting their integral valorization within the circular bioeconomy concept. [ABSTRACT FROM AUTHOR]

Probiotic viability, metabolite concentrations, physicochemical parameters, and volatile compounds were characterized in Gueuze beers formulated with probiotic lactic acid bacteria (LAB) and yeast. Additionally, the sensory profile of the beers and the resistance of the probiotics to digestion were determined. The use of 2 International Bitterness Units resulted in high concentrations of probiotic LAB but a decline in probiotic yeast as pH decreased. Secondary fermentation led to the consumption of maltose, citric acid, and malic acid, and the production of lactic and propionic acids. Carbonation and storage at 4 °C had minimal impact on probiotic viability. The addition of probiotic LAB resulted in a distinct aroma profile with improved sensory characteristics. Our results demonstrate that sour beers produced with probiotic LAB and a probiotic yeast, and fermented using a two-step fermentation process, exhibited optimal physicochemical parameters, discriminant volatile compound profiles, promising sensory characteristics, and high probiotic concentrations after digestion. [Display omitted] • Lactic acid bacteria (LAB) reduced S. boulardii concentrations by lowering pH. • LAB used maltose, citric and malic acids, and produced lactic and propionic acids. • Carbonations and cold storage maintained probiotic viability after 10 days. • Probiotic LAB generated a distinct aroma profile with better sensory characteristics. • Most probiotic-enriched sour beers provided high LAB levels post-digestion. [ABSTRACT FROM AUTHOR]

The volatilomic fingerprint of nine different whiskeys was established using a rapid and sensitive analytical approach based on dispersive liquid–liquid microextraction (DLLμE) followed by gas chromatography mass spectrometry detection (GC-MS) and gas chromatography with flame ionization detection (GC-FID). The influence of the extractor solvent on the extraction efficiency of volatile compounds (VOCs) was evaluated by DLLμE/GC-MS. The highest amounts of VOCs were obtained using 5 mL of sample, dichloromethane as the extractor solvent, and acetone as the disperser solvent. The proposed method showed no matrix effect, good linearity (R2 ≥ 0.993) in the assessed concentration range, recovery (ranging from 70 to 99%, precision (RSD ≤ 15%) and sensitivity (low limits of detection and quantification). A total of 37 VOCs belonging to different biosynthetic pathways including alcohols, esters, acids, carbonyl compounds, furanic compounds and volatile phenols were identified and quantified using DLLμE/GC-MS and DLLμE/GC-FID, respectively. Alcohols (3-methylbutan-1-ol, propan-1-ol), esters (ethyl decanoate, ethyl octanoate, ethyl hexanoate), and acids (decanoic acid, octanoic acid, hexanoic acid) were the most abundant chemical families. The multivariate statistical analysis allowed for the discrimination of whiskeys based on their volatilomic fingerprint, namely octanoic acid, 2-furfural, ethyl octanoate, ethyl hexanoate, acetic acid, ethyl dodecanoate, butan-1-ol, and ethyl decanoate.

Summary: Volatile profiles of fresh tomato pulp, concentrated pastes and distillates during evaporation were analysed by headspace‐gas chromatography‐ion mobility spectrometry (HS‐GC‐IMS), and volatile fingerprints were established. Topographic plots showed ninety signal peaks, forty‐two peaks (monomers and dimers) for twenty‐five compounds were identified, including four alcohols, ten aldehydes, eight ketones, two esters and a furan. The fingerprints showed clear differences. After evaporation, phenylacetaldehyde, pentanal, 2‐pentanone, 3‐methylbutanal and benzaldehyde were newly detected in the concentrated pastes and distillates, while 2‐heptanol, octanal, isopropyl acetate and 2‐pentylfuran were no longer detectable. Prolonged evaporation caused volatile components in both pastes and distillates to decrease; most were evaporated into distillates, including all alcohols and esters, most aldehydes and some ketones. The fresh pulp, concentrated pastes and distillates were clearly distinguished by principal component analysis and hierarchical clustering analysis. This work provides a theoretical reference for tomato paste processing and the utilisation of distillate discarded. [ABSTRACT FROM AUTHOR]

Coffee is one of the most popular beverages worldwide, whose production and consumption result in large amounts of waste, namely spent coffee grounds, constituting an important source of compounds for several industrial applications. This work focused on the establishment of the volatile fingerprint of five spent coffee grounds from different geographical origins using headspace solid-phase microextraction coupled with gas chromatography-mass spectrometry (HS-SPME/GC-MS), as a strategy to identify volatile organic metabolites (VOMs) with potential application in the food industry as antioxidant, anti-inflammatory, and antiproliferative agents. One hundred eleven VOMs belonging to different chemical families were identified, of which 60 were found in all spent coffee grounds analyzed. Furanic compounds (34%), nitrogen compounds (30%), and esters (19%) contributed significant to the total volatile fingerprint. The data obtained suggest that spent coffee grounds have great potential to be used as raw material for different approaches in the food industry towards the development of new food ingredients or products for human consumption, in addition to pharmaceutical and cosmetic applications, namely as antioxidant (e.g., limonene, carvacrol), antimicrobial (e.g., pyrrole-2-carboxaldehyde, β-myrcene) and anti-inflammatory (e.g., furfural, 2-furanmethanol) agents, promoting their integral valorization within the circular bioeconomy concept.

In spite of the high added value and tremendous output from duck processing industries, duck liver (DLv) is underutilized and a major factor is related to its prominent off-flavor perception which hampers the consumption and processing attributes. This work was designed to investigate the impact of low-frequency ultrasound (US) pretreatments on the headspace volatilome evolution of DLv and its isolated protein (DLvP) microstructure, aiming at exploring the potential of US technology to inhibit off-flavor perception and possible mechanisms behind. Results suggested that US pretreatment resulted in decreased lipid oxidation and off-flavor perception, simultaneously without significantly causing physicochemical influence including texture, pH and color. US induced obvious tertiary structural changes of DLvP, as revealed by the intrinsic fluorescence and surface hydrophobicity (H0), whereas the SH, S-S, secondary structure and molecular weight of DLvP remained unaffected, suggesting the presence of molten globule state (MG-state) under ultrasonic conditions. Besides, the headspace contents of flavor compounds, mainly aldehydes and alcohols, were significantly decreased whereas acids were increased. Multivariate analysis suggested an obvious US-induced effect on the volatilome evolution of DLv samples. Discriminant analysis recognized the aroma compounds including aldehydes and alkenals as the major contributors leading to the change of olfactory characteristics of DLv after ultrasonic treatment. Correlation analysis demonstrated the positive relationship between the volatile markers variation and the increased H0 values, a characteristic attribute of MG-state protein. The results obtained in this work suggested that US technology matched with suitable parameters could be a very promising approach to modulate the off-flavor perception of liver products by altering DLvP conformation.

The Criollo cocoa bean is classified as “fine” or flavor cocoas, being perceived as aromatic or smooth with fruity, raisin, floral, spicy, nutty, molasses, and caramel notes. In the present work, gas chromatography coupled to mass spectrometry was used to study the volatile fingerprint of roasted and unroasted Criollo cocoa from four Amazon districts: Nieva, Cajaruro, Copallín and La Peca located in the Amazon Region of Peru. The results showed that the main sensory perception of cocoa is fruit, and this decreases as the roasting intensity increases. A total of 96 volatile compounds were found, of which the esters had a greater presence in the volatile fingerprint of Criollo cocoa. Propyl acetate (3.5%), acetoin acetate (1.3%) and diethyl succinate (0.8%) were found as the characteristic compounds of Criollo cocoa analyzed, which give it its fruit perception. The linalool/benzaldehyde ratio was between 0.56 and 0.89 for La Peca and Cajaruro cocoa. Principal component analysis revealed that the Criollo cocoa in each district has a different volatile fingerprint, whether it is roasted or unroasted beans. The roasting process generates a greater differentiation of the volatile fingerprint of Criollo cocoa.

The Criollo cocoa bean is classified as “fine” or flavor cocoas, being perceived as aromatic or smooth with fruity, raisin, floral, spicy, nutty, molasses, and caramel notes. In the present work, gas chromatography coupled to mass spectrometry was used to study the volatile fingerprint of roasted and unroasted Criollo cocoa from four Amazon districts: Nieva, Cajaruro, Copallín and La Peca located in the Amazon Region of Peru. The results showed that the main sensory perception of cocoa is fruit, and this decreases as the roasting intensity increases. A total of 96 volatile compounds were found, of which the esters had a greater presence in the volatile fingerprint of Criollo cocoa. Propyl acetate (3.5%), acetoin acetate (1.3%) and diethyl succinate (0.8%) were found as the characteristic compounds of Criollo cocoa analyzed, which give it its fruit perception. The linalool/benzaldehyde ratio was between 0.56 and 0.89 for La Peca and Cajaruro cocoa. Principal component analysis revealed that the Criollo cocoa in each district has a different volatile fingerprint, whether it is roasted or unroasted beans. The roasting process generates a greater differentiation of the volatile fingerprint of Criollo cocoa. [ABSTRACT FROM AUTHOR]

Black cumin (Nigella sativa L.) seed oil consists of many volatile oils dissolved in the fixed oil. In this work, the seed oil samples were obtained from supercritical CO2 (SCCO2) extraction under various pressures (20.0–30.0 MPa) and temperatures (40–60 °C). The volatile compound fingerprints of SCCO2-extracted oils were analyzed by static headspace-gas chromatography (SH-GC-FID) without using any organic solvent. The comparison of volatile compound fingerprints of SCCO2 and n-hexane extracts was compared with the direct analysis of milled seed.

The cocoa bean shell (CBS) is a main by-product of cocoa processing, with great potential to be used as an ingredient for functional foods because of its nutritional and flavour properties. This study aimed to characterise and classify CBSs obtained from cocoa beans of diverse cultivars and collected in different geographical origins through their volatile profile assessed using headspace solid-phase microextraction gas chromatography–mass spectrometry (HS-SPME/GC-qMS) and E -nose combined with principal component analysis (PCA). The study provides, for the first time in a representative set of samples, a comprehensive fingerprint and semi-quantitative data for >100 volatile organic compounds (VOCs), such as aldehydes, ketones, pyrazines, alcohols, and acids. Through PCA, a clear separation of the Criollo cultivar from the other cultivars was achieved with both GC-qMS and E -nose analytical techniques because of the high content of key-aroma VOCs. Several biomarkers identified by GC-qMS, such as 2-hepanol, 2-methylpropanoic acid, and 2,3,5-trimethylpyrazine, recognized as key-aroma compounds for cocoa beans, were found suitable for the classification of CBSs according to their quality and origin. GC-qMS and E -nose appeared to be suitable analytical approaches to classify CBSs, with a high correlation between both analytical techniques. The volatile fingerprint and classification of CBSs could allow for the selection of samples with a specific flavour profile according to the food application and, therefore, constitute an interesting approach to valorise this by-product as a food ingredient. Unlabelled Image • The volatile fingerprint of CBS was established by HS-SPME/GC-qMS. • CBSs were classified by GC-qMS/PCA according to geographical origin and cultivar. • Several cocoa key-flavour markers present in CBSs contribute to the classification. • GC-qMS and E -nose allowed the discrimination of Criollo CBSs. • High correlations were found between E-nose and GC-qMS data sets. [ABSTRACT FROM AUTHOR]

Highlights • Volatile fingerprints of three kiwifruit cultivars have been analyzed using HS-SPME-GC-MS. • Multivariate analysis was used to differentiate the volatiles in different cultivars. • Six compounds have been identified as maturity-independent biomarkers for kiwifruit cultivars. Abstract Volatile aroma of kiwifruit is a mixture of complicated and time-dependent compounds, and thereby the study of these compounds required distinguished analytical techniques as well as robust data analysis techniques. In this work, we report on the volatile fingerprints and biomarkers of three representative kiwifruit cultivars with commercial importance using headspace solid-phase microextraction gas chromatography-mass spectrometric (HS-SPME-GC-MS) coupled with multivariate analysis. As a result, 95 volatiles have been analyzed from the fingerprints, and ultimately six of which were identified as volatile biomarkers of the kiwifruit cultivars studied, which are formic acid octyl ester, 2-Methylbicyclo[4.3.0]non-1(6)-ene, 1-ethoxy-2,4-hexadiene, and 2-methyl-5-(1-methylethyl)-bicyclo[3.1.0]hex-2-ene for Jintao (A. chinensis), and 1-methoxy-2-methyl-benzene and (E,E)-2,4-heptadienal for Cuiyu (A. deliciosa), respectively. Since the samples of each cultivar were in various maturities, these compounds could be taken as the maturity-independent volatile biomarkers for the kiwifruit cultivars, which would be valuable for marker-assisted flavour breeding in the kiwifruit production. [ABSTRACT FROM AUTHOR]

Aroma attribute and aroma compound (AOC) composition of fresh-cut flower mushrooms under different static magnetic field (SMF) intensities (2 mT, 4 mT, 6 mT, and 8 mT) were evaluated via coupling aroma sensory assessment and headspace-gas chromatography-ion mobility spectrometry with principal component analysis and partial least squares-relationship analysis. Results showed that aroma quality was severely loss after dicing treatment. A total of 43 AOCs were identified from flower mushrooms, and 3-octanone was the predominant compound. Application of 2 mT SMF maintained more acceptable raw mushroom-like, earthy/musty, and almond-like/roasted, and cooked cabbage-like aroma attributes of diced samples, related to maximally retaining the contents of the key AOCs (i.e. 3-octanone, 2-methylbutanal, and dimethyl trisulfide). These findings could provide a technical reference and theoretical basis for improving the aroma quality of fresh-cut mushrooms via magnetic fields and explain the mechanism of aroma enhancement. • A total of 43 aroma compounds (AOCs) were identified from flower mushrooms. • Dicing caused a severe loss of sample aroma attributes and AOCs. • Reduced 3-Octanone, 2-methylbutanal, and dimethyl trisulfide were key causes for aroma loss. • Optimized static magnetic fields (SMFs) improved aroma quality of diced samples. • 2 mT SMF, a "window" condition, best retained key AOCs and aroma attributes of diced samples. [ABSTRACT FROM AUTHOR]

[Display omitted] • Characteristic volatile fingerprint of LPT was established via SBSE-GC–MS. • The key aroma compounds of LPT were arranged in molecular aroma wheel. • Variations in volatile compounds between LPT and LPM were explored. Liu-pao tea (LPT) has unique aroma characteristics, and is a special microbial fermented tea produced using dark raw tea (LPM) as its raw material. In this study, stir bar sorptive extraction (SBSE) combined with gas chromatography–mass spectrometry (GC–MS) was applied to investigate the volatiles of 16 LPTs and 6 LPMs. Moreover, variations in volatile profiles between LPTs and LPMs were explored. Results showed that a total of 132 volatile compounds were identified from LPTs. The volatile fingerprint was constructed with a similarity ranged from 0.85 to 0.99. Furthermore, twenty-six aroma compounds were selected to depict the molecular aroma wheel of LPT. Multivariate statistical analysis revealed that the contents of 24 aroma compounds changed significantly (P < 0.05) when LPMs were processed into LPTs. These results reveal the volatile profiles of LPTs and aroma composition changes during microbial fermentation process, which might provide chemical basis of the aroma quality of LPT. [ABSTRACT FROM AUTHOR]

Propionibacterium freudenreichii is widely used in Swiss-type cheese manufacture, where it contributes to flavour and eye development. It is currently divided into two subspecies, according to the phenotype for lactose fermentation and nitrate reduction (lac/nit and lac/nit for P. freudenreichii subsp. shermanii and subsp. freudenreichii, respectively). However, the existence of unclassifiable strains (lac/nit and lac/nit) has also been reported. The aim of this study was to revisit the relevance of the subdivision of P. freudenreichii into subspecies, by confirming the existence of unclassifiable strains. Relevant conditions to test the ability of P. freudenreichii for lactose fermentation and nitrate reduction were first determined, by using 10 sequenced strains, in which the presence or absence of the lactose and nitrate genomic islands were known. We also determined whether the subdivision based on lac/nit phenotype was related to other phenotypic properties of interest in cheese manufacture, in this case, the production of aroma compounds, analysed by gas chromatography-mass spectrometry, for a total of 28 strains. The results showed that a too short incubation time can lead to false negative for lactose fermentation and nitrate reduction. They confirmed the existence of four lac/nit phenotypes instead of the two expected, thus leading to 13 unclassifiable strains out of the 28 characterized (7 lac/nit and 6 lac/nit). The production of the 15 aroma compounds detected in all cultures varied more within a lac/nit phenotype (up to 20 times) than between them. Taken together, these results demonstrate that the division of P. freudenreichii into two subspecies does not appear to be relevant. [ABSTRACT FROM AUTHOR]

Flavor is an important sensory property of fermented food products, including cheese, and largely results from the production of aroma compounds by microorganisms. Propionibacterium freudenreichii is the most widely used species of dairy propionibacteria; it has been implicated in the production of a wide variety of aroma compounds through multiple metabolic pathways and is associated with the flavor of Swiss cheese. However, the ability of other dairy propionibacteria to produce aroma compounds has not been characterized. This study sought to elucidate the effect of interspecies and intraspecies diversity of dairy propionibacteria on the production of aroma compounds in a cheese context. A total of 76 strains of Propionibacterium freudenreichii , Propionibacterium jensenii , Propionibacterium thoenii , and Propionibacterium acidipropionici were grown for 15 days in pure culture in a rich medium derived from cheese curd. In addition, one strain each of two phylogenetically related non-dairy propionibacteria, Propionibacterium cyclohexanicum and Propionibacterium microaerophilum were included. Aroma compounds were analyzed using headspace trap-gas chromatography-mass spectrometry (GC–MS). An analysis of variance performed on GC–MS data showed that the abundance of 36 out of the 45 aroma compounds detected showed significant differences between the cultures. A principal component analysis (PCA) was performed for these 36 compounds. The first two axes of the PCA, accounting for 60% of the variability between cultures, separated P. freudenreichii strains from P. acidipropionici strains and also differentiated P. freudenreichii strains from each other. P. freudenreichii strains were associated with greater concentrations of a variety of compounds, including free fatty acids from lipolysis, ethyl esters derived from these acids, and branched-chain acids and alcohols from amino acid catabolism. P. acidipropionici strains produced less of these compounds but more sulfur-containing compounds from methionine catabolism. Meanwhile, branched-chain aldehydes and benzaldehyde were positively associated with certain strains of P. jensenii and P. thoenii . Moreover, the production of compounds with a common origin was correlated. Compound abundance varied significantly by strain, with fold changes between strains of the same species as high as in the order of 500 for a single compound. This suggests that the diversity of dairy propionibacteria can be exploited to modulate the flavor of mild cheeses. [ABSTRACT FROM AUTHOR]

Highlights: [•] For the first time volatile compounds are quantified in defective Brazilian seeds. [•] One hundred and fifty-nine volatile compounds were identified in raw and roasted defective seeds. [•] Defective seeds showed higher number and concentration of volatile compounds than control seeds. [•] Eight compounds were suggested as potential defective coffee seeds’ markers. [•] Sixteen volatile compounds were suggested as low coffee quality indicators. [ABSTRACT FROM AUTHOR]

New insight was systematically elucidated on variations of overall flavor characteristics in shiitake mushrooms (Lentinula edodes) affected by different drying techniques (hot air-drying (HD), vacuum freeze-drying (VFD), and VFD combined with HD (VFD-HD)). The volatile fingerprints of shiitake mushrooms were successfully established by headspace-gas chromatography-ion mobility spectrometry (HS-GC-IMS), and taste profiles and concentrations of non-volatile substances in mushrooms were analyzed. Comparison of aroma fingerprints associated with three drying approaches demonstrated that HD caused considerable losses of volatile compounds except for volatile acids, while VFD and VFD-HD preserved aroma compounds effectively. By application of PLSR analysis, strong "seasoning-like" and "fruity" aromas of VFD-HD mushrooms were closely correlated with 2,6-dimethylpyrazine and esters respectively. Additionally, the umami intensity of VFD-HD mushrooms was similar to HD samples and significantly higher than VFD ones. Furthermore, the correlation between the electronic tongue and sensory attributes was explored. The results obtained from this study revealed that VFD-HD could combine the advantages of single HD and VFD, producing high flavor quality mushroom products. • Comparison of three drying techniques (HD, VFD, and VFD-HD) was conducted on shiitake mushrooms. • HS-GC-IMS was used to detect the volatile compounds in shiitake. • PLSR analysis revealed the correlation between volatiles and sensory characteristics. • VFD-HD led to high levels of umami flavor substances and volatile compounds. [ABSTRACT FROM AUTHOR]

• Low-frequency ultrasound was proposed to mitigate off-flavor of duck liver (DLv); • Ultrasound favored the maintenance of physicochemical properties of DLv; • Volatilome of DLv was characterized responding to ultrasound treatment; • Molten globule state (MGS) of DLv protein isolate was induced by ultrasound; • MGS was linked to the DLv volatilome via the variation in surface hydrophobicity. In spite of the high added value and tremendous output from duck processing industries, duck liver (DLv) is underutilized and a major factor is related to its prominent off-flavor perception which hampers the consumption and processing attributes. This work was designed to investigate the impact of low-frequency ultrasound (US) pretreatments on the headspace volatilome evolution of DLv and its isolated protein (DLvP) microstructure, aiming at exploring the potential of US technology to inhibit off-flavor perception and possible mechanisms behind. Results suggested that US pretreatment resulted in decreased lipid oxidation and off-flavor perception, simultaneously without significantly causing physicochemical influence including texture, pH and color. US induced obvious tertiary structural changes of DLvP, as revealed by the intrinsic fluorescence and surface hydrophobicity (H0), whereas the SH, S-S, secondary structure and molecular weight of DLvP remained unaffected, suggesting the presence of molten globule state (MG-state) under ultrasonic conditions. Besides, the headspace contents of flavor compounds, mainly aldehydes and alcohols, were significantly decreased whereas acids were increased. Multivariate analysis suggested an obvious US-induced effect on the volatilome evolution of DLv samples. Discriminant analysis recognized the aroma compounds including aldehydes and alkenals as the major contributors leading to the change of olfactory characteristics of DLv after ultrasonic treatment. Correlation analysis demonstrated the positive relationship between the volatile markers variation and the increased H0 values, a characteristic attribute of MG-state protein. The results obtained in this work suggested that US technology matched with suitable parameters could be a very promising approach to modulate the off-flavor perception of liver products by altering DLvP conformation. [ABSTRACT FROM AUTHOR]

Volatile fingerprints of a lager beer were carried out throughout five brewing steps to characterize the changes encompassing this process. Overall, 60 volatile organic metabolites (VOMs) were identified by headspace solid-phase microextraction followed by gas chromatography mass spectrometry (HS-SPME/GC-MS). Specific profiles were observed at different brewing steps - aldehydes and furans dominate in wort, whereas the aliphatic esters and alcohols predominate in the following steps. Such variations can be assigned to specific VOMs, as 3-methylbutanal (wort), ethyl alcohol and ethyl octanoate (fermentation, maturation and filtration), or ethyl alcohol and isoamyl acetate (final product). These VOMs can influence the beer final flavour. Ethyl alcohol contributes to its strong and pungent smell and taste, while isoamyl acetate adds intense 'fruity' and 'banana' odours. These beer volatile fingerprints constitute a valuable tool to obtain insights on the impact of each brewing step on the final product, being also very useful for certification purposes., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Ltd. All rights reserved.)