Phase Microextraction Gas Chromatography Mass Research Articles

Comprehensive analysis of the dynamic changes of volatile and non-volatile metabolites in boletus edulis during processing by HS-SPME-GC–MS and UPLC-MS/MS analysis

In order to investigate the dynamic changes of flavor compounds, Ultra Performance Liquid Chromatography Tandem Mass Spectrometry (UPLC-MS/MS) combined with Headspace Solid Phase Microextraction Gas Chromatography Mass Spectrometry (HS-SPME-GC–MS) was used to detect the metabolites in different drying processes. A total of 80 volatile compounds and 1319 non-volatile compounds were identified. The trend in the changes of C-8 compounds and sulfur-containing compounds were generally consistent with the trend of key enzyme activities. 479 differential metabolites were identified and revealed that metabolic profiles of compounds in Boletus edulis were altered with increased organic acids and derivatives and lipids and lipid-like molecules. Fatty acids and amino acids were transformed into volatile compounds under the action of enzymes, which played a significant role in the formation of the distinctive flavor of Boletus edulis. Our study provided a theoretical support for fully comprehending the formation mechanism of flavor from Boletus edulis during drying processes.

Geographical identification of Chinese wine based on chemometrics combined with mineral elements, volatile components and untargeted metabonomics

Identifying the geographic origin of a wine is of great importance, as origin fakery is commonplace in the wine industry. This study analyzed the mineral elements, volatile components, and metabolites in wine using inductively coupled plasma-mass spectrometry, headspace solid phase microextraction gas chromatography–mass spectrometry, and ultra-high-performance liquid chromatography-quadrupole-exactive orbitrap mass spectrometry. The most critical variables (5 mineral elements, 13 volatile components, and 51 metabolites) for wine origin classification were selected via principal component analysis and orthogonal partial least squares discriminant analysis. Subsequently, three algorithms—K-nearest neighbors, support vector machine, and random forest —were used to model single and fused datasets for origin identification. These results indicated that fused datasets, based on feature variables (mineral elements, volatile components, and metabolites), achieved the best performance, with predictive rates of 100% for all three algorithms. This study demonstrates the effectiveness of a multi-source data fusion strategy for authenticity identification of Chinese wine.

Innovative Bicultured Lactic–Acetic Acid Co-fermentation Improves Jujube Puree’s Functionality and Volatile Compounds

Jujubes (Ziziphus jujuba Mill), characterized by a rich profile of bioactive compounds, have been historically less exploited due to their unappealing sensory characteristics when dried, including delayed bitterness and a limited shelf life when fresh. Co-fermented jujube puree has emerged as a strategy for enhancing its functional food potential. This study examined the impact of 8-day bicultured Junzao jujube puree, employing both commercial and indigenous Chinese lactic and acetic acid bacteria. Our investigation encompassed an assessment of functionality (cellular profile, antioxidant properties, color, free amino acids, phenolic profiling, volatiles elucidation using headspace-solid phase microextraction gas chromatography–mass spectrometry (HS-SPME-GC-MS), aroma analysis using electronic nose), and microstructural analysis using scanning electron microscopy (SEM). Viable counts of bicultured purees showed probiotic effects exceeding 6–7 log CFU/mL. Strong positive correlations were observed between phenolic compounds (chlorogenic acid, rutin, p-coumaric acid) and antioxidant capacities (ABTS-RSA and DPPH-RSA). The darker color of raw jujube puree was modified, exemplified by a significant (p < 0.05) negative correlation between overall color difference and cyanidin 3-O-rutinoside (R2 = −0.768). Purees, particularly those containing bicultures of Lactobacillus helveticus Lh 43 and Acetobacter pasteurianus Ap-As.1.41 HuNiang 1.01 exhibited the highest potential free amino acid content (157.17 ± 1.12 mg/100 g FW) compared to the control (184.03 ± 1.16 mg/100 g FW) with a distinctive formation of L-methionine in biculture of Lactiplantibacillus plantarum Lp 28 and A. pasteurianus Ap-As.1.41 HuNiang 1.01. The phenolic profile of Lacticaseibacillus casei Lc 122 and A. pasteurianus Ap-As.1.41 HuNiang 1.01 increased by 22.79% above the control (48.34 mg/100 g FW) while biculture: L. helveticus Lh 43 and A. pasteurianus Ap-As.1.41 HuNiang 1.01 were enhanced by 4.37%, with the lowest profile in Lp. plantarum Lp 28 and A. pasteurianus Ap-As.1.41 HuNiang 1.01 (46.85 mg/100 g FW). The electronic nose revealed the predominant presence of sulfur, terpenes, and alcohol sensor bioactives in the fermented purees. HS-SPME-GC-MS analysis identified 80 volatile compounds in the bicultured purees, with esters constituting the major group (42%). Furthermore, SEM analysis unveiled massive microscopic alterations in the bicultured purees compared to the unfermented puree. These results collectively demonstrated that lactic–acetic acid co-fermentation serves to biovalorize Junzao jujube puree, enhancing its organoleptic appeal and extending its shelf life.

Quantitative detection of formaldehyde using solid phase microextraction gas chromatography–mass spectrometry coupled to cysteamine scavenging

Formaldehyde (HCHO) is a toxic and carcinogenic pollutant and human metabolite that reacts with biomolecules under physiological conditions. Quantifying HCHO is essential for ongoing biological and biomedical research on HCHO; however, its reactivity, small size and volatility make this challenging. Here, we report a novel HCHO detection/quantification method that couples cysteamine-mediated HCHO scavenging with SPME GC–MS analysis. Our NMR studies confirm cysteamine as an efficient and selective HCHO scavenger that out-competes O-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine, the most commonly used scavenger, and forms a stable thiazolidine amenable to GC–MS quantification. Validation of our GC–MS method using FDA and EMA guidelines revealed detection and quantification limits in the nanomolar and micromolar ranges respectively, while analysis of bacterial cell lysate confirmed its applicability in biological samples. Overall, our studies confirm that cysteamine scavenging coupled to SPME GC–MS analysis provides a sensitive and chemically robust method to quantify HCHO in biological samples.

Analysis of the Volatile Organic Compound Fingerprint of Greek Grape Marc Spirits of Various Origins and Traditional Production Styles

The most well-known traditional Greek grape marc distillate made from winemaking pomace is called “Tsipouro”. Its production involves various grape pomace cultivars, preparation protocols, and anise-flavoring or not, and it should be a colorless liquid with intense organoleptic properties due to the raw materials used in its production and have a minimum alcoholic strength of 37.5% by volume. This study aimed to characterize the volatilome of tsipouro products by covering as many geographical areas and production styles as possible, as there is a lack of characterization of the aromatic composition of this Greek traditional alcoholic beverage. A Headspace Solid Phase Microextraction Gas Chromatography–Mass Spectrometry (HS-SPME-GC-MS) method was applied in 60 samples, resulting in the identification and semi-quantification of over 90 volatile compounds. The statistical analysis pointed out the metabolites that characterized each traditional product group and underlined the influence of the geographical origin and the production protocol. Aniseed spirits from Northern Greece, Macedonia, Limnos Island, and Thessaly, produced from Muscat pomaces, were found to be richer in terpenes, terpenoids, and flavored compounds, attributing to product aroma and quality; different terpenoids were found to be dominant in Muscat distillates from different regions, showing the importance of geographical origin and production process. In conclusion, the results demonstrated the high aroma variability of the Greek Tsipouro, explained that this diversity is caused mainly by the raw material, and could be helpful in the better protection of the origin of this traditional product and the improvement of its quality.

Breeding of Persian melon: Purpose to increase volatile compounds in melon (Cucumis melo) intergroup F1 cross population

AbstractUnderstanding the volatile profile of melon is an ever increasingly important task for breeders for enhancing their flavour component. For this purpose, F1 progeny and parental lines were analysed using headspace‐solid phase microextraction gas chromatography–mass spectrometry‐based analysis. Diallel analysis showed that most of the investigated compounds were controlled via non‐additive genetic effects with general combining ability to specific combining ability ratios of less than 0.4. High heterosis results were observed in alcohols such as ethanol and octanol in both rind and mesocarp samples and benzylalcohol in the rind. It was also noted that the ester‐based compounds with high heterosis values in mesocarp samples differed from those with heterosis in rind samples. These observations further emphasize the non‐additive control of these compounds. It can be concluded that non‐additive genetic control is strongly governing the genetic profile within the studied progeny. This finding indicated that dudaim lines as a valuable genetic material enhanced the volatile profile of odourless commercial types of ameri and inodorus melon.

Effects of ultraviolet and infrared radiation absence or presence on the aroma volatile compounds in winegrape during veraison

Light environmental factors have been identified to influence grape aromas greatly. Among them, the effect of non-visible light on grape aroma compounds has scarcely been investigated during grape growth and development. In the present study, ultraviolet (UV) or infrared (IR) radiation was eliminated in the grape bunch zone, and the grape bunches were irradiated with UV or IR light in vitro. The effect of UV and IR radiation on the grape aroma profile of the Cabernet Sauvignon variety was assessed by headspace solid phase microextraction gas chromatography mass spectrometer (HS-SPME GC–MS). A total of 16 aroma compounds were identified in the grape berries under UV radiation absence (UV-) or IR radiation absence (IR-). They were classified into aliphatic alcohols, aliphatic acids, benzenolds, aldehydes, and monoterpenes. A total of 23 aroma compounds were identified in the grape berries under UV radiation presence (UV+) or IR radiation presence (IR+), which were classified into aliphatic alcohols, aliphatic ketones, aliphatic esters, aliphatic acids, monoterpenes, aldehydes, volatile phenols, and other volatiles. Linalool and hexanal aroma compounds were the most responsive to UV- and UV+, according to OPLS-DA analysis. Hexanal was increased by UV- and decreased by UV+, thus was negatively correlated with UV radiation. Benzaldehyde and 2-decanone were also found as the main differing aroma compounds according to VIP scores in the IR- and IR+, respectively. The significant differences of aroma compounds in three UV and IR intensities were also observed by headspace gas chromatography-ion mobility spectrometry (HS-GC-IMS). The content of acetic acid, 2-methylbutanal, and pentanal were reduced with the radiation intensity increase, and the content of 2–3-butanedione, butyl acetate, and 1-hexanol was enhanced, especially with UV radiation. This study improves our understanding of the non-visible light role in volatile aroma compound accumulation and further expands on the useful wavelength for plant growth and development. Our study provides a theoretical basis for non-visible light field management and indoor plant growth applications.

Investigation of Solid Phase Microextraction Gas Chromatography–Mass Spectrometry, Fourier Transform Infrared Spectroscopy and 1H qNMR Spectroscopy as Potential Methods for the Authentication of Baijiu Spirits

The baijiu spirit is often the focus of fraudulent activity due to the widely varying prices of the products. In this work, Solid Phase Microextraction Gas Chromatography (SPME GCMS), Fourier Transform Infrared (FTIR) Spectroscopy and 1H qNMR spectroscopy were evaluated as potential methods to authenticate baijiu samples. Data were collected for 30 baijiu samples produced by seven different distilleries. The data from the SPME GCMS and FTIR methods were treated by a Principal Component Analysis to identify clusters that would suggest chemical differences in the products from different distilleries. The results suggest that SPME GCMS has the potential to be a fully portable method for baijiu authentication. FTIR did not appear suitable for authentication but can be used to find the %ABV range of the sample. 1H quantitative NMR (1H qNMR) was utilized to quantify the ethanol concentrations and calculate the observable congener chemistry comprising ester, ethanol, methanol, fusel alcohol, and organic acids. Discrepancies in ethanol content were observed in three samples, and a lack of major congeners in two samples indicates the possible presence of a counterfeit product. Detailed and quantitative congener chemistry is obtainable by NMR and provides a possible fingerprint analysis for the authentication and quality control of baijiu style, producer, and the length of the ageing process.

Distant heteroploid hybridization improved Hedychium floral scent, floral color and morphologcal traits

Heteroploid hybridization is an important breeding technique for producing heteropolyploids with superior traits. Hedychium is widely used in medicine and as an ornamental plant; however, the fact that no current varieties exhibit both fragrance and colorful flowers causes a bottleneck in the genetic improvement of Hedychium. In the current study, diploid Hedychium coronarium 'ZS' (with strong fragrance and white flowers) and tetraploid Hedychium coccineum 'KMH' (scentless with red flowers) were used for the reciprocal heteroploid hybridization, and the 34 flowering hybrid offspring were analyzed for ploidy and hybrid authenticity, phenotype and floral scent. In 'ZS' ♀ × 'KMH' ♂, eight hybrids were triploids, while there were nine triploids and seventeen tetraploids in 'KMH' ♀ × 'ZS'♂. Furthermore, all hybrids were true hybrids as determined by simple sequence repeat (SSR) markers, and the presence of unreduced pollen in 'ZS' flowers was confirmed. Compared with the parents, 15 morphological traits and four flower color traits of hybrid offspring were widely separated. Hierarchical clustering analysis (HCA) and principal component analysis (PCA) showed that the parents and 34 hybrids could be divided into three groups mainly depending on organ size and color intensity. Headspace solid phase microextraction–gas chromatography–mass spectrometry (HS–SPME–GC–MS) identified 16 volatile organic compounds (VOCs), all of which were widely separated in the hybrid offspring. The HCA and PCA results confirmed that the parents and 34 hybrids could be classified into three groups mainly based on linalool, (E)-β-ocimene, eucalyptol, and methyl benzoate. Partial least squares discriminant analysis (PLS-DA) revealed that morphology, floral color and floral scent differed significantly between triploids and tetraploids, and the variable importance in projection (VIP) of 14 indexes was greater than 1. Finally, this study screened four new allopolyploid germplasms (HB30, HB46, HB54 and HB61) with colorful flowers and rich floral scent. These findings suggest a new strategy for cultivating new varieties with strong fragrance and bright colors.

Differential characterization of volatile components and aroma sensory properties of different types of Hehong tea (Congou black tea)

AbstractTo explore the flavour characteristics and their different molecular mechanisms of different types of Hehong tea (Gongya, GY; Congou, CG and Laocong, LC) from the perspective of dry tea, we investigated their volatile compounds and sensory aroma sub‐attribute characteristics by headspace–solid phase microextraction–gas chromatography–mass spectrometry (HS‐SPME‐GC–MS), quantitative description analysis (QDA), and chemometrics. A total of 42 volatile compounds were identified in Hehong tea, of which alcohol content was the highest, the number of esters was the largest and pyrrole showed the largest differences. The volatile components of GY and LC differed, whereas those of CG and LC were more similar. There were 34 volatile components with a significant difference in the three types of Hehong tea. We established the aroma quantitative system of Hehong tea by using QDA. We found that sweety was probably the symbolic aroma sub‐attribute of Hehong tea, and woody was the characteristic sub‐attribute of LC, and there was a certain correlation among the aroma sub‐attributes. A total of 21 volatile components importantly contributed to the aroma sub‐attributes of Hehong tea. Furthermore, we screened out 18 marker volatile compounds that may be used as important indicators for distinguishing the three types of Hehong tea. Our findings add to our understanding of the flavour characteristics and aromas of the three types of Hehong tea and provide new strategies and thoughts for the evaluation of tea flavour using dry tea.

An enzymatic tandem reaction to produce odor-active fatty aldehydes

Aldehydes represent a versatile and favored class of flavoring substances. A biocatalytic access to odor-active aldehydes was developed by conversion of fatty acids with two enzymes of the α-dioxygenase pathway. The recombinant enzymes α-dioxygenase (α-DOX) originating from Crocosphaera subtropica and fatty aldehyde dehydrogenase (FALDH) from Vibrio harveyi were heterologously expressed in E. coli, purified, and applied in a coupled (tandem) repetitive reaction. The concept was optimized in terms of number of reaction cycles and production yields. Up to five cycles and aldehyde yields of up to 26% were achieved. Afterward, the approach was applied to sea buckthorn pulp oil as raw material for the enzyme catalyzed production of flavoring/fragrance ingredients based on complex aldehyde mixtures. The most abundant fatty acids in sea buckthorn pulp oil, namely palmitic, palmitoleic, oleic, and linoleic acid, were used as substrates for further biotransformation experiments. Various aldehydes were identified, semi-quantified, and sensorially characterized by means of headspace–solid phase microextraction–gas chromatography–mass spectrometry–olfactometry (HS–SPME–GC–MS–O). Structural validation of unsaturated aldehydes in terms of double-bond positions was performed by multidimensional high-resolution mass spectrometry experiments of their Paternò–Büchi (PB) photoproducts. Retention indices and odor impressions of inter alia (Z,Z)-5,8-tetradecadienal (Z,Z)-6,9-pentadecadienal, (Z)-8-pentadecenal, (Z)-4-tridecenal, (Z)-6-pentadecenal, and (Z)-8-heptadecenal were determined for the first time.Key points• Coupled reaction of Csα-DOX and VhFALDH yields chain-shortened fatty aldehydes.• Odors of several Z-unsaturated fatty aldehydes are described for the first time.• Potential for industrial production of aldehyde-based odorants from natural sources.Graphical abstract

Correlations between microbiota with physicochemical properties and volatile compounds during the spontaneous fermentation of Cabernet Sauvignon (Vitis vinifera L.) wine

Understanding the diversity and evolution of microorganisms during wine fermentation is essential for controlling its production. However, the flavors profiles associated with microbiota changes during the spontaneous fermentation have not yet been described in detail. In this study, we explored the correlations between microbial community with physicochemical properties and flavor components during the spontaneous fermentation of Cabernet Sauvignon wine. Microbial community diversity at different fermentation stages was identified using high-throughput sequencing, and physicochemical properties and volatile compounds were identified through fermentation features testing and headspace solid phase microextraction gas chromatography mass spectrometry. First, the diversity of the fungi community decreased with the fermentation process, whereas the bacteria did not change significantly until the end of the fermentation. Second, the changes of the fermentation environment had reshaped the diversity and composition of the microbial community. Finally, Aureobasidium, Cladosporium, Filobasidium, Hanseniaspora, Hannaella, Saccharomyces, Alternaria, Wickerhamomyce, Starmerella, Candida, Papiliotrema, Bradyrhizobium, Gluconobacter, Leuconostoclia, Comamonas, Acetobacter, and Massilia, were significantly correlated with changes of physicochemical properties and volatile compounds. Overall, our research results provide important insights for understanding the metabolically active microbiota, which is conducive to the expression of wine "terroir".

Association Between Serum Aldehydes and Hypertension in Adults: A Cross-Sectional Analysis of the National Health and Nutrition Examination Survey.

BackgroundExposure to ambient pollutants and chemicals were found to be associated with increased risk of hypertension. However, the relationship between the increased aldehyde exposure and hypertension are still unclear. This study aimed to investigate the potential associations of serum aldehydes levels with prevalent hypertension.MethodsA total of 1,733 U.S. adults with data on hypertension outcome and serum aldehydes measurement from the National Health and Nutrition Examination Survey 2013–2014 were included. The serum levels of aldehydes were measured via an automated analytical method using solid phase microextraction gas chromatography and high-resolution mass spectrometry. Multivariate logistic regression models were adopted to assess the associations between six selected aldehydes exposure (benzaldehyde, butyraldehyde, heptanaldehyde, hexanaldehyde, isopentanaldehyde, and propanaldehyde) and prevalence of hypertension.ResultsThe mean age was 48.0 ± 16.7 years and an approximately equivalent of sex distribution was observed (female 49.9%). There seems to be a numerically higher level of hexanaldehyde in participants with hypertension when compared to participants without hypertension (2.6 ± 3.9 ng/mL vs. 2.3 ± 1.1 ng/mL). After adjusting for potential confounders, the odds ratio (OR) for hypertension was 2.15 [95% confidence interval (CI): 1.33–3.51] in participants from the highest quartile of serum hexanaldehyde concentration in comparison to those from the lowest quartile. Subgroup analyses and sensitivity analyses showed generally similar results.ConclusionIn summary, current evidence suggested that increased serum hexanaldehyde level was positively associated with prevalent hypertension in U.S. adults.

Disclosing the chemistry of oil curing by mass spectrometry using methyl linoleate as a model binder

The structure of the polymeric fraction in an oil painting is believed to be strongly connected to the stability of the paint layers over time, but its molecular characterisation is extremely difficult given the complex composition of a vegetable oil-based polymer.In this study we report the implementation of a methodological approach for the systematic mass spectrometric investigation of the molecular features of the products of oxidative degradation and cross-linking of oil paint layers upon curing. The approach is based on the use of methyl linoleate as a simplified model of an oil paint binder. Gas-chromatography coupled with mass spectrometry, solid phase microextraction gas chromatography mass spectrometry, flow injection electrospray mass spectrometry and evolved gas analysis mass spectrometry, are used to analyse the evolution of compounds produced over seven months of natural ageing, from the volatile products to the macromolecular and cross-linked fractions. The aim is to improve our fundamental molecular understanding of the curing process of oil paints, and to investigate the balance between oxidative degradation and cross-linking when specific binder-pigment combinations are in place.Model paint layers were prepared using lead white and ultramarine blue as pigments. These two pigments are known to produce paint layers with different stability over time. The use of methyl linoleate as model oil binder greatly simplifies the mass spectral features of the lipid paint fraction, enabling the detection of products of oxidation and cross-linking with a new high level of molecular detail. Data clearly show that crucial differences between paints containing the two pigments establish with time, which are mostly related to the cross-linked fraction.

Optimization of Volatile Compounds Extraction from Industrial Celery (Apium graveolens) By-Products by Using Response Surface Methodology and Study of Their Potential as Antioxidant Sources.

In this study, the potential of industrial celery by-products (the stalk and root) serving as sources of aromatics and antioxidants was investigated. A headspace solid phase microextraction–gas chromatography–mass spectrometry (HS-SPME–GC–MS) procedure was optimized to isolate volatile compounds from celery by-products. A Box–Behnken experimental design was proposed to optimize the procedure through a response surface methodology. The optimal extraction conditions were found to be 1.6 g of homogenized fresh by-product at 30 °C for 60 min. Under these conditions, 26 volatile compounds in stalk and root samples were identified, monoterpenes and sesquiterpenes being the main components. The content of limonene and γ-terpinene found in the stalk was significantly higher in comparison with root samples. Total phenolic content and antioxidant activity (ABTS and FRAP) results underlined the celery wastes studied as good sources of free radical scavengers. This work suggests the potential application of these by-products in the food industry and opens new pathways to valorize celery residues, contributing to the circular economy.

Dynamic changes of 3-MCPD esters and glycidyl esters contents as well as oil quality during repeated deep-frying

In this study, the dynamic changes of 3-monochloropropane-1,2-diol esters (3-MCPDEs) and glycidyl esters (GEs) in both oils and French fries were assessed using headspace–solid phase microextraction–gas chromatography–mass spectrometry over the course of 5 days repeated deep-frying. The color parameter, as well as the concentrations of tocopherols and total polar components (TPC) in frying oils, were also evaluated. The content of 3-MCPDEs in frying oil reduced by 71.2% in the first two days of frying while GEs increased steadily. The concentration of 3-MCPDEs in French fries increased over the repeated frying while GEs and oil uptake maintained constant. The concentration of tocopherols decreased while TPC increased significantly during repeated deep-frying. Microstructure analysis of French fries by X-ray micro-computed tomography (micro-CT) indicated the reduction of micropores and the appearance of bigger oil-filled macropores, which might be responsible for the enrichment effect of French fries on 3-MCPDEs and GEs. This research broadens the understanding of the fate of 3-MCPDEs and GEs in repeated deep-frying.

Interaction mechanism of collagen peptides with four phenolic compounds in the ethanol-water solution

This study demonstrated the interaction mechanism of collagen peptides (CPs) with 4-ethylphenol (4-EP), phenol, guaiacol, and 4-ethylguaiacol (4-EG) in the ethanol-water solution. The ultraviolet visible spectroscopy, zeta potential tests and hydrogen nuclear magnetic spectroscopy manifested that CPs interacted with the phenolic compounds. Meanwhile, Isothermal titration calorimetry determination indicated that the CPs was hydrogen bonded with 4-EP in 52 %(v/v) ethanol-water solution, while the hydrophobic forces played a major role in the interaction of CPs with guaiacol and 4-EG, respectively. Moreover, hydrogen and hydrophobic bonds were involved in the interaction between CPs and phenol. Finally, Head Space-solid Phase Microextraction Gas Chromatography Mass Spectrometry analysis indicated that the content of phenolic compounds in model solution efficiently decreased with the presence of CPs. In the real liquor, it was found that the content of volatile compounds (including phenolic compounds) was obviously decreased after CPs added.

Production and recovery of volatile compounds from fermented fruit by-products with Lacticaseibacillus rhamnosus

In the last years, due to the increasing interest of consumers in natural products, market and industry choices were more directed towards the use of fragrances and flavors obtained from natural sources. Fermentation is a biological approach helpful to produce diverse aromatic compounds modifying precursors present in raw material, due to a wide array of extracellular enzymes which could be produced by microorganisms. Following this direction Lacticaseibacillus rhamnosus was employed as a starter for melon and orange by-products fermentation. Simple and vacuum distillation were applied for the recovery of the aromatic fraction and compared to identify the more promising in terms of aromatic profile composition. Detection and characterization of aromatic compounds were achieved using Head SpaceSolid Phase MicroExtraction Gas Chromatography–Mass Spectrometry (HS-SPME/GC–MS) approach. Fermentation led to interesting changes, increasing floral, herbal green and fruity notes. Overall, simple distillation allowed the greater recovery of aromatic compounds in terms of concentration for both substrates. This study highlights a possible strategy to produce complex distillates, composed of a mixture of aroma compounds, to be employed as additives in food, feed or perfumery industries as ingredients of natural origin.

Comprehensive SPME-GC-MS Analysis of VOC Profiles Obtained Following High-Temperature Heating of Pork Back Fat with Varying Boar Taint Intensities.

Boar taint detection is a major concern for the pork industry. Currently, this taint is mainly detected through a sensory evaluation. However, little is known about the entire volatile organic compounds (VOCs) profile perceived by the assessor. Additionally, many research groups are working on the development of new rapid and reliable detection methods, which include the VOCs sensor-based methods. The latter are susceptible to sensor poisoning by interfering molecules produced during high-temperature heating of fat. Analyzing the VOC profiles obtained by solid phase microextraction gas chromatography–mass spectrometry (SPME-GC-MS) after incubation at 150 and 180 °C helps in the comprehension of the environment in which boar taint is perceived. Many similarities were observed between these temperatures; both profiles were rich in carboxylic acids and aldehydes. Through a principal component analysis (PCA) and analyses of variance (ANOVAs), differences were highlighted. Aldehydes such as (E,E)-nona-2,4-dienal exhibited higher concentrations at 150 °C, while heating at 180 °C resulted in significantly higher concentrations in fatty acids, several amide derivatives, and squalene. These differences stress the need for standardized parameters for sensory evaluation. Lastly, skatole and androstenone, the main compounds involved in boar taint, were perceived in the headspace at these temperatures but remained low (below 1 ppm). Higher temperature should be investigated to increase headspace concentrations provided that rigorous analyses of total VOC profiles are performed.

The Stool Volatile Metabolome of Pre-Term Babies.

The fecal metabolome in early life has seldom been studied. We investigated its evolution in pre-term babies during their first weeks of life. Multiple (n = 152) stool samples were studied from 51 babies, all <32 weeks gestation. Volatile organic compounds (VOCs) were analyzed by headspace solid phase microextraction gas chromatography mass spectrometry. Data were interpreted using Automated Mass Spectral Deconvolution System (AMDIS) with the National Institute of Standards and Technology (NIST) reference library. Statistical analysis was based on linear mixed modelling, the number of VOCs increased over time; a rise was mainly observed between day 5 and day 10. The shift at day 5 was associated with products of branched-chain fatty acids. Prior to this, the metabolome was dominated by aldehydes and acetic acid. Caesarean delivery showed a modest association with molecules of fungal origin. This study shows how the metabolome changes in early life in pre-term babies. The shift in the metabolome 5 days after delivery coincides with the establishment of enteral feeding and the transition from meconium to feces. Great diversity of metabolites was associated with being fed greater volumes of milk.