Solid-phase Microextraction-gas Chromatography-mass Spectrometry Research Articles

Canine-Inspired Chemometric Analysis of Volatile Organic Compounds in Urine Headspace to Distinguish Prostate Cancer in Mice and Men.

Canines can identify prostate cancer with high accuracy by smelling volatile organic compounds (VOCs) in urine. Previous studies have identified VOC biomarkers for prostate cancer utilizing solid phase microextraction (SPME) gas chromatography-mass spectrometry (GC-MS) but have not assessed the ability of VOCs to distinguish aggressive cancers. Additionally, previous investigations have utilized murine models to identify biomarkers but have not determined if the results are translatable to humans. To address these challenges, urine was collected from mice with prostate cancer and men undergoing prostate cancer biopsy and VOCs were analyzed by SPME GC-MS. Prior to analysis, SPME fibers/arrows were compared, and the fibers had enhanced sensitivity toward VOCs with a low molecular weight. The analysis of mouse urine demonstrated that VOCs could distinguish tumor-bearing mice with 100% accuracy. Linear discriminant analysis of six VOCs in human urine distinguished prostate cancer with sensitivity = 75% and specificity = 69%. Another panel of seven VOCs could classify aggressive cancer with sensitivity = 78% and specificity = 85%. These results show that VOCs have moderate accuracy in detecting prostate cancer and a superior ability to stratify aggressive tumors. Furthermore, the overlap in the structure of VOCs identified in humans and mice shows the merit of murine models for identifying biomarker candidates.

Unraveling the microbial succession during the natural fermentation of grass carp and their correlation with volatile flavor formation

Complex microbial communities contribute significantly to the flavor formation of traditional fermented fish products. However, the relationship between microorganisms and flavor formation in traditional fermented grass carp products is still unclear. In this study, the diversity and succession of microbial communities and the variation of volatile compounds during natural fermentation of grass carp were analyzed using high-throughput sequencing of 16S rRNA and headspace solid-phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS), respectively. The core functional microorganism and key volatile compounds were identified, and their potential relationship was revealed using a correlation network model analysis. The microbial community analysis result showed that the microbial diversity during natural fermentation of grass carp decreased markedly with increasing fermentation time, and Lactiplantibacillus, Staphylococcus, and Enterobacter were the dominant genera in naturally fermented grass carp. HS-SPME-GC-MS analysis result showed that 45 volatile compounds were identified from fermented samples, among which 13 compounds (e.g., hexanal, heptanal, nonanal, decanal, 3-octanone, 3-methyl-1-butanol, 1-hexanol, 1-heptanol, 1-octen-3-ol, 1-octanol, ethyl acetate, 3-methyl-1-butanol acetate, and 2-methoxy-4-vinylphenol) were identified as the key volatile compounds. Additionally, the correlation network model analysis result revealed that Lactiplantibacillus showed significantly positive correlations with most of the key volatile compounds, making an important contribution to the formation of volatile flavor in naturally fermented grass carp. This study may lead to an understanding of the role of core functional microorganisms in the formation of volatile flavor during the natural fermentation of grass carp and provide some theoretical guidance for the industrial production of high-quality fermented grass carp products.

A volatile producing Bacillus subtilis strain from the rhizosphere of Haloxylon ammodendron promotes plant root development

AimsThe colonization of plant growth-promoting rhizobacteria (PGPR) along plant roots in turn facilitates their ability to promote plant growth and health. In this study, we found that Bacillus subtilis strain WM13-24 from the rhizosphere of Haloxylon ammodendron was able to promote the growth of both Arabidopsis and its host plant. Furthermore, we found that volatile organic compounds (VOCs) from strain WM13-24 could promote plant growth by stimulating lateral root formation and root hair growth. However, the molecular mechanism underlying WM13-24-stimulated root development is still unknown.MethodsIn this study, a series of Arabidopsis mutants defective in specific plant hormone signaling pathways were used as materials to preliminarily study the effect of VOCs released by strain WM13-24 on plant root development through genetic and pharmacological methods. The volatile compounds of strain WM13-24 were identified by solid-phase microextraction gas chromatography-mass spectrometry (SPME–GC–MS).ResultsWM13-24 was able to promote the growth of both Arabidopsis and its host plant, H. ammodendron. Auxin signaling and transport played a crucial role in WM13-24-stimulated changes of root architectures in Arabidopsis. SPME–GC–MS analysis revealed that WM13-24 produces various classes of compounds. We further showed that 2,3-butanediol and benzyl alcohol were active in promoting plant growth and the growth responses of plants to the two VOCs were concentration dependent.ConclusionsAll these results suggested that VOCs emitted from B. subtilis strain WM13-24 from the rhizosphere of H. ammodendron improves root development depending on auxin signaling.

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.

Volatile Aroma Compounds of Gavina® Watermelon (Citrullus Lanatus L.) Dietary Fibers to Increase Food Sustainability

To deal with climate emergency and reduce environmental impact, agro-industrial wastes are gradually gaining interest and are being used for new products and applications. The large production of watermelons represents an opportunity because of the many byproducts that can be transformed into innovative and valuable foodstuffs. In this study, we examined the lycopene-rich whole dietary fiber (WDF) obtained from the watermelon pomace of a peculiar cultivar, Gavina® (Oristano, Italy) a seedless fruit from Sardinia (Italy). The volatile chemical composition of the WDF was investigated using Solid-Phase Microextraction-Gas Chromatography/Mass Spectrometry (SPME-GC/MS). The aim was to follow the evolution of the Volatile Organic Compounds (VOCs) fraction during storage and verify its stability over time. Since watermelon is an excellent source of carotenoids, their byproducts were the most abundant VOCs of the freshly prepared samples, but their overall abundance decreased significantly during storage. The opposite trend was observed for acids and aldehydes, whose increase over time is related to amino acid degradation. Freshly prepared WDF can be used in the food industry as an antioxidant-rich dietary fiber that imparts a characteristic and pleasant aroma. Over time, its aroma profile and carotenoid content change considerably, reducing its health properties and limiting its potential application as a natural flavor.

Natural overexpression of CAROTENOID CLEAVAGE DIOXYGENASE 4 in tomato alters carotenoid flux.

Carotenoids and apocarotenoids function as pigments and flavor volatiles in plants that enhance consumer appeal and offer health benefits. Tomato (Solanum lycopersicum.) fruit, especially those of wild species, exhibit a high degree of natural variation in carotenoid and apocarotenoid contents. Using positional cloning and an introgression line (IL) of Solanum habrochaites "LA1777', IL8A, we identified carotenoid cleavage dioxygenase 4 (CCD4) as the factor responsible for controlling the dark orange fruit color. CCD4b expression in ripe fruit of IL8A plants was ∼8,000 times greater than that in the wild type, presumably due to 5' cis-regulatory changes. The ShCCD4b-GFP fusion protein localized in the plastid. Phytoene, ζ-carotene, and neurosporene levels increased in ShCCD4b-overexpressing ripe fruit, whereas trans-lycopene, β-carotene, and lutein levels were reduced, suggestive of feedback regulation in the carotenoid pathway by an unknown apocarotenoid. Solid-phase microextraction-gas chromatography-mass spectrometry analysis showed increased levels of geranylacetone and β-ionone in ShCCD4b-overexpressing ripe fruit coupled with a β-cyclocitral deficiency. In carotenoid-accumulating Escherichia coli strains, ShCCD4b cleaved both ζ-carotene and β-carotene at the C9-C10 (C9'-C10') positions to produce geranylacetone and β-ionone, respectively. Exogenous β-cyclocitral decreased carotenoid synthesis in the ripening fruit of tomato and pepper (Capsicum annuum), suggesting feedback inhibition in the pathway. Our findings will be helpful for enhancing the aesthetic and nutritional value of tomato and for understanding the complex regulatory mechanisms of carotenoid and apocarotenoid biogenesis.

Isolation of Volatiles in Honeysuckle by Multiple Approaches with Determination by Gas Chromatography–Mass Spectrometry (GC–MS) and Headspace Solid-Phase Microextraction-Gas Chromatography–Mass Spectrometry (HS-SPME/GC–MS)

The volatile components of honeysuckle were determined using hydro-distillation (HD), water extraction coupling rectification (WER), and water extraction coupling rectification with solvent extraction (WER-SE). Gas chromatography–mass spectrometry (GC–MS) and headspace solid-phase microextraction–gas chromatography–mass spectrometry (HS-SPME/GC–MS) identified 127 compounds. There were 27 common compounds extracted by these methods. A heatmap of the 27 common compounds indicates that WER-SE and WER were complementary approaches. In addition, 59 compounds were detected for the first time in honeysuckle. The results of this study provide a reference for the determination of volatile components in plants.

Malodorous volatile organic compounds (MVOCs) formation after dewatering of wastewater sludge: Correlation with the extracellular polymeric substances (EPS) and microbial communities

Malodorous volatile organic compounds (MVOCs) are often the key odorants in determining sludge odor character and odor impact. However, the emission characterization and generation mechanisms of MVOCs from various dewatered sludge have not been sufficiently understood partly due to the diverse and complex composition and low concentration of odorants. In this study, waste activated sludge (WAS) was collected to examine the variation of MVOC emission from sludge after different dewatering treatment in lab-scale trials. The MVOCs were measured using the electronic nose (eNose), headspace gas chromatography-coupled ion mobility spectrometry (HS-GC-IMS), and headspace solid-phase microextraction gas chromatography–mass spectrometry (HS-SPME-GC–MS). The results showed that centrifugation treatment promoted the generation of various odorous volatiles. The identified key odorants included dimethyl sulfide (DMS), dimethyl disulfide (DMDS), dimethyl trisulfide (DMTS), geosmin, and p-cresol according to their odor activity values (OAVs). The effects of the enhanced dewatering on volatile production were greater than thickening, however, the key odorants of dewatered sludge using gravity thickening varied more greatly than sludges from centrifuge thickening. The distribution of extracellular polymeric substances (EPS) and variation of microbial community showed correlations with the production of key odorants. Tryptophan-like substances in the inner layer of EPS (LB-EPS and TB-EPS) were better correlated with the key odorants. The bound EPS released by centrifugation may play the role of precursor for odorous microbial volatiles. According to the predicted functions of differential microbial genera, Desulfobulbus (Desulfobacterota), Gordonia (Actinobacteriota), and Hyphomicrobium (Proteobacteria) were associated with the production of DMS, DMDS, and DMTS, while Gordonia and Hyphomicrobium were related to p-cresol production.

Investigating the Aromatic Compound Changes in Table Grape Varieties during Growth and Development, Using HS-SPME-GC/MS

This study aimed to identify the aromatic compounds present in the different aroma types of different table grape varieties and deeply understand the changes in the aromatic compounds during the growth and development process. The skin and flesh of three table grape varieties (‘Kyoho’, ‘Shine Muscat’, and ‘Ryuho’) in different growth and development stages were selected to determine their aromatic compounds using headspace solid-phase microextraction gas chromatography-mass spectrometry and principal component analysis. The results showed that the aromatic compounds of the ‘Kyoho’ and ‘Ryuho’ grapes were similar, mainly containing C6 compounds and esters, whereas ‘Shine Muscat’ was characterized by C6 compounds and terpenes. The levels of aromatic compounds in the skin were higher than those in the flesh. The content of esters in ‘Ryuho’ was significantly higher than that in ‘Kyoho’ and ‘Shine Muscat’. This showed that ‘Ryuho’ combines the advantages of the parents in its aroma composition. Selecting suitable parents for hybridization is one method for obtaining new varieties with a special aroma. This provides a theoretical basis for future molecular hybrid breeding and molecular-assisted breeding, as well as molecular biology research on aroma synthesis and metabolism in table grapes.

Microbial Diversity and Volatile Flavor Compounds in Tibetan Flavor Daqu.

In this study, the microbial diversity in Tibetan flavor Daqu was analyzed based on single molecule real-time sequencing (SMRT). The volatile flavor compounds in Daqu were detected using the headspace solid-phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS). In addition, the correlation between various microbes and volatile flavor compounds was explored. Our studies indicated that the dominant bacterial genera in Tibetan flavor Daqu were Oceanobacillus, Kroppenstedtia, Virgibacillus, Enterococcus, Pediococcus, Streptomyces, Saccharopolyspora, Leuconostoc, uncultured_bacterium_f_Lachnospiraceae and Lactobacillus. The dominant fungal genera were Wickerhamomyces, Monascus, Aspergillus and Rhizomucor. 101 volatile compounds were detected in the Daqu samples, including alcohols, acids, esters, aldehydes, hydrocarbons, ketones, ethers, aromatics and pyrazines, and 10 key flavor compounds were identified using the relative odor activity value (ROAV). The results of our correlation analysis showed that Enterococcus was mainly associated with the synthesis of aldehydes such as trans-2-octenal, and uncultured_bacterium_f_lachnospiraceae was associated with the synthesis of most aldehydes. This paper has systematically investigated the physicochemical indices, microbial community structure and flavor compounds of Tibetan flavor Daqu, which is helpful in gaining a deeper understanding of the characteristics of Tibetan flavor Daqu.

GC–MS and LC-MS/MS metabolomics revealed dynamic changes of volatile and non-volatile compounds during withering process of black tea

High-performance liquid chromatography (HPLC), headspace solid-phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC–MS) and ultra-high performance liquid chromatography–Q-Exactive HF-X mass spectrometer (UHPLC–Q-Exactive HF/MS) were carried out to reveal dynamic changes of volatile and non-volatile compounds during the withering process of black tea. A total of 118 volatile organic compounds (VOCs) and 648 metabolites were identified in fresh and withered tea-leaves, respectively. Among them, 47 VOCs (OAV > 1.0) for the aroma formation, and 46 characteristic metabolites (VIP > 1.50, p < 0.01) selected through orthonormal partial least squares-discriminant analysis, indicated the withering contribution during black tea processing. Overall, the withering promoted alcohols, aldehydes, phenols, heterocyclic oxygen, hydrocarbons and halogenated hydrocarbons through relevant hydrolyzation, decomposition, terpene synthesis, and O-methylation. The hydrolyzation, O-methylation, condensation and N-acylation of kaempferol glycosides, quercetin glycosides, ester catechins, and gallic acid generated the accumulation of methoxyl flavonoids and flavonoid glucosides, dihydrokaempferol, syringic acid, theaflavins, and N-acylated amino acids, respectively.

Investigation of simultaneous volatile organic compound removal by indoor plants using solid phase microextraction-gas chromatography-mass spectrometry.

Volatile organic compounds (VOCs) are significant indoor air pollutants, and employing plants offers a simple and cost-effective approach to reduce their concentration. It is important to determine which plant exhibits greater efficiency in removing specific VOCs. This study aimed to compare the efficacy of various common indoor plants in simultaneously removing multiple hazardous VOCs. A sealed chamber was utilized to expose five different species of houseplants to eight commonly found VOCs. The concentrations of each compound were monitored over an extended period using solid phase microextraction (SPME) coupled with gas chromatography-mass spectrometry (GC-MS). The study determined and reported the efficiency of removal per leaf area for all compounds by each plant under different conditions, including removal by the entire plant (with and without light) and removal by the plant's leaf area. The paper discusses the efficiency and rate of removal of each VOC for the tested plants, namely Chlorophytum comosum, Crassula argentea, Guzmania lingulata, Consolea falcata, and Dracaena fragrans.

Tea pairings: Impact of aromatic congruence on acceptance and sweetness perception

Food pairing is a relevant tool for the food industry and for culinary professionals to develop successful flavor combinations and memorable experiences, but it could also be useful for encouraging consumers to adhere to a healthier diet. The general purpose of this study was to further investigate the perception of teas and butter cookies with and without aromatic congruence, deepening in sweetness perception. The experimental included: 1) a projective mapping test (30 semi-trained panelists) to group tea samples and choose representatives of each aromatic group; 2) the determination of the main volatile organic compounds using Solid Phase Micro Extraction-Gas Chromatography Mass Spectrometry (SPME-GC-MS) to prove the aromatic congruence of the designed tea-cookie pairings; 3) a consumer study (n = 89) to assess liking, sweetness perception, of the single samples and pairings, and the pairing principles of the congruent and non-congruent parings. Results of the projective mapping showed that the tea samples could be grouped into 3 main categories by their herbal, fruity-sweet, and brown-sweet notes, results also supported by the GCMS data. Harmony was positively correlated to liking, and Balance and Similarity seemed to be related to aromatic “congruence”, although all pairings were similarly liked. Sugar content was similar in all the cookie samples and pairings, but sweetness perception was significantly influenced by the aroma of the samples, being the samples and pairings made with spearmint the least sweet ones. Pairing a tea with sweet aromas with the spearmint cookie, independently of the kind of sweet aromatics (e.g.: coconut, almond, vanilla, fruity, tropical), seemed to slightly increase sweetness perception, although significant differences were not detected with other spearmint cookie pairings. Findings of the present research sum knowledge to the food pairing area, but further research is needed in recommending appropriate methodologies for pairing assessment, as well as the potential uses of driven pairings in specific food cultures.

Effects of household-scale cooking on volatile compounds, sensory profile, and hypotensive effect of Kenikir (&lt;i&gt;Cosmos caudatus&lt;/i&gt;)

&lt;abstract&gt; &lt;p&gt;Kenikir (&lt;italic&gt;Cosmos caudatus&lt;/italic&gt;) can be used in the preparation of raw and cooked vegetables in some Indonesian dishes. The cooking process may affect the appearance, chemical properties, and flavor of kenikir. This study aims to determine the effect of household scale cooking on the volatile compounds, sensory profiles, and hypotensive activity of kenikir. Fresh kenikir samples and samples boiled or steamed at 100 ℃ (for 3 and 5 minutes) were analyzed for volatile compounds compositions (solid-phase microextraction-Gas chromatography-mass spectrometry, SPME-GCMS), sensory profiles by free choice profiling, and in-vivo study by using stroke-prone spontaneously hypertensive rats (SHRSP)—a model of spontaneous hypertension. The GCMS analysis identified 30 volatile compounds from 5 compound groups, namely alcohols (2 compounds), benzenes (3 compounds), esters (3 compounds), monoterpenes (10 compounds), and sesquiterpenes (12 compounds). Several compounds, namely (Z)-3-hexenol, α-cadinol, and 3-carene were only detected in fresh kenikir, whereas β-myrcene and β-elemene compounds were only identified after cooking. The principal component analysis of sensory attributes associated fresh kenikir with bright color and minty taste, steamed kenikir with floral aroma, and boiled kenikir with juicy, moist, tender, and smooth texture. Furthermore, a hypotensive effect was shown in the water extract of kenikir after 2 and 4 hours of single oral administration in SHRSP. In summary, the heating process (boiled and steamed) of kenikir has changed its volatile compound composition, which can affect its sensory profiles. In addition, the water extract of kenikir can diminish hypertension in SHRSP.&lt;/p&gt; &lt;/abstract&gt;

Variabilidade dos perfis de compostos voláteis durante dois períodos de fermentação do café no norte do Peru usando SPME-GC/MS

Abstract The time of the fermentation process of coffee from northern Peru is variable (9 to 48 hours) since coffee farmers do not use standardized processes, causing a variety of coffee qualities. This study aimed to identify volatile compounds in both short (9 hours) and long (32 hours) coffee fermentation processes from coffee farms in northern Peru using Solid-Phase Microextraction-Gas Chromatography/Mass Spectrometry (SPME-GC/MS) to associate the coffee quality and diversity of volatile compounds. Sensory analyses showed that the short fermentation process (SFP) scored 77.8 ± 0.39 and had chocolate, wood, cardboard, dry, fatty and rough notes, while the long fermentation process (LFP) showed higher punctuations 85.5 ± 3.16 and citrus, fruity, floral, caramel and chocolate sensory attributes. A total of 90 compounds were found in the SFP, whereas 141 compounds were identified in the LFP. Significant differences in the relative abundance of 14 chemical compounds were reported in the SFP and LFP (p &lt; 0.05). From these results, the presence of benzaldehyde, methional, hexanal, 2-heptanone, pentadecane, 1-butanol-3-methyl-acetate, and benzene-acetic acid ethyl ester seems to impact the quality of coffee. The analysis of similarities showed that coffee samples (5 h and 9 h) during the SFP were very variable, whereas coffee samples from LFP showed some tendency to group, which may be related to the difference in altitude and temperature in coffee farms making comparison between them difficult. In addition, this study highlights the complex relationship between coffee fermentation and flavour and the influence of several factors and variables that may affect the composition of flavour and aroma precursors in green coffee beans obtained from wet fermentation.

Characterization of physical properties, volatile compounds and aroma profiles of different salted egg yolk lipids

Salted egg yolks (SEY) have a desirable and unique flavor with multiple underlying applications in food processing, and their abundant lipids contribute to a creamy and pleasant aroma. However, it is important to maintain the stability of the SEY flavor, which depends to a large extent on the egg species and the processing method. This study aimed to extract different SEY lipids with conventional solvents, analyze the fatty acid composition, and screen the volatile compounds to elucidate the flavor differences between salted hen eggs and duck eggs. Compared to ethanol extraction, acetone-extracted lipids had lower acid value and viscosity, and almost had no phospholipid content. Fatty acid analysis revealed that the highest content of fatty acid in SEY lipids was oleic acid, followed by palmitic acid and linoleic acid, while there were significant variations of different SEY lipids in the fatty acid profiles. The volatile compounds were identified by headspace solid-phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC–MS), and the overall odor was detected by the electronic nose (E-nose). A total of 27 volatile compounds were analyzed in SEY lipids and divided into 8 chemical classes. The aldehydes, furans and pyrazines were decreased, and the hydrocarbons were increased compared with untreated SEY. The combination of the physical properties and flavor evaluation of SEY lipids could provide a theoretical basis for the extension of the characteristic flavor matrix in SEY.

Controlled air exchange rate method to evaluate reduction of volatile organic compounds by indoor air cleaners

Air cleaning technologies are needed to reduce indoor concentrations and exposure to volatile organic compounds (VOCs). Currently, air cleaning technologies lack an accepted test standard to evaluate their VOC removal performance. A protocol to evaluate the VOC removal performance of air cleaning devices was developed and piloted with two devices. This method injects a VOC mixture and carbon dioxide into a test chamber, supplies outdoor air at a standard building ventilation rate, periodically measures the VOC concentrations in the chamber using solid phase microextraction-gas chromatography-mass spectrometry over a 3-h decay period, and compares the decay rate of VOCs to carbon dioxide to measure the VOC removal air cleaning performance. The method was demonstrated with both a hydroxyl radical generator and an activated carbon air cleaner. It was shown that the activated carbon air cleaner device tested had a clean air delivery rate an order of magnitude greater than the hydroxyl radical generator device (72.10 vs 6.32 m3/h).

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.

The Flavor Profiles of Highland Barley Fermented with Different Mushroom Mycelium.

Highland barley was fermented with Cordyceps militaris, Stropharia rugoso-annulata, Morchella esculenta, Schizophyllum commune and Tremella sanguinea. The flavor profiles were investigated by electronic nose (E-nose), headspace solid-phase microextraction gas chromatography-mass spectrometry (HS-SPME-GC-MS) and sensory evaluation by train panel. Fermentation with mushroom mycelium was able to change the aroma profile of highland barley. The original strong grassy taste was reduced due to a decrease in hexanal, decanal and 2-pentylfuran, and new aromatic flavors (floral, sweet and mushroom fragrance) were acquired after fermentation. The overall flavor of the fermented highland barley varied with mushroom strains. Schizophyllum commune gave a heavier sour taste to the fermented highland barley. However, fermentation with T. sanguinea increased the content of methyl 4-methoxybenzoate making the sample difficult to accepted. Fermentation with C. militaris, M. esculenta, and S. rugoso-annulata increased the volatile contents. The high levels of 1-octen-3-ol and esters gave a strong mushroom, oily and fruity flavor. Morchella esculenta showed the best performance and the highest acceptance in the fermented highland barley. Our results suggest that fermentation with mushroom mycelium can improve the flavor of highland barley, which provides an innovative utilization of highland barley.

Characterization of a novel flavored yogurt enriched in γ-aminobutyric acid fermented by Levilactobacillus brevis CGMCC1.5954

This study developed and characterized a γ-aminobutyric acid (GABA)-enriched yogurt fermented by Levilactobacillus brevis CGMCC1.5954. The GABA content in the yogurt was 147.36 mg/100 mL, which was 317.06% higher than that of the control group. Furthermore, there was a significant improvement in the aroma, hardness, adhesion, cohesiveness, and gelatinousness of yogurt. The chromatography and metabolomics analyses further confirmed the high GABA content in yogurt and its nutritional value, and the metabolic pathway for GABA production by L. brevis 54 was identified. A total of 58 volatile flavor compounds were identified using headspace solid-phase microextraction-gas chromatography-mass spectrometry, of which 2-nonanone and 2-heptanone may be responsible for the high odor score of GABA-enriched yogurt. This study developed a nutritious and unique GABA-enriched flavored yogurt, summarized the metabolic pathway of GABA, and provided a flavor fingerprint that could guide the production of specifically flavored yogurts.