Headspace Solid-phase Microextraction Gas Chromatography-mass Research Articles

Comparable analysis of flavor compounds and quality assessment of fermented bean curd using HS-SPME-GC/MS and colorimetric sensor array

This study aims to develop an effective tool by integrating traditional analysis methods with advanced sensor array technology and multiple algorithms, to achieve rapid characterization, qualitative identification, and flavor quality evaluation of fermented bean products. Firstly, the flavor compounds and flavor profiles of fermented bean curd from different manufacturers were identified using headspace solid-phase microextraction gas chromatography-mass spectrometry (HS-SPME-GC/MS) and quantitative descriptive analysis (QDA). A total of 63 volatile compounds were identified, of which 13 volatile compounds were identified as the key differential compounds in selected samples. Eight descriptors were selected to represent the aroma characteristics of fermented bean curd. Based on the key differential compounds, a low-cost colorimetric sensor array (CSA) was designed and constructed. Furthermore, the feasibility of CSA combined with multiple algorithms was investigated for brand discrimination and flavor quality assessment. Linear discriminant analysis (LDA) exhibited a better performance in distinguishing different flavor quality samples, and the recognition accuracy of its prediction set was 97.22%. The study suggests that CSA combined with multiple algorithms can be an effective tool for flavor characterization and qualitative discrimination of fermented bean curd, and can provide a new multi-dimensional analysis method for food analysis.

Influence of germination and roasting on the characteristic volatile organic compounds of quinoa using sensory evaluation, E-nose, HS-GC-IMS, and HS-SPME-GC-MS

This study aimed to investigate the effects of germination and roasting on the flavor of quinoa. Firstly, the aroma of quinoa and germinated quinoa roasted under different conditions was analyzed using sensory evaluation and electronic nose (E-nose). Results showed that the best favorable aroma of quinoa and germinated quinoa was obtained when roasted at 160 °C for 15 min. Then, a total of 34 and 80 volatile organic compounds (VOCs) of quinoa and germinated quinoa roasted at 160 °C for 15 min were determined using headspace-gas chromatography-ion mobility spectrometry (HS-GC-IMS) and headspace solid-phase microextraction gas chromatography–mass spectrometry (HS-SPME-GC–MS), respectively. Germination and roasting effectively reduced the contents of VOCs that produced undesirable flavor. Moreover, germination improved the floral aromas, while roasting mainly produced caramel, cocoa, and roasted nut aromas of quinoa. This study indicated that germination and roasting treatments might serve as promising processing methods to improve the flavor of quinoa.

Tracking dry gin volatile organic compounds over distillation: a time course study

Why was the work done: The influence of distillation time on the volatile composition of gin has not been examined in detail at a commercial distillery. How was the work done: Headspace Solid-Phase Micro-Extraction Gas Chromatography-Mass Spectrometry (HS-SPME-GC-MS) was used to tentatively identify 74 aroma compounds, with their concentration tracked in distillate samples over the course of three gin distillations. What are the main findings: Four unique fractions were identified using Agglomerative Hierarchical Clustering: ‘heads’, ‘early hearts’, ‘late hearts, and ‘tails’. The hearts fraction (n=24 samples) was examined further, fitting statistically appropriate models to 54 aroma volatiles. Three sub-groups of volatiles were identified, (i) highly volatile monoterpenes with rapidly decreasing concentration over the early hearts fraction, (ii) volatiles whose concentration increased gradually over the hearts fraction and (iii) less volatile sesquiterpenes, sesquiterpenoids, and monoterpenoids which increased rapidly in concentration in the later distillate. Complex cubic models fit 34 volatiles with very high significance (p>0.0001) over the hearts fraction (72%). Informal aroma sensory bench testing identified distinct aroma categories with, for example, ‘Spicy’ being commonly detected in the later distillate. Why is the work important: This investigation characterises the kinetics of flavour extraction over the course of a commercial gin distillation process. These findings highlight the potential for the expression of specific flavour characteristics by modifying the cut points of the distillation process

Effect of incubation temperature on identification of key odorants of sewage sludge using headspace GC analysis

Currently, headspace gas chromatography-mass spectrometry is a widely used method to identify the key odorants of sludge. However, the effect of incubation temperature on the generation and emission of key odorants from sludge was still uncertain. Thus, in this paper, headspace solid-phase microextraction gas chromatography-mass spectrometry (HS-SPME-GC-MS) and headspace gas chromatography-coupled ion mobility spectrometry (HS-GC-IMS) were carried out to analyze the volatiles emitted from the sludge incubated at different temperatures (30°C, 50°C, 60°C, and 80°C). The results indicated that the total volatile concentration of the sludge increased with temperatures, which affected the identified proportion of sludge key odorants to a certain extent. Differently from the aqueous solutions, the variation of volatile emission from the sludge was inconsistent with temperature changes, suggesting a multifactorial influence of incubation temperature on the identification of sludge odorants. The microbial community structure and adenosine triphosphate (ATP) metabolic activity of the sludge samples were analyzed at the initial state, 30°C, and 80°C. Although no significant effect of incubation temperature on the microbial community structure of the sludge, the incubation at 80°C led to a noticeable decrease in microbial ATP metabolic activity, accompanied by a significant change in the proportion of odor-related microorganisms with low relative abundances. Changes in the composition and activity of these communities jointly contributed to the differences in odor emission from sludge at different temperatures. In summary, the incubation temperature affects the production and emission of volatiles from sludge through physicochemical and biochemical mechanisms, by which the microbial metabolism playing a crucial role. Therefore, when analyzing the key odorants of sludge, these factors should be considered.

Volatile flavor behavior characterization of Hericium erinaceus during postharvest storage using E-nose, HS-GC-IMS, and HS-SPME-GC–MS after treated with electron-beam generated X-ray irradiation

Flavor alteration is a crucial factor affecting the quality of mushrooms during preservation. The dynamic variations of volatile profiles of fresh Hericium erinaceus with electron-beam generated X-ray irradiation were investigated by combining E-nose, headspace-gas chromatography-ion mobility spectrometry (HS-GC-IMS), and headspace solid-phase microextraction gas chromatography–mass spectrometry (HS-SPME-GC–MS). E-nose analysis achieved rapid discrimination in all treatments over storage time. 65 and 73 volatile organic compounds (VOCs) were identified by HS-GC-IMS and HS-SPME-GC–MS, respectively. Thereinto, 1-octen-3-ol, 1-octen-3-one, and 2-octanone were screened out as the characteristic VOCs, which contents declined during storage. While the contents of (E)-2-octenal, (E)-2-nonenal, and 1-octanol increased. The flavor profile changes from distinct mushroom and floral odor to an intense alcohol and fatty odor. Notably, one-kGy irradiation remained more volatiles and denser mushroom odor after storage. Multivariate analysis further confirmed that 1.0 kGy irradiation contributed to the overall aroma retention during postharvest storage of H. erinaceus.

Identification of key off-flavor compounds during storage of fried pepper (Zanthoxylum bungeanum Maxim.) oils by sensory-directed flavor analysis and partial least squares regression (PLSR)

Fried pepper oil (FPO) is a widely used flavoring oil in China, but it suffers from complex chemical reactions that give an unpleasant odor. The aim of this paper is to study the main causes of off-flavor in FPO, as well as identify key off-flavor compounds in FPO. Fifty-eight volatiles were identified using HS-SPME–GC–MS (headspace solid-phase microextraction–gas chromatography–mass spectrometry) during storage. Fifteen off-flavor compounds were initially targeted by odor activity values (OAVs) calculations and partial least squares regression (PLSR) analysis. Eventually, five key off-flavor compounds were identified by recombination experiments and omission test, which were hexanal, (E)-2-octenal, terpinyl acetate, α-terpineol, and hexanoic acid. The off-flavors could derive from the oxidative degradation of long-chain fatty acids and the acid-catalyzed rearrangement of terpenes. The results of the study provide a theoretical basis for the regulation of off-flavor in FPO and a practical guide for the industrial production of FPO.

Enhancing the Quality of Low-Alcohol Navel Orange Wine through Simultaneous Co-Fermentation Using Saccharomyces cerevisiae SC-125, Angel Yeast SY, and Lactiplantibacillus plantarum BC114.

To date, there has been limited research on the interactive effects of yeast and lactic acid bacteria (LAB) on the sensory qualities of navel orange wine. In this study, using Jintang navel orange juice as the raw material, multi-microbial fermentation was conducted with Saccharomyces cerevisiae SC-125 and Angel yeast SY, as well as Lactiplantibacillus plantarum BC114. Single yeast and co-fermentation with Lactiplantibacillus plantarum were used as the control groups. The research aimed to investigate the physicochemical parameters of navel orange wine during fermentation. Additionally, headspace solid-phase microextraction gas chromatography-mass spectrometry (HP-SPME-GC-MS) was employed to determine and analyze the types and levels of flavor compounds in the navel orange wines produced through the different fermentation methods. The co-fermentation using the three strains significantly enhanced both the quantity and variety of volatile compounds in the navel orange wine, concomitant with heightened total phenol and flavonoid levels. Furthermore, a notable improvement was observed in the free radical scavenging activity. A sensory evaluation was carried out to analyze the differences among the various navel orange wines, shedding light on the impact of different wine yeasts and co-fermentation with LAB on the quality of navel orange wines.

Improvement mechanism of volatile flavor in fermented tilapia surimi by cooperative fermentation of Pediococcus acidilactici and Latilactobacillus sakei: Quantization of microbial contribution through influence of genus

Single starter can hardly improve the volatile flavor of fermented fish surimi. In this study, the changes of volatile compounds (VCs) and microbial composition during cooperative fermentation of Latilactobacillus sakei and Pediococcus acidilactici were studied by headspace solid-phase microextraction gas chromatography–mass spectrometry and 16S rRNA gene high-throughput sequencing. During cooperative fermentation, most VCs and the abundance of Latilactobacillus and Lactococcus significantly increased, while Pediococcus, Acinetobacter, and Macrococcus obviously decreased. After evaluation of correlation and abundance of each genus, Latilactobacillus and Lactococcus possessed the highest influence on the formation of volatile flavor during cooperative fermentation. Compared with the natural fermentation, cooperative fermentation with starters significantly enhanced most of pleasant core VCs (odor activity value≥1), but inhibited the production of trimethylamine and methanethiol, mainly resulting from the absolutely highest influence of Latilactobacillus. Cooperative fermentation of starters is an effective method to improve the volatile flavor in the fermented tilapia surimi.

Detection of Maize Mold Based on a Nanocomposite Colorimetric Sensor Array under Different Substrates.

This study developed a novel nanocomposite colorimetric sensor array (CSA) to distinguish between fresh and moldy maize. First, the headspace solid-phase microextraction gas chromatography-mass spectrometry (HS-SPME-GC/MS) method was used to analyze volatile organic compounds (VOCs) in fresh and moldy maize samples. Then, principal component analysis and orthogonal partial least-squares discriminant analysis (OPLS-DA) were used to identify 2-methylbutyric acid and undecane as key VOCs associated with moldy maize. Furthermore, colorimetric sensitive dyes modified with different nanoparticles were employed to enhance the dye properties used in the nanocomposite CSA analysis of key VOCs. This study focused on synthesizing four types of nanoparticles: polystyrene acrylic (PSA), porous silica nanospheres (PSNs), zeolitic imidazolate framework-8 (ZIF-8), and ZIF-8 after etching. Additionally, three types of substrates, qualitative filter paper, polyvinylidene fluoride film, and thin-layer chromatography silica gel, were comparatively used to fabricate nanocomposite CSA combining with linear discriminant analysis (LDA) and K-nearest neighbor (KNN) models for real sample detection. All moldy maize samples were correctly identified and prepared to characterize the properties of the CSA. Through initial testing and nanoenhancement of the chosen dyes, four nanocomposite colorimetric sensitive dyes were confirmed. The accuracy rates for LDA and KNN models in this study reached 100%. This work shows great potential for grain quality control using CSA methods.

Towards an index of damage of olive paste during virgin olive oil extraction: The role of β-OH-acteoside diastereomers for risk assessment of the fusty/muddy sediment sensory defect

The aim of this study was to propose an index/marker of thermal/oxidative damage of olive paste during virgin olive oil extraction to assess the risk of sensory defects in the obtained oil. Several olive oil extraction trials were carried out over two production years applying different time, temperature, and oxygen exposure conditions during malaxation. The phenolic composition of the olive pastes was analyzed by High Performance Liquid Chromatography-Diode Array Detector-Mass Spectrometry (HPLC-DAD-MS). The chemical (legal quality indexes, phenolic compounds by HPLC-DAD-MS, volatile compounds by Head Space-Solid Phase Microextraction-Gas Chromatography-Mass Spectrometry (HS-SPME-GC-MS)) and sensory characteristics of the obtained oils were analyzed. The content of the β-OH-acteoside diastereomers in olive paste increased linearly with malaxation time as a function of malaxation temperature and oxidative conditions, following a pseudo-zero order kinetic. At the same time, two volatile compounds linked to sensory defects (2- and 3-methylbutanal) increased in the obtained oils when increasing malaxation time and temperature, and a relationship between them and the fusty/muddy sediment defect in olive oil samples was observed. A further direct relationship between the β-OH-acteoside content in the olive pastes and the 2+3-methylbutanal content in the oils was observed. Therefore, the β-OH-acteoside diastereomers content in olive pastes has been suggested as an index/marker to indicate the risk of sensory defects in virgin olive oil as a function of the thermal and oxidative conditions during malaxation. A threshold value of 100 mg/kg of the content of β-OH-acteoside diastereomers was proposed, above which the fusty/muddy sediment defect is perceptible.

Volatile profile of bee bread

Bee bread is one of the least studied bee products. In this study, ten bee bread samples were characterized using palynology and HS–SPME–GC–MS (headspace solid-phase microextraction gas chromatography-mass spectrometry). In total, over one hundred different volatile components were identified, belonging to different chemical groups. Only ten common components were detected in all the samples. These volatiles were ethanol, methylene chloride, ethyl acetate, acetic acid, α-pinene, furfural, nonane, nonanal, n-hexane and isovaleric acid. Several other components were commonly shared among various bee bread samples. Over sixty detected compounds have not been previously reported in bee bread. The analysis required a mild extraction temperature of 40 °C, as higher temperatures resulted in the Maillard reaction, leading to the production of furfural. The profile of volatile compounds of the tested bee pollen samples was complex and varied. Some relationships have been shown between botanical origin and volatile organic compound profile.

Qualitative and quantitative analysis for monitoring the fishy odor of anchovy oil

Abstract The fishy odor of fish oil, a popular nutritional supplement, affects its quality as well as consumer acceptance and eating experience. An objective or scientific method for analyzing fish oil’s olfactory characteristics is still lacking. This study examined anchovy oil to develop qualitative and quantitative approaches for identifying fishy odor components. Multiple fish oil refining samples were analyzed using gas chromatography-ion mobility spectrometry (GC-IMS). Due to their significant alterations during fish oil refining, low threshold values, and distinct olfactory properties, the unsaturated aldehydes (E)-2-pentenal and (E,E)-2,4-heptadienal and the unsaturated ketone 1-penten-3-one may contribute to the fishy odor. Among the chemicals, (E,E)-2,4-heptadienal was chosen as the marker for developing a method to quantify fishy odor and analyze deodorization samples using headspace solid-phase micro-extraction gas chromatography-mass spectrometry (HS-SPME-GC-MS). The quantitative study of fishy odor in fish oil is a pioneering approach that can help improve quality assurance and refining process.

Evaluation of aroma characteristics of Penaeus vannamei with different drying methods using HS-SPME-GC-MS, MMSE-GC-MS, and sensory evaluation

The effects of microwave drying (MD), hot air drying (HAD), vacuum hot air drying (VD), and vacuum freeze drying (VFD) on the volatile profiles of Penaeus vannamei were investigated. A total of 89 and 94 volatile compounds were identified by headspace solid-phase microextraction-gas chromatography–mass spectrometry (HS-SPME-GC–MS) and monolithic material sorptive extraction gas chromatography–mass spectrometry (MMSE-GC–MS), respectively. Orthogonal partial least squares-discriminant analysis (OPLS-DA) and variable influence on projection (VIP) models were utilized to select characteristic volatiles and key marker compounds (e.g., octanal, 1-octen-3-ol, 2-methyl-butanal, 2-ethyl-furan, and trimethyl-pyrazine) to discriminate among four drying methods. Based on synthesis of odor descriptions and sensory evaluation, it was found that P. vannamei via MD, HAD, and VD greatly reduced the fishy and generated roasted, fatty, and smoked odors. This study systematically analyzed the aroma characteristics of four traditional dried P. vannamei products, which may provide theoretical guidance for industrial production.

Comparative Analysis of Volatile Compounds in the Flower Buds of Three Panax Species Using Fast Gas Chromatography Electronic Nose, Headspace-Gas Chromatography-Ion Mobility Spectrometry, and Headspace Solid Phase Microextraction-Gas Chromatography-Mass Spectrometry Coupled with Multivariate Statistical Analysis.

The flower buds of three Panax species (PGF: P. ginseng; PQF: P. quinquefolius; PNF: P. notoginseng) widely consumed as health tea are easily confused in market circulation. We aimed to develop a green, fast, and easy analysis strategy to distinguish PGF, PQF, and PNF. In this work, fast gas chromatography electronic nose (fast GC e-nose), headspace-gas chromatography-ion mobility spectrometry (HS-GC-IMS), and headspace solid phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS) were utilized to comprehensively analyze the volatile organic components (VOCs) of three flowers. Meanwhile, a principal component analysis (PCA) and heatmap were applied to distinguish the VOCs identified in PGF, PQF, and PNF. A random forest (RF) analysis was used to screen key factors affecting the discrimination. As a result, 39, 68, and 78 VOCs were identified in three flowers using fast GC e-nose, HS-GC-IMS, and HS-SPME-GC-MS. Nine VOCs were selected as potential chemical markers based on a model of RF for distinguishing these three species. Conclusively, a complete VOC analysis strategy was created to provide a methodological reference for the rapid, simple, and environmentally friendly detection and identification of food products (tea, oil, honey, etc.) and herbs with flavor characteristics and to provide a basis for further specification of their quality and base sources.

Correlation analysis between volatile flavor compounds and microbial succession of Lithocarpus litseifolius [Hance] Chun (L. litseifolius) kombucha during fermentation

Llitseifolius with various health benefits, which has been approved as a new food material in China since 2017, can be a promising substrate for kombucha. In this study, kombucha using L. litseifolius (L. Komb) as sole raw material was successfully prepared by inoculating a symbiotic culture of bacteria and yeast (SCOBY). The alterations in flavor compounds and microbial communities, as well as their potential correlations during fermentation were investigated. A total of 113 volatile flavor compounds (VFCs) were identified using headspace-solid phase microextraction-gas chromatography mass spectrometry (HS-SPME-GC-MS). Among them, alcohols and acids accounted for a larger proportion. During fermentation, the contents of ethanol, 3-methyl-1-butanol, phenylethyl Alcohol, and acetic acid was 142.73–290.92, 108.59–371.74, 36.09–184.80, and 255.91–685.82 μg/L, respectively. The results of high-throughput sequencing analysis indicated that Komagataeibacter, Gluconobacter, and Ralstonia were the dominant bacterial genera, while Zygosaccharomyces was the predominant fungal genus. The Spearman correlation coefficient demonstrated medium-high correlations (|ρ| > 0.6) between VFCs and 13 core microbes. The primary alcohols, acids, and esters in L. Komb exhibited strong associations with specific microorganisms, including Komagataeibacter, Gluconobacter, Ralstonia, Stenotrophomonas, and Starmerella. It contributes to understanding the role of core microorganisms in the overall flavor formation of L. Komb, providing valuable reference for practical flavor promotion of kombucha.

HS-SPME-GC-MS Combined with Orthogonal Partial Least Squares Identification to Analyze the Effect of LPL on Yak Milk's Flavor under Different Storage Temperatures and Times.

Flavor is a crucial parameter for assessing the sensory quality of yak milk. However, there is limited information regarding the factors influencing its taste. In this study, the effects of endogenous lipoprotein lipase (LPL) on the volatile flavor components of yak milk under storage conditions of 4 °C, 18 °C and 65 °C were analyzed via headspace solid-phase microextraction gas chromatography-mass spectrometry (HS-SPME-GC-MS) combined with orthogonal partial least-squares (OPSL) discrimination, and the reasons for the changes in yak milk flavors were investigated. Combined with the difference in the changes in volatile flavor substance before and after the action of LPL, LPL was found to have a significant effect on the flavor of fresh yak milk. Fresh milk was best kept at 4 °C for 24 h and pasteurized for more than 24 h. Principal component analysis (PCA) and orthogonal partial least squares discriminant analysis (OPLS-DA) were employed to characterize the volatile components in yak milk under various treatment conditions. Twelve substances with significant influence on yak milk flavor were identified by measuring their VIP values. Notably, 2-nonanone, heptanal, and ethyl caprylate exhibited OAV values greater than 1, indicating their significant contribution to the flavor of yak milk. Conversely, 4-octanone and 2-heptanone displayed OAV values between 0.1 and 1, showing their important role in modifying the flavor of yak milk. These findings can serve as monitoring indicators for assessing the freshness of yak milk.

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.

Use of NMR, FTIR and GC–MS to monitor the oxidation products of phospholipids in bighead carp head during cooking process

Bighead carp head soup is a traditional Chinese cuisine with a pleasant aroma, but the effect of fish head phospholipids (FPLs) on the odorants is not fully understood. In this study, nuclear magnetic resonance (NMR), attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) and headspace solid-phase microextraction gas chromatography–mass spectrometry (HS-SPME–GC–MS) were used to monitor the oxidation products of phospholipids in fish head soup during the cooking process, and the fish head triglycerides (FTGs) were used as controls. In 1H NMR spectra, the signals of unsaturated acyl groups and the oxidation compounds in FPLs were significantly higher than those in FTGs. The results of FTIR showed that the changes of functional group absorptions of the oxidation compounds in FPLs were greater than FTGs. GC–MS demonstrated that FPLs samples produced more lipid-derived volatile compounds than FTGs samples. These results showed that FPLs were more prone to oxidation and could produce more lipid-derived odorants. Therefore, FPLs rather than FTGs, were the main precursor substance of lipid-derived odorants in bighead carp head soup.

Comparison of the Correlations of Microbial Community and Volatile Compounds between Pit-Mud and Fermented Grains of Compound-Flavor Baijiu.

The microbial composition and volatile components of fermented grains (FG) and pit mud (PM) are crucial for the quality and flavor of compound-flavor baijiu (CFB). The physicochemical indices, culturable microorganisms, microbial communities, and volatile components of FG and PM were analyzed and correlated in our research. Considering FG and PM, amplicon sequencing was used to analyze the microbial community and the volatile components were detected by headspace solid-phase microextraction-gas chromatography-mass spectrometry (HS-SPME). For FG, redundancy analysis and correlation perfume Circos were used to clarify the correlations between the dominant microbial community and volatile components. The results showed that Aspergillus, Pichia, and Rhizopus were the main fungal microflora in FG and PM, whereas Lactobacillus and Bacillus were the dominant bacteria in FG, and Methanosarcina and Clostridium sensu stricto 12 were the dominant bacteria in the PM. The microbial community and volatile compounds in the CB sampled from the bottom layers of the FG were greatly affected by those in the PM. There were 32 common volatile components in CB and PM. For FG, most of the volatile components were highly correlated with Lactobacillus, Bacillus, Aspergillus, Pichia, and Monascus, which includes alcohols, acids and esters. This study reveals correlations between microbial composition, volatile components, and the interplay of FG and PM, which are conducive to optimizing the fermentation process and improving the quality of CFB base.

Relationship between phospholipid molecules species and volatile compounds in grilled lambs during the heating process

The present study used a comprehensive analysis combining headspace solid-phase microextraction gas chromatography-mass spectrometry (HS-SPME-GC-MS) and ultra-performance liquid chromatography-electrospray ionization-tandem mass spectrometry (UPLC-ESI-MS/MS) to investigate changes in volatile compounds and phospholipid molecules in grilled lambs. The results revealed 19 key volatile compounds (OAV > 1) involved in the grilling process of lambs. Additionally, UPLC-ESI-MS/MS analysis detected 142 phospholipid molecules in grilled lamb, with phosphatidylcholine exhibiting the highest content (36.62 %), followed by phosphatidyl ethanolamine, phosphatidylinositol, phosphatidylserine, phosphatidyl glycerol, and phosphatidic acid. Through partial least squares analysis, 63 key differential phospholipids were identified. Principal component analysis of the key differential phospholipids and volatile compounds indicated that phosphatidylcholine and phosphatidyl ethanolamine phospholipids are the key substrates in forming volatile compounds in grilled lambs. This information is essential for precisely regulating the flavor profile, enhancing the grilling process, and minimizing the production of harmful compounds in grilled meat products.