Recent progress in food flavor analysis using gas chromatography–ion mobility spectrometry (GC–IMS)

Insight into the chemical composition, antioxidant capacity, meat quality, fatty acid profile, and volatile compounds of yellow-feathered chickens fed with fermented pineapple residue

This study aimed to evaluated the effect of dietary fermented pineapple residue (FPR) on the chemical composition, antioxidant capacity, meat quality, fatty acid profile, and volatile compounds in yellow-feathered chickens. GC-IMS technique combined with multivariate analysis were performed to clarify the key volatile compounds. The results showed that dietary FPR improved meat quality by increasing the antioxidant capacity and pH value and decreasing cooking loss of breast muscle. The fatty acid profile was altered in breast muscle of chickens that fed with FPR. GC-IMS detected 43 volatile compounds in breast muscle, including mainly aldehydes, alcohols, esters, and ketones. Among them, 12 volatile compounds could serve as potential aroma markers to distinguish meat flavor of chickens fed with FPR. Correlation analysis revealed that C18:1n9c, C18:2n6, and PUFA are important contributors for meat flavor formation. In conclusion, dietary FPR improved antioxidant capacity, meat quality, fatty acid profile, and volatile compounds of breast muscle in chickens.

Volatile flavor characteristics of scallops (Chlamys farreri) with different drying methods were analyzed based on GC-IMS and GC-O-QTOF

To investigate the effects of different drying methods on the flavor of scallops, headspace gas chromatography-ion mobility spectrometry (HS-GC-IMS) combined with gas chromatography-olfactometry-quadrupole time-of-flight (GC-O-QTOF) was used to analyze the flavor of scallops processed by five drying methods. A total of 62 volatile organic compounds (VOCs) were identified by GC-IMS. 27 characteristic aroma compounds were identified by GC-O-QTOF, and the highest content was trimethylamine. 17 aroma compounds with GC-O ≥ 6 were screened by the time-intensity method, and the maximum aroma intensity value of 2-acetyl-1-pyrroline was 9.9 aroma compounds with relative odor activity value (ROAV) ≥ 1 were identified. Using GC-O ≥ 6 and ROAV ≥1 as the criteria, 6 differential aroma compounds were further screened, and the results proved that naturally dried scallops had a heavier fishy odor. These findings will provide deeper insights into the processing of scallops.

Characterisation of the volatile compounds in nine varieties and three breeding selections of celery using GC-IMS and GC-MS

Celery (Apium graveolens L.) is a popular vegetable crop planted worldwide. In this study, the volatile compound characteristics of three A. graveolens var. dulce varieties (type D), and six A. graveolens var. secalinum varieties (type S), and three breeding selections were analysed and 41 and 73 volatile compounds were identified using GC-MS and GC-IMS, respectively. The results showed that type S emitted more terpenes and phthalides than type D varieties. Both GC-MS and GC-IMS could discriminate between type S and type D. Six potential biomarkers, i.e., sabinene, (E)-caryophyllene, α-phellandrene, limonene, γ-terpinene, and hexanal, were identified using both models. Both GC-MS and GC-IMS could discriminate between parent and breeding selection. The relative contents of seven (GC-IMS OPLS-DA model) and ten (GC-MS OPLS-DA model) volatile compounds showed over-parent heterosis. This study provides a technical reference for distinguishing celery varieties in the same habitat and preliminarily reveals the aroma relationship between breeding selections and their parents.

Effectiveness of Differentiating Mold Levels in Soybeans with Electronic Nose Detection Technology

This study employed electronic nose technology to assess the mold levels in soybeans, conducting analyses on artificially inoculated soybeans with five strains of fungi and distinguishing them from naturally moldy soybeans. Principal component analysis (PCA) and linear discriminant analysis (LDA) were used to evaluate inoculated and naturally moldy samples. The results revealed that the most influential sensor was W2W, which is sensitive to organic sulfur compounds, followed by W1W (primarily responsive to inorganic sulfur compounds), W5S (sensitive to small molecular nitrogen oxides), W1S (responsive to short-chain alkanes such as methane), and W2S (sensitive to alcohols, ethers, aldehydes, and ketones). These findings highlight that variations in volatile substances among the moldy soybean samples were predominantly attributed to organic sulfur compounds, with significant distinctions noted in inorganic sulfur, nitrogen compounds, short-chain alkanes, and alcohols/ethers/aldehydes/ketones. The results of the PCA and LDA analyses indicated that while both methods demonstrated moderate effectiveness in distinguishing between different dominant fungal inoculations and naturally moldy soybeans, they were more successful in differentiating various levels of moldiness, achieving a discriminative accuracy rate of 82.72% in LDA. Overall, the findings suggest that electronic nose detection technology can effectively identify mold levels in soybeans.

The Ion Formation and Quantitative Response of Isoprene, Monoterpenes and Terpenoids in Ion Mobility Spectrometry with Atmospheric-Pressure Chemical Ionization as a Function of Temperature

Ion mobility spectrometry is successfully used as a sensor technology for different applications. A feature of this method is that characteristic ion mobility spectra are obtained for each measurement rather than a sum signal. The spectra result from the different drift velocities of ions in a drift tube at atmospheric pressure. In this study, we investigated the ion formation processes and the quantitative response of isoprene, monoterpenes and monoterpenoids as a function of the temperature of the spectrometer using a tritium ionization source. These substances are important target analytes in atmospheric monitoring and in the analysis of essential oils in different matrices. A drift tube temperature above 120 °C permitted the most sensitive detection of isoprene and monoterpenes, while 80 °C was sufficient for the sensitive detection of most terpenoids. Dimer ions were formed for isoprene over the whole temperature range. The ionization processes of monoterpenes and terpenoids were strongly influenced by the temperature. At temperatures of 40 °C, adduct ions were formed in addition to MH+ ions for monoterpenes. Enhanced temperatures provided a single peak with the same drift time for all monoterpenes. Structural differences influenced the ion formation of terpenoids, and much more complex spectra were obtained. The nature of the product ions changed depending on the temperature.

Exploring the Impact of Different Saccharomyces cerevisiae Strains on the Flavor Profile of Greengage Alcoholic Beverage Using GC-E-Nose, HS-GC-IMS, and HS-SPME-GC-MS

Greengage alcoholic beverage (GAB) is gaining popularity for its distinctive fruity aroma and nutritional benefits. The Saccharomyces cerevisiae strain applied for fermentation significantly influences the metabolic production of aroma compounds, making the selection of S. cerevisiae strains to be critical for enhancing the unique flavor profile of the GAB in commercial production. In this study, the effects of two common commercial S. cerevisiae strains (SY, EC-1118) and two laboratory-derived strains (ET008-c54, NM-8) on the flavor profile of the GAB were investigated. Volatile organic compounds (VOCs) of the GAB samples were analyzed using GC-E-Nose, HS-SPME-GC-MS, and HS-GC-IMS. Results showed significant differences in the flavor compound content of the GAB fermented by different strains. Nine VOCs were identified as potential markers by partial least squares-discriminant analysis (PLS-DA) combined with variable importance in projection (VIP), with ethyl esters playing a key role in distinguishing the aroma characteristics of different groups. Consequently, 13 aromatic compounds were selected and considered to be the typical VOCs of the GAB. Notably, β-ionone and ethyl octanoate emerged as representative aroma compounds, both showing the highest concentrations in the SY sample. These findings will provide valuable insights into the aroma differences of the GAB fermented by different strains and offer theoretical guidance for selecting suitable strains in the industrial production of the GAB.

Quality Characteristics and Volatile Components of Chili Oil Prepared from the Combination of Shuanla and Erjingtiao Peppers

This study aimed to investigate the influence of varying weight ratios of Shuanla and Erjingtiao peppers (10:0, 8:2, 6:4, 5:5, 4:6, 2:8, and 0:10, corresponding to samples PA, PB, PC, PD, PE, PF, and PG, respectively) on the sensory attributes, chromatism, acid values (AVs), peroxide values (POVs), capsaicinoids, and volatile organic compounds (VOCs) of seven chili oil samples. GC-IMS was employed to detect the VOCs of the chili oil samples, which were subsequently analyzed using multivariate statistical methods. The results revealed significant differences in pungency among the samples, with the PA sample exhibiting the strongest pungency. The PG sample demonstrated the highest values for a*, b*, and C*, while the PA sample displayed the highest L* and h*. The AVs of seven samples ranged from 0.490 ± 0.005 to 1.727 ± 0.015 mg/g. The POVs of the chili oil samples, ranging from 0.094 ± 0.000 to 0.127 ± 0.002 g/100 g, were significantly lower than those of extra virgin olive oil, 0.183 ± 0.001 g/100 g. The contents of capsaicinoids ranged from 15.26 ± 0.07 g/kg in the PA sample to 0.38 ± 0.00 g/kg in the PG sample (p < 0.05). Additionally, 56 volatile flavor substances were identified, and 10 key flavor compounds (ROAV ≥ 1) were screened among them. Multivariate data analysis via OPLS-DA indicated that 20 VOCs (VIP > 1) could serve as flavor markers in a clustering heat map to differentiate among the seven chili oil varieties. The findings of this study provide a valuable reference for the promotion of Shuanla and Erjingtiao peppers in chili oil production and the development of specific flavor profiles in chili oil to cater to diverse consumer preferences.

Determination of Geographical Origin of Southern Shaanxi Congou Black Teas Using Sensory Analysis Combined with Gas Chromatography-Ion Mobility Spectrometry

Southern Shaanxi is one of China's high-quality congou black tea production areas. However, the differences in geography, cultivation, and management techniques and production processes lead to uneven qualities of southern Shaanxi congou black tea in different production areas. This study used sensory analysis combined with gas chromatography-ion mobility spectrometry (GC-IMS) to determine southern Shaanxi congou black teas' geographical origin and volatile fingerprints to prevent economic losses caused by fraudulent labeling. A total of 61 volatile compounds were identified and quantified by GC-IMS. Three main aroma types were found by sensory analysis coupled with significant difference analysis, and a clear correlation between volatile compounds, aroma type, and geographical origin was found by sensory and gallery plot analysis. The black tea with a green/grassy-roast aroma type was mainly distributed in production areas with an altitude of 400-800 m and 1-pentanol, cyclohexanone, 1-penten-3-one, 2-heptanone, dihydroactinidiolide and butyrolactone were the key aroma markers. The black teas produced in production areas with an altitude of 800-1000 m mainly presented strong honey and caramel-like aromas, and sotolone, furaneol, and phenylacetaldehyde played an important role. These results will be helpful for discriminating black tea from different tea production areas in southern Shaanxi.

Characterization and exploration of dynamic variation of volatile compounds in vine tea during processing by GC-IMS and HS-SPME/GC-MS combined with machine learning algorithm

It is imperative to unravel the dynamic variation of volatile components of vine tea during processing to provide guidance for tea quality evaluation. In this study, the dynamic changes of volatile compounds of vine tea during processing were characterized by GC-IMS and HS-SPME/GC-MS. As a result, 103 volatile compounds were characterized by the two technologies with three overlapped ones. The random forest approach was employed to develop the models and explore key volatile compounds. 23 key compounds were explored, among which 13 were derived from GC-IMS and ten were from HS-SPME/GC-MS. Moreover, the area under the receiver operating characteristics curve with 100 cross validations by the pair-wised models were all 1 for the established models. Furthermore, the primary aroma formation mechanism for the key volatile compounds were mainly involved in fatty acid and amino acid metabolism. Besides, this study provides a theoretical support for directed processing and quality control of vine tea.

An open source isolated data acquisition with trigger pulse generation for ion mobility spectrometry

Ion mobility spectrometers (IMS) are used in a wide variety of applications, including trace gas detection in safety and security applications, but also in more analytical applications, e.g., in medicine or food quality monitoring. Consequently, IMS are often coupled with other separation techniques and laboratory equipment, requiring synchronization between the external equipment and the IMS electronics. In addition, IMS and the associated electronics are becoming increasingly complex due to ongoing instrumental developments. In this work, we present an open source data acquisition hardware tailored to the requirements of advanced IMS, but also applicable to other applications. The data acquisition hardware provides trigger pulses for synchronized operation of the IMS ion gate or external devices. In addition, the data acquisition hardware allows for parallel digitalization using two isolated 16-bit analog-to-digital converters (ADC) with up to 250 kilosamples per second. The galvanically isolated trigger input ensures a synchronized start of the IMS measurements, particularly when connecting external instrumentation such as a gas chromatograph. Furthermore, due to the isolated ADCs, the hardware allows great flexibility in defining the ground potential of the instrument setup.

The revelation of characteristic volatile compounds in egg powder and analysis of their adsorption rules based on HS-GC-IMS technology

The study constructed fingerprints and analyzed adsorption rules of volatile compounds (VOCs) in egg powder (EP) under different production processes, including egg white powder (EWP), egg yolk powder (EYP) and whole egg powder (WEP) by HS-GC-IMS. The 29 VOCs identified were primarily ketones and aldehydes. Characteristic VOCs responsible for flavor differences were clarified by difference comparison, clustering and PCA analysis. Additionally, variations in lipid and protein were the primary causes of the VOCs differences in EP through microscopy imaging, infrared and fluorescence spectroscopy. EWP's stretched structure favored fishy-smelling VOCs adsorption but limited total aldehyde binding due to strong hydrophobic interaction. EYP's higher β-sheet ratio and fewer hydrogen bond sites weakened its alcohol VOCs binding capacity. The abundance of ketone VOCs in EP was linked to their low steric hindrance. Therefore, this study elucidated the flavor differences reasons among EWP, EYP and WEP, laying foundation for EP applications in food industry.

Effect of inoculation with different Eurotium cristatum strains on the microbial communities and volatile organic compounds of Fu brick tea

Eurotium cristatum is the primary fungus in Fu brick tea (FBT) and plays a crucial role in its special flavor. This study investigated the effect of inoculation with different E. cristatum strains (i.e., ZJ, GX, GZ, HN, and SX) on the microbial communities and volatile organic compounds (VOCs) of FBT. A total of 113 VOCs were identified in all samples, with the concentration of VOCs (alcohols, aldehydes, and ketones) significantly higher in GXE FBT than in other samples. The core VOCs of GXE (19), GZE (16), HNE (19), SXE (15), and ZJE (13) FBT were identified using orthogonal partial least squares discriminant analysis and relative odor activity value (ROAV) analysis. Methional (a27), butanal (a41), 1-octen-3-one (a69), and ethyl acetate (a77) were key markers for inoculated FBTs, and 1-octen-3-ol, dimethyl disulfide, and acetoin-M were the specific markers of HNE. Linalool and (E)-2-octenal were particularly prominent in GXE, and isoamyl acetate-D was an important aroma component of GZE. Differences in microbial diversity were observed among the different inoculated fermented FBTs, and E. cristatum inoculation remarkably influenced the richness and diversity of bacterial communities. The VOCs were closely associated with fungi and bacteria, and 19 potentially dominant microorganisms (10 fungal and 9 bacterial genera) correlated with VOCs were identified. Among them, Aspergillus (fungi) and Pseudomonas (bacteria) exerted the greatest role. The FBT inoculated with E. cristatum from ZJ had the highest content of theaflavins and theabrownins, which intensified the red and yellow colors of the tea. E. cristatum greatly decreased the free amino acids and fatty acids, contributing to the aroma formation of FBT. Therefore, inoculating FBT with E. cristatum remarkably influenced the microbial communities and improved its flavor profile. This work provides a theoretical foundation on the role of E. cristatum in the formation and regulation of FBT flavor.

Characteristic volatile compounds of white tea with different storage times using E-nose, HS-GC-IMS, and HS-SPME-GC-MS

This paper studied the influence of storage duration on the flavor profile of white tea in detail, with samples produced between 2020 and 2023. Sensory evaluation was performed by quantitative descriptive analysis (QDA), followed by an in-depth aroma components analysis employing an electronic nose (E-nose), headspace gas chromatography-ion mobility spectrometry (HS-GC-IMS), and headspace solid-phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS). The QDA findings revealed a gradual transition in the flavor profile of white tea during storage, shifting from sweet, fruity, and floral to more herbal and stale characteristics. E-nose could well distinguish white tea with different storage times. A total of 55 and 53 volatile compounds were identified by HS-GC-IMS and HS-SPME-GC-MS, respectively. The orthogonal partial least squares-discriminant analysis models, based on HS-GC-IMS (R2Y = 0.998, Q2 = 0.987) and HS-SPME-GC-MS (R2Y = 0.984, Q2 = 0.993), successfully distinguished white tea samples stored for different storage times. Furthermore, 14 and 8 key compounds were screened based on the double variable criterion of one-way analysis of variance (p < 0.05) and variable importance in projection (VIP) >1.2, and their content changes were also compared. It is the gradual decrease of important aroma components such as 2-hexenal, 2-methyl-2-hepten-6-one, linalool, and geraniol, which are positively correlated with sweet, fruity, and floral aromas, and the gradual increase of hexanoic acid, thiophene, propanoic acid, dimethyl disulfide, and borneyl acetate, which are positively correlated with herbal and stale flavor, that leads to the changes in flavor and aroma of white tea during storage. The results of the study provided a reference for elucidating the aroma characteristics of white tea at different storage times as well as a theoretical basis for the quality control of white tea.

Different stages of flavor variations among canned Antarctic krill (Euphausia superba): Based on GC-IMS and PLS-DA

The aim of the present study was to explore changes in the profile of volatile compounds (VCs) in canned Antarctic krill (Euphausia superba) at different processing stages using partial least squares discriminant analysis (PLS-DA) and gas chromatography-mass spectrometry (GC-IMS). A total of 43 VCs were detected using GC-IMS in all krill meat samples, which included mainly alcohols, aldehydes, ketones, esters, and furans. Considering the different processing stages, the highest variation in VCs and the highest VC content were observed in krill meat which underwent both blanching and salt addition. PLS-DA further revealed flavor differences in canned Antarctic krill meat at different processing stages, with octanal, 2-hexanol, 2-octane, 2,3,5-trimethyl pyrazine, and cis-3-hexanol as the main contributors to observed differences in VC profiles. These findings contribute to the production of high-quality canned krill meat, enhancing its flavor quality and providing a feasible theoretical basis for future krill meat pretreatment and industry development.

Changes in microbial diversity and volatile metabolites during the fermentation of Bulang pickled tea

The present study aimed to determine microbial community, short-chain fatty acids (SCFAs), and volatilome of Bulang pickled tea during fermentation. Sequencing of 16S rRNA and ITS revealed that Bualng pickled tea was dominated by Lactobacillus plantarum, unclassified Enterobacteriaceae, unclassified Debaryomyces, Candida metapsilosis, Cladosporium sphaerospermum, and unclassified Aspergillus. The overall contents of SCFAs increased, with acetic acid showing the highest content. A total of 398 differential volatile metabolites were detected using differential metabolomics analysis. Out of these different volatile compounds, ten key volatile compounds including (Z)-4-heptenal, 1-(2-thienyl)-ethanone, 5-methyl-(E)-2-hepten-4-one, 2-ethoxy-3-methylpyrazine, p-cresol, 2-methoxy-phenol, ethy-4-methylvalerate, 3-ethyl-phenol, p-menthene-8-thiol, and 2-s-butyl-3-methoxypyrazinewere were screened based on odor activity value (OAV). The Spearman correlation analysis showed a high correlation of SCFAs and volatile compounds with microorganisms, especially L. plantarum and C. sphaerospermum. This study provided a theoretical basis for elucidating the flavor quality formation mechanism of Bulang pickled tea.

Rapid bacterial identification through volatile organic compound analysis and deep learning

BACKGROUND

The increasing antimicrobial resistance caused by the improper use of antibiotics poses a significant challenge to humanity. Rapid and accurate identification of microbial species in clinical settings is crucial for precise medication and reducing the development of antimicrobial resistance. This study aimed to explore a method for automatic identification of bacteria using Volatile Organic Compounds (VOCs) analysis and deep learning algorithms.

RESULTS

AlexNet, where augmentation is applied, produces the best results. The average accuracy rate for single bacterial culture classification reached 99.24% using cross-validation, and the accuracy rates for identifying the three bacteria in randomly mixed cultures were SA:98.6%, EC:98.58% and PA:98.99%, respectively.

CONCLUSION

This work provides a new approach to quickly identify bacterial microorganisms. Using this method can automatically identify bacteria in GC-IMS detection results, helping clinical doctors quickly detect bacterial species, accurately prescribe medication, thereby controlling epidemics, and minimizing the negative impact of bacterial resistance on society.

Cooperative effects of three preservatives on physiological quality, endophytic bacterial community and volatile organic compounds of postharvest Codonopsis pilosula var. modesta roots

BACKGROUND

Codonopsis pilosula var. modesta (CPVM) is a famous medicinal and edible plant of Campanulaceae. However, fresh CPVM roots (FCPVR) are prone to softening, browning and spoilage after concentrated harvesting in the main production area of Gansu Province, China in autumn, which poses great challenges to their large-scale storage and modern processing. In this study, effects of chitosan (CS), natamycin (NA) and modified atmosphere agent (MA) on the postharvest quality of FCPVR were first investigated. The roots after different treatments were stored at 4 °C and relative humidity of 75 ± 5% for 100 days. Their overall quality changes were evaluated from three perspectives: physiological quality, endophytic bacterial community and volatile organic compounds.

RESULTS

The clustering heatmap and principal component analysis results indicated that CS (2 g kg-1), NA (0.5 g kg-1) and MA (5 g) had a synergistic effect on physiological quality. The roots in the CS + NA + MA group maintained better physiological state, effective components and antioxidant capacity throughout the storage process. On this basis, compared with room temperature storage, the relative abundance of the main spoilage bacterium Pseudomonas in the CS + NA + MA group roots decreased by 44% on the 100th day of storage. Furthermore, after CS + NA + MA composite treatment, the roots produced richer esters with fruit aroma during low-temperature storage.

CONCLUSIONS

The CS + NA + MA composite treatment could maintain the physiological quality and flavor of FCPVR, inhibit spoilage by microbial contamination and maintain the optimal quality during low-temperature storage for up to 100 days. © 2024 Society of Chemical Industry.

Rapid separation of bile acid isomers via ion mobility mass spectrometry by complexing with spiramycin

Bile acid (BA) is one of the main active components of bile and has multiple isomers, the structure or content of its isomers often changes due to diseases and other health problems; thus, the accurate detection of BA isomers is very important. In this study, two groups of BA isomers of glycine-conjugated BAs and taurine-conjugated BAs were simultaneously separated and quantitatively analyzed by ion mobility mass spectrometry (IM-MS). Especially, baseline mobility separation between the isomers was achieved by the formation of binary complexes via simple interaction with spiramycin (SPM), for which a separation resolution (Rp-p) of 1.96 was reached. Moreover, BA isomers were quantitatively analyzed, and the limit of detection (LOD) of absolute quantification for TCDCA/TUDCA and GUDCA/GCDCA/GHDCA was 0.514 and 0.611 ng∙mL-1, respectively; the LODs for molar ratio ranges of relative quantification for TCDCA/TUDCA, GUDCA/GHDCA, and GCDCA/GHDCA were 1:18-30:1, 1:18-21:1, and 1:19-21:1, respectively. Additionally, BA isomers analyzed in pig bile powder and bear bile powder were measured, which were in good consistency with those labeled, revealing the differences in BA composition and content between the two powders. Finally, BA detection and recovery analyses were performed on serum samples, with a recovery rate of ≥73.69%, RSD of ≤6.8%, and SR (standard deviation of recoveries, the degree of difference between measured values and average recovery) of ≤1.27. Due to the simple, rapid, and lack of need for complex sample preparation and chromatographic separation, the proposed method can be an effective method for BA detection in practical samples.

HS-SPME-GC-MS untargeted metabolomics reveals key volatile compound changes during Liupao tea fermentation

This study used headspace solid-phase microextraction-gas chromatography-mass spectrometry and multivariate statistical analysis to comprehensively analyze the volatile components in Liupao tea samples throughout fermentation. In total, 1009 volatile organic compounds were detected and identified, including terpenoids, heterocyclic compounds, esters, ketones, hydrocarbons, alcohols, aromatics, and acids. Principal component and hierarchical cluster analyses, characterize the volatile components of Liupao tea samples were characterized at various fermentation stages. Orthogonal partial least squares discriminant analysis identified 248 differentiating compounds (VIP ≥ 1, P < 0.05, and |Log2FC| ≥ 1.0) during fermentation. K-means clustering analysis showed that 11 metabolites increased significantly throughout the fermentation process, whereas 31 metabolites decreased continuously. Annotation of these differential compounds revealed significant changes in sensory flavor characteristics in "green, sweet, fruity, floral, and woody" flavors. The results demonstrated significant variations in the volatile components of Liupao tea fermentation, along with notable changes in flavor characteristics.

Identification of characteristic flavor quality of ceramic-pot sealed meat after reheating based on HS-GC-IMS, bionic sensory combined chemometrics

This study investigated the impacts of microwave reheating (MR), boil reheating (BR), and steam reheating (SR) on the flavor profile of Ceramic-Pot Sealed Meat (CPSM). Electronic nose and tongue revealed that the microwaving was superior in preserving the original olfactory and gustatory profiles of CPSM compared to the other methods. Headspace- Gas chromatography- ion mobility spectrometry (HS-GC-IMS) detected 48 compounds, encompassing 15 alcohols, 11 aldehydes, 9 ketones, 7 esters, 2 alkenes, and 2 others, 1 acid. Spectral and clustering analysis revealed a significant rise in the content of Warmed-over flavor compounds after boil reheating, culminating in pronounced flavor distortion and a decline in sensory scores. Relative odor activity value (ROAV) and chemometrics identified nine substances as the principal flavor compounds responsible to flavor distortion. In conclusion, all reheating methods induce changes in the original flavor characteristics profiles of CPSM. However, microwave reheating offers superior preservation of the flavor characteristics of CPSM.

Dynamic changes in quality and flavor compounds of pork tendons during puffing process

To improve the portability of dried pork tendons for consumption, this study investigated the effects of different puffing temperatures (190 °C - 250 °C) and times (1-7 min) on the quality and flavor of pork tendons. As the temperature and time increased, the expansion ratio of pork tendons exhibited a gradual increase. The microstructure of the puffed pork tendons exhibited a uniform porous structure at 230 °C and 250 °C for 6 min. However, further puffing treatment destroyed the spatial structure. GC-IMS identified 68 volatile organic compounds (VOCs), and a total of 16 key VOCs including 2-trans-4-trans-decadienal were screened by GC-MS. Nonanal, 1-octen-3-ol, 2-amylfuran and 2-ethylfuran proved to have a significant effect on the flavor of the puffed pork tendon. The combined puffing performance and flavor analysis revealed that puffing at 230 °C for 6 min was the preferred parameter for puffed pork tendons.

Comprehensive characterization and comparison of aroma profiles of rambutan seed oils using GC-MS and GC-IMS combined with chemometrics

Background

Aroma significantly influences the quality of rambutan seed oil. Nonetheless, few studies have examined the volatile composition of rambutan seed oil. Thus, there is a need for a comprehensive characterization of the aroma profile of rambutan seed oil.

Methods

This study systematically investigated and compared the aroma characteristics of three types (BR-4, BR-5 and BR-7) of rambutan seed oils using HS-SPME-GC-MS and HS-GC-IMS techniques, augmented by chemometric modeling.

Results

GC-MS identified 135 volatile compounds, primarily hydrocarbons and esters, while GC-IMS characterized 35 compounds, mainly aldehydes and alcohols. Multivariate statistical analyses revealed significant differences in the aroma profiles among the oil samples. BR-5 exhibited the highest levels of aldehydes and hydrocarbons, whereas BR-7 demonstrated the highest content of esters and ketones. 21 and 15 differentially volatile compounds were extracted from the datasets obtained via GC-MS and GC-IMS. These compounds primarily comprised esters (floral and fruity) and aldehydes (green and fatty), interacting to create the distinctive aroma profiles of the three rambutan seed oils.

Conclusion

This study provides theoretical support for evaluating the flavor characteristics and utilization potential of rambutan seed oil.

Analysis of volatile flavor compounds in Antarctic krill paste with different processing methods based on GC-IMS

In this study, shrimp paste was prepared using Antarctic krill and fermented Antarctic krill shrimp paste as raw materials. Two commonly used heating methods, stir-fried and steaming, were analyzed, the main difference between the two methods being that stir-frying involves putting the shrimp paste into a wok and stir-frying it for different periods of time, while steaming involves putting the shrimp paste into a steamer and steaming it for different periods of time. The effects of different salt concentrations and processing techniques on the volatile flavor compounds of shrimp paste were also observed. Electronic nose and gas chromatography-ion mobility spectrometry (GC-IMS) were employed to analyze the volatile flavor compounds. A total of 52 volatile flavor compounds were detected by GC-IMS, of which 38 were identified (including monomers, dimers, and polymers). The identified compounds included 11 aldehydes, 6 ketones, 14 alcohols, 2 esters, 2 acids, 1 pyridine compound, and 2 sulfur compounds. In addition, 14 compounds were identifiable. Using the results of the electronic nose analysis, we were also able to differentiate between the volatile flavor compounds in shrimp pastes produced by different processing methods.

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.

Characterization of the volatile components in the processing of Citri Exocarpium Rubrum black tea based on HS-SPME and GC/MS

Citri Exocarpium Rubrum black tea (CER tea) is a novel blend tea infusion combining tea and CER. Due to its potential health benefits and unique flavor, it has gained popularity among consumers. Nevertheless, the aroma characteristics and key odorants of it remain to be distinguished and cognized. The HS-SPME and GC/MS techniques were employed to analyze the alterations in volatile constituents throughout the critical stages of CER tea production. A total of 200 chemical compounds exhibited notable disparities during the processing procedures. Among them, terpenes and esters were the most abundant compounds in CER tea, which might be the key material basis for the aroma quality of CER tea. It is worth noting that 124 metabolites were significantly increased in the kneading stage and drying stage, including benzeneacet aldehyde, trans-nerolidol, and D-limonene, with contained floral and fruity odors, which might be closely related to the aroma of CER tea. Monoterpenes might be important contributors to the aroma of CER tea. This study provided a theoretical basis for the quality improvement of CER tea.

Discriminative analysis of aroma profiles in diverse cigar products varieties through integrated sensory evaluation, GC-IMS and E-nose

Cigars, treasured for their rich aromatic profiles, occupy a notable segment in the global consumer market. The objective of this study was to characterize the volatile aroma compounds that shape the flavor profiles of six distinct varieties of Great Wall cigars, contributing to the understanding of cigar aroma analysis. Utilizing HS-GC-IMS and sensory evaluation, the study discerned the aroma profiles of GJ No. 6 (GJ), Animal from the Chinese zodiac (SX), Range Rover No. 3 Classic (JD), Miracle 132 (QJ), Sheng Shi No. 5 (SS), and Red 132 (HS) cigars. The analysis uncovered a spectrum of characteristic aromas, including tobacco, creaminess, cocoa, leather, baking, herbaceous, leathery, woodsy, and fruity notes. A total of 88 compounds were identified, categorized into 11 chemical classes, with their quantities varying among the cigars in a descending order of QJ, JD, GJ, SS, HS, and SX. 24 compounds, such as 2-heptanone, n-butanol, 2,6-dimethylpyrazine and 2-furfuryl methyl sulfide were considered as key differential components. The volatile components were effectively differentiated using principal component analysis (PCA), orthogonal partial least squares-discriminant analysis (OPLS-DA), and cluster analysis, revealing correlations between sensory attributes, key components, and electronic nose (E-nose). This research introduces a novel method for analyzing volatile aroma components in cigars, offering insights to enhance cigar quality and to foster the development of new products with unique aroma profiles.

Differences in the Determination of Volatile Organic Compounds between Chrysanthemum morifolium Ramat. and Chrysanthemum indicum L. (Wild Chrysanthemum) by HS-GC-IMS

Chrysanthemums and wild chrysanthemums are herbs with high application value. As edible plants of the Asteraceae family, they have good antioxidant, anti-inflammatory and hepatoprotective properties. Chrysanthemums and wild chrysanthemums contain a wide variety of volatile organic compounds, and these volatile components are the main factors contributing to the flavor differences. Therefore, in this study, we investigated the volatile components of holland chrysanthemum from Bozhou, Anhui Province, Chu-chrysanthemum from Chuzhou, Anhui Province, Gong-chrysanthemums from Huangshan, Anhui Province, Huai-chrysanthemums from Jiaozuo, Henan Province, Hang-chrysanthemum from Hangzhou, Zhejiang Province, and wild chrysanthemum from Dabie Mountain by headspace-gas chromatography-ion mobility spectrometry (HS-GC-IMS) coupled with principal component analysis (PCA). The results showed that Chrysanthemum and wild chrysanthemum contain alcohols, esters, hydrocarbons, ketones, aldehydes, acids, camphor, pyrazines and furans. Among them, alcohols, esters and hydrocarbons accounted for more than 15%. It was hypothesized that 2-methyl-1-propanol, 2-methylbutanol, 1-hexanol in alcohols and hexyl acetate, 3-methylbutyl acetate and ethyl 2-methylpropanoate in esters might be the main reasons for the alcoholic and sweet flavors of chrysanthemum and chrysanthemum officinale. Based on the principal component analysis, cluster analysis with the Euclidean distance and similarity analysis of fingerprints, it was found that there were significant differences in the volatile components in chrysanthemums from different origins, among which the differences between Chu-chrysanthemum and Hang-chrysanthemum were the most significant. In addition, as a genus of wild chrysanthemum with the same species, it contains a richer variety of volatile organic compounds, and the content of hydrocarbons and alcohols is significantly higher than that of chrysanthemum.

Quality-Driven Design of Pandan-Flavored Sponge Cake: Unraveling the Role of Thermal Processing on Typical Pandan Aroma

Pandan (Pandanus amaryllifolius Roxb.) has been used in the production of bakery goods either as a functional ingredient or a natural flavoring that, when roasted, exerts a fragrant rice-like aroma and an attractive green color. This study elucidated the typical aroma compounds from pandan leaves and explored the influence of thermal treatments on their aroma profiles using GC-O-MS, E-nose, and GC-IMS analyses. The effects of formulation and baking conditions on the qualities of pandan-flavored sponge cake were comprehensively evaluated through a holistic approach covering several aspects including cake batter gravity, color, texture, and sensory characteristics. The baking treatment introduced more types of pleasant aromas (9 aromas vs. 17 aromas) and increased the odor intensities of the original volatile compounds, especially for the roasted and steamed rice-like odors. The increased amount of pandan flavoring reshaped the color of the cake crumb (especially for the L* and a* spaces) and significantly decreased the hardness (3.87 N to 1.01 N), gumminess (3.81 N to 0.67 N), and chewiness (13.22 mJ to 4.56 mJ) of the sponge cake. The perceived intensities of bitterness and sweetness can be adjusted by modulating the levels of 2-phenylethanol, 2-methyl-1-butanol, hexyl alcohol, and decanal, along with the total alcohols and aldehydes, due to their significant correlations revealed by correlation heatmap analyses.

Early warning of Aspergillus contamination in maize by gas chromatography-ion mobility spectrometry

Introduction

As one of the main grain crops in China, maize is highly susceptible to Aspergillus infection during processing, storage and transportation due to high moisture at harvest, which results in the loss of quality. The aim of this study is to explore the early warning marker molecules when Aspergillus infects maize kernels.

Methods

Firstly, strains MA and MB were isolated from moldy maize and identified by morphological characterization and 18S rRNA gene sequence analysis to be Aspergillus flavus (A. flavus) and Aspergillus niger (A. niger). Next, fresh maize was moldy by contaminated with strains MA and MB. The volatile organic compounds (VOCs) during the contamination process of two fungal strains were analyzed by gas chromatography-ion mobility spectrometry (GC-IMS). A total of 31 VOCs were detected in maize contaminated with strain MA, a total of 32 VOCs were detected in maize contaminated with strain MB, including confirmed monomers and dimers. Finally, heat maps and principal component analysis (PCA) showed that VOCs produced in different growth stages of Aspergillus had great differences. Combined with the results of GC-IMS, total fungal colony counts and fungal spores, it was concluded that the Aspergillus-contaminated maize was in the early stage of mold at 18 h.

Results

Therefore, the characteristic VOCs butan-2-one, ethyl acetate-D, Benzaldehyde, and pentan-2-one produced by maize at 18 h of storage can be used as early mildew biomarkers of Aspergillus infection in maize.

Discussion

This study provided effective marker molecules for the development of an early warning and monitoring system for the degree of maize mildew in granaries.

Characterization and discrimination of volatile organic compounds and α-glucosidase inhibitory activity of soybeans (Glycine max L.) during solid-state fermentation with Eurotium cristatum YL-1

In this study, the influence of solid-state fermentation (SSF) using probiotic Eurotium cristatum on the change of volatile organic compounds (VOCs) and α-glucosidase inhibition activity of soybeans was investigated. A total of 46 VOCs were characterized via headspace gas chromatography-ion mobility spectrometry (HS-GC-IMS), the majority of which were aldehydes (17), alcohols (10), and ketones (7). SSF by E. cristatum drastically affected the flavor characteristics of soybeans, and the levels of unpleasant beany flavor components, such as hexanal-D, 1-octen-3-ol, 1-hexanol-D, 1-hexanol-M, heptanal-M, 1-pentanol, heptanal-D, and 2-pentyl furan were all substantially decreased by 50% after 15 days of SSF, while volatiles with floral, caramel, and desirable flavors such as pentanal-D, methylpropanal, 2-propanol, and propyl acetate drastically (p < 0.05) increased by 1.1-, 19.2-, 3.6-, and 2.6-fold, respectively. Key aroma-active compounds analysis revealed that 18 VOCs (ROAV, relative odor activity value ≥ 1) play a great role in shaping the flavor characteristics of the soybean samples. After 15 days of SSF, the ROAV values of methylpropanal, 2-propanol, and propyl acetate drastically (p < 0.05) increased to 8.48, 63.88, and 11.29, respectively, which greatly contributed to the desirable flavor characteristics of fermented soybeans. Furthermore, E. cristatum greatly improved the α-glucosidase inhibitory activity of soybean by 22.4% after 15 days fermentation, which was closely correlated with the accumulated phenolic compounds during SSF. Molecular docking showed that genistein and daidzein have high binding affinity for α-glucosidase active sites, primarily driven by hydrogen bonds and hydrophobic interactions. These results demonstrated that soybeans fermented with E. cristatum substantially improved the flavor characteristics and α-glucosidase inhibitory effect, and were greatly helpful to promote the application of soybeans in food products.

Characterization of the flavor profile and dynamic changes in Chinese traditional fish sauce (Yu-lu) based on electronic nose, SPME-GC-MS and HS-GC-IMS

In this study, flavor characteristics and dynamic change of Chinese traditional fermented fish sauce (Yu-lu) with different fermentation time (2, 4, 6, 8, and 12 months) were analyzed. The electronic nose analyses confirmed a notable flavor change in fish sauce samples from different stages. During the 12-months fermentation, the total volatile compounds in fish sauce increased from 3.9 mg/L to 13.53 mg/L. Acids, aldehydes, esters and phenols were the main aroma substances and their contents gradually increased during the fermentation process. The PCA of GC-MS and GC-IMS showed that fish sauce samples from different fermentation periods can be well distinguished. A total of 110 volatile compounds identified by GC-MS, and 102 volatile compounds were detected by GC-IMS. Among them, 13 compounds were identified by both GC-MS and GC-IMS. The most varieties (49) of volatiles appeared after 8 months of fermentation. The odor activity value (OAV) analysis showed that 10 volatile compounds were considered as characteristic flavor in traditional fish sauce. The variable influence on projections (VIPs) in PLS-DA models constructed by GC-MS and GC-IMS identified 5 and 10 volatile compounds as biomarkers, respectively. Our results revealed the dynamic changes of characteristic flavor in fish sauce in combination of GC-MS and GC-IMS, which provides theoretical basis for the production and flavor regulation of fish sauce.

Characterization of the flavor profile of Hulatang using GC-IMS coupled with sensory analysis

Background

Hulatang is a traditional specialty snack in Henan, China, and is well known for its unique flavor.

Methods

In this study, the volatile organic compounds (VOCs) in four kinds of Hulatang from two representative regions in Henan Province (Xiaoyaozhen and Beiwudu) were evaluated using headspace-gas chromatography-ion mobility spectrometry (HS-GC-IMS).

Results

The results showed that Xiaoyaozhen Hulatang exhibited more ethers, fewer terpenes and ketones than Beiwudu Hulatang. Additionally, Hulatang from different regions were classified using the orthogonal partial least squares-discriminant analysis (OPLS-DA) based on GC-IMS data. Twenty aroma substances were selected as the potential markers using the variable importance in the projection (VIP) variable selection method. Additionally, fifteen aroma components significantly contributing to the aroma of Hulatang were screened using the relative odor activity value (ROAV) (ROAV > 1). Combined with the sensory score results, twelve key substances with significant correlation with odor perception were selected. The flavor characteristics of the key substances revealed that the flavor of Hulatang was mainly composed of volatile components with camphor, green, almond, fatty, spicy, herbal, vegetable, fruity, floral, musty, and solvent aromas.

Conclusion

Overall, the experimental results provide a theoretical basis for evaluating the flavor characteristics of Hulatang from different regions using GC-IMS.

Comparison of Different Deodorizing Treatments on the Flavor of Paddy Field Carp, Analyzed by the E-Nose, E-Tongue and Gas Chromatography-Ion Mobility Spectrometry

Changes in the flavor and taste profiles of Paddy Field Carp after deodorization with perilla juice (PJ), cooking wine (CW) and a mixture of the two (PJ-CW) were analyzed using the E-nose, E-tongue, gas chromatography-ion mobility spectrometry (GC-IMS), free amino acid analysis and taste nucleotide analysis. The E-nose and E-tongue revealed that deodorization reduced the content of sulfur-containing compounds, enhanced umami, bitterness, sourness and astringency, and decreased saltiness. PCA and OPLS-DA analysis successfully distinguished between the effects of the treatments. Free amino acids increased from 8777.67 to 11,125.98 mg/100 g and umami amino acids increased from 128.24 to 150.37 mg/100 g after PJ-CW deodorization (p < 0.05). Equivalent umami concentration (EUC) comparisons showed that PJ-CW treatment produced the greatest synergistic umami enhancement (to 3.15 g MSG equiv./100 g). GC-IMS detected 52 aroma compounds; PJ treatment produced the greatest diversity of aldehydes, including heptanal, nonanal, hexanal, 3-methylbutanal, (E)-2-heptenal and (E,E)-2,4-heptadienal. The total content of volatile flavor compounds was the highest after PJ-CW treatment, and the content of many characteristic flavor substances (3-hydroxy-2-butanone, benzaldehyde, 5-methyl-2(3H)-furanone) increased. These findings provided a theoretical basis for the further development of deodorization methods for Paddy Field Carp.

Characterization of flavor profile of Steamed beef with rice flour using gas chromatography-ion mobility spectrometry combined with intelligent sensory (Electronic nose and tongue)

The intelligent senses (Electronic nose and tongue), were combined with headspace gas chromatography-ion mobility spectrometry (HS-GC-IMS) and free amino acid were used in combination to determine the aroma and taste components during the processing of Chinese traditional dish Steamed beef with rice flour (SBD). The findings revealed that E-nose and E-tongue, could clearly distinguish and identify the aroma and taste of SBD. A total of 66 volatile substances and 19 free amino acids were identified by HS-GC-IMS and amino acid analyzer, respectively. The highest contribution to aroma in the production of SBD was alcohols, esters and aldehydes. Further analysis of relative odor activity showed that 3-Methylbutanol-D, 3-Methylbutanol-M and 3-Methylthio propanal is the marinating stage (T2) main aroma components. Ethyl 3-methylbutanoate-M and Ethyl 3-methylbutanoate-D were the main aroma components in the seasoning stage (T3). Additionally, the calculation of the taste activity value showed that Glutamic contributed significantly to the umami of SBD. Alanine was a representative taste component in the marinating stage (T2), while Proline, Aspartic, Lysine, Glutamic, Valine, Arginine, and Histidine were characteristic amino acids of the seasoning stage (T3). Consequently, this study offers valuable insights into the industrial-scale production and flavor regulation of SBD products.

Comparative Analysis of Commercially Available Flavor Oil Sausages and Smoked Sausages

This study utilized gas chromatography-ion mobility spectrometry (GC-IMS) to analyze the volatile flavor compounds present in various commercially available sausages. Additionally, it conducted a comparative assessment of the distinctions among different samples by integrating sensory evaluation with textural and physicochemical parameters. The results of the GC-IMS analysis showed that a total of 65 volatile compounds were detected in the four samples, including 12 hydrocarbons, 11 alcohols, 10 ketones, 9 aldehydes, 12 esters, and 1 acids. Fingerprinting combined with principal component analysis (PCA) showed that the volatiles of different brands of sausages were significantly different (p < 0.05). The volatiles of S1 and S4 were more similar and significantly different from the other two samples (p < 0.05). Among them, there were 14 key volatile substances in the four samples, of which 3-hydroxy-2-butanone and diallyl sulfide were common to all four sausages. Combined textural and sensory evaluations revealed that smoked sausages exhibited superior characteristics in resilience, cohesiveness, springiness, gumminess, and chewiness. Additionally, smoked sausages were found to be more attractive in color, moderately spicy, and salty, while having a lower fat content. In conclusion, smoked sausages are preferred by consumers over flavored oil sausages.

HS-GC-IMS Analysis of Volatile Organic Compounds in Six Spicy Spices and Their Effects on Ulcerative Colitis

The volatile organic compounds of six spices, including black pepper, dried ginger, cinnamon, fennel, clove, and zanthoxylum, were analyzed by gas chromatography-ion mobility spectrometry (HS-GC-IMS) combined with principal component analysis (PCA) and Euclidean distance. In further analyses, the effects of volatile oils in six spices on ulcerative colitis were assayed in a zebrafish model induced by 3-nitrobenzenesulfonic acid. A total of 120 kinds of volatile organic compounds were detected and 80 among them were identified, which included 10 common components and 3 to 24 characteristic components belonging to different spices. The major VOCs in six spices were estimated to be terpenes with the contents of 45.02%, 56.87%, 36.68%, 58.19%, 68.68%, and 30.62%, respectively. Meanwhile, the volatile components of fennel, dried ginger, black pepper, and cinnamon are quite similar, but differ from clove and zanthoxylum. The volatile oils in six spices presented efficient activity to improve ulcerative colitis which can decrease the number of neutrophils, restore the structure of intestinal epithelial and the morphology of the epithelial cells. Our study achieved rapid analysis of the volatile organic compounds and flavors in six spices and further revealed the potential health benefits of their volatile oils on ulcerative colitis, especially for clove and zanthoxylum. This study is expected to provide certain data support for the quality evaluation and the potential use in functional foods of six spices.

Binary probiotic fermentation promotes signal (cyclic AMP) exchange to increases the number of viable probiotics, anthocyanins and polyphenol content, and the odor scores of wolfberry fermented beverages

The effects and underlying molecular mechanisms of binary probiotics (Lactiplantibacillus plantarum subsp. plantarum CGMCC 1.5953 and Lacticaseibacillus casei CGMCC 1.5956) on the quality of wolfberry fermented beverages (WFB) were investigated. The results indicated that binary probiotics increased the number of probiotics, anthocyanin (89.92 ± 1.64 mg/L), polyphenol content (283.04 ± 3.81 µg/mL), and odor score (24.19) in WFB. Metabolomics found that they could enhance signal exchange (cyclic AMP) between binary probiotics and improve the utilization of citrulline, d-proline, d-glucose, and d-galactose through galactose metabolism and amino acid biosynthesis pathway to promote probiotics growth. Furthermore, HS-SPME-GC-MS and GS-IMS revealed that the improvement in flavor was mainly due to an increase in the content of the aromatic flavor substances 3-heptanol, glutaraldehyde, and 2-heptanone, and a decrease in the content of the off-flavor substances methyl isobutyl ketone-D and 2-undecanone. This is strategically important for the development of WFB with high probiotic content and unique flavor.

The formation and conversion of characteristic aroma profiles and key harmful substances in different high-temperature processing of hairtail (Trichiurus Haumela)

The balance regulation between characteristic aroma and hazards in high-temperature processed fish is a hot spot. This study was aimed to explore the interactive relationship between the nutritional value, microstructures, aroma, and harmful substances of hairtail under different frying methods including traditional frying (TF), air frying (AF), and vacuum frying (VF) via chemical pattern recognition. The results indicated that VF-prepared hairtail could form a crunchy mouthfeel and retain the highest content of protein (645.53 mg/g) and the lowest content of fat (242.03 mg/g). Vacuum frying reduced lipid oxidation in hairtail, resulting in the POV reaching 0.02 mg/g, significantly lower than that of TF (0.05 mg/g) and AF (0.21 mg/g), and TBARS reached 0.83 mg/g, significantly lower than that of AF (1.96 mg/g) (P < 0.05), respectively. Notable variations were observedin the aroma profileof hairtail preparedfrom different frying methods. Vacuum frying of hairtail resulted in higher levels of pyrazines and alcohols, whereas traditional frying and air frying were associated with the formation of aldehydes and ketones, respectively. Air frying was not a healthy way to cook hairtail which produced the highest concentration of harmful substances (up to 190.63 ng/g), significantly higher than VF (5.72 ng/g) and TF (52.78 ng/g) (P < 0.05), especially norharman (122.57 ng/g), significantly higher than VF (4.50 ng/g) and TF (32.63 ng/g) (P < 0.05). Norharman and acrylamide were the key harmful substances in hairtail treated with traditional frying. The vacuum frying method was an excellent alternative for deep-fried hairtail as a snack food with fewer harmful substances and a fine aroma, providing a theoretic guidance for preparing healthy hairtail food with high nutrition and superior sensory attraction.

Rapid detection and quantification of melamine, urea, sucrose, water, and milk powder adulteration in pasteurized milk using Fourier transform infrared (FTIR) spectroscopy coupled with modern statistical machine learning algorithms

There is an evident requirement for a rapid, efficient, and simple method to screen the authenticity of milk products in the market. Fourier transform infrared (FTIR) spectroscopy stands out as a promising solution. This work employed FTIR spectroscopy and modern statistical machine learning algorithms for the identification and quantification of pasteurized milk adulteration. Comparative results demonstrate modern statistical machine learning algorithms will improve the ability of FTIR spectroscopy to predict milk adulteration compared to partial least square (PLS). To discern the types of substances utilized in milk adulteration, a top-performing multiclassification model was established using multi-layer perceptron (MLP) algorithm, delivering an impressive prediction accuracy of 97.4 %. For quantification purposes, bayesian regularized neural networks (BRNN) provided the best results for the determination of both melamine, urea and milk powder adulteration, while extreme gradient boosting (XGB) and projection pursuit regression (PPR) gave better results in predicting sucrose and water adulteration levels, respectively. The regression models provided suitable predictive accuracy with the ratio of performance to deviation (RPD) values higher than 3. The proposed methodology proved to be a cost-effective and fast tool for screening the authenticity of pasteurized milk in the market.

Removal of Cu (II) by ion exchange resin and its re-utilization of the residual solution from the distilled Lycium barbarum wine

In order to re-utilize the residual from the distillation of the Chinese wolfberry wine and reduce the environmental pollution, the residual is firstly filtered by the ceramic membrane of 50 nm, then the Cu (II) has transferred from the distillation is removed using the ion exchange resin, and the treated solution is recombined with the distilled liquor to make the Chinese wolfberry brandy and the comparison has conducted on the physicochemical properties, antioxidant activity and flavor compounds between the recombined brandy and the finished brandy. The results indicate that the Cu (II) was effectively removed by ceramic membrane combined with the D401 resin. Compared with finished brandy, the recombined brandy contains high contents of polysaccharides, phenols and flavonoids, thus contributing to the improvement of antioxidant capacity. The gas chromatography-ion mobility spectrometry (GC-IMS) reveals that 25 volatile compounds like esters and alcohols have identified in the brandy samples, and the differences are significant between the recombined and the finished brandy. In summary, the distilled residual from the Chinese wolfberry wine might be re-used after the appropriate treatment so as to reduce the discharge and environmental pollution.

Characterization of flavor substances in cooking and seasoned cooking brown seaweeds by GC-IMS and E-nose

The flavor of algae was one of the key factors for consumer acceptance. The objective of this study was to investigate the characteristic volatile compounds in cooking and seasoned cooking edible brown seaweeds (Undaria pinnatifida and Laminaria japonica). The gas chromatography-ion mobility spectrometry (GC-IMS) and electronic nose (E-nose) analysis showed that baking resulted in significant difference in flavor of brown seaweeds. However, the overall effect of cooking was not as significant as that of the seasoning solution treatment. Additionally, brown seaweeds treated with the seasoning solution were more acceptable. Undaria pinnatifida was found to contain 72 volatile flavor compounds, while Laminaria japonica had a total of 70. This study proved the applicability of GC-IMS combined with E-nose technology to detect the changes of volatile components of brown seaweeds after processing, providing beneficial knowledge and basic theory for the deep processing of brown seaweeds.

The potential correlation between the succession of microflora and volatile flavor compounds during the production of Zhenba bacon

Microbial composition plays an important role in the quality and flavor of bacon. The aims of this study were to detect bacterial community succession using high-throughput sequencing (HTS) and volatile flavor compound changes using gas chromatography-ion mobility spectrometry (GC-IMS) during the production of Zhenba bacon. The results showed that a total of 70 volatile compounds were detected. Among them, ketones, hydrocarbons, aldehydes, esters and alcohols were the main substances in the curing and smoking stages. In addition, the fungal abundance was greater than the bacterial abundance, and there was obvious succession of the microbial community with changes in fermentation time and processing technology. The main functional bacterial genera in the curing and smoking stages were Staphylococcus, Psychrobacter and Latilactobacillus, and the main fungal genera were Fusarium and Debaryomyces. Through correlation analysis, we found that pyrrole, 2-pentanol, methyl isobutyl ketone (MIBK) and ethyl acetate (EA) were significantly correlated with Staphylococcus, Psychrobacter, Pseudomonas and Myroides (p < 0.01), and it is speculated that they contribute significantly to flavor formation. The results of this study are helpful for understanding the microbial dynamics and characteristic volatile flavor compounds in Zhenba bacon, and provide new insights into the relationship between microorganisms and flavor through potential correlations.

Comparison of Volatile Compounds among Four Types of Teas Analyzed Using Gas Chromatography-Ion Mobility Spectrometry

Gas chromatography-ion mobility spectrometry (GC-IMS) is a smart method that has been applied to determine the volatile compounds in Chinese teas, but its use in comparing the volatile compounds of different types of tea has not been mentioned. In this study, the volatile compounds found in four types of samples (green, yellow, white, and black teas) made with fresh leaves of Camellia sinensis (L.) Kuntze 'Zhongcha 111' were analyzed using GC-IMS. The results showed that 93 volatile compounds were identified from our tea samples and that the average volume of aldehydes was higher than that for other compounds, especially in white tea. The different samples were successfully categorized using multivariate statistical analysis. Using partial least squares discriminant analysis (PLS-DA), we found 15 key compounds, including four differential components: (E)-2-hexenal, 2-furanmethanethio, 2-hexanol, and 1-octene. There were 29 common components, and their total content reached 386.0 μg/g. Moreover, the 3-methyl-2-butenal and dimethyl disulfide detected in the four samples were also differential compounds, varying according to the manufacturing technology. Thus, this study demonstrates that different types of teas can be discriminated easily using GC-IMS and that this is helpful to shorten the time for improving tea quality and developing new products.

Discrimination and screening of volatile metabolites in atractylodis rhizoma from different varieties using headspace solid-phase microextraction-gas chromatography-mass spectrometry and headspace gas chromatography-ion mobility spectrometry, and ultra-fast gas chromatography electronic nose

Atractylodis rhizoma is a common bulk medicinal material with multiple species. Although different varieties of atractylodis rhizoma exhibit variations in their chemical constituents and pharmacological activities, they have not been adequately distinguished due to their similar morphological features. Hence, the purpose of this research is to analyze and characterize the volatile organic compounds (VOCs) in samples of atractylodis rhizoma using multiple techniques and to identify the key differential VOCs among different varieties of atractylodis rhizoma for effective discrimination. The identification of VOCs was carried out using headspace solid-phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS) and headspace gas chromatography-ion mobility spectrometry (HS-GC-IMS), resulting in the identification of 60 and 53 VOCs, respectively. The orthogonal partial least squares discriminant analysis (OPLS-DA) model was employed to screen potential biomarkers and based on the variable importance in projection (VIP ≥ 1.2), 24 VOCs were identified as critical differential compounds. Random forest (RF), K-nearest neighbor (KNN) and back propagation neural network based on genetic algorithm (GA-BPNN) models based on potential volatile markers realized the greater than 90 % discriminant accuracies, which indicates that the obtained key differential VOCs are reliable. At the same time, the aroma characteristics of atractylodis rhizoma were also analyzed by ultra-fast gas chromatography electronic nose (Ultra-fast GC E-nose). This study indicated that the integration of HS-SPME-GC-MS, HS-GC-IMS and ultra-fast GC E-nose with chemometrics can comprehensively reflect the differences of VOCs in atractylodis rhizoma samples from different varieties, which will be a prospective tool for variety discrimination of atractylodis rhizoma.

Highly sensitive photoacoustic gas sensor based on near-concentric cavity

The precise detection of trace gases in the atmosphere is vital for both environmental preservation and human health. Addressing the inherent challenges in enhancing the sensitivity of photoacoustic spectroscopy, a highly sensitive photoacoustic gas detection method utilizing a near-concentric cavity was proposed. By constructing a near-concentric optical cavity, laser reflections within the photoacoustic cell were substantially amplified, resulting in enhanced sensitivity of photoacoustic signal detection. Additionally, to align with the optical path characteristics of the near-concentric cavity, a miniaturized dumbbell-like photoacoustic cell was designed. Characterized by its high-frequency resonance, this design effectively mitigated background noise while maintaining a high sound pressure level. Experimental results demonstrated a remarkable enhancement in both signal intensity and signal-to-noise ratio by factors of 22.06 and 21.26, respectively, compared to traditional excitation methods. According to the 1σ standard, with a laser power of 21 mW, the setup achieved a detection limit of 10.15 ppb for NO2. The corresponding normalized noise equivalent absorption was calculated to be 2.84 × 10-9 cm-1WHz-1/2, with a gas consumption rate of merely 15.19 mL.

Anti-mildew and fresh-keeping effect of Lactiplantibacillus paraplantarum P3 cell-free supernatant on fresh in-shell peanuts during storage process

Lactiplantibacillus paraplantarum P3 (L. paraplantarum P3) cell-free supernatant (CFS) with good antifungal effect was sprayed on fresh in-shell peanuts stored at 5 °C and 30 °C to explore its effect on the microorganisms and quality of fresh in-shell peanuts during storage process. Results showed that L. paraplantarum P3 CFS effectively maintained good quality of fresh in-shell peanuts by not only reducing fungi amount and the mildew rate, but also improving the morphology, color and flavor. Besides, L. paraplantarum P3 CFS activated plant mitogen-activated protein kinase signaling pathway and plant hormone signaling pathway to produce more ethylene, gibberellin regulatory proteins and other substances to enhance plant resistance to pathogenic microorganisms. L. paraplantarum P3 CFS could also induce the biosynthesis of glycerophospholipid and arginine to increase the stress resistance of fresh peanuts. This study provides research data for the application of L. paraplantarum P3 CFS in the preservation and antimildew of fresh in-shell peanuts.

Development and comprehensive SBSE-GC/Q-TOF-MS analysis optimization, comparison, and evaluation of different mulberry varieties volatile flavor

Optimization of seven parameters of stir bar sorptive extraction (SBSE) on mulberry volatile components for the first time. A total of 347 volatile components were identified and quantified in 14 mulberry varieties, predominantly encompassing esters, aldehydes, terpenoids, hydrocarbons, ketones, alcohols, heterocyclics, acids, and phenols. Hexanal and (E)-2-hexenal were the dominant volatiles. Furthermore, 79 volatile compounds characterized by odor activity values (OAVs) > 1 were identified, making a significant contribution to the distinctive mulberry flavor. "Green" notes were the most intense, followed by "fatty" and "fruity". Utilizing odor ring charts, the volatile flavor characteristics of the 14 mulberry varieties could be intuitively distinguished. This study not only established a viable methodology for differentiating mulberry varieties but also laid a theoretical foundation for the quality evaluation and variety breeding of mulberry flavor.

Use of GC-IMS and Stoichiometry to Characterize Flavor Volatiles in Different Parts of Lueyang Black Chicken during Slaughtering and Cutting

Chilled and cut chicken is preferred by consumers for its safeness and readiness to cook. To evaluate the quality characteristics of various chilled chicken products, differences in volatile organic components (VOCs) of six different cut parts (breast, back, leg, heart, liver, and gizzard) of Lueyang black chicken were characterized through gas chromatography-ion mobility spectroscopy (GC-IMS) combined with stoichiometry. A total of 54 peaks in the signal of VOCs were detected by GC-IMS, and 43 VOCs were identified by qualitative analysis. There were 22 aldehydes (20.66-54.07%), 8 ketones (25.74-62.87%), 9 alcohols (4.17-14.69%), 1 ether (0.18-2.22%), 2 esters (0.43-1.54%), and 1 furan (0.13-0.52%), in which aldehydes, ketones, and alcohols were the main categories. Among the six cut parts, the relative content of aldehydes (54.07%) was the highest in the gizzard, and the relative content of ketones (62.87%) was the highest in the heart. Meanwhile, the relative content of alcohols (14.69%) was the highest in the liver. Based on a stable and reliable predictive model established by orthogonal partial least squares-discriminant analysis (OPLS-DA), 3-hydroxy-2-butanone (monomer and dimer), acetone, 2-butanone monomer, hexanal (monomer and dimer), isopentyl alcohol monomer, and n-hexanol monomer were picked out as characteristic VOCs based on variable importance in projection (VIP value > 1.0, p < 0.05). Principal component analysis (PCA) and the clustering heatmap indicated that the characteristic VOCs could effectively distinguish the six cut parts of Lueyang black chicken. The specific VOCs responsible for flavor differences among six different cut parts of Lueyang black chicken were hexanal (monomer and dimer) for the gizzard, 2-butanone monomer and hexanal dimer for the breast, hexanal monomer for the back, 3-hydroxy-2-butanone monomer for the leg, 3-hydroxy-2-butanone (monomer and dimer) for the heart, and acetone and isopentyl alcohol monomer for the liver. These findings could reveal references for quality assessment and development of chilled products related to different cut parts of Lueyang black chicken in the future.

Traditional method of rhubarb processing optimized by combining flavor analysis with anthraquinone content determination

Introduction

Rhubarb is a popular food that relieves constipation and aids with weight loss. The traditional method of preparation, includes steaming and sun-drying rhubarb nine times (SDR-9) to reduce its toxicity and increase efficacy.

Methods

Flavor analysis includes odor analysis by gas chromatography-ion mobility spectrometry and taste characterization using an electronic tongue.

Results

Odor analysis of the samples prepared through SDR-9 identified 61 volatile compounds, including aldehydes, esters, alcohols, ketones, acids, alkenes, and furans. Of these, 13 volatile components were the key substances associated with odor. This enabled the process to be divided into two stages: 1-5 times of steaming and sun-drying and 6-9 times. In the second stage, SDR-6 and SDR-9 were grouped together in terms of odor. Analysis using electronic tongue revealed that the most prominent taste was bitterness. A radar map indicated that the bitterness response was the highest for raw rhubarb, whereas that for processed (steamed and sun-dried) rhubarb decreased. Orthogonal partial least squares discriminant analysis (OPLS-DA) clustering results for SDR-6 and SDR-9 samples indicated that their tastes were similar. Anthraquinones were analyzed via high-performance liquid chromatography; moreover, analysis of the taste and components of the SDR samples revealed a significant correlation.

Discussion

These results indicate that there are similarities between SDR-6 and SDR-9 in terms of smell, taste, and composition, indicating that the steaming and sun-drying cycles can be conducted six times instead of nine.

Unleashing the Potential of Digitalization in the Agri-Food Chain for Integrated Food Systems

Digitalization transforms many industries, especially manufacturing, with new concepts such as Industry 4.0 and the Industrial Internet of Things. However, information technology also has the potential to integrate and connect the various steps in the supply chain. For the food industry, the situation is ambivalent: It has a high level of automatization, but the potential of digitalization is so far not used today. In this review, we discuss current trends in information technology that have the potential to transform the food industry into an integrated food system. We show how this digital transformation can integrate various activities within the agri-food chain and support the idea of integrated food systems. Based on a future-use case, we derive the potential of digitalization to tackle future challenges in the food industry and present a research agenda.