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

Analysis of aroma components changes in Gannan navel orange at different growth stages by HS-SPME-GC–MS, OAV, and multivariate analysis

The ripe Gannan navel oranges have an appealing aroma, but few studies have reported the changes of these aromatic substances during the growth of navel oranges. In this study, changes of aroma components in Gannan navel orange from 119 to 245 days after flowering were systematically studied using headspace solid-phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC–MS) coupled with multivariate analysis, including principal component analysis (PCA) and partial least squares discriminant analysis (PLS-DA). A total of 43 and 54 aroma components were identified in pulp and peel of navel orange, respectively. The odor active value (OAV) results indicated that 14 substances were the key aroma components during the growth of navel orange. Among them, the contribution of linalool, β-myrcene and limonene were the highest. The multivariate statistical analysis further confirmed that 14 and 18 compounds could be used as key markers to distinguish the pulp and peel at different growth stages, respectively. Results from this study contributed to a better understanding of the dynamic variation and retention of aroma compounds during navel orange growth, and have great potential for industrial application.

Functional properties and flavor characteristics of milk from cows supplemented with jujube powder

Jujube has various functional properties and is a promising source of bioactive compounds and flavors. This study investigated the functional properties and flavor characteristics of milk from cows supplemented with jujube powder (JP). Here, milk volatile profiles and taste properties were analyzed by using an electronic nose and headspace solid-phase microextraction GC-MS. Compared with the control group, the total antioxidant capacity, 2,2'-azino-bis-3-ethylbenzothiazoline-6-sulphonic free-radical-scavenging activity, lactoferrin, and IgG levels increased significantly in the JP group. Volatile flavor analysis indicated that ketone levels increased, acid abundance decreased, and toluene and dimethyl sulfone significantly increased in the JP group. Taste-profile analyses demonstrated that jujube supplementation altered the taste of the milk. In summary, dietary JP supplementation affects the volatile flavor composition and aroma of milk, as well as the bioactive components and antioxidant properties. These findings enhance our understanding of milk production using direct dietary supplementation to produce sustainable dairy products.

Flavor and sensory profile of Chinese traditional fish noodles produced by different silver carp (hypophthalmichthys molitrix) mince ingredients

This study employs sensory evaluation, headspace gas chromatography–ion mobility spectrometry (HS-GC-IMS), and headspace solid-phase microextraction gas chromatography–mass spectrometry (HS-SPME-GC-MS) techniques to investigate the effect of different pretreatment of fresh silver carp mince (running water rinsing 0, 1, or 2 times) and commercially frozen surimi on the odor characteristics of fish noodles. The free choice profiling (FCP) and check all that apply (CATA) sensory analysis methods were utilized to identify 10 characteristic descriptors, which include “grass, fish fragrance, unpleasant fishy, fatty, roast, ammonia, caramel, warmed-over, earthy, and mushroomy”. HS-GC-IMS and HS-SPME-GC-MS detected 80 and 37 volatile compounds (VCs) in fish noodles. The 1-Penten-3-ol, (E)-2-pentenal-D, hexanal-D, pentanal-D, (E,E)-2, 4-heptadienal-D contents were significantly correlated with “fish fragrance” and “unpleasant fishy”, and octanal, nonanal, heptanal, 2-methylpyrazine contents were significantly correlated with “warmed-over” flavor. The results of this study can be helpful for fish noodle quality improvement and industrial production.

The odor deterioration of tilapia (Oreochromis mossambicus) fillets during cold storage revealed by LC-MS based metabolomics and HS-SPME-GC-MS analysis.

Odor deterioration of tilapia during cold storage is unavoidable and affects flavor and quality severely. Odor is characterized by the abundance of volatile compounds and metabolites. In this study, headspace-solid phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS) and metabolomic analysis were applied to explore the volatile compounds, differential metabolites, and metabolic pathways related to the odor deterioration of tilapia during cold storage. A total of 29 volatile compounds were detected to be associated with the odor deterioration of tilapia. And 485 differential metabolites were screened, of which 386 differential expressions were up-regulated and 99 differential expressions were down-regulated. Three major metabolic pathways including linoleic acid metabolism, alanine, aspartate, glutamate metabolism, and nucleotide metabolism were obtained. A potential metabolic network map was also proposed. This study contributes to revealing the metabolic mechanisms of odor deterioration in tilapia during cold storage and providing a theoretical reference for the regulation of flavor and quality.

Influence of an indigenous yeast, CECA, from the Ningxia wine region of China, on the yeast community dynamics and aroma of Cabernet Sauvignon wines

Commercial yeasts are normally used in the wine industry to achieve stable and enhanced wine flavors and aromas, but they can lead to a loss of diversity and a peculiar regional wine style. An indigenous commercial wine yeast, CECA, has been isolated from a well-known wine-producing region, Ningxia, China. As CECA is a young commercial yeast, further research into its characteristics is required. In this study, the performance of CECA in Cabernet Sauvignon wine fermentation, three different fermentation treatments, spontaneous without inoculation, inoculated with CECA, and inoculated with CECA after treatment of the grape must with dimethyl dicarbonate, were performed. During fermentation, six species of yeast identified through a culture-dependent method were also identified with a culture-independent method, although the relative abundance differed between the methods. The floral and fruity were confirmed as characteristics of CECA-inoculated wines using headspace solid-phase microextraction-gas chromatography-mass spectrometry and sensory evaluation. This study enables winemakers to better understand an indigenous commercial yeast, make a peculiar aroma for Ningxia wines and promote the reputation of Ningxia region.

Insights into the influence of physicochemical parameters on the microbial community and volatile compounds during the ultra-long fermentation of compound-flavor Baijiu.

While the variation in physicochemical parameters, microbial communities, metabolism, composition, and the proportion of volatile components in fermented grains (FG) affect final Baijiu quality, their complex interactions during the ultra-long fermentation of compound-flavor Baijiu (CFB) are still poorly understood. In this study, amplicon sequencing was used to analyze the microbial community, and headspace solid-phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS) was used to analyze the volatile components in FG during ultra-long fermentation of CFB. The relationships between the dominant microbial communities, physicochemical parameters, and volatile components were analyzed using redundancy analysis and network analysis. During ultra-long fermentation, bacterial diversity was initially higher than during the mid and late stages. Fungal diversity in the mid stages was higher than that initially and later in the process. A total of 88 volatile components, including six alcohols, 43 esters, eight aldehydes and ketones, 13 acids, and 18 other compounds were detected in FG. Starch and reducing sugars in FG strongly affected the composition and function of bacterial and fungal communities. However, acidity had little effect on the composition and function of the bacterial flora. Lactobacillus, Bacillus, Weissella, and Pichia were the core microbial genera involved in metabolizing the volatile components of FG. We provide insights into the relationships and influences among the dominant microbial communities, physicochemical parameters, and volatile components during ultra-long fermentation of CFB. These insights help clarify the fermentation mechanisms of solid-state fermentation Baijiu (SFB) and control and improve the aroma quality of CFB.

Comparative Evaluation of Volatile Organic Compounds in Two Bottle Gourd Accessions with Distinct Fruit Shapes.

Bottle gourd (Lagenaria siceraria L.) belongs to the cucurbit family and has a long history of cultivation in tropical and subtropical regions worldwide, both for food and medicine. Popularized by its unique fruit shapes, gourds are used to make ornaments and musical instruments. However, there is limited information on volatile organic compounds (VOCs) in the bottle gourd fruit. In the present study, we conducted a comparative analysis of VOCs profiled in two accessions (USVL5 and USVL10) with distinct fruit shapes: bottle and cylinder. While USVL5 only produced long cylinder fruits, USVL10 produced two fruit types, cylinder (USVL10CYN) and bottle (USVL10A and USVL10B). VOCs in each line were analyzed using headspace solid-phase microextraction-gas chromatography/mass spectrometry (HS-SPME-GC/MS). Aliphatic aldehydes and alcohols were the most abundant compounds found in these bottle gourd accessions. Based on the functional profile of the identified VOCs, our results reveal the suitability of our tested line (USVL10), enriched in functionally important VOCs such as hexanal (abundance = 381.07), nonanal (abundance = 9.85), 2-methoxy-2-methylpropane (abundance = 21.26) and D-limonene (abundance = 31.48). The VOCs profiling and functional analyses support the notion that the bottle gourd accession USVL10 can be a good candidate for its use in agriculture, the health care industry and domestic uses.

Model inversion and three-way decompositions in the analytical quality by design strategy for the determination of phthalates BY HS-SPME-GC-MS

In this work, strategies within Analytical Quality by Design (AQbD) with tools of the Process Analytical Technology (PAT) were used in the development of a head space-solid phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS) procedure for the multiresidue analysis of four phthalic acid esters, benzyl butyl phthalate, bis(2-ethylhexyl) phthalate, dibutyl phthalate and diethyl phthalate (regulated by Commission Regulation (EU) No 10/2011). The approach is based on the fact that the intended quality of the resulting chromatograms is defined in terms of the loadings on the sample mode of a Parallel Factor Analysis (PARAFAC2) decomposition. These loadings are the ones used for the inversion of a Partial Least Squares (PLS2) prediction model that has been previously fitted. The inversion gives the experimental conditions that represent a compromise solution in terms of the desired or target values of the responses (Critical Quality Attributes, CQAs), while guaranteeing that these experimental conditions are inside the experimental domain of the Control Method Parameters (CMPs).This strategy results in experimental conditions of extraction time and temperature that lead to a chromatogram of predefined quality for the four analytes together, with the subsquent saving of time and energy. The experimental conditions achieved have been experimentally verified and figures of merit of the analytical method have been determined. The method has been applied to a case study, bottled natural and flavoured mineral water. Concentrations around 0.3 μg L−1 of dibutyl phthalate have been found in 5 of the 22 bottles of water analysed.

Insights on the binding mechanism between specified aldehydes and flaxseed protein using multispectral image and molecular docking.

The binding and release behavior of flaxseed proteins to aldehydes is significant for the sensory properties of flaxseed foods. The key aldehydes of flaxseed were selected by headspace solid-phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS) and odor activity value (OAV) method, and the interaction between flaxseed protein and flaxseed protein was investigated by multispectral, molecular docking, molecular dynamics simulation, and particle size techniques. The results showed that 2,4-decadienal presented a higher binding capability and a higher Stern-Volmer constant with flaxseed protein than pentanal, benzaldehyde, and decanal. Thermodynamic analysis revealed that hydrogen bonding and hydrophobic interactions were the main forces. Aldehydes contributed to a certain reduction in radius of gyration (Rg) value and α-helix content of flaxseed protein. In addition, the results of particle size showed that aldehydes caused the proteins to aggregate toward larger particles. This study could provide new insights into the interactions between flaxseed food and flavor.

Basic amino acids treatment prior to spray drying improved the functional properties and flavor attributes of soy protein isolate

This work investigated the effect of treatment of soy protein isolate (SPI) with basic amino acids (BAA) (l-Arginine, l-Histidine, and l-Lysine) at different concentrations prior to spray drying on the beany-flavor and functional properties. The results illustrated that the BAA prominently improved the solubility and emulsifying properties of SPI, and reduced the its release of beany-flavor compounds. Additionally, l-Arginine was more effective in increasing the solubility and emulsifying properties of the SPI than l-Histidine and l-Lysine. Notably, 0.3% l-Arginine improved the solubility, emulsifying activity index, emulsifying stability index of the SPI by 43.5%, 64.2% and 45.3% respectively. Through the headspace solid-phase microextraction gas chromatography-mass spectrometry (HS-SPME-GC-MS) and headspace-gas chromatography-ion mobility spectrometry (HS-GC-IMS), the 0.3% BAA showed the better mitigation effect on the beany flavor of SPI among three addition concentrations. The increased ζ-potential showed that BAA enhanced the electrostatic repulsion of the SPI, facilitating its dissolution and formation of a more stable emulsion system. Surface hydrophobicity and fluorescence spectral results revealed that BAA enhance the exposure of hydrophobic groups, enhancing the stability of oil-water interface and promoting the interaction between beany-flavor compounds and SPI. These findings lay the theoretical groundwork for further research and application of soy protein.

Volatile Organic Compounds of Scheffersomyces spartinae W9 Have Antifungal Effect against Botrytis cinerea on Strawberry Fruit.

This study aims to evaluate the antifungal effects of volatile organic compounds (VOCs) produced by a marine biocontrol yeast, Scheffersomyces spartinae W9. The results showed that the VOCs from the yeast inhibited the growth of Botrytis cinerea mycelium and spore germination by 77.8% and 58.3%, respectively. Additionally, it reduced the disease incidence and lesion diameter of gray mold on the strawberry fruit surface by 20.7% and 67.4%, respectively. Electronic micrographs showed that VOCs caused damage to the morphology and ultrastructure of the hyphae. Based on headspace solid-phase microextraction gas chromatography-mass spectrometry (HS-SPME/GC-MS), S. spartinae W9 emitted 18 main VOCs, and the pure substance of VOCs, such as 3-methyl-1-butanol, 2-methyl-1-butanol, 2-phenylethanol, and isoamyl acetate, showed antifungal effects against B. cinerea mycelium growth. Among them, 2-phenylethanol exhibited the strongest antifungal activity. It has been concluded that VOCs are the key antifungal mechanism of S. spartinae W9, and a promising strategy for controlling gray mold on strawberry fruit.

Analysis of Volatile Compounds in Different Varieties of Plum Fruits Based on Headspace Solid-Phase Microextraction-Gas Chromatography-Mass Spectrometry Technique

To investigate the differences in the volatile compounds of plum fruit samples from different cultivars, the volatile compounds of the ‘Fengtang’ plum, ‘Kongxin’ plum, and ‘Cuihong’ plum fruits were analyzed using headspace solid-phase microextraction–gas chromatography–mass spectrometry (HS-SPME-GC-MS). The results demonstrated that a total of 938 volatile compounds were identified in three plum fruits, including 200 terpenoids, 171 esters, 116 heterocyclic compounds, 89 hydrocarbons, 82 ketones and alcohols, 63 aldehydes, 54 aromatic hydrocarbons, 21 amines, 18 acids, 17 phenols, 10 nitrogenous compounds, 7 sulfur compounds, and other compounds, 470 of which were common to all the cultivars. Moreover, 704, 691, and 704 volatile substances were detected, respectively, in the ‘Fengtang’ plum, ‘Kongxin’ plum, and ‘Cuihong’ plum, with terpenoids, esters, and heterocycles as the main compounds, accounting for 62.12~72.03% of the volatile compounds. The results of principal component analysis (PCA) and cluster analysis (CA) illustrated that the ‘Fengtang’ plum and ‘Cuihong’ plum were similar in terms of volatile compounds; the ‘Kongxin’ plum compounds were different from those in the other cultivars. Orthogonal partial least squares discriminant analysis was performed, revealing the typical volatile compounds that differed among the plum fruits of the different varieties; thus, the three plum fruits could be better distinguished. These results can provide a theoretical basis for the studies of plum fruit flavor, quality, and geographical origin identification.

Effect of milling degree on volatile profiles of cooked rice determined by electronic nose and HS‐SPME‐GC‐MS

AbstractBackground and ObjectivesVolatile components are mainly distributed in the rice bran layer; thus, rice with different milling levels exhibit different volatile profiles, which affects the aroma of rice and cooked rice. Seven diverse rice varieties were investigated to explore the effect of milling degree on volatile profiles of cooked rice, odor activity value (OAV) was applied to identify key aroma compounds, and partial least squares discriminant analysis (PLS‐DA) was applied to determine important marker compounds that may affect aroma.FindingsThe volatile profiles of cooked rice with different milling times were different according to the result of electronic nose. A total of 82 volatiles were identified by headspace solid‐phase microextraction‐gas chromatography‐mass spectrometry. The number and total content of volatile compounds in most samples decreased with increasing milling time. The number of key aroma compounds (OAV > 1) in most samples also showed a decreasing trend with increasing milling time. PLS‐DA model successfully discriminated the differential volatile compounds in cooked rice samples with different milling times. Tridecane, 6‐methyl‐5‐heptene‐2‐one, nonanal, decanal, 2‐butyl‐2‐octenal, pentadecanal, 2,4‐decadienal, anethole, geranylacetone, 1‐dodecanol, 2‐pentadecanone, 2‐methoxy‐4‐vinylphenol, and indole were identified as 13 marker aroma‐active compounds.ConclusionsThe effect of milling degree on the volatile profiles of cooked rice was closely related to the rice varieties. Longer milling time was not in favor of the aroma of cooked rice. Milling degree mainly affected the nutty, citrus, fruity, waxy, herbal, fatty, celery, smoky, and floral aromas of cooked rice.Significance and NoveltyThe study provided important information for understanding the impacts of milling degree on volatile compounds and aroma properties of cooked rice. This is of great significance for advocating moderate processing of rice and regulating the aroma quality of cooked rice.

The ester production capacity of Pichia kudriavzevii based on functional annotation of genes.

Esters were identified as the primary volatile flavor compounds in Chinese Baijiu, exerting a significant influence on its quality and aroma. This study focused on the yeast strain Pichia kudriavzevii, renowned for its high capacity to produce esters. Whole genome sequences were annotated and analyzed using the GO, KEGG, KOG, CAZy, and Pfam databases to determine the genetic basis underly the enhanced ester production capacity. Results showed that P. kudriavzevii gene function was concentrated in biosynthetic capacity, metabolic capacity, amino acid translocation capacity, glycoside hydrolysis capacity and transfer capacity. Additionally, acyltransferase and kinase were predicted as active sites contributing to P. kudriavzevii high ester production. We further compared the volatile composition differences between P. kudriavzevii and Saccharomyces cerevisiae through Headspace solid-phase microextraction-gas Chromatography-mass spectrometry (HS-SPME-GC-MS), revealing P. kudriavzevii produced 3.5 times more esters than S. cerevisiae. Overall, our findings suggest that P. kudriavzevii had potential applications in the Baijiu brewing industry.

Optimization of the Fermentation Conditions of Huaniu Apple Cider and Quantification of Volatile Compounds Using HS-SPME-GC/MS.

The fermentation process and composition of volatile compounds play a crucial role in the production of Huaniu apple cider. This study aimed to optimize the fermentation conditions of Huaniu apple cider and quantify its volatile compounds using headspace solid-phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC/MS). The optimal fermentation parameters were determined using response surface methodology (RSM). The optimal fermentation temperature was 25.48 °C, initial soluble solids were 18.90 degrees Brix, inoculation amount was 8.23%, and initial pH was 3.93. The fermentation rate was determined to be 3.0, and the predicted value from the verification test was 3.014. This finding demonstrated the excellent predictability of a RSM-optimized fermentation test for Huaniu apple cider, indicating the reliability of the process conditions. Moreover, the analysis of volatile compounds in the optimized Huaniu cider identified 72 different ingredients, including 41 esters, 16 alcohols, 6 acids, and 9 other substances. Notably, the esters exhibited high levels of ethyl acetate, ethyl octanoate, and ethyl capricate. Similarly, the alcohols demonstrated higher levels of 3-methyl-1-butanol, phenethylethanol, and 2-methyl-1-propanol, while the acids displayed increased concentrations of acetic acid, caproic acid, and caprylic acid. This study provides the essential technical parameters required for the preparation of Huaniu apple cider while also serving as a valuable reference for investigating its distinct flavor profile.

Exploring metabolic dynamics during the fermentation of sea buckthorn beverage: comparative analysis of volatile aroma compounds and non-volatile metabolites using GC-MS and UHPLC-MS.

Sea buckthorn has a high nutritional value, but its sour taste and foul odor make it unpalatable for consumers. In this study, we analyzed the metabolite changes occurring during the yeast-assisted fermentation of sea buckthorn juice using the HeadSpace Solid-Phase Microextraction Gas Chromatography-Mass Spectrometry (HS-SPME-GC-MS) and Ultra-High Performance Liquid Chromatography-Mass Spectrometry (UHPLC-MS) techniques. A total of 86 volatile aroma compounds were identified during the fermentation process. The content of total volatiles in sea buckthorn juice increased by 3469.16 μg/L after 18 h of fermentation, with 22 compounds showing elevated levels. Notably, the total content of esters with fruity, floral, and sweet aromas increased by 1957.09 μg/L. We identified 379 non-volatile metabolites and observed significant increases in the relative abundance of key active ingredients during fermentation: glycerophosphorylcholine (increased by 1.54), glutathione (increased by 1.49), L-glutamic acid (increased by 2.46), and vanillin (increased by 0.19). KEGG pathway analysis revealed that amino acid metabolism and lipid metabolism were the primary metabolic pathways involved during fermentation by Saccharomyces cerevisiae. Fermentation has been shown to improve the flavor of sea buckthorn juice and increase the relative content of bioactive compounds. This study provides novel insights into the metabolic dynamics of sea buckthorn juice following yeast fermentation through metabolomics analysis. These findings could serve as a theoretical foundation for further studies on the factors influencing differences in yeast fermentation.

2-Heptanone, 2-nonanone, and 2-undecanone confer oxidation off-flavor in cow milk storage

Flavor sensation is one of the most prevalent characteristics of food industries and an important consumer preference regulator of dairy products. So far, many volatile compounds have been identified, and their molecular mechanisms conferring overall flavor formation have been reported extensively. However, little is known about the critical flavor compound of a specific sensory experience in terms of oxidized off-flavor perception. Therefore, the present study aimed to compare the variation in sensory qualities and volatile flavors in full-fat UHT milk (FFM) and low-fat UHT milk (LFM) samples under different natural storage conditions (0, 4, 18, 25, 30, or 37°C for 15 and 30 d) and determine the main component causing flavor deterioration in the FFM and LFM samples using sensory evaluation, electronic nose, and headspace solid-phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS). In addition, the Pearson correlation between the volatile flavor components and oxidative off-flavors was analyzed and validated by sensory reconstitution studies. Compared with the LFM samples, the FFM samples showed a higher degree of quality deterioration with increased storage temperature. Methyl ketones of odd carbon chains (i.e., 2-heptanone, 2-nonanone, 2-undecanone, 2-tridecanone, and 2-pentadecanone) reached a maximum content in the FFM37 samples over 30 d storage. The combined results of the Pearson correlation and sensory recombination study indicated that 2-heptanone, 2-nonanone, and 2-undecanone conferred off-flavor perception. Overall, the present study results provide potential target components for detecting and developing high-quality dairy products and lay a foundation for specific sensory flavor compound exploration in the food industry.

Comparative analysis of the aroma profile of pineapple beers brewed with juice added at different times

Pineapple juice was added at three different points in the brewing process, (i) wort, (ii) toward the end of fermentation and (iii) at the beginning of maturation. The physicochemical properties, taste and aroma of the three fruit beers was compared to a control beer without addition of pineapple juice. The beers analysed using an electronic nose (E-nose), headspace solid phase micro-extraction gas chromatography-mass spectrometry (HS-SPME-GC-MS) and headspace gas chromatography-ion mobility spectrometry (HS-GC-IMS). Of the three fruit beers, esters characteristic of pineapple aroma was found in the beer produced with juice added late during primary fermentation. Further, the abundance of esters - isoamyl acetate, ethyl butyrate, ethyl acetate, ethyl hexanoate and phenethyl acetate - was higher. Sensory analysis showed the beer produced from the addition of juice late in fermentation had a superior aroma and was the most preferred in sensory testing. These results provide technical support for process optimisation and for improving the aroma of fruit beers.

Widely targeted metabolomic analysis reveals that volatile metabolites in cigar tobacco leaves dynamically change during fermentation

Changes in volatile metabolites during cigar tobacco leaves fermentation as well as the metabolic pathways of metabolites with significant differences were investigated to determine the influence of cigar tobacco leaves fermentation on its flavor. The volatile substances in cigar tobacco leaves at different stages were detected by headspace-solid phase microextraction gas chromatography-mass spectrometry (HS-SPME-GC-MS), and the main differences in volatile substances in cigar tobacco leaves at different fermentation stages of Yunxue1 in Yuxi production area were analyzed by principal component analysis (PCA) and orthogonal partial least squares discriminant analysis (OPLS-DA). The results show that in the process of cigar tobacco leaves fermentation (YXF0, YXF1, YXF2, YXF3, YXF4, YXF5), a total of 613 volatile metabolites were detected, and a significant difference was found in 263 kinds of metabolites. Among them, the main upregulated differential metabolites were 1,3,6,10-Cyclotetradecatetraene, 3,7,11-trimethyl-14-(1-methylethyl)-, [S-(E,Z,E,E)]-, Benzoic acid, Benzaldehyde, etc. While the main downregulated differential metabolites included beta.-Myrcene, trans-Farnesol, etc. The metabolites with significant differences are mainly concentrated in the biosynthesis of monoterpenes, diterpenes, sesquiterpenes and triterpenes, the degradation metabolism of amino acids, such as valine, leucine and isoleucine, and the biosynthesis of phenylpropyl. There were 8 different metabolites in 5 groups, including 4- (1-methylethyl) -1-cyclohexene-1-formaldehyde、2, 4-dihydroxyacetophenone、2-methylbutyl 3-methylbutyrate and methylpyrazine, all of which showed upregulation trend during fermentation. In the fermentation process, volatile metabolites participate in various synthesis and degradation pathways. The biosynthesis pathway of terpenes and amino acid synthesis and degradation pathway are connected to produce various terpenes, aldehydes and other substances, such as 1,3,6,10-Cyclotetradecatetraene, 3,7,11-trimethyl-14-(1-methylethyl)-, [S-(E,Z,E,E)]-、benzaldehyde and 4-hydroxybenzaldehyde, which are conducive to the overall flavor and quality of cigar tobacco leaves.

Analysis of volatile compounds in rice porridge of different japonica rice varieties in Northeast China

Japonica rice is a widely cultivated and consumed cereal globally. There are many studies on the aroma of japonica rice, but few are on japonica rice porridge. Electronic nose and headspace solid-phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS) techniques combined with sensory evaluation were used to analyze the volatile compounds of 21 kinds of japonica rice porridges from Northeast China. The results of electronic nose analysis showed that different varieties of rice porridges had distinct aromas, and principal component analysis effectively distinguished between them. A total of 69 volatile compounds were identified by GC-MS, including 19 hydrocarbons, 17 aldehydes, 9 alcohols, 3 ketones, 3 phenols, 5 esters, 4 ethers, 4 acids, and 5 other compounds. Then the odor activity value (OAV) was calculated to determine the contribution of each aroma compound to the overall aroma of rice porridge. Finally, it is found that the key aroma compounds of japonica rice porridge were hexanal, octanal, nonanal, decanal, (E)-2-nonenal, naphthalene, (E, E)-2,4-decadienal, butylated hydroxytoluene, 1-dodecanol, and 2-pentadecanone. This study preliminarily determined the key aroma substances and aroma attributes in japonica rie porridge, which can provide a valuable theoretical basis for selecting rice raw materials in the japonica rice porridge processing industry.