Characteristic Aroma Components Research Articles

Analysis of Aroma Characteristics of 'Binzi' and 'Xiangguo' Apple-Ancient Cultivars in China.

'Binzi' (BZ) (Malus domestica subsp. chinensis var. binzi Li Y.N.) and 'Xiangguo' (XG) (Malus domestica subsp. chinensis var. xiangguo Li Y.N.) are the ancient cultivars in China. The BZ fruits have a low-fragrant flavor on harvest day but a high-fragrant flavor after storage at room temperature, while the XG fruits have a stronger flavor when mature. 'Starking' (SK) and 'Golden Delicious' (GD) fruits have a rich flavor and are recognized by all countries in the world. However, information on the differences between ancient Chinese cultivars and Western apple cultivars in aroma compounds remains unknown. The apple fruits were collected for continuous two years. Aroma compounds in the skin and pulp of the fruits were detected at room temperature (20 ± 1 °C) during storage. The dynamics of VOCs in BZ and SK fruits were more similarly reflected in esters, while those of XG and GD fruits were reflected in aldehydes and alcohols. Ethyl 2-methylbutyrate, with an extremely low odor threshold, was the main source of typical apple flavor in SK, BZ, and XG fruits, while hexyl acetate was the source of the banana flavor in GD fruits. 6-methyl-5-hepten-2-one and β-damascenone were the important ketones produced in the later stage of storage, derived from the carotenoid metabolism pathway and providing a citrus and rose flavor to the four apple cultivars. SK had the highest number of characteristic aroma components, which were mainly derived from the amino acid metabolism pathway, providing fruits with a sweet and fruity flavor. Although the characteristic aroma components of GD were derived from the fatty acid metabolic pathway, the number of volatile esters was lower. Ethyl butyrate, derived from the saturated fatty acid metabolism, had the highest content in BZ, providing a pineapple flavor; the flavor of XG was mainly derived from ethyl 2-methylbutyrate, 6-methyl-5-hepten-2-one, and β-damascenone. Therefore, we suggest BZ and XG apples as the aroma-breeding material with which to enrich new cultivars' aroma components, derived from the fatty acid metabolism and carotenoid metabolism pathways, respectively.

Preparation, flavor component and antioxidant activity analysis of Lactiplantibacillus plantarum NCU137 fermented rice protein

Rice protein is the main component in the byproducts of rice processing such as rice dregs and rice bran. This study aims to develop lactic acid bacteria-fermented rice protein and analyze the changes of component and bioactivity. Lactiplantibacillus plantarum NCU137 was selected as the optimum fermentation strain from sixty lactic acid bacteria strains using fermentation performance and sensory score as the criteria. NCU137 was then applied to rice protein fermentation and the process parameters were optimized by single factor and orthogonal experiments. NCU137 fermentation significantly increased the acidity, antioxidant activity, and peptide content of rice protein, and eight volatile flavor compounds were identified as characteristic aroma components as determined by SPME-GC-MS. Of them, the OAV value of 1-hexanol was up to 50.94, contributing the most to the flavor of fermented rice protein. Furthermore, the antioxidant activity and mechanism of rice protein antioxidant peptide (RPAP) on H2O2-induced Caco-2 cell damage were investigated by CCK-8 method and fluorescence microscopy. RPAP showed protective effect on cell damage in a dose-dependent manner, accompanying by reduction of oxidative components such as ROS and MDA, and increasement of antioxidant components such as SOD, CAT, and GSH-PX. The protective effect might lie in the regulation of gene transcription in Nrf2/HO-1 and apoptosis Bax/Bcl pathway, as validated by RT-qPCR assay. Shortly, the rice protein fermented by NCU137 displayed significant improvement of flavor, nutritional components, and antioxidant bioactivity. The fermentation technology provides alternative strategy for processing rice protein in rice dregs and rice bran into high-valued products.

Effects of dietary β‐carotene on color and flavor quality of ovaries in adult female Chinese mitten crab (Eriocheir sinensis)

AbstractThis study aimed to investigate the effects of adding different levels (0, 50, 100, 200 and 300 mg/kg) of dietary β‐carotene on the color and flavor quality of adult female E. sinensis ovaries. Adding moderate amount of β‐carotene to the feed could regulate the distribution of carotenoids, fatty acids, and free amino acids in the ovaries of E. sinensis, as well as increase the content of total carotenoids, total fatty acids, sweet and umami amino acids in the ovaries. The dietary β‐carotene have limited coloring effects and a significant impact on the flavor of the ovaries. During thermal process, the addition of 100 mg/kg β‐carotene could effectively promote formation of aroma precursors and generate more characteristic aroma components (2‐methylbutanal, 3‐methylbutanal, hexanal, benzaldehyde, methylpyrazine). However, excessive β‐carotene supplementation (300 mg/kg) led to adverse effects on physiological metabolism and flavor of E. sinensis ovaries. Considering both feed cost and quality improvement, β‐carotene supplementation at 100 mg/kg can be considered the optimal feed supplementation for adult female E. sinensis within a 70‐day rearing period to improve edible quality of ovaries.

Identification and variation of specific volatile compounds during fruit development and postharvest stage in Japanese apricot (Prunus mume Sieb. et Zucc.) fruit

AbstractFruit aroma of Japanese apricot is distinct, and the specific volatile compounds are not clearly known during fruit development and during post‐harvest stage. This study therefore aimed to explore the volatile compounds present during these stages. The volatile compounds were analysed by headspace solid‐phase microextraction and gas chromatography–mass spectrometry. OAV, PCA and electronic nose techniques were used to determine the characteristic aroma components. Enzyme‐linked immunoassay (ELISA) was also applied to determine the activity of enzymes. The results showed that in the cultivars ‘Xiyeqing’ a total of 52 components that included 20 terpenes, 15 aldehydes, 9 esters, 3 ketones and 5 other substances were detected during fruit development and post‐harvest stage. While in the cultivar ‘Xiaoyezhugan’ a total of 49 components that included 25 terpenes, 7 aldehydes, 11 esters, 1 alcohol, 3 ketones and 2 other substances were also detected during fruit development and post‐harvest stage. We concluded that the characteristic volatile compounds of mature Japanese apricot fruit were (+)‐limonene, linalool, damascenone, β‐damascenone and nonanal, finding the basis for the fruity, floral and sweet aroma of the Japanese apricot fruit. Further analysis indicated that low temperature inhibited the synthesis of esters and terpenes, and dark conditions were more favourable to the synthesis of volatile compounds than light conditions. Short‐term storage of Japanese apricot fruit at room temperature and dark conditions was conducive for the maintenance of volatile compounds, and low‐temperature storage was the most destructive to the fruit volatile compounds. These findings form a theoretical foundation for exploring the specific volatile compound of Japanese apricot and helped to determine the optimal storage condition of post‐harvest stage for Japanese apricot fruit.

Effect of osmotic dehydration combined with vacuum freeze-drying treatment on characteristic aroma components of peach slices

Hot air drying (HD), vacuum freeze drying (FD), and pilot-scale freeze drying (PSFD) are extensively used to prepare peach slices. However, the aroma of hot air drying and vacuum freeze-drying is yet to be addressed. In this study, HS-SPME-GC–MS was used to characterize and quantify the volatile compounds in peach slices. First, 33, 36, and 46 volatile compounds were identified and quantified in the HD, FD, and PSFD groups, respectively. PSFD is preferable to HD and FD in terms of the volatile compound types, content, and aroma profiles. PSFD was selected for subsequent permeation and dehydration experiments. The key aroma compounds with an OAV ≥ 1 were found in the PSFD30 group. GC-O analysis was conducted on the PSFD30 group, leading to the preliminary identification of 2-methylbutanal, pentanal, hexanal, 2-hexenal, phenylacetaldehyde, ethyl acetate, 2-methylbutyl acetate, ethyl lactate, linalool, methyl heptenone, and γ-octalactone as distinctive aromas in dried peach slices.

Integrated transcriptomics and metabolomics analysis provides insights into aromatic volatiles formation in Cinnamomum cassia bark at different harvesting times.

Cinnamomum cassia Presl, classified in the Lauraceae family, is widely used as a spice, but also in medicine, cosmetics, and food. Aroma is an important factor affecting the medicinal and flavoring properties of C. cassia, and is mainly determined by volatile organic compounds (VOCs); however, little is known about the composition of aromatic VOCs in C. cassia and their potential molecular regulatory mechanisms. Here, integrated transcriptomic and volatile metabolomic analyses were employed to provide insights into the formation regularity of aromatic VOCs in C. cassia bark at five different harvesting times. The bark thickness and volatile oil content were significantly increased along with the development of the bark. A total of 724 differentially accumulated volatiles (DAVs) were identified in the bark samples, most of which were terpenoids. Venn analysis of the top 100 VOCs in each period showed that twenty-eight aromatic VOCs were significantly accumulated in different harvesting times. The most abundant VOC, cinnamaldehyde, peaked at 120 months after planting (MAP) and dominated the aroma qualities. Five terpenoids, α-copaene, β-bourbonene, α-cubebene, α-funebrene, and δ-cadinene, that peaked at 240 MAP could also be important in creating C. cassia's characteristic aroma. A list of 43,412 differentially expressed genes (DEGs) involved in the biosynthetic pathways of aromatic VOCs were identified, including phenylpropanoids, mevalonic acid (MVA) and methylerythritol phosphate (MEP). A gene-metabolite regulatory network for terpenoid and phenylpropanoid metabolism was constructed to show the key candidate structural genes and transcription factors involved in the biosynthesis of terpenoids and phenylpropanoids. The results of our research revealed the composition and changes of aromatic VOCs in C. cassia bark at different harvesting stages, differentiated the characteristic aroma components of cinnamon, and illuminated the molecular mechanism of aroma formation. These foundational results will provide technical guidance for the quality breeding of C. cassia.

Non-Targeted Metabolomics Reveals the Effects of Different Rolling Methods on Black Tea Quality.

A non-targeted metabolomics approach and sensory evaluation, coupled with multivariate statistical analysis, systematically uncover the impact of the rolling time on the quality parameters of black tea. GC-MS analysis reveals that a moderate extension of rolling time favorably contributes to the accumulation of characteristic aroma components in black tea. The volatile components reach their highest concentration in black tea samples processed during an 80-min rolling period. UHPLC-Q-TOF/MS analysis demonstrates a substantial decrease in the contents of catechins and flavonoids with an increase in rolling time. Simultaneously, the production of theaflavins, coupled with the degradation of green bitterness volatiles (GBVs), significantly contributes to the formation of endogenous aroma components in black tea. These findings underscore the close relationship between rolling time control and black tea quality, emphasizing that a moderate extension of the rolling time fosters the development of improved black tea flavor quality. The comprehensive quality evaluation indicates that the optimal duration is 80 min. However, the initial 0 to 20 min of rolling is a crucial phase for the genesis and transformation of black tea quality. This study offers valuable insights into the influence of rolling time on black tea quality, potentially enhancing future studies of rolling technology. It provides theoretical guidelines for optimizing the processing of Gongfu black tea.

Exploring the effect of mold fermentation on the taste and flavor properties of traditional Japanese smoked-dried bonito (katsuobushi)

The present study aimed to investigate the differences in the physicochemical properties, taste characteristics, and flavor compounds of Katsuobushi, a traditional Japanese smoked-dried bonito product, including Arabushi (unfermented) and Karebushi (mold-fermented), as well as the effects of surface fermentation on the internal, middle, and external of Karebushi products. The findings showed that mold fermentation could be an effective method for improving the color characteristics of Katsuobushi. Karebushi possessed the highest content of flavorful amino acids and nucleotides, which synergistically enhanced the level of umami taste profiles. Notably, the EUC value of the exterior (12.51 g MSG/100 g) is significantly higher than that of the interior (8.81 g MSG/100 g), which means that the surface fermentation imparts a stronger umami taste to the exterior. In addition, the abundance of organic acids in the Karebushi helped to improve the umami and sweet tastes. The electronic nose and fingerprint profiles revealed that Karebushi was found to have higher types and contents of flavor compounds than Arabushi. 3-Methyl-1-butanol, 2,5-dimethylpyrazine, and α-pinene are the characteristic volatile aroma components of Karebushi, contributing to the exceptional malty, nutty, and roasted aroma. This study may be conducive to a better understanding of the effect of mold surface fermentation on the flavor characteristics of Katsuobushi, and provide a theoretical basis for the development of appropriate start cultures.

Characterizing and Decoding the Effects of Different Fermentation Levels on Key Aroma Substances of Congou Black Tea by Sensomics.

Fermentation is the key technology for black tea aroma formation. The key aroma substances of black tea at different fermentation stages (unfermented (WDY), underfermented (F1H), fully fermented (F4H), and overfermented (F8H)) were characterized by the methodology of Sensomics. Aroma extract dilution analysis was performed on volatile fractions extracted by using solvent-assisted flavor evaporation and solid-phase microextraction, yielding 93 odor-active areas. Internal standard method plus stable isotope dilution analysis was used for quantitative analysis. The omission experiment identified 23 aroma substances. Further reduction and addition experiments revealed phenylacetaldehyde, (E,E)-2,4-heptadienal, geraniol, linalool, β-damascenone, 2-methylbutyraldehyde, dimethyl sulfide, and isovaleraldehyde with odor activity values (OAV) > 100 as the characteristic aroma components of F4H and also as the main contributors to aroma differences between different fermentation degrees. The green odor of (E,E)-2,4-heptadienal was highlighted in WDY and F1H relative to that in F4H due to the lower contribution of phenylacetaldehyde and β-damascenone in the former two samples. Additionally, excessive OAV increase of fatty aldehydes in F8H masked its similar floral and fruity aroma.

A Comprehensive Evaluation of Tomato Fruit Quality and Identification of Volatile Compounds.

Tomatoes (Lycopersicon esculentum) are the most valuable vegetable crop in the world. This study identified the morphological characteristics, vitamin content, etc., from 15 tomato varieties in total, that included five each from the three experimental types, during the commercial ripening period. The results showed that the hardness with peel and the moisture content of tasty tomatoes were 157.81% and 54.50%, and 3.16% and 1.90% lower than those of regular tomatoes and cherry tomatoes, respectively, while the soluble solids were 60.25% and 20.79% higher than those of the latter two types. In addition, the contents of vitamin C, lycopene, fructose, glucose, and total organic acids of tasty tomatoes were higher than those of regular tomatoes and cherry tomatoes. A total of 110 volatile compounds were detected in the 15 tomato varieties. The average volatile compound content of tasty tomatoes was 57.94% higher than that of regular tomatoes and 15.24% higher than that of cherry tomatoes. Twenty of the 34 characteristic tomato aroma components were identified in tasty tomatoes, with fruity and green being the main odor types. Ten characteristic aroma components in regular tomatoes were similar to those of tasty tomatoes; ten types of cherry tomatoes had floral and woody aromas as the main odor types. The flavor sensory score was significantly positively correlated with the content of soluble solids, fructose, glucose, citric acid, fumaric acid, and β-ionone (p < 0.01), and significantly negatively correlated with water content and firmness without peel. Regular, tasty, and cherry tomatoes were separated using principal component analysis, and the quality of tasty tomatoes was found to be better than cherry tomatoes, followed by regular tomatoes. These results provide valuable information for a comprehensive evaluation of fruit quality among tomato varieties to develop consumer guidelines.

Metabolomics analysis reveals the patterns and mechanisms of volatile metabolite in oolong tea during storage

Oolong tea is famous for its rich floral and fruity aroma which further develops into a distinct aged aroma over time. Storage plays an important role in the quality of the aroma. However, the precise aroma characteristics and profile components of long-term stored oolong tea have not been fully elucidated. In this study, we adopted gas chromatography-mass spectrometry (GC-MS) in combination with multivariate statistical analysis to investigate the dynamic changes in volatile metabolites of oolong tea during different storage periods. Our findings revealed 14 aroma components that served as markers distinguishing aged oolong tea from new tea. With storage years increased, the characteristic woody aroma components of (6,6-dimethyl-2-bicyclo[3.1.1]hept-2-enyl)methanol, 3,5,5-trimethylcyclohex-2-en-1-one gradually increased. Additionally, specific floral and fruity aroma components, such as 2-(4-methylcyclohex-3-en-1-yl)propan-2-yl acetate, 2-[(1S)-4-methylcyclohex-3-en-1-yl]propan-2-ol, ethyl 3-(furan-2-yl)propanoate were also found to be accumulated year by year, contributing to the woody, floral, and fruity character observed in aged tea. 5-Methyl-6,7-dihydro-5H-cyclopentapyrazine decreased regularly during storage. KEGG enrichment analysis demonstrated that the significant enrichment pathways of differential volatile metabolites were primarily related to metabolic pathways and the biosynthesis of secondary metabolites. This study provided a comprehensive understanding of the changes in volatile metabolites and aroma quality of oolong tea during storage, thereby providing guidance for the optimal storage conditions of oolong tea.

Exploring the ecological interactions of Bacillus and their contribution to characteristic aroma components in Zhenjiang aromatic vinegar

Zhenjiang aromatic vinegar (ZAV), known for its distinctive flavors, is produced through traditional solid-state fermentation involving multiple strains. The development of functional microbial communities during repeated batch acetic acid fermentation (AAF) is crucial for flavor formation in ZAV. Hence, investigating the two pivotal factors, namely flavor synthesis and microbial strains, within the vinegar ecosystem is essential for the vinegar industry to modulate the metabolic function of vinegar microbiota, monitor the fermentation process, and maintain the desired flavor quality of the final product. This study aimed to explore the ecological interactions of Bacillus within the vinegar Pei and examine the correlation between the Bacillus community and the characteristic aroma components of ZAV. The findings demonstrated that the dynamic of Bacillus community was drove by environmental factors represented by temperature and acidity, together with the interactions between microorganisms. Moreover, Bacillus exhibited a significant positive correlation with 34 volatile flavor components, including 7 alcohols, 1 acid, 20 esters, 3 aldehydes, 2 ketones, and 1 phenol. The characteristic aroma components strongly associated with Bacillus were identified as lactic acid, six ethyl esters, namely ethyl acetate, benzeneacetaldehyde, and 3-methylbutyraldehyde. Overall, this study revealed the crucial role of Bacillus in maintaining fermentation system stability and facilitating flavor synthesis. The detailed insights provided here contributed to a better understanding of the fermentation mechanisms underlying ZAV.

Exploring the Characteristic Aroma Components of Traditional Fermented Koumiss of Kazakh Ethnicity in Different Regions of Xinjiang by Combining Modern Instrumental Detection Technology with Multivariate Statistical Analysis Methods for Odor Activity Value and Sensory Analysis.

To investigate the characteristic aromatic compounds, present in the traditional fermented koumiss of the Kazakh ethnic group in different regions of Xinjiang, GC-IMS, and GC-MS were used to analyze the volatile compounds in koumiss from four regions. A total of 87 volatile substances were detected, and esters, acids, and alcohols were found to be the main aroma compounds in koumiss. While the types of aroma compounds in koumiss were similar across different regions, the differences in their concentrations were significant and displayed clear regional characteristics. The fingerprint spectrum of GC-IMS, combined with PLS-DA analysis, indicates that eight distinctive volatile compounds, including ethyl butyrate, can be utilized to distinguish between different origins. Additionally, we analyzed the OVA value and sensory quantification of koumiss in different regions. We found that aroma components such as ethyl caprylate and ethyl caprate, which exhibit buttery and milky characteristics, were prominent in the YL and TC regions. In contrast, aroma components such as phenylethanol, which feature a floral fragrance, were more prominent in the ALTe region. The aroma profiles of koumiss from the four regions were defined. These studies provide theoretical guidance for the industrial production of Kazakh koumiss products.

Analysis of Volatile Aroma Components and Regulatory Genes in Different Kinds and Development Stages of Pepper Fruits Based on Non-Targeted Metabolome Combined with Transcriptome.

Aroma is a crucial attribute affecting the quality of pepper and its processed products, which has significant commercial value. However, little is known about the composition of volatile aroma compounds (VACs) in pepper fruits and their potential molecular regulatory mechanisms. In this study, HS-SPME-GC-MS combined with transcriptome sequencing is used to analyze the composition and formation mechanism of VACs in different kinds and development stages of pepper fruits. The results showed that 149 VACs, such as esters, alcohols, aldehydes, and terpenoids, were identified from 4 varieties and 3 development stages, and there were significant quantitative differences among different samples. Volatile esters were the most important aroma components in pepper fruits. PCA analysis showed that pepper fruits of different developmental stages had significantly different marker aroma compounds, which may be an important provider of pepper's characteristic aroma. Transcriptome analysis showed that many differential genes (DEGs) were enriched in the metabolic pathways related to the synthesis of VACs, such as fatty acids, amino acids, MVA, and MEP in pepper fruits. In addition, we identified a large number of differential transcription factors (TFs) that may regulate the synthesis of VACs. Combined analysis of differential aroma metabolites and DEGs identified two co-expression network modules highly correlated with the relative content of VACs in pepper fruit. This study confirmed the basic information on the changes of VACs in the fruits of several Chinese spicy peppers at different stages of development, screened out the characteristic aroma components of different varieties, and revealed the molecular mechanism of aroma formation, providing a valuable reference for the quality breeding of pepper.

Variations of main quality components of matcha from different regions in the Chinese market.

Matcha has a unique aroma of seaweed-like, which is popular with Chinese consumers. In order to effectively understand and use matcha for drinks and tea products, we roundly analyzed the variation of main quality components of 11 matcha samples from different regions in the Chinese market. Most of matcha samples had lower ratio of tea polyphenols to amino acids (RTA), and the RTA of 9 samples of matcha was less than 10, which is beneficial to the formation of fresh and mellow taste of matcha. The total volatile compounds concentrations by HS-SPME were 1563.59 ~ 2754.09 mg/L, among which terpenoids, esters and alcohols were the top three volatile components. The total volatile compounds concentrations by SAFE was 1009.21 ~ 1661.98 mg/L, among which terpenoids, heterocyclic compounds and esters ranked the top three. The 147 volatile components with high concentration (>1 mg/L) and no difference between samples are the common odorants to the 11 samples of matcha. The 108 distinct odorants had differences among the matcha samples, which were important substances leading to the different aroma characteristics. Hierarchical cluster analysis (HCA) and orthogonal partial least squares discriminant analysis (OPLS-DA) showed that 11 samples of matcha were well clustered according to different components. Japanese matcha (MT, MY, ML, MR, MJ) could be clustered into two categories. The aroma composition of Guizhou matcha (GM1, GM2) was similar to that of Japanese matcha, 45 volatile components (decanal, pyrazine, 3,5-diethyl-2-methyl-, 1-hexadecanol, etc. were its characteristic aroma components. The aroma characteristics of Shandong matcha and Japanese matcha (ML, MR, MJ) were similar, 15 volatile components (γ-terpinene, myrtenol, cis-3-hexenyl valerate, etc.) were its characteristic aroma components. While Jiangsu matcha and Zhejiang matcha have similar aroma characteristics due to 225 characteristic aroma components (coumarin, furan, 2-pentyl-, etc). In short, the difference of volatile components formed the regional flavor characteristics of matcha. This study clarified the compound basis of the flavor difference of matcha from different regions in the Chinese market, and provided a theoretical basis for the selection and application of matcha in drinks and tea products.

Ultrasonic treatment maintains the flavor of the melon juice

Thermal treatment usually leads to the flavor deterioration of melon juice. This study was initiated to evaluate the retention effect of ultrasonic (US) and ultra-high pressure (UHP) on volatile components of melon juice by gas chromatography-mass spectrometer (GC-MS) and gas chromatography-ion mobility spectrometry (GC-IMS). The electronic nose, electronic tongue, and GC-IMS analysis showed that US was much better way to contain the flavor of melon juice than UHP was does. The correlation coefficient between the US and the control was as high as 0.99. The concentration of characteristic aroma components in melon juice after ultrasonic treatment was 2.77 times and 3.02 times higher than that in the control and UHP, respectively. Moreover, the US treatment gave no significant difference in the total soluble solids, pH, and color of the juice. And it dramatically enhanced the flavor profile of melon juice.

Systematic Review of Actinomycetes in the Baijiu Fermentation Microbiome.

Actinomycetes (a group of filamentous bacteria) are the dominant microbial order in the Daqu (DQ) fermentation starter and in the pit mud (PM) of the Baijiu fermentation microbiome. Actinomycetes produce many of the key enzymes and flavor components, and supply important precursors, which have a major influence on its characteristic aroma components, to other microorganisms during fermentation. This paper reviews the current progress on actinomycete research related to Baijiu fermentation, including the isolation and identification, distribution, interspecies interactions, systems biology, and main metabolites. The main metabolites and applications of the actinomycetes during Baijiu fermentation are also discussed.

Difference in volatile components of Lonicerae Japonicae Flos of different origins: based on GC-MS and multivariate statistical analysis

Lonicerae Japonicae Flos(LJF), a bulk medicinal material, has long been used in clinical settings. The main/Dao-di production areas are Shandong, Henan, and Hebei. However, no systematic study on the difference in volatile components of LJF from different areas is available at the moment. In this study, gas chromatography-mass spectrometry(GC-MS) was used to detect the volatile components in 30 batches of LJF from 3 main production areas. Based on the relative odor activity value(ROAV), the key aroma components were analyzed. Multivariate statistical analysis was performed to analyze the differential components and characteristic aroma components in the samples from the 3 areas. Finally, 113 volatiles were identified from the samples, which were mainly alcohols, esters, acids, aldehydes, ketones, and alkenes. Among the common components of the three areas, linalool, myristic acid, and α-linolenic acid methyl ester had high content. A total of 15 key and 9 modifying aroma components in LJF were determined based on ROAV. The 15 differential components can be used for origin identification. Among them,(E, E)-2,4-decadienal and hexanal contributed a lot to the aroma of LJF from Henan and α-nerol was a characteristic aroma component of LJF in Hebei. In addition, lauryl aldehyde was a biomarker of LJF from Shandong. This study can provide a reference for the origin identification and quality evaluation of LJF.

Characterization of the Key Aroma Compounds of Shandong Matcha Using HS-SPME-GC/MS and SAFE-GC/MS.

Shandong matcha has the quality characteristics of bright green color, seaweed-like aroma and strong, fresh and brisk taste. In order to identify the characteristic aroma components and clarify the contribution of the grinding process to the aroma of Shandong matcha. Three grades of Shandong matcha and corresponding tencha material were firstly tested with sensory evaluation, and the volatile components were extracted with headspace solid-phase microextraction (HS-SPME) and solvent-assisted flavor evaporation (SAFE) and analyzed using GC–MS. The sensory evaluation results showed that high-grade matcha (M-GS) had prominent seaweed-like, fresh and roasted notes, whereas medium and low-grade matcha (M-G1, M-G2) were gradually coupled with grassy, fatty and high-fired aromas. GC–MS results showed that in the HS-SPME method, heterocyclic compounds (45.84–65.35%) were the highest in Shandong matcha, followed by terpenoids (7.44–16.92%) and esters (6.91–15.27%), while in the safe method, esters were the highest (12.96–24.99%), followed by terpenoids (10.76–25.09%) and heterocyclic compounds (12.12–17.07%). As a whole, the composition of volatile components between M-G1 and M-G2 is relatively close, and there are more differences in volatile components between them and M-GS. The volatile components unique to M-GS were screened using the odor activity value (OAV) evaluation method, with components such as 3-methyl-2-butene-1-thiol, 3-ethyl-Phenol, 2-thiophenemethanethiol, 2,4-undecadienal, (E,E)-2,6-nonadienal, (E,Z)- being evaluated. There were other differentially volatile components, that is, volatile components that coexist in the three grades of matcha, but with different concentrations and proportions. M-G1 and M-G2 contained more volatile substances with high-fired aroma, such as 2-ethyl-3-methyl-pyrazine, coumarin and 5,6,7,8-tetrahydroquinoxaline. The grinding process not only changes the appearance of tencha, but also increases the content of volatile components of matcha as a whole, enhancing the aroma and flavor characteristics of matcha. In this study, the contents of 24 volatile components in matcha were mainly increased, such as benzene, (2,2-dimethoxyethyl)-, cis-7-decen-1-al, safranal and fenchyl acetate. The dual factors of material tencha and matcha grinding technology are indispensable in forming the differences in aroma and flavor of Shandong matcha at different levels.

Volatile components analysis of Camellia oleifera shells and related products based on HS-SPME-GC-MS

The headspace-solid phase microextraction method with the off-flavor database was used to establish odor components in Camellia oleifera shells (COS) and the corresponding particleboard (PB). The concentration of the odor components remarkably varied in fresh COS compared with dry shell and particleboard, owing to the reaction of volatile aroma compounds during drying and hot pressing. Relative odor activity value (ROAV) analysis was used to compare the key and characteristic aroma components of different products. There were four key aroma compounds found in fresh COS, which were m-cresol, p-cresol, borneol, and 2,3-xylenol; 16 found in dry COS, including 2-nonenal, n-decanal, geraniol, borneol, etc.; and 13 found in COS PB, including n-decanal, 2-nonenal, vanillin, isoeugenol, etc. Among them, m-cresol, p-cresol, 2-nonenal, n-decanal and 2,3-xylenol may be the main difference in fresh COS with dry COS and COS PB. The spatial distribution region of principal component analysis reflects the variances among samples. During the drying of the COS, the gradual peroxidation or reduction of fatty acids through lipoxygenases affect the content of the aroma substances, which leads to the difference of the compounds among samples. This study helps to realize the utilization of Camellia oleifera shells as a new interior decoration and building material by providing basic information on aroma substances.