Aroma Types Research Articles

Aroma classification and characterization of Lactobacillus delbrueckii subsp. bulgaricus fermented milk.

The aroma of the fermented milk produced by twenty-eight Lactobacillus delbrueckii subsp. bulgaricus strains was evaluated via quantitative descriptive analysis. According to the sensory analysis results, the fermented milks were grouped into milky-type, cheesy-type, fermented-type and miscellaneous-type. The representative samples of cheese-type and fermented-type were analyzed by headspace-gas chromatography-ion mobility spectrometry (HS-GC-IMS) and flavoromics. A total of 95 volatile compounds were identified and particularly, 12 aroma-active compounds were detected by using gas chromatography-olfactometry-mass spectrometry (GC-O-MS). Among the different aroma types, 2,3-butanedione, δ-decalactone, acetaldehyde, butanoic acid, acetic acid and hexanoic acid were finally screened out as the key aroma-active compounds by quantitative and odor activity value (OAV) analysis combined with aroma recombination, omission and addition experiments. These findings were valuable in developing specific fermented milk products with different aroma profiles.

Wine recommendation algorithm based on partitioning and stacking integration strategy for Chinese wine consumers

This study tries to propose a wine recommendation algorithm based on partitioning and Stacking Integration Strategy for Chinese wine consumers. The approaches follow the idea of partitioning, decomposing traditional recommendation task into several subtasks according to wine attributes, using neural network, support vector machine (SVM), decision tree, random forest, optimized random forest, Adaboost and XGBoost as recommendation models. Then, based on Stacking integration method, five models are screened out for each recommendation index as the base classifier, and the decision tree or logistic regression model is selected as the meta-learner to construct a two-layer Stacking integration framework. Finally, the optimal recommendation algorithm be built for recommendation subtasks according to the prediction accuracy. The result showed that the Stacking integrated recommendation model was suitable for the recommendation of eight attributes including colour, sweetness, foamability, mouthfeel, aroma type, year, packaging and brand, while SVM model was suitable to recommend aroma concentration and price, and the XGboost model was most appropriate for origin. This study would subserve consumers to choose the wine more easily and conveniently and provide support for wine companies to improve customer satisfaction with consumer services. The study expands the approach of concerning research and proposes a specific multi-model recommendation strategy based on artificial intelligence models to recommend multiattribute commodities.

Dynamic changes of color, volatile, and non‐volatile components during mechanized processing of green tea

The quality formation of green tea is closely related to the mechanized processing. Numerous papers involved with tea processing have been reported to optimize tea production. Nonetheless, there are seldom reports about the changes in chemical composition in green tea during mechanized processing. In this paper, the dynamic changes of main quality components in green tea during mechanized processing were analyzed with fresh leaves of tea tree variety (E-Cha No. 10) as raw materials. The content of tea polyphenols and free amino acids showed a downward trend during mechanized processing and decreased significantly during the fixing and drying stages. The content of soluble sugar increased first and then decreased during processing, reaching the maximum value after rolling. The content of total chlorophyll (Chl), chlorophyllide (Cd) a and b, and pheophorbide (Po) a and b displayed a decreasing trend during processing, but the content of pheophytin (Py) a and b showed a significantly increasing trend. The number of aroma type of tea leaves increased successively during the process of fixing, initial drying, and shaping, while the total amount of aroma declined significantly from fresh leaves to fixed leaves. The aroma types of tea leaves after fixing were relatively similar, which demonstrated that fixation was the basis of aroma formation in green tea. These results are conducive to understanding the impact of processing stages on tea quality and provide a powerful basis for the process optimization of green tea. Practical applications We found tea processing procedures have a great impact on the quality and composition of green tea (color, volatile, and non-volatile components), especially in the fixing process, which is conducive to the understanding of dynamic changes in main components of green tea during mechanized processing and has practical significance for the optimization of production parameters of green tea.

Bacterial Diversity and Lactic Acid Bacteria with High Alcohol Tolerance in the Fermented Grains of Soy Sauce Aroma Type Baijiu in North China.

Soy sauce aroma type baijiu (also known as Maotai-flavor baijiu) is one of the most popular types of baijiu in China. Traditionally, it is mainly produced in Southwest China. However, in recent decades, some other regions in China have also been able to produce high-quality soy sauce aroma type baijiu, but their microbial flora characteristics during fermentation are still unclear. Here, the bacterial microbial community structure of fermented grains in different rounds of Lutaichun soy sauce aroma type baijiu produced in North China was studied by high-throughput sequencing technology, and the potential probiotics strains with good characteristics (alcohol tolerance, etc.) were screened. The results showed that lactic acid bacteria were the main bacteria in the process of baijiu fermentation. However, as the number of repeated fermentation rounds increased, the proportion of lactic acid bacteria decreased. Firmicutes (96.81%) were the main bacteria in baijiu fermentation at the phylum level, and Lactobacillus (66.50%) were the main bacteria at the genus level. Finally, two strains with high resistance to alcohol stress, Lactiplantibacillus plantarum LTJ12 and Pediococcus acidilactici LTJ28, were screened from 48 strains of lactic acid bacteria in the fermented grains. The survival rates of L. plantarum LTJ12 and P. acidilactici LTJ28 under the 8% alcohol stress treatment were 59.01% and 55.50%, respectively. To the best of our knowledge, this study is the first to reveal the microbial succession of fermented grains in different rounds of soy sauce aroma type baijiu from North China, and has the benefit of explaining the deep molecular mechanism in the process of baijiu fermentation. In addition, the obtained lactic acid bacteria strains with high alcohol tolerance could be conducive to the development of new products such as active probiotic alcoholic beverages and may have important industrial development prospects also.

Aroma classification and flavor characterization of Streptococcus thermophilus fermented milk by HS-GC-IMS and HS-SPME-GC-TOF/MS

46 Streptococcus thermophilus strains, isolated from commercial starters cultures, were studied. The aroma of the fermented milk by these strains was evaluated by quantitative descriptive analysis (QDA). According to its major sensory attribute, the fermented milks were classified into milky-type, creamy-type, cheesy-type, fermented-type and miscellaneous-type groups. One representative sample of each group was analyzed by headspace-gas chromatography-ion mobility spectrometry (HS-GC-IMS) and headspace-solid phase microextraction-gas chromatography-time-of-flight mass spectrometry (HS-SPME-GC-TOF/MS) to describe their volatile compositions. 48 and 72 volatile compounds were identified, respectively. The fingerprint analysis showed that each aroma type had specific volatile compounds. Six important differential volatile compounds including 2,3-butanedione, 2,3-pentanedione, 2-undecanone, octanoic acid, hexanoic acid and 2-hydroxy-3-pentanone were selected as key compounds by principal component analysis (PCA) and orthogonal partial least squares discriminant analysis (OPLS-DA), which allowed to discriminate the specific aroma types. These key compounds could be used as indicators to develop fermented milks with specific aroma and flavor features.

Characterization of the key aroma compounds in black teas with different aroma types by using gas chromatography electronic nose, gas chromatography-ion mobility spectrometry, and odor activity value analysis

Aroma is one of the key factors in evaluating tea quality. However, the dominant aroma components of black teas with different aroma characteristics are still unknown. In this study, the key aroma compounds in black teas with floral aroma, sweet aroma, and sweet & floral aroma were systematically characterized by the combination of gas chromatography electronic nose (GC-E-Nose), gas chromatography-ion mobility spectrometry (GC-IMS), and odor activity value (OAV) analysis. A satisfactory discrimination was obtained by using partial least squares-discriminant analysis, based on the volatile fingerprints from the GC-E-Nose and GC-IMS, with robustness model parameters (R2Y = 0.981, and Q2 = 0.967) and (R2Y = 0.893, and Q2 = 0.86), respectively. Among the 38 identified aroma compounds, 15 volatiles were simultaneously identified as important odorants with OAVs greater than 1 in three fragrant black teas, namely (E)-2-nonenal, linalool, nonanal, benzene acetaldehyde, octanal, benzaldehyde, oct-1-en-3-ol, heptanal, ethyl 2-methylpentanoate, (E)-2-hexen-1-ol, hexanal, 2-methylbutanal, 3-methylbutanal, (E)-3-penten-2-one, and butanal, with ethyl 2-methylpentanoate (176.44≤OAV≤1453.47), 3-methylbutanal (19.59≤OAV≤76.16), (E)-2-nonenal (37.43≤OAV≤56.46) and linalool (3.29≤OAV≤56.72) being the most notable. The results provide a theoretical support for flavor quality improvement and oriented processing of black tea.

A biomimetic olfactory recognition system for the discrimination of Chinese liquor aromas

Aroma is an important attribute influencing the perceived quality of Chinese liquors, with each liquor characterized by a unique collection of volatile chemicals. Here, a biomimetic olfactory recognition system combining an optimal panel of 10 mouse odorant receptors with back propagation neural network model was designed to discriminate the aromas of Chinese liquors. Our system shows an excellent predictive capacity with an average accuracy of 96.5% to discriminate liquors of different aroma types, as well as those of different brands and ageing years within the same aroma type. A total of 124 interactions between liquor aroma compounds and odorant receptors were further elucidated to understand odorant coding at the molecular level, including 14 newly deorphaned odorant receptors. Our work represents a proof of concept for combining receptors and machine learning in the discrimination of complex odorant stimuli.

Characterization analysis of flavor compounds in green teas at different drying temperature

Drying is an important factor in the formation of green tea flavor. In this study, metabolomic analysis were used to detect characteristic components of four green teas with clean aroma (CA), chestnut-like aroma (CLA), bean-like aroma (BLA) and high-fired aroma (HFA) produced by adjusting drying temperature. The sensory evaluation results showed that the tea dried at 90°C, 110°C, 140°C and 160°C had a clean aroma, chestnut-like aroma, bean-like aroma and high-fired aroma respectively. A total of 95 volatile compounds were identified. Linalool, naphthalene, 2-methyl-naphthalene, 1-octen-3-ol contributed most to the clean aroma. 1,2-dihydro-1,1,6-trimethyl-naphthalene was the key component of the chestnut-like aroma. 2,3-diethyl-5-methyl-pyrazine, 2-methyl-butanal, 3-ethyl-2,5-dimethyl-pyrazine had the biggest contribution to the bean-like aroma. 2,3-diethyl-5-methyl-pyrazine, 3-ethyl-2,5-dimethyl-pyrazine and 2-ethyl-5-methyl-pyrazine contributed most to the high-fired aroma. A total of 838 non-volatile compounds were detected and amino acids, saccharides decreased while catechins, flavonols increased during the increasing of drying temperature. It's found that they were related to the taste of umami, astringency and bitterness. This result provides a guidance and theoretical basis for the processing of green tea with different aroma types.

Optimization of an intra-oral solid-phase microextraction (SPME) combined with comprehensive two-dimensional gas chromatography–time-of-flight mass spectrometry (GC × GC-TOFMS) method for oral aroma compounds monitoring of Baijiu

The ‘‘after-odor” is essential to the quality and consumer preference of Baijiu. An intra-oral solid-phase microextraction (SPME) combined with comprehensive two-dimensional gas chromatography–time-of-flight mass spectrometry (GC × GC-TOFMS) was developed for oral aroma compounds monitoring of Baijiu. The extraction time, sip volume and rinse time were 120 s, 5 mL, and 10 s, respectively. The procedure showed good performances at concentrations of 1.56 μg/L–1500 mg/L for different aroma compounds of Baijiu (most R2 > 0.9). Furthermore, the optimized procedure detected 85 aroma compounds with different chemical structures and provided good representations of the light, strong, soy sauce and mix aroma type Baijiu’s oral aroma profiles. Principal component analysis’s (PCA) cumulative interpretation rate was 72.42%. The acceptable performance of this procedure can be combined with dynamic sensory evaluation to improve the quality of the Baijiu aroma.

Characterization of key aroma compounds and relationship between aroma compounds and sensory attributes in different aroma types of Fu brick tea

Aroma is one of the most important sensory properties of tea. Floral-fungal aroma type, ripe-fungal aroma type and fresh-fungal aroma type were the main aroma types of Fu brick tea by QDA. A total of 112 volatile compounds were identified and quantified in tea samples by HS-SPME/GC-MS analysis. Ten voaltiles in floral-fungal aroma type, eleven voaltiles in ripe-fungal aroma type, and eighteen voaltiles in fresh-fungal aroma type were identified as key aroma compounds for the aroma characteristics formation in three aroma types of Fu brick tea. In addition, PLS analysis revealed that 3,4-dehydro-β-ionone, dihydro-β-ionone, (+)-carotol and linalool oxide Ⅱ were the key contributors to the 'floral and fruity' attribute, α-terpineol contributed to 'woody' and 'stale' attributes, and thirteen aroma compounds related to 'green' attribute. Taken together, these findings will provide new insights into the formation mechanism of different aroma characteristics in Fu brick tea.

Characterization of key aroma compounds and core functional microorganisms in different aroma types of Liupao tea

Liupao tea is a representative Chinese dark tea. Stale-aroma type, betelnut-aroma type and fungal-aroma type were the main aroma types of Liupao tea. In this study, aroma profiles and fungal communities of the three aroma types of Liupao tea were examined by HS-SPME/GC–MS and Illumina MiSeq analysis. A total of 102 volatiles were identified and quantified in Liupao tea. Indicated by OPLS-DA analysis, six aroma compounds with stale, woody, roasted notes in stale-aroma type samples, five aroma compounds possessing smoky, minty, pungent notes in betelnut-aroma type samples, and nine aroma compounds owned minty, floral, fruity, woody, green notes in fungal-aroma type samples were responsible for the different aroma characteristics formation of Liupao tea. In addition, a total of 60 fungal genera were identified in Liupao tea. Aspergillus, Wallemia, Xeromyces were the predominant fungal genera in Liupao tea. Ten fungal genera, including Wallemia, Tritirachium, Debaryomyces, Trichomonascus, unclassified_o_Hypocreales in betelnut-aroma type, Rasamsonia, Candida, Blastobotrys, Acremonium in stale-aroma type, and Xeromyces in fungal-aroma type, were identified as the biomarkers in the three aroma types of Liupao tea. Furthermore, fungal genera including Aspergillus, Wallemia, Xeromyces, and Blastobotrys were identified as the core functional microorganisms contributing to the variation of volatile profiles based on O2PLS analysis. This study provided useful information on the key aroma compounds and core functional microorganisms that drive the different aroma characteristics formation of Liupao tea.

Distribution and Quantification of 1,2-Propylene Glycol Enantiomers in Baijiu.

Enantiomers of 1,2-Propylene glycol (1,2-PG) were investigated in 64 commercial Chinese Baijiu including soy sauce aroma-type Baijiu (SSB), strong aroma-type Baijiu (STB), and light aroma-type Baijiu (LTB), via chiral gas chromatography (β-cyclodextrin). The natural enantiomeric distribution and concentration of 1,2-PG in various baijiu were studied to evaluate whether the distribution and content of the two isomers of 1,2-PG were correlated with the aroma type and storage year. The results showed that 1,2-PG has a high enantiomeric ratio and the (S)-configuration predominated in SSB. The average S/R enantiomeric ratio of this compound in SSB was approximately 87:13 (±3.17), with an average concentration of 52.77 (±23.70) mg/L for the (S)-configuration and 8.72 (±3.63) mg/L for the (R)-enantiomer. The (R)-configuration was predominant in the STB, whereas neither (S) nor (R)-form of 1,2-PG were detected in LTB. The content of the two configurations of 1,2-PG in the JSHSJ vintage of SSB showed a wave variation, with an average S/R enantiomeric ratio of 89:11 (±1.15). The concentration of (R)-1,2-PG in XJCTJ vintage liquors showed an upward and then downward trend with aging time, with an overall downward trend, and the concentration of (S)-form showed a wavy change with an overall upward trend. Except for the LZLJ-2019 vintage where both (R) and (S)-1,2-PG were present, all other samples only existed (R)-form, and a decreasing trend of (R)-enantiomer with aging time was observed. The enantiomeric ratio of 1,2-PG might be one of the potential markers for adulteration control of Baijiu as industrial 1,2-PG usually presented in the racemic mixture. Sensory analysis revealed olfactory thresholds of 4.66 mg/L and 23.92 mg/L for the (R)- and (S)-configurations in pure water respectively. GC-O showed both enantiomers exhibited different aromatic nuances.

Headspace Volatiles and Endogenous Extracts of Prunus mume Cultivars with Different Aroma Types.

Prunus mume is a traditional ornamental plant, which owed a unique floral scent. However, the diversity of the floral scent in P. mume cultivars with different aroma types was not identified. In this study, the floral scent of eight P. mume cultivars was studied using headspace solid-phase microextraction (HS-SPME) and organic solvent extraction (OSE), combined with gas chromatography-mass spectrometry (GC-MS). In total, 66 headspace volatiles and 74 endogenous extracts were putatively identified, of which phenylpropanoids/benzenoids were the main volatile organic compounds categories. As a result of GC-MS analysis, benzyl acetate (1.55–61.26%), eugenol (0.87–6.03%), benzaldehyde (5.34–46.46%), benzyl alcohol (5.13–57.13%), chavicol (0–5.46%), and cinnamyl alcohol (0–6.49%) were considered to be the main components in most varieties. However, the volatilization rate of these main components was different. Based on the variable importance in projection (VIP) values in the orthogonal partial least-squares discriminate analysis (OPLS-DA), differential components of four aroma types were identified as biomarkers, and 10 volatile and 12 endogenous biomarkers were screened out, respectively. The odor activity value (OAV) revealed that several biomarkers, including (Z)-2-hexen-1-ol, pentyl acetate, (E)-cinnamaldehyde, methyl salicylate, cinnamyl alcohol, and benzoyl cyanide, contributed greatly to the strong-scented, fresh-scented, sweet-scented, and light-scented types of P. mume cultivars. This study provided a theoretical basis for the floral scent evaluation and breeding of P. mume cultivars.

Multifunctional MgO/HKUST-1 Composite for Capture, Catalysis, and Cyclic Cataluminescence Detection of Esters All-In-One to Rapidly Identify Scented Products.

The integration of metallic oxide and metal-organic frameworks has attracted considerable attention as obtained composite materials because they show synergistic effects in applications of catalysis and sensing. Herein, we developed the hybrid MgO and HKUST-1 for efficient capture, catalysis, and cyclic cataluminescence (CCTL) detection of esters all-in-one to rapidly identify scented products. The multifunctional MgO/HKUST-1 composite with high CCTL activity was synthesized and characterized. The multifunctional MgO/HKUST-1 composite acts as an enrichment material for ester capture and serves as a catalyst, assisting the analyte to trigger multistage signals. The multistage signals of ester-containing scented products also satisfy the exponential decay equation with a certain τ-value. The τ-values obtained by the CCTL system were applied to identify the brands of essential oils. The working temperature served as the sensor element to obtain various τ-values. The τ-values constituted a digital code to label the different brands of cigarettes with the same aroma type. The multistage signals could be used to distinguish the origin regions of essential oils and tobacco. This work combines the CCTL strategy with the sample pretreatment, opening up a new direction to develop CCL and providing a new platform to rapidly identify ester-containing scented products.

The Application of Consumer Neuroscience in Evaluating the Effect of Aroma Marketing on Consumer Preferences in the Food Market

Technologies that affect humans through autonomous physiological functions are nothing remotely new. A lot of research, observations and studies around the world have shown that various smells have an impact on people's changing moods, preferences, and emotions. This study, however, integrates subjective association of preference projection and objective measurements with a mobile electroencephalograph and facial recognition technology under controlled conditions in a laboratory of consumer studies to compare the impact of selected aromatic compounds for restaurants on the emotional response of respondents, as well as explicit evaluation of the selected aroma type under real conditions in order to verify targeted impact on the choice or preference of a particular food type. The paper highlights innovative approaches to assessing the impact of aromas on consumer preferences under laboratory and real conditions measured by objective parameters, as well as the importance of air quality that can cause completely opposite effects.

Characteristic-Aroma-Component-Based Evaluation and Classification of Strawberry Varieties by Aroma Type.

The unique fruity aroma of strawberries, a popular fruit of high economic value, is closely related to all the volatile organic compounds (VOCs) contained within them. Despite extensive studies on the identification of VOCs in strawberries, systematic studies on fruit-aroma-related VOCs are few, resulting in a lack of effective standards for accurately distinguishing aroma types. In the present study, solid-phase micro extraction and gas chromatography–mass spectrometry were used to analyze and identify VOCs in the ripe fruit of each of the 16 strawberry varieties at home and abroad and to explore their characteristic aroma components and the classification of such varieties by aroma type. The results suggested remarkable variations in the types and contents of VOCs in different strawberry varieties, of which esters were dominant. The principal volatile components, consisting of four esters, three alcohols, one aldehyde, and one ketone, in 16 strawberry varieties were detected based on the absolute and relative contents of VOCs in the fruit. The characteristic aroma components in strawberries, containing nine esters, six aldehydes, and one alcohol, were determined based on the aroma values of different VOCs, and the characteristic aroma components were divided into five types further based on aroma descriptions. Sixteen strawberry varieties were finally divided into four aroma types, namely, peachy, pineapple, fruity, and floral, based on the contributions of different types. The results provided a basis and standard for classifying strawberries by aroma type, studying the hereditary regularity of the fruity aroma of strawberries, and improving aroma quality.

Functional Characterization of Hedychium coronarium J. Koenig MYB132 Confers the Potential Role in Floral Aroma Synthesis.

The R2R3-MYB transcription factors (TFs) play several key roles in numerous plant biological processes. Hedychium coronarium is an important ornamental plant well-known for its elegant flower shape and abundant aroma type. The floral aroma of H. coronarium is due to the presence of a large amount of terpenes and benzenoids. However, less is known about the role of R2R3-MYB TFs in the regulatory mechanism of floral aroma production in this breed. Herein, we isolate and functionally characterize the R2R3-MYB TF HcMYB132, which is potentially involved in regulating floral aroma synthesis. Sequence alignment analysis revealed that it includes a nuclear localization signal NLS(s) and a 2R, 3R motif signature in the sequences. A subcellular localization assay revealed that HcMYB132 protein localizes to the nucleus. Real-time qPCR assays showed that HcMYB132 is specifically expressed in flowers and its expression pattern correlates with the emission of floral volatile compounds. In HcMYB132-silenced flowers, the levels of floral volatile compounds were significantly reduced, and the expression of key structural volatile synthesis genes was downregulated compared to control. Collectively, these results suggest that HcMYB132 might play a significant role in the regulation of terpenoid biosynthesis in H. coronarium.

Fermentation Flavor Characteristics and Chemical Characterization of Lactococcus lactis in Commercial Starters

In order to deeply analyze the flavor contribution and characteristic aroma components of Lactococcus lactis in fermented milk, twenty-one strains of Lactococcus lactis were isolated from different commercial starters, and subjected to single-strain fermentation. The aroma type was defined according to the results of sensory evaluation, and then determination of volatile flavor compounds in fermented milk was performed using GC-IMS technology, and finally flavor substances were analyzed by chemometric method. The results showed that these single-strain fermented milk can be divided into three flavor types: Milk flavor, cream flavor, and butter flavor. Twenty-five compounds were identified by GC-IMS, including nine alcohols, eight ketones, three aldehydes, one carboxylic acid, and four esters. By drawing the GC-IMS fingerprint map, the characteristic compound composition of fermented milk from different strains was presented. The fermented milks of four strains of Lactococcus lactis subsp. lactis var. diacetylactis were well distinguished by principal component analysis, and the results were consistent with the sensory evaluation results. The correlation between sensory flavor classification and volatile components was analyzed by PLSR, and it was found that the volatile flavor components that had a greater contribution to the “butter flavor” were 1-hexanal and 1-hexanol, the compound which had a greater contribution to the “creamy flavor” was ethyl acetate, the compounds which contributed to the “milk flavor” were obscure, and further analysis was needed for revealing the key ingredients. This research provides a reference for exerting the flavor enhancement effect of Lactococcus lactis in fermented milk.

Carbonyl flavor compound-targeted colorimetric sensor array based on silver nitrate and o-phenylenediamine derivatives for the discrimination of Chinese Baijiu

Baijiu is a distilled liquor of great importance in the food industry. Various aroma types, brands, and grades of Baijiu have filled the market; thus, discrimination for quality control is required. Herein, we constructed a novel colorimetric sensor array based on the redox reaction between silver nitrate and o-phenylenediamine or its derivatives for the discrimination of carbonyl flavor compounds (CFCs) and Baijius. The specific colored products were changed by CFCs depending on the influence of silver nanoparticle aggregation and chemical reactions. The array was used to qualitatively and quantitatively identify 21 CFCs with fast response (<14 min), wide linear range (0.025–25 mmol/L), and low detection limits (<60 μmol/L, 29 nmol/L for carboxylic acids). Finally, the array was successfully applied to the discrimination of 56 Baijius. The method proposed in this study is simple, fast, reliable, and has good application potential for the visual determination of Chinese Baijiu.

The appearance of volatile aromas in Tieguanyin tea with different elevations.

Chinese people have consistentlypreferred high mountain tea because specific flavors are memorable for them, and also, people have traditionally considered this type of tea to be good for health. Tieguanyin is one of the famous traditional Chinese tea that has ever-changing aromas. To illustrate the various characteristics in volatile fragment compounds from Tieguanyin tea, fresh tea leaves collected from different elevations (450, 650, and 900m) were detected using GC-MS by solid-liquid extraction. The results showed that volatile aromatic compounds, such as benzyl alcohol, phenyl ethanol, and acetophenone, were the most abundant in tea leaves located with high elevation. Meanwhile, 1-hexanol, 1-nananol, and nanoic acid, as a type of aliphatic aroma, were more prevalent in low-elevation tea orchards. Catechols and alkaloids are largely cumulated in low- and high-elevation tea leaves, respectively. Our findings also showed that elemene was widely consisted of high-elevation tea metabolites. It provided practicality for the preparation of tea manufacturing in major Tieguanyin tea-producing regions.