Characterization of Volatile and Semi‐Volatile Compounds in Chinese Rice Wines by Headspace Solid Phase Microextraction Followed by Gas Chromatography‐Mass Spectrometry

The volatile and semi‐volatile compounds of Chinese rice wines were extracted by headspace solid phase microextraction (HS‐SPME) and analyzed by gas chromatography‐mass spectrum (GC‐MS). The original Chinese rice wine samples were diluted with deionized water to a final concentration of 6% (v/v) ethanol and then extracted by HS‐SPME. The samples were pre‐equilibrated at 50°C for 15 min and extracted with stirring at the same temperature for 45 min prior to injection into a GC‐MS. A total of 97 volatile and semi‐volatile compounds were identified from ten Chinese typical rice wine samples, including 13 alcohols, 8 acids, 28 esters, 4 aldehydes and ketones, 17 aromatic compounds, 3 lactones, 6 phenols, 3 sulphides, 9 furans and 6 nitrogen‐containing compounds, of which, 39 compounds were firstly reported in Chinese rice wine. By stepwise linear discrimination analysis, the ten Chinese rice wine samples could be classified into three groups according to the production area, and in particular, the production technologies.     

Characterization of the aroma-active compounds in Daqu: a tradition Chinese liquor starter

Daqu is a fermentation starter and substrate complex that is used to initiate the solid fermentations for the production of Chinese liquor. The aroma of Daqu is one of the most important factors that influence the flavor of Chinese liquor. The objective of this study was to evaluate the potent aroma-active compounds in Daqu. Odorants of Daqu extracted by solvent-assisted flavor evaporation (SAFE) were investigated by gas chromatography–olfactometry (GC–O) system with two olfactometric methods: detection frequency (DF) method and aroma extract dilution analysis (AEDA). A total of 43 compounds were identified in Daqu. Thirty-eight aroma-active components were further detected among which 33 were identified. Among these compounds, 4 odorants seem to contribute actively to the aroma of Daqu: hexanal (green grass), unknown (no.u2, nutty, roasted), phenylacetaldehyde (floral, rose) and 4-ethyl guaiacol (clove, spicy).     

Influence of Oak Chips Geographical Origin,Toast Level,Dosage and Aging Time on Volatile Compounds of Apple Cider

The effects of different geographical origin, levels of toasting, dosage and the aging time of oak chips on volatile compounds released into ciders were studied. The oak chips tested were the same size and with three different toast levels (light, medium and heavy) from French, American and Chinese oak. The oak wood chips were immersed in identical ciders. Higher alcohols, acids and esters were determined by headspace (HS)–solid phase microextraction (SPME) and gas chromatography (GC)–mass spectrometry (MS), while oak‐related aroma compounds including trans‐and cis‐oak lactones, guaiacol, 4‐methylguaiacol, furfural, 5‐methylfurfural, vanillin, eugenol and isoeugenol, were determined by liquid‐liquid extraction by means of ultrasound and GC/MS selective ion monitoring (SIM). The results showed that there was little difference between the oak‐related volatile compositions of ciders aged with French oak chips and those aged with American oak chips, but that there were obvious differences with Chinese oak chips. It was observed that oak chips, at medium toasting levels, released the highest concentrations of volatile components into the ciders. Most of the oak‐related volatile aroma compounds extracted had an increase that depended on the oak chip dosage with the exception of guaiacol and furfural.     

固相微萃取-气相色谱-质谱法分析中高温大曲发酵、贮存过程中挥发性风味成分的变化

采用顶空固相微萃取-气相色谱-质谱联用(HS-SPME-GC-MS)技术,分析大曲在发酵和贮存过程中香气成分变化规律。结果表明,多数挥发性化合物含量从发酵的第1天开始增加,到第5天达到最大值,随后下降,20 d后趋于稳定;含氮类化合物从发酵的第5天快速增加,第9天达到最大值,发酵20天后含量趋于稳定。     

Microbial Community Composition Associated with Maotai Liquor Fermentation

The solid‐state fermentation state of Chinese Maotai liquor involves the interaction of several complex microbial communities leading to the generation of the most complex liquor fermentation system in the world and contributes to the unique flavor and aroma of the liquor. In this study, total DNA was extracted from 3 fermented grain samples (FG1, FG2, and FG3) and 12 environmental samples, including Daqu (DA1, DA2, DA3, and DA4), cellar mud (CS1, CS2, and CS3), soil (SL1 and SL2), air (A1 and A2), and sorghum (SH), and the 16S and 18S rRNA genes were amplified. The distribution of typical microorganisms in the samples was analyzed using nested PCR‐denaturing gradient gel electrophoresis, while quantitative PCR amplification of 16S rRNA and internal transcribed spacer genes was performed to estimate the microbial abundance present in each sample. The results indicated that Daqu was the primary source of bacteria, followed by the air, soil, and sorghum samples, while the majority of the fungi responsible for Maotai liquor fermentation were from Daqu and sorghum. Highest bacterial concentrations were found in fermented grains, followed by Daqu and sorghum, while the highest fungal concentrations were found in Daqu, followed by sorghum and an air sample from outside the liquor production area. The findings of this study may provide information regarding the mechanisms responsible for flavor development in Maotai liquor, and may be used to further optimize the traditional art of making liquor.     

Analysis and characterization of aroma‐active compounds of Schizandra chinensis (omija) leaves

Volatile components from leaves of Schizandra chinensis (omija), a native plant of Korea, were extracted by simultaneous distillation–extraction (SDE) and analyzed by gas chromatography–mass spectrometry (GC‐MS) using two types of capillary column with different polarities (DB‐5MS and DB‐Wax). The GC‐MS analysis of volatile compounds obtained by SDE revealed that germacrene D is the most abundant compound (22.6%) in omija leaves, followed by β‐elemene (17.4%), (E)‐2‐hexenal (8.7%), and (E)‐β‐ocimene (7.2%). Aroma‐active compounds were determined by gas chromatography–olfactometry (GC‐O) using the aroma‐extract‐dilution analysis method. (E,Z)‐2,6‐Nonadienal (cucumber) was the most intense aroma‐active compound due to its higher flavor‐dilution factor (243–729) than any other compound. (Z)‐3‐Hexenal (green/apple), (E)‐2‐hexenal (green/fruity), and (E)‐β‐ocimene (wither green/grass) were also identified as important aroma‐active compounds by GC‐O. In addition, the volatile compounds were extracted by solid‐phase microextraction (SPME), and the quantitative analysis of the SPME samples gave slightly different results, depending on the type of SPME fiber, compared with those from SDE, However, the aroma‐active compounds identified in SPME were similar to those in SDE. Copyright © 2004 Society of Chemical Industry     

SDE and SPME Analysis of Flavor Compounds in Jin Xuan Oolong Tea

Simultaneous distillation‐extraction (SDE) and solid phase micro extraction (SPME) are procedures used for the isolation of flavor compounds in foods. The purpose of this study was to optimize SDE conditions (solvent and time) and to compare SDE with SPME for the isolation of flavor compounds in Jin Xuan oolong tea using GC‐MS and GC‐O. The concentration of volatile compounds isolated with diethyl ether was higher (P < 0.05) than for dichloromethane and concentration was higher at 40 min (P < 0.05) than 20 or 60 min extractions. For SDE, 128 volatiles were identified using GC‐MS and 45 aroma active compounds using GC‐O. Trans‐nerolidol was the most abundant compound in oolong tea. The number of volatiles identified using GC‐MS was lower in SPME than SDE. For SPME, 59 volatiles and 41 aroma active compounds were identified. The composition of the volatiles isolated by the 2 methods differed considerably but provided complementary information.     

Characterization of Aroma Compounds in Chinese Bayberry (Myrica rubra Sieb. et Zucc.) by Gas Chromatography Mass Spectrometry (GC‐MS) and Olfactometry (GC‐O)

Abstract: The aroma‐active compounds in Chinese bayberry were identified using gas chromatography‐olfactometry (GC‐O) and GC‐mass spectrometry techniques. The volatile compounds were extracted using Liquid–liquid extraction, solvent‐assisted flavor evaporation and headspace solid‐phase microextraction (HS‐SPME), respectively. On the basis of odor intensity, the most important aroma compounds in Chinese bayberry samples were caryophyllene, menthol, 4‐terpineol, linalool oxide, linalool, benzyl alcohol, α‐methylbenzyl alcohol, β‐phenylethanol, 3‐methylbutanoic acid and acetic acid, and so on. Moreover, HS‐SPME technique was employed to investigate the aroma compounds among immature and mature waxberry fruits. The results showed that terpenes (for example, β‐caryophyllene) was predominant and its concentration represented over 89.9% of the overall compounds, and alcohols, aldehydes, ketones, esters, acids, and others were typically present in lesser amounts. Finally, principal component analysis revealed that there was also significant difference between immature and mature waxberry fruits     

Profile of Volatile Compounds in 12 Chinese Soy Sauces Produced by a High‐Salt‐Diluted State Fermentation

There have been limited studies on the flavour compounds in Chinese soy sauces. In order to obtain wider information about the chemical composition of the volatile fractions in 12 brands of Chinese soy sauces produced by high‐salt‐diluted state fermentation (HSDSF) and to compare them, a headspace solid microextraction method coupled to gas chromatography‐mass spectrometry (HS‐SPME‐GC‐MS) method was proposed and developed. A 50/30μm Divinylbenzene/Carboxen/Polydimethylsiloxane (DVB/CAR/PDMS) fibre was used for extraction of volatiles. The adsorption time and temperature of the SPME fibre were optimized separately for various aroma compounds in the soy sauce (50°C and 40 min for alcohols and esters; 40°C and 50 min for ketones, aldehydes and pyrazines; 60°C and 50 min for acids, phenols and furans). From the study, a total of 80 compounds were identified in the 12 samples, of which 34 volatiles were in common. Alcohols and acids were the main volatiles present in the soy sauces. Dominant volatile alcohols were ethanol, 2/3‐methyl butanol and β‐phenylethyl alcohol; and important acids were acetic acid, butanoic acid, and 3‐methylbutanoic acid. Miscellaneous, esters, furans and phenols also made large contributions to the total volatiles of the soy sauces. According to the scatter point plot obtained from principal component analysis, the 12 soy sauces could be classified into four groups.     

顶空固相微萃取-气相色谱-质谱联用法测定即食酱牛肉的挥发性香气成分

采用顶空固相微萃取-气相色谱-质谱联用法测定即食酱牛肉的挥发性香气成分,对影响萃取效率的几个关键因素进行优化,分析各因素对不同相对分子质量化合物萃取效果的影响。结果表明：在3.0 g即食酱牛肉中加入0.6 g氯化钠,用50/30 μm DVB/CAR/PDMS萃取头于60 ℃条件下萃取30 min,解吸5 min,能够达到较好的萃取效率。在最佳萃取条件下提取即食酱牛肉的挥发性成分,结合气相色谱-质谱共鉴定出39 种主要挥发性物质,其中酚类和烃类化合物的相对含量较高,分别为46.15%和24.99%,为即食酱牛肉的主要挥发性成分。本实验测定了即食酱牛肉中各香气成分的组成及贡献模型,结果可为优化生产工艺条件提供参考。     

清香型大曲中产香细菌的分离筛选及鉴定

为提升麸曲清香型白酒风味品质，该研究采用稀释平板涂布培养法从清香型白酒大曲中分离纯化细菌，采用感官嗅闻法从中筛选出具有产香气功能的细菌菌株，将其应用于麸曲白酒酿造，并通过形态观察及分子生物学技术对其进行菌种鉴定。结果表明，分离筛选得到2株具有香气功能的细菌，编号分别为HXX7和HXX12，其发酵液中挥发性香气成分丰富，均含有酯类、醛酮类、酚类、杂环类化合物等，具有较强产香能力。将菌株HXX7和HXX12分别应用于麸曲清香型白酒生产，其中，菌株HXX7发酵酒样中丁酸乙酯（41.91 mg/L）、4-乙基愈创木酚（148.70 mg/L）、3-羟基-2-丁酮（312.68 mg/L）、苯乙醛（79.27 mg/L）、β-苯乙醇（128.38 mg/L）含量升高。结果表明，菌株HXX7可增加原酒香气，改善原酒风味，从而提升白酒品质。菌株HXX7被鉴定为地衣芽孢杆菌（Bacillus licheniformis）。     

顶空固相微萃取-气相色谱-质谱法测定药香型白酒中萜烯类化合物

应用顶空固相微萃取与气相色谱-质谱联用技术定量药香型白酒中的痕量萜烯类化合物。实验考察萃取头、样品酒精度、萃取温度和萃取时间对萜烯类化合物萃取效果的影响。最优顶空固相微萃取条件为将酒样稀释到酒精度10%,采用50/30μm碳分子筛/聚二乙烯苯/聚二甲基硅氧烷(DVB/CAR/PDMS)萃取头在60℃条件下萃取45min。该方法具有良好的线性,所有化合物的线性相关系数良好,R2≥0.9921,检测限为0.01～3.62μg/L,定量限为0.03～12.05μg/L,相对标准偏差小于15%,加标回收率为81.01%～118.94%。用该方法对药香型白酒的成品酒、原酒中的萜烯类化合物进行测定,共定量41种挥发萜烯类化合物,结果发现大曲香醅原酒中的萜烯总含量要多于小曲酒醅原酒中萜烯总含量,D-樟脑等17萜烯只在大曲香醅原酒中检测到,在小曲酒醅原酒中没有检测到,排除蒸馏时酸、热等带来的影响,推测这17种萜烯主要来源于大曲香醅,相反卡拉烯只在小曲酒醅原酒中检测到,推测其来源于小曲酒醅。顶空固相微萃取适合药香型白酒中的萜烯类化合物定量分析。     

基于GC×GC-TOF-MS法比较两种不同香型白酒的挥发性香气成分

为比较大曲清香型白酒和复合香型白酒中的挥发性香气成分,以明确不同香型白酒的香气特点,采用顶空固相微萃取（HS- SPME）结合全二维气相色谱-飞行时间质谱法（GC×GC-TOF-MS）分别检测2种香型白酒中的挥发性香气成分,并对各挥发性香气成分进行分类对比。结果表明,采用多级鉴定策略,分别在大曲清香型白酒和复合香型白酒中确认了可信度较高的挥发性香气成分251种和341种,主要包括酯类、醇类、酸类、醛酮类,还包括呋喃类、含氮、含硫及其他类物质。在复合香型白酒中鉴定出的特有挥发性含硫和吡嗪类化合物分别为8种和7种,二者为区别于大曲清香型白酒的特征香气成分。白酒香气成分及其感官特征关联分析结果表明,复合香型白酒具有“香气复合幽雅”的风格特点。     

Quantification of volatile compounds in Chinese soy sauce aroma type liquor by stir bar sorptive extraction and gas chromatography-mass spectrometry

BACKGROUND: Considering the important of aroma compounds on the quality of baijiu, stir bar sorptive extraction (SBSE) coupled with gas chromatography–mass spectrometry was applied to the aromas analysis of baijiu (Chinese liquor). RESULTS: Based on the results of optimization, a total of 76 volatile compounds were identified from 14 Chinese liquors, including 25 esters, 10 alcohols, 9 aldehydes and ketones, 8 aromatic compounds, 5 furans, 3 nitrogen‐containing compounds, 6 acids, 4 phenols, 3 terpenes, 1 sulfide‐containing compound, 1 lactone, and 1 acetal. By principal component analysis based on quantification results, 14 Chinese liquor samples could be classified into three groups. CONCLUSION: SBSE is a fast, simple, effective, and reliable method for extracting volatile compounds from Chinese liquor. The chemometrics approach revealed that LJ liquor with soy sauce aroma could exhibit more prominent sauce flavor through extending the time of storage, and its peculiar manufacturing practice was responsible for the soy sauce flavor. Copyright © 2011 Society of Chemical Industry     

The Influence of Yeast Strains on the Volatile Flavour Compounds of Chinese Rice Wine

In order to assess the influence of yeast strains on volatile flavour profiles of Chinese rice wine, small‐scale Chinese rice wine brewing was carried out with eight yeast strains from three different typical Chinese rice wine brewing regions. The volatile flavour compounds were extracted by headspace solid phase microextraction (HS‐SPME) and analyzed by gas chromatography‐mass spectrometry (GC‐MS). The volatile flavour profiles of the different Chinese rice wines showed statistically significant differences depending on the yeast strains used. Yeast strains from the Shaoxing region showed a higher capacity to produce the esters 2‐phenylethanol and 3‐methylthiopropanol, while yeast strains from the Shanghai region stood out for their production of branched‐chain higher alcohols. Chinese rice wine fermented with a yeast strain from the Jiangsu region had the highest levels of organic acids. Using principal component analysis of the Chinese rice wine volatile flavour compounds, the eight yeast strains could be classified into three groups according to their origins. This is the first report about the volatile flavour characteristics of Chinese rice wine yeast. The data obtained in this work shows that the yeast strains contributed significantly to the flavour differences of the Chinese rice wines from the different regions.     

Evaluation of the chemical,microbiological and volatile aroma characteristics of Ispir Kaymak,a traditional Turkish dairy product

The gross chemical composition, microbiological quality and volatile aroma composition of Ispir Kaymak, a Turkish creamy dairy product, were investigated in 10 samples. The chemical composition of the samples varied widely: dry matter content ranged from 70.8% to 91.3% and fat varied between 43.0% and 63.0%; probably due to the lack of standardised production in practice. The microbiological counts were found to be (as mean values): 4.02, 3.06, 0.33, <2 log cfu/g for aerobic plate count, yeast and mould, coliform and Staphylococcus aureus, respectively. The sample quality showed that the production and storage conditions should be controlled and the hygienic quality of this product should be improved. A total of 73 volatile compounds, including esters, acids, ketones, aldehydes, alcohols, terpenes and miscellaneous compounds, were identified in the volatile fraction of the samples by gas chromatography–mass spectrometry (GC–MS) using a solid‐phase microextraction technique (SPME/GC–MS). Esters were the main volatiles in Ispir Kaymak, and ketones, alcohols and terpenes were found at high levels; however, the levels of acids were low in all samples.     

不同工艺和风格酱香型白酒香气成分GC指纹图谱的研究

采用气相色谱（GC）对不同工艺和风格酱香型白酒香气成分指纹图谱相似度进行研究。以16个主要共有峰为评价指标,采用“中药色谱指纹图谱相似度评价系统”软件建立2种不同工艺大曲酱香型白酒、碎沙酱香型白酒,2种不同风格钓鱼台大曲酱香型白酒、国台大曲酱香型白酒的香气成分GC共有指纹图谱,同时对不同样品之间的相似度进行评价。结果表明,2种不同工艺酱香型白酒各具特色,其6个色谱骨架成分含量存在显著差异。2种不同风格大曲酱香型白酒共有峰相对标准偏差（RSD）＞15%的分别有3个峰（钓鱼台）和6个峰（国台）,表明不同风格大曲酱香型白酒勾调质量较稳定。     

Effects of Different β‐D‐Glycosidases on Bound Aroma Compounds in Muscat Grape Determined by HS‐SPME and GC‐MS

Important “floral” aromas naturally occur in grapes predominantly as flavourless glycoconjugate precursors. Since these aroma compounds can be released by hydrolysis, different glycosidase enzymes can potentially contribute different aromas to wines. In this paper, we first established a procedure for profiling the free and bound volatile compounds in grape using GC‐MS combined with headspace solid‐phase microextraction (HS‐SPME). Comparison of the free and bound aroma compounds revealed that non‐volatile glycosides, known as aroma precursors, occur in high concentrations in musts. Among all compounds identified, 11 were fully quantified according to established standard calibration curves, while others were semi‐quantified. Using three different glycosidase enzymes, a total of 38 bound volatile compounds were identified in Muscat grape, including terpenes, higher alcohols, C‐6 compounds, and phenols, among others. The different enzymes had significant effects on the varietal aroma. Principal component analysis indicated that the characteristic aroma hydrolyzed by the commercial enzyme AR2000 was clearly different from that produced by other enzymes.