Analysis of Tobacco Headspace Volatiles Using Tenax GC or Active Carbon†

Two simple methods, the Tenax GC method and the active carbon method, have been developed to analyze the headspace volatiles of tobacco. The headspace volatiles swept by helium from cut tobacco were collected by either Tenax GC or active carbon and were analyzed by gas chromatography after desorption by heating the Tenax GC or by extracting the active carbon with dichloromethane. The gas chromatograms of the headspace volatiles of flue-cured tobacco obtained by these two methods differed. Both methods showed good reproducibility and were applied to the analysis of the headspace volatiles of American and Japanese flue-cured tobacco samples. By principal component analysis, three or four principal components were. extracted from the 15 selected peaks of the headspace volatiles of these samples that had been obtained from both the Tenax GC and the active carbon methods.     

Objective Evaluation of Soy Sauce by Statistical Analysis of GC Profiles

The relationships between GC data of volatiles and sensory score of the heighest grade of soy sauce (Tokusen shoyu) were analyzed by multivariate analyses. Samples belonging to four brands could be unambiguously classified into the correct brands and the statistical distance among them suggested a close relation with sensory evaluation. The precise predictive equations for the aroma quality were calculated from GC data and sensory evaluation by multiple regression analysis. Eight principal components were extracted from 39 GC peaks as significant factors constituting soy sauce aroma. The second PC can explain 58% of the variation among total variation contained in the sensory score. Discriminant functions on the basis of the 8 PCs can clearly classify all samples.     

Evaluation and Discrimination of Soy Sauce by Computer Analysis of Volatile Profiles

The relationships between gas chromatographic (GC) profiles and sensory data of 72 purely fermented soy sauce samples were analyzed by multiple regression analysis and principal component analysis (PCA). Prior to the analysis, GC data was transformed into 7 different modes in order to compare the fitting to a hypothetical linear model. The result from logarithmically transformed ratio of each peak to the sum of whole peaks showed the best precision of predictability for sensory score (R = 0.978). As the result of PCA, eigen values of 10 PCs were shown to be larger than 1.0 but the 5 major PCs could account for 66% of the variance in the total variance of 39 GC peaks. The first and second PCs showed great importance for aroma quality and similarity or dissimilarity in profiles of extracted PCs showed a similar trend with quality differences evaluated by sensory tests. These results showed the importance of the harmonious balance of each aroma compound to create a preferable soy sauce aroma.     

Classification of Tobaccos with Analytical Data of Nitrogen containing Compounds in Their Headspace Volatiles

In order to examine the relationship between tobacco aroma and the nitrogen-containing compounds in the tobacco headspace volatiles, the volatiles of flue-cured, Burley and Turkish tobaccos collected with Tenax GC were analyzed by a gas chromatograph equipped with a flame thermionic detector. Of the 21 compounds identified in the chromatogram, 2,5-dimethylpyridine, 2,4-dimethylpyridine, pyrrole and N-methylpyrrole have not been previously reported as present in the tobacco headspace volatiles. By principal component analysis and stepwise discriminant analysis, three principal components and discriminant functions with four peaks were obtained. The results of these statistical analyses classified the samples into each variety respectively.     

Glass Capillary Chromatographic Profiles of Soy Sauce Aroma Correlated with Sensory Assessment

The relationship between soy sauce gas chromatographic (GC) patterns precisely analyzed on a glass capillary column and ranked order in sensory analysis was investigated by stepwise multiple regression analysis. The most negative and positive correlation between the GC peaks and sensory data were shown by trans-2-hexen-l-ol contributing to preferable aroma and iso-butyric acid concerning to unpleasant smell, respectively. Highly predictable multiple regression models were calculated in the analysis. The variety of volatile components selected for the equations indicated that these constituents represented not only different groups of chemical structures in aroma compounds but also growth of various microorganisms during the soy sauce making process.     

Preparation of reminiscent aroma mixture of Japanese soy sauce

To prepare an aroma mixture of Japanese soy sauce by fewest components, the aroma concentrate of good sensory attributes was prepared by polyethylene membrane extraction, which could extract only the volatiles with diethyl ether. GC-MS-Olfactometry was done with the aroma concentrate, and 28 odor-active compounds were detected. Application of aroma extract dilution analysis to the separated fraction revealed high flavor dilution factors with respect to acetic acid, 4-hydroxy-2(or5)-ethyl-5(or2)-methyl-3(2H)-furanone (HEMF), 3-methyl-1-butanol (isoamyl alcohol), and 3-(methylsulfanyl)propanal (methional). A model aroma mixture containing above four odorants showed a good similarity with the aroma of the soy sauce itself. Consequently, the reminiscent aroma mixture of soy sauce was prepared in water. The ratio of acetic acid, HEMF, isoamyl alcohol, and methional was 2500:300:100:1.     

藏药镰形棘豆挥发性成分研究(英文)

本文通过水蒸气蒸馏、超临界CO2萃取和顶空萃取三种方法并结合GC和GC/MS技术分析藏药镰形棘豆(Oxytropis falcate Bunge)中的挥发性成分,共鉴定出58个化合物,分别占71.0%,85.6%和84.5%。烷烃类、黄酮类和醛类化合物为主要挥发性成分。3种方法得到的挥发性成分在保留时间值上具有一定的连续性,能更完全地阐述清楚藏药镰形棘豆的挥发性成分,为进一步开发利用这种药用植物提供科学依据。     

2-Amino-5-phosphono-3-pentenoic Acid,a New Amino Acid from N-1409 Substance,an Antagonist of Threonine

Discrimination of soy sauce samples consist of different 8 brands on the basis of principal components extracted from GC profiles of aroma concentrates was performed by stepwise discriminant analysis. Considering the results from sensory evaluation, classification of samples into 8, 3, and 2 groups was examined. Statistically significant difference was found among the 8 brands on the basis of principal components. The three groups consist of good, common, and inferior samples also classified correctly. Completely correct two way discrimination, good and bad, was accomplished in the same manner. These clear classifications suggested that evaluation and discrimination in sensory tests were performed by comparing the profiles of aroma substances.     

酱香型与清香型白酒发酵过程中乳酸菌菌群的差异性分析

【目的】为认识乳酸菌在中国白酒酿造过程中的作用与影响, 分析、比较了酱香型与清香型白酒发酵过程中乳酸菌的菌群结构及其差异。【方法】运用PCR-DGGE技术分析酱香型与清香型白酒发酵过程中乳酸菌群的演变规律。并利用传统微生物分离筛选方法进一步确定酱香型白酒发酵中的主要乳酸菌种。【结果】DGGE图谱表明, 白酒发酵过程中的主要乳酸菌种是乳杆菌。但两种香型白酒发酵过程中乳酸菌群组成及动态变化均呈现出明显的差异。清香型白酒酒醅中Lactobacillus fuchuensis是优势菌种, 而酱香型白酒发酵中检测到多种含量较高的乳酸菌种。利用MRS培养基从酱香型白酒酒醅中共筛选获得5种乳酸菌种。通过两种方法, 确定Lactobacillus homohiochii是酱香型白酒发酵过程中含量最高的乳酸菌。【结论】深入研究白酒发酵过程中乳酸菌的组成及分布规律, 对于更好地认识中国白酒酿造中主要的细菌类群——乳酸菌的作用, 具有重要的理论意义和实践价值。     

Metabolism of propionic acid by golden delicious apples

The headspace of whole Golden Delicious apples treated with propionic acid vapour, was analysed by means of GC, after enrichment on Tenax GC, and its c     

Evaluation of Soy Sauce Flavor by Stepwise Multiple Regression Analysis of Gas Chromatographic Profiles

The linear correlation was found by the stepwise multiple regression analysis between the sensory test of soy sauce flavor and the gas Chromatographic (GLC) data transformed with arc-sine and logarithm. GLC data will possibly be used for objective evaluation of soy sauce flavor. A multiple correlation coefficient or of a determination coefficient of more than 0.9 was respectively obtained at the 5 th or 10th of 47 steps. The fact that the minimum standard error of an estimate was found at the 24th step suggests the importance of selecting proper peaks from the whole gas chromatogram. High estimated accuracy was acquired by application of GLC data to the calculated multiple regression model.     

Characterisation of volatile organic compounds in stemwood using solid-phase microextraction

Solid-phase microextraction (SPME), hydrodistillation and dynamic headspace combined with GC and GC-MS were applied and compared for the analysis of volatile organic compounds (VOCs) from coniferous wood. The SPME conditions (type of fibre, size of wood sample, temperature and exposure time) were optimised, and more than 100 VOCs and semi-volatile compounds extracted and identified from the sapwood and heartwood of Norway spruce (Picea abies). The total number of mono- and sesquiterpenes eluted and identified was similar for the SPME and hydrodistillation methods, but more semi-volatile compounds were released by hydrodistillation. By applying dynamic headspace at room temperature, it was possible to analyse only the most volatile compounds. The qualitative composition of VOCs was similar in spruce sapwood and heartwood, although Z-beta-ocimene occurred only in sapwood while fenchol was present only in heartwood. SPME sampling coupled with GC, applied here to the analysis of VOCs released from stemwood of firs for the first time, is a convenient, sensitive, fast, solvent-free and simple method for the determination of wood volatiles. The technique requires much smaller sample amounts compared with hydrodistillation, and the total amount of VOCs extracted and identified is higher than that obtained by hydrodistillation or dynamic headspace. The relative ratios of the main mono- and sesquiterpenes and -terpenoids were similar using the SPME-GC and hydrodistillation methods.     

Industrial production of soy sauce

Summary Soy sauce is a seasoning agent with a salty taste and a distinct aroma suggestive of meat extracts. The sauce is made by fermentation of a combination of soy beans and wheat in water and salt. This paper covers the method for production of fermented soy sauce, and that for acid-hydrolysis of defatted soy bean proteins. The microorganisms involved in soy sauce production, and biochemical and chemical changes in soy bean and wheat during fermentation influence greatly the sensory attributes and quality of soy sauce. Recent progress in industrialization of soy sauce manufacture is discussed.This paper is dedicated to Professor Herman Jan Phaff in honor of his 50 years of active research which still continues.     

诱茶尺蠖天敌寄生蜂的茶树挥发物的分离与鉴定

采用Tenax GC动态吸附法对茶树-茶尺蠖Ectropis obliqua (Prout)-单白绵绒茧蜂Apanteles sp.三重营养关系中茶树的新梢挥发性化合物进行了捕集,经GC、GC-MS鉴定结果表明,不同来源的挥发物的组成和数量是不同的,完整茶树新梢(IS)的挥发物有11种组份;机械损伤新梢(MDS)的挥发物有13种组份;茶树-茶尺蠖取食复合体(PHC)的挥发物有15种组份,而用经典的SDE法获得的新梢精油有13种组份,4种挥发物数量的大小顺序为SDE>MDS>PHC>IS。生物测定结果表明,无气味经历的雌单白绵绒茧蜂对IS和MDS的气味的选择作用无统计上的显著性,对机械损伤新梢+幼虫口腔分泌物(MDS+Reg), 幼虫取食损伤(LDS)和PHC的气味有较强的偏好选择性。     

Isolation and Identification of the Constituents of Volatiles of Dry Flowers of Aglaia odorata Lour

The headspace volatiles of the dry flowers of Aglaia odorata were trapped by a modified circulating adsorption method and were analyzed by GC/MS techniques after desorption by solvent. The components were identified by re, ass spectral and temperature-programmed retention index data on two types of glass capillary columns (OV-101 and PEG-20 M). 54 compounds have been identified from the volatiles, including 21 sesquiterpenes, 8 aldehydes, 7 alkyl benzenes, 6 alkanes, 6 other oxygen-containing compounds and I nitrogen containing compound. 29 compounds have not been reported in the studies on the constituents of the essential oil or absolute oil of the flowers.     

Perceptual characterization and analysis of aroma mixtures using gas chromatography recomposition-olfactometry

This paper describes the design of a new instrumental technique, Gas Chromatography Recomposition-Olfactometry (GC-R), that adapts the reconstitution technique used in flavor chemistry studies by extracting volatiles from a sample by headspace solid-phase microextraction (SPME), separating the extract on a capillary GC column, and recombining individual compounds selectively as they elute off of the column into a mixture for sensory analysis (Figure 1). Using the chromatogram of a mixture as a map, the GC-R instrument allows the operator to "cut apart" and recombine the components of the mixture at will, selecting compounds, peaks, or sections based on retention time to include or exclude in a reconstitution for sensory analysis. Selective recombination is accomplished with the installation of a Deans Switch directly in-line with the column, which directs compounds either to waste or to a cryotrap at the operator's discretion. This enables the creation of, for example, aroma reconstitutions incorporating all of the volatiles in a sample, including instrumentally undetectable compounds as well those present at concentrations below sensory thresholds, thus correcting for the "reconstitution discrepancy" sometimes noted in flavor chemistry studies. Using only flowering lavender (Lavandula angustifola 'Hidcote Blue') as a source for volatiles, we used the instrument to build mixtures of subsets of lavender volatiles in-instrument and characterized their aroma qualities with a sensory panel. We showed evidence of additive, masking, and synergistic effects in these mixtures and of "lavender' aroma character as an emergent property of specific mixtures. This was accomplished without the need for chemical standards, reductive aroma models, or calculation of Odor Activity Values, and is broadly applicable to any aroma or flavor.     

Diversity of <Emphasis Type="Italic">Aspergillus oryzae</Emphasis> genotypes (RFLP) isolated from traditional soy sauce production within Malaysia and Southeast Asia

DNA fingerprinting was performed on 64 strains of Aspergillus oryzae and 1 strain of Aspergillus sojae isolated from soy sauce factories within Malaysia and Southeast Asia that use traditional methods in producing “tamari-type” Cantonese soy sauce. PstI digests of total genomic DNA from each isolate were probed using the pAF28 repetitive sequence. Strains of A. oryzae were distributed among 32 genotypes (30 DNA fingerprint groups). Ten genotypes were recorded among 17 A. oryzae isolates from a single soy sauce factory. Genotypes Ao-46 and GTAo-47, represented by 8 and 5 strains, respectively, were isolated from a soy sauce factory in Kuala Lumpur and factories in two Malaysian states. Four strains of GTAo-49, isolated from three soy sauce factories in Malaysia; each produced sclerotia. Two strains were found to be naturally occurring color mutants of NRRL 32623 (GTAo-49) and NRRL 32668 (GTAo-52). Only two fingerprint matches were produced with the 43 DNA fingerprint groups in our database, representing A. oryzae genotypes from Japan, China, and Taiwan. Aspergillus sojae NRRL 32650 produced a fingerprint matching GTAo-9, the only known genotype representing koji strains of A. sojae. No aflatoxin was detected in broth cultures of these koji strains as determined by TLC.     

Isolation and Identification of the Constituents of Volatiles of Flowers of Chloranthus spieatus (Tunb.) Makino

The headspace volatiles of the flowers of Chloranthus spicatus (Tunb.) Makino were trapped by a modified circulation adsorption method and were analyzed by GC/MS techniques after desorption by solvent. The componends were identified by mass spectral and temperature-programmed retention index data on dual glass capillary columns (OV-101 and PEG-20 M). 32 compounds have been identified from the volatiles, including 11 monoterpenes, 11 sesquiterpenes, and 7 oxygen-containing compounds.The major consitituents are cis-methyl jasmonatecis-β-ocimene, and β-pinene.     

New Method for Analyzing the Volatiles in Beer

A new method is reported for analyzing the medium- and high- boiling-point volátiles in beer, using CCl₃F for extracting the whole volatiles and then the headspace trapping method with Tenax TA. This method seems to be effective for analyzing the flavor not only of beer but also of other beverages, especially those containing a large amount of ethanol.     

普通大蓟马聚集信息素的分离和鉴定

【目的】普通大蓟马Megalurothrips usitatus是我国华南地区重要的豆科害虫,给我国豇豆种植产业带来巨大损失。开发利用基于聚集信息素的引诱剂是普通大蓟马的绿色防控措施之一,对于普通大蓟马生物防治具有重要意义。【方法】采用Y型嗅觉仪测定普通大蓟马雌雄成虫对其雌虫和雄虫气味源的嗅觉反应;用顶空固相微萃取法(head space solid-phase microextraction, HS-SPME)和溶液浸提法提取普通大蓟马雌雄成虫挥发物;应用气质联用仪(gas chromatography-mass spectrometry, GC-MS)对收集的气体挥发物和正己烷提取物进行活性成分分离鉴定;应用Y型嗅觉仪测定人工合成聚集信息素组分对雌雄成虫的引诱效果。【结果】行为学试验结果表明,普通大蓟马雄成虫气味源对其雌雄成虫均具有显著的引诱作用,而雌成虫气味源则没有。顶空固相微萃取法和溶液浸提法均可提取雄成虫挥发物主要组分,但顶空固相微萃取法获得的TIC图基线平稳,杂峰少,提取效果优于溶剂浸提法。GC-MS分析结果表明,普通大蓟马雄成虫挥发物中主要含有 1种化合物,为反式,反式-金合欢醇乙酸酯［(E,E)-farnesyl acetate］,该化合物在雌成虫挥发物中不存在。室内行为学实验结果表明,特定剂量的人工合成的(E,E)-farnesyl acetate对普通大蓟马雌雄成虫均具有显著的引诱作用。【结论】本研究证明了普通大蓟马雄成虫可以释放聚集信息素,并鉴定了其主要组分(E,E)-farnesyl acetate,为应用聚集信息素开展普通大蓟马的监测和诱杀提供了基础。