Determination of major volatile compounds during the production of fruit vinegars by static headspace gas chromatography-mass spectrometry method

A static headspace gas chromatography coupled to mass spectrometry (SHS-GC-MS) method was validated to determine several major volatile components during the production process of fruit vinegars. The method is simple, fast, linear in the working range, suitably sensitive, repeatable and reproducible, and has a good degree of accuracy for most of the compounds studied. Different conditions were tested in the production process of vinegars by means of double fermentation. The addition of SO₂ and pectolytic enzymes produced a considerable increase in methanol and acetaldehyde, especially in strawberry purees, whereas pressing led to a loss of these volatile compounds. In the alcoholic fermentation of persimmon and strawberry purees, the Saccharomyces cerevisiae strain used had a great influence on the production of acetaldehyde and higher alcohols in wines. Considering the influence of these studied compounds in the final profile of the vinegars, our results showed that the S. cerevisiae strain isolated in this study produced the most suitable wine substrates for the production of vinegars. Moreover, semisolid fruit substrate provides better results than liquid substrate. Inoculated acetification in wood recipients yielded vinegars with a better volatile profile, as these contained higher levels of most compounds except acetaldehyde.     

努格特啤酒花挥发性成分的气相色谱-质谱分析

采用气相色谱-质谱联用（Gas chromatography-Mass spectrometer,GC-MS）方法,谱库检索结合保留指数（retention index,RI）定性,比较了顶空固相微萃取（Headspace-solid phase microextraction,HS-SPME）和水蒸气蒸馏法（Steam distillation,SD）得到的国产努格特啤酒花的挥发性成分,同时采用峰面积归一化法对各成分进行定量,并与美国原产地该酒花的主要挥发性风味成分进行对照。结果表明,两种方法检测的挥发性成分存在较大差异。HS-SPME法定性了106个挥发性成分,相对含量为99.11%,而SD法仅定性88个成分,相对含量为94.38%。努格特啤酒花的挥发性成分以碳氢化合物（包括萜烯类化合物）为主,其次为酯类化合物和醇类化合物;含有的主要风味成分有β-蒎烯、β-香叶烯、反式-石竹烯、α-葎草烯和L-芳樟醇等,且上述指标均与美国原产地该啤酒花品种的主要挥发性风味成分含量范围一致或接近,表明引种后的努格特啤酒花基本上保持了原产地品种的风味成分。      

顶空固相微萃取-气质联用技术分析秘鲁鱿鱼肉的挥发性风味成分

采用顶空固相微萃取-气质联用技术(SPME-GC/MS)分析检测了秘鲁鱿鱼肉不同部分的挥发性风味成分。结果表明:烃类物质含量最多,在肉中呈对称分布;醇类、酮类物质主要分布在肉的内侧;而秘鲁鱿鱼肉中的杂环化合物及酯类物质分布较均匀,对肉品风味主要贡献芳香味。杂环化合物主要为吡嗪类物质,酯类主要为乙酸乙酯。另外,乙酸和N,N-二甲基甲酰胺及二甲胺对秘鲁鱿鱼肉产生"怪酸"味起主要作用,且这两种物质在肉中的分布均符合中间含量多、两边含量少的规律。     

固相微萃取-气相色谱-质谱联用法测定水中的 32种挥发性有机物

目的通过优化固相微萃取(SPME)条件,确定最优实验条件,建立一种固相微萃取与气相色谱-质谱(GC-MS)联用法测定饮用水中32种挥发性有机物的方法。方法采用固相微萃取-气相色谱-质谱联用法对饮用水中的32种挥发性有机物进行测定,确定各化合物的定性定量参数,并优化固相微萃取条件,如萃取头类型、加盐量、平衡时间、萃取时间、萃取温度等,获得最优的测定条件。结果确定的最优条件为:萃取头:CAR/PDMS萃取头;加盐量:10%;平衡时间:20 min;萃取时间:30 min;萃取温度:60℃。本方法的检出限为0.005~5μg/L,在所测浓度范围内回归曲线的线性相关性良好,加标回收率为74.5%~129.5%,RSD均不大于15%(n=6)。结论该方法的前处理操作简单,具有较好的精密度和准确度,且检出限远低于国家限定标准,可对饮用水中多种挥发性有机物同时进行分析。     

Source identification of volatile organic compounds in Houston, Texas

The complexity of the volatile organic compound (VOC) mixture in the Houston area makes studies of the air quality in that area very challenging. In this paper, a novel factor analysis model, where the normal chemical mass balance model was augmented by a parallel equation that accounted for wind speed and direction, temperature, and weekend/weekday effects, was fitted with a multilinear engine (ME) to provide identification and apportionment of the VOC sources at the La Porte Municipal Airport site in Houston during the Texas Air Quality Study (TexAQS) 2000. The analysis determined the profiles and contributions of nine sources and the corresponding wind speed, wind direction, temperature, and weekend factors. The reasonableness of these results not only suggests the high resolving power of the expanded factor analysis model for source apportionment but also provides the novel and effective auxiliary information for more specific source identification. In addition, a new approach to estimate the measurement uncertainty and the details of determining the source number and dealing with missing values are also presented as important parts of the data analysis process. This study demonstrates the feasibility of the expanded model to identify sources in complex VOC systems and extract useful information for locating VOC emitters and controlling their emissions in the Houston area.     

卷烟包装纸中挥发性有机化合物(VOCs)的顶空-气相色谱分析

采用顶空-气相色谱法分析了卷烟包装纸中的16种挥发性有机化合物(VOCs),方法快速简便,准确可靠。对部分国内卷烟包装纸进行了检测,并对卷烟包装纸的VOCs现状进行了讨论。      

自动顶空-气相色谱法检测食品包装材料中挥发性有机物

建立一种适用于食品包装材料中常见的19种挥发性有机物(醇类、酯类、苯系物等)含量的顶空-气相色谱检测方法,同时研究不同色谱柱、不同的顶空平衡温度与时间对分离检测的影响。研究结果表明:平衡温度在110℃、平衡时间15min时,选用DB-WAX(30m×0.32mm,0.25μm)毛细管色谱柱,上述19种挥发性有机物能很好地分离;该法在含量0.001～10mg/m2范围内线性关系良好,19种挥发性有机物的相关系数均大于0.998,加标回收率为90.3%～105.9%,样品相对标准偏差(RSD)为1.6%～5.0%,最低检出限为0.001mg/m2。该方法简单、快速、准确、灵敏度高,完全能够满足食品包装材料中挥发性有机物定量的分析。     

Analysis of volatile compounds in beef fat by dynamic-headspace solid-phase microextraction combined with gas chromatography-mass spectrometry

ABSTRACT:  A solid-phase microextraction (SPME) technique has been applied to the determination of the volatile compounds, including diterpenoids and lactones, in cooked beef fat. The ability of static-headspace SPME to extract lactones was disappointing, regardless of the type of SPME fiber or the temperature used. Dynamic-headspace SPME extraction with 50-/30-μm divinylbenzene-Carboxen on a polydimethylsiloxane fiber at 100 °C, by contrast, enabled the analysis of volatiles, including delta-lactones, gamma-lactones, and diterpenoids, with 50-/30-μm divinylbenzene-Carboxen on a polydimethylsiloxane fiber at 100 °C. Fifty-three compounds were identified from only 0.20 g of rendered beef fat, and 76% of these showed reliable peak size repeatability: the coefficient of variation was less than 10% on the total ion chromatograms obtained from gas chromatography–mass spectrometry (GC–MS) analysis. Some lactones showed higher CV values (>10%), but single-ion mode GC–MS analysis reduced them to 10% or less. In a study of beef samples available to the Japanese market, our analytical procedure revealed significantly higher levels of 1-hexanol, octadecane, ethyl tetradecanoate, gamma-nonalactone, but lower levels of delta-decalactone, delta-dodecalactone, and neophytadiene, in Japanese Black cattle than in beef imported from Australia.     

Production of volatile organic compounds by pears

There is considerable variation between the rates of production of volatile organic compounds by different cultivars of pears, as has been shown for apples; the rates are lower in controlled atmosphere (C.A. ) storage than in air. When pears which have been cold stored, in air or in C.A. are ripened at a higher temperature, the rate of evolution of ethylene rises rapidly to a high value, but subsequently declines as the pears develop overripe symptoms.     

Production of volatile organic compounds by apples

There is great variation in the rate at which different apple cultivars produce volatiles. The rate of production of volatiles, in terms of loss of carbon, is some 0.3–1.0% of the loss of CO₂; depending on conditions of storage, some 50–95% of the carbon lost as volatiles is accounted for by ethylene. Increase in concentration of CO₂ in the storage atmosphere reduces the rate of production of volatiles. Reduction of the oxygen concentration to a low level has the same effect, and ethylene production ceases in the complete absence of oxygen. The peel of the fruit is more active in production of ethylene than is the pulp; the rate of production is greater for small apples than for large. When the volatiles are removed from the storage atmosphere, the rate of production increases. The incidence of superficial scald, and the shape of the time/rate graph for ethylene are related. This could be due to an effect of climate during the growing period, affecting the porosity of the peel.     

低盐鱼酱油挥发性成分的固相微萃取和气相色谱-质谱法分析

用固相微萃取装置(SPME)萃取鱿鱼废弃物低盐鱼酱油的挥发性成分,利用气相色谱-质谱联用仪(GC-MS)对挥发性化合物成分进行了检测和定性分析。结果表明,鱿鱼废弃物低盐鱼酱油的挥发性成分有91种,包括7种酸、5种醇类化合物、26种羰基化合物、4种酯类化合物、18种含氮化合物、14种含硫化合物、5种呋喃类化合物、5种酚类化合物、7种碳氢类化合物,共同构成了鱼酱油的特殊风味。同时根据峰面积百分比可以初步推断,苯基乙醇、2-甲基丁醛、苯甲醛、苯乙醛、安息香酸乙酯、2-二甲氧基-苯酚、2-甲氧基-4-乙烯基苯酚、2-乙基呋喃、二甲基三硫化物、二甲基二硫化物、3-苯基呋喃、2-乙基-6-甲基吡嗪是鱿鱼加工废弃物低盐鱼酱油的主要挥发性化合物。     

气相色谱-离子迁移谱法检测农产食品中挥发性有机化合物的研究进展

气相色谱-离子迁移谱法(gas chromatography-ion mobility spectrometry,GC-IMS)结合了气相色谱的高分离能力和离子迁移谱的高灵敏度,可得到保留时间、漂移时间和信号强度的三维谱图,使定性分析更加准确,有效地解决了气相色谱低鉴别能力和离子迁移谱对混合物进行检测时存在的交叉灵敏度...     

顶空-固相微萃取-气相色谱-质谱联用法分析啤特果挥发性风味物质

啤特果是一种品质极高的绿色水果,为研究其风味特征,基于优化的顶空-固相微萃取法（headspace-solidphase microextraction,HS-SPME）提取果肉挥发性风味物质,并经气相色谱-质谱联用法（gas chromatography-mass spectrometry,GC-MS）测定。结果显示,carboxen/polydimethylsiloxane（CAR/PDMS）萃取头在40℃、萃取40 min的萃取效果较好;经鉴定得到44种化合物,包括30种酯、6种醛、4种醇、2种酮和2种碳氢化合物,含量最高的是酯类（89.176%）,其次是醇类（7.844%）、碳氢化合物（1.172%）、醛类（0.912%）和酮类（0.896%）。2-己烯酸乙酯（30.337%）、乙酸丁酯（16.661%）、乙酸乙酯（14.002%）、己酸乙酯（13.315%）和丁酸乙酯（7.349%）是啤特果中含量较高的风味物质。研究啤特果挥发性成分,便于我们初步认识这个品种的特点,为进一步开发和利用该资源提供基础科学理论依据。      

顶空固相微萃取气相色谱质谱联用法分析马油挥发物组成及其腥味物质

目的建立顶空固相微萃取气相色谱质谱联用法分析马油挥发物组成,并初步判断马油主要腥味物质。方法采用顶空固相微萃取(headspacesolid-phasemicro-extractions,HS-SPME)、气相色谱-质谱(gas chromatography-massspectrometry,GC-MS)联用技术,通过单因素与响应面分析,以分离的峰个数和峰面积为考察指标,建立马油挥发性物质的分析方法。根据马脂肪、炼制马油、粗马油和精制马油这4种样品的挥发性成分物质种类的变化,可初步判断马油腥味成分的种类。结果 HS-SPME最佳条件为65μm聚二乙烯苯/聚二甲基硅氧烷(divinylbenzene/polydimethylsiloxane, DVB/PDMS)微萃取头、萃取温度83℃、平衡时间40 min、萃取时间59 min、样品用量4.500 g、解吸时间5 min。确定了43种化合物结构,初步判断己醛、Z-2-庚烯醛、反-2-辛烯醛、壬醛、反-2-壬烯醛、癸醛、反,反-2, 4-壬二烯醛、反-2-癸烯醛、反,反-2, 4-癸二烯醛、2-十一烯醛为马油腥味成分。结论该方法可用于马油挥发性成分的分析,并初步判断马油腥味成分的种类。     

Electrostatic separation of volatile organic compounds by ionization

Removal technique of trace volatile organic compounds (VOCs) from air or other gases is of great concern in order to obtain contamination-free indoor air and various process gases for semiconductor manufacturing process. We propose a new technique for separating trace gas components. This technique utilizes preferential ionization and electrical migration of ions. Nitrogen and oxygen gas flow containing toluene vapor is divided into two flows, while the flow is irradiated with alpha-ray from 241Am under a DC electric field. The ionized toluene vapor in one flow electrically migrates into the other flow causing toluene rich and free flows. The separation efficiency of toluene is 50% when 0.5 L/min of inlet nitrogen stream contains 0.15 ppm of toluene at the applied voltage of 250 V. The separation efficiency of toluene increases with the mole fraction of oxygen in the carrier gas. The cation concentration flowing out from the separator is lower than the number of separated toluene molecules by 6 orders of magnitude, but the dependency of toluene separation efficiency on the applied voltage is the same as that of cation separation efficiency. The dependency of separation efficiency on the applied voltage and the gas flow velocity is qualitatively explained by the separation model which accounts for the generation and neutralization of VOC ions in the separator.     

Recovery of volatile fruit juice aroma compounds by membrane technology: Sweeping gas versus vacuum membrane distillation

The influence of temperature (10–45 °C), feed flow rate (300–500 L/h) and sweeping gas flow rate (1.2–2 m³/h) on the recovery of berry fruit juice aroma compounds by sweeping gas membrane distillation (SGMD) was examined on an aroma model solution and on black currant juice in a lab scale membrane distillation set up. The data were compared to recovery of the aroma compounds by vacuum membrane distillation (VMD). The flux of SGMD increased with an increase in temperature, feed flow rate or sweeping gas flow rate. Increased temperature and feed flow rate also increased the concentration factors (C_permeate/C_feed) of the aroma compounds. At 45 °C the most volatile and hydrophobic aroma compounds obtained the highest concentration factors: 12.1–9.3 (black currant juice) and 17.2–12.8 (model solution). With black currant juice a volume reduction of 13.7% (vol.%) at 45 °C, 400 L/h, resulted in an aroma recovery of 73–84 vol.% for the most volatile compounds. Compared to VMD, the aroma recovery with SGMD was less influenced by the feed flow rate but more influenced by the temperature. Higher fluxes were achieved during concentration by VMD and this reduced the operation time, which in turn reduced the degradation of anthocyanins and polyphenolic compounds in the juice.

Industrial relevance

High temperature evaporation is the most widely used industrial technique for aroma recovery and concentration of juices, but membrane distillation (MD) may provide for gentler aroma stripping and lower energy consumption. This study gives important clues about the fate of berry juice aroma compounds and polyphenols during concentration by MD, and identifies the main factors influencing the aroma recovery efficiency with MD. Both SGMD and VMD are promising techniques for gentle stripping of berry juice aroma compounds and deserve further consideration as alternative techniques for gentle aroma stripping in industrial fruit juice processing.     

利用顶空固相微萃取联动气相色谱-质谱分析对比分析刺果番荔枝和普通番荔枝的挥发性香气成分

目的比较普通番荔枝(Annonasquamosal)与刺果番荔枝(Annonamuricata)挥发性香气成分上的差异。方法本研究利用顶空固态微萃取(headspace-solid phase microextraction, HS-SPME)方法吸附收集样品挥发性香气成分,通过色谱-质谱法(gas chromatography-mass spectrometry, GC-MS)分析,结合NIST 08标准谱库数据,比较普通番荔枝与刺果番荔枝挥发性香气成分组成差异。结果实验中共检出70种挥发性香气物质,其中酯类25种、醇类18种、烯烃类12种、酮类8种、醛类6种,酸类与烷烃类各1种,普通番荔枝占57种,刺果番荔枝占33种。2者拥有20种相同的挥发性香气成分,分别为乙醛、乙醇、丙醇、正丁醛、乙酸乙酯、异丁醇、正丁醇、丁酸甲酯、异戊醇、顺-3-己烯醇、正己醇、2-庚醇、丁二酮、柠檬烯、正辛醇、2-壬酮、芳樟醇、苯乙醇、辛酸甲酯、辛酸乙酯。此外,普通番荔枝特有37种挥发性香气成分,而刺果番荔枝有13种。结论 2种番荔枝共有的挥发性香气成分构成番荔枝属果实的基本香气,成分间含量的差异使得番荔枝之间大体香气相似但亦有轻微差异,各自拥有特有挥发性香气组成则构成它们自身的特征香。     

Evaluation of volatile compounds in different types of ghee using direct injection with gas chromatography-mass spectrometry

Desi ghee (DG) was prepared from fermented cream followed by heat clarification (desi method) in the laboratory and butter oil (BO) was prepared from fresh butter by melting and centrifugation. Fresh samples of three brands of industrial ghee (IG-1, IG-2, IG-3) were collected from the local market. Volatile compounds of desi and industrial ghee and butter oil were isolated and concentrated using direct injection and cryofocussing techniques; separation and identification was by Gas Chromatography Mass Spectrometry (GCMS). A maximum of 36 compounds were detected in desi ghee whereas compounds detected in three industrial ghee samples varied from 22-29. The lowest number of compounds (16) was detected in butter oil. Of the identified compounds, maltol, 5-hydroxymethyl furfuraldehyde, dihydrodihydroxypyranone, 1,3-butanediol and 1-octanol were identified only in desi ghee volatiles. The concentration of acetic acid was found to be remarkably higher in desi ghee volatiles than in industrial ghee. Also the levels of identified fatty acids, methyl ketones, aldehydes, lactones and alcohols were high in desi ghee volatiles compared with industrial ghee and butter oil. In total, 62 compounds were detected, which included 6 aldehydes, 12 ketones, 8 each of fatty acids, alcohols and lactones, 4 each of esters and hydrocarbons or other compounds, and 12 compounds remained unidentified.     

Determination of volatile compounds in apple pomace by stir bar sorptive extraction and gas chromatography-mass spectrometry (SBSE-GC-MS)

A method based on stir bar sorptive extraction combined with gas chromatography-mass spectrometry detection (SBSE-GC-MS) has been optimized with the aim of applying it to the analysis of apple pomace. The method allowed the identification of 124 volatile compounds after 3 h of extraction with a precision (RSDs) ranging between 2% (linalool) and 11% (ethyl hexanoate). Its use in analyzing varietal apple pomace revealed the interest of this substrate as regards its content in aromas. From a semi-quantitative point of view, the higher content in aldehydes and esters of the Blanquina variety is worth highlighting, as are the greater concentration of acids in the Clara variety and the higher content of terpenes and norisoprenoides in the Coloradona variety. In contrast, the Ernestina and Perico varieties presented the lowest levels of aromas. PRACTICAL APPLICATION: The analysis of varietal apple pomaces showed the importance of this type of waste in the food industry, both for its content in aromas such as for its use as substrate in biotechnological processes.     

Characterization of volatile compounds in fermented milk using solid-phase microextraction methods coupled with gas chromatography-mass spectrometry

Lactic acid bacteria (LAB) are industrially important bacteria that are widely used in the fermented food industry, especially in the manufacture of yogurt. Characteristic flavors are produced by LAB during fermentation and storage that affect the quality and acceptability of fermented milk products. In this study, the volatile compounds in milk fermented by Streptococcus thermophilus IMAU80842 alone, Lactobacillus delbrueckii ssp. bulgaricus IMAU20401 alone, or both species together were identified using solid-phase microextraction methods coupled with gas chromatography-mass spectrometry. A total of 53, 43, and 32 volatile compounds were identified in milk fermented by S. thermophilus alone, L. delbrueckii ssp. bulgaricus alone, or both species together, respectively. The presence of some important flavor compounds was confirmed: acetic acid, acetaldehyde, acetoin, 2,3-butanedione, ethanol, and 1-heptanol. Our results demonstrate that the composition of the volatile compounds in fermented milk depends on the species of LAB used and whether they are used alone or in combination. This is important for the selection of appropriate starter cultures for the production of different types of fermented milk product with particular flavors.