Analysis of the headspace volatiles of freshly brewed arabica coffee using solid-phase microextraction

ABSTRACT:  Headspace volatiles of freshly brewed drip coffee were investigated by gas chromatography/mass spectrometry (GC/MS) and gas chromatography/olfactometry (GC/O, CharmAnalysis™) analyses. For this purpose, a solid-phase microextraction (SPME) sampling method for the headspace volatiles of freshly brewed drip coffee was developed. SPME fiber coated with divinylbenzene (DVB)/carboxen/polydimethylsiloxane (PDMS) was selected from 6 types, and sampling time was determined at 2 min. The headspace coffee volatiles stayed constant in proportion for the first 2 min to keep the freshness of the brewed coffee aroma. Using this sampling method, the headspace volatiles of freshly brewed drip coffee (Ethiopian arabica coffee, roast degree: L value; 23) were examined by GC/MS and GC/O analyses. From the GC/O results, 1-(3,4-dihydro-2 H -pyrrol-2-yl)-ethanone (nutty-roast odor) and 4-(4'-hydroxyphenyl)-2-butanone (raspberry ketone, sweet-fruity odor) were newly detected as components in the aroma of coffee.     

Optimization of roasting conditions according to antioxidant activity and sensory quality of coffee brews

Response surface methodology (RSM) was used to determine the optimal roasting temperature and roasting time of coffee beans used for preparing brews with high antioxidant activity and sensory quality. Green coffee beans (Coffea arabica L. cv. Colombia Organic Tamata) were roasted at temperatures ranging from 140 to 220°C for 2–10 min and were then brewed with dripping hot water. The effects of the roasting conditions on the browning index, antioxidant activity, color, aroma, taste, and overall acceptability of the coffee brewed from the bean were investigated using a second-order central composite design. The quality indicators except the taste were significantly affected by roasting temperature and time, tending to increase and then decrease with increasing roasting temperature and time. Superimposed contour plots indicated that the optimal roasting temperature was 182°C and optimal roasting time was 7 min.     

Comparison of the characterisation of the fruit‐like aroma of Teucrium flavum L. subsp flavum by hydrodistillation and solid‐phase micro‐extraction

BACKGROUND: Teucrium species (Lamiaceae) are interesting for the food industry since many of them are used in the preparation of flavoured wines and beers, herbal teas, bitters and liqueurs. On this basis, the analysis of the aroma components of Teucrium flavum L. subsp. flavum growing in central Italy was carried out by means of both hydrodistillation (HD) and headspace solid‐phase micro‐extraction (HS‐SPME), coupled with GC/FID and GC/MS. RESULTS: A total of 102 components were identified in the essential oils, representing 99.0‐99.3% of the total oils. Sesquiterpenes hydrocarbons constituted the major fraction (48.5–49.4%), with the apple‐like flavour (Z,E)‐α‐farnesene being the major component. HS‐SPME allowed the analysis of the volatiles not only emitted by specific plant parts, but also by different parts within a single flower: flower calyx afforded the highest contribution, in terms of volatiles, to the aroma of the plant. CONCLUSION: The chemical profile of the volatile fraction obtained by HD and HS‐SPME, demonstrated the plant fruit‐like aroma, confirming the usefulness for flavouring wines, bitters and other kind of beverages, and also suggested other applications, as aroma and taste enhancer in food processing. In particular, SPME resulted in a very useful technique, which permits a choice between the part of the plant which has the highest concentration of a specific fragrance, and therefore establishes the best way of sampling during industrial applications of aromatic plants. Copyright © 2009 Society of Chemical Industry     

景芝芝麻香型白酒重要挥发性香气成分研究

芝麻香型白酒是1949年后新发展起来的一种新香型白酒,一直以来对其重要香气成分认识不清。应用顶空固相微萃取（HS-SPME）、液液微萃取（LLME）结合气相色谱-质谱（GC-MS）及气相色谱-氢火焰离子化（GC-FID）检测技术,共分析定量出86种香气成分。其中α-雪松烯和α-萜品醇首次在芝麻香型白酒中被定量,平均浓度分别为45.34μg/L和15.77μg/L。结合香气活力值（OAV）分析,发现景芝酒中重要的香气成分为辛酸乙酯、己酸乙酯、丁酸乙酯、3-甲基丁醛、二甲基三硫、3-甲基丁酸乙酯、2-甲基丙酸乙酯和戊酸乙酯（OAV>1000）。剖析芝麻香型白酒的重要挥发性香气成分,将为芝麻香型白酒的生产质量控制提供理论依据与实践指导作用。      

黄皮糯米酒的酿造工艺及香气成分的研究

研究了不同比例黄皮与糯米混合发酵黄皮糯米酒的工艺及风味改善方法。结果表明,黄皮汁与糯米比例为6∶4,糯米糖化48h后添加黄皮汁,并接入酿酒酵母在20℃下进行乙醇发酵,于成熟的酒中勾兑黄皮皮渣蒸馏酒,不但使成品酒突出了黄皮果酒清新淡雅的香气和糯米酒酒香醇厚特点,还对黄皮皮渣进行了有效利用。采用气质联用技术(GC/MS)分析黄皮糯米酒香气成分的结果表明,既含有黄皮主体香,又含有糯米酒的香气成分。     

SPME/GC/MS analysis of headspace aroma compounds of the Cameroonian fruit Tetrapleura tetraptera (Thonn.) Taub.

The aroma components of fresh and dried fruit shell of Tetrapleura tetraptera (Thonn.) Taub. (Mimosaceae) from Cameroon were analyzed by GC/FID, GC/MS, SPME/GC/FID, SPME/GC/MS, and olfactometry. The headspace is characterized by a high percentage of lower acids and esters. The main compounds in the SPME-headspace samples are 2-methylbutanoic acid (8.1%-14.5%), 2-methylbutenoic acid (3.5%-5.4%), acetic acid (13.0%-48.2%), butanoic acid (1.9-9.5%), 2-methylbutanoic acid ethyl ester (1.4%-3.4%), and 2-methylbutenoic acid ethyl ester (0.9%-10.3%) as well as 3-methylbutanone (0.3%-3.9%), butanol (0.4%-4.6%), 2-hydroxy-3-butanone (8.1%-31.6%), and 2-methylbutanol (3.6%-6.1%). Additional information on volatiles of an oleo-resin and a headspace sample from dried T. tetraptera fruits has been given and the analytical data correlated with olfactoric impressions to provide information about the aroma compounds responsible for the characteristic odour impression of these fruit samples.     

The effect of roasting method on headspace composition of robusta coffee bean aroma

Robusta coffee beans were roasted by three methods, i.e. convectively at 230 °C, by microwaves at 700 W, and by the coupled convective–microwave (CMR) method (the simultaneous convective heating at 230 °C and microwaving at 700 W) for 590, 670, and 370 s, respectively. The ultimate temperature of roasted beans was 238, 207, and 228 °C, respectively. Volatile compounds were determined in the headspace by GC-SPME both in samples of roasted coffee and in green beans to find effects of roasting methods on their formation and retention. Eighty-two and 148 odorants were identified in green and roasted coffee, respectively. The highest contents of the latter were found in coffee roasted by the coupled method because both the relatively short time of roasting and moderately high final temperature of beans favored retention of volatile aroma compounds. Because of these reasons, the contents of odorants were the lowest in convectively roasted coffee.     

新天霞多丽干白葡萄酒香气成分的GC/MS分析

采用溶液萃取法提取霞多丽干白葡萄酒中的香气成分,再经气相色谱-质谱联机分析,共鉴定出了49种挥发性化合物。相对含量排在前十位的分别是3-甲基-1-丁醇、苯乙醇、庚酸、双2-乙基邻苯二甲酸、吲哚-3-乙醇、乙酸-3-甲基丁酯、己酸、2,3-丁二醇、癸酸、4-羟基苯乙醇,初步查清了霞多丽干白葡萄酒中主要的香气物质组成。     

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     

造纸法再造烟叶致香成分的分析

应用同时蒸馏萃取装置 ,结合气相色谱仪与气相色谱 /质谱联用仪 ,对进口烤烟型造纸法再造烟叶和国产烤烟型造纸法再造烟叶二氯甲烷提取物中的主要成分进行了定性分析 ,并采用内标法测定了主要致香成分的相对含量。结果表明 ,进口再造烟叶中主要致香成分含量高于国产再造烟叶 ,国产再造烟叶A的致香成分含量高于国产再造烟叶B ,并通过感官评吸对分析结果进行了验证 ,两者较为吻合。     

不同萃取温度哥伦比亚咖啡萃取液香气分析

为研究不同咖啡豆经冷萃和热萃后的香气差异,以及香气感官描述与香气物质之间的相关性,本研究以云南和西达摩咖啡豆为原料,分别进行冷萃和热萃,再通过固相微萃取-气相色谱-质谱联用技术对其萃取液的香气成分进行测定,同时进行香气感官评价,最后通过多元统计分析方法找出对感官描述有重要贡献的香气物质。结果表明,在4种不同的咖啡萃取液中,共有69种挥发性成分被鉴定出,其中有39种物质的气味活性值（OAV）>1,冷萃中大部分的挥发性物质含量高于热萃,热萃中含量高于冷萃的物质为4-乙基愈创木酚、2,4-二叔丁基苯酚和对乙烯基愈创木酚;在香气感官评价上,冷萃的青香、果香、坚果香得分都明显高于热萃,而热萃的熏烤香得分高于冷萃;4-乙基愈创木酚和对乙烯基愈创木酚对熏烤香贡献较大,己醛则对青香贡献率较大,异戊酸甲酯、2-正丁基呋喃、壬酸乙酯和丁酸乙酯对果香贡献率较大,2,3-二乙基-5-甲基吡嗪对坚果香贡献率较大。本研究为探索冷萃与热萃咖啡萃取液的香气品质提供了数据参考。

     

Impact of Roasting Conditions on the Formation of Aroma Compounds in Coffee Beans

ABSTRACT: Hot air roasting of coffee beans results in a large number of aroma compounds. For a given coffee, the aroma profile is determined by the specific conditions for chemical reactions as controlled by the process parameters. Therefore, the influence of roasting temperatures on the formation of key aroma compounds was investigated. Coffee was roasted in 6 different processes to equal degrees of roast and the developing aroma compound profiles were characterized by gas chromatography, mass spectrometry, and olfactometry. A majority of aroma compounds showed the highest increase in concentration at medium stage of dehydration with bean water content from 7 to 2% (wb). Different time-temperature histories led to distinct aroma compound profiles. To reach a specific flavor profile, precise control of roasting time and temperature is required.     

Volatile aroma compounds in wines from Chinese wild/hybrid species

The volatile aroma compounds in wines produced from Chinese wild/hybrid species were investigated in comparison to wines from European grapes. Volatiles were extracted by headspace solid‐phase micro‐extraction and identified by gas‐chromatography/mass‐spectrometry. The identification of analyte was performed by a combination of the linear retention index approach with the comparison of the obtained mass spectra. A total of 98 peaks were tentatively assigned as wine aroma components, and 15 odorants can be found at concentrations above their odor threshold among the odor activity values (OAVs) of 46 compounds evaluated in all of the wines. The “OAVs’ aroma wheels” showed that the classes of aromatic series are first fruity, next herbaceous and roasty and no spicy and caramelized notes. Via principal component analysis, all the grape germplasm studied could be divided into four groups: “Jingsheng‐1,” “Cabernet Gernischt,” “Beibinghong,” and others, which exhibited distinctive aroma features, respectively. Practical applications Chinese wild grape species have many desirable properties for wine grape breeding such as possessing strong resistant genes to fungal diseases and cold condition, especially after hybridization with European grapes. As an emerging wine country, wines from Chinese wild/hybrid species have achieved much success in the last few years. The chemical content and biological properties have been studied extensively in many but there are a few studies in our knowledge about the wine tastes of these species. In this paper, the key odorants in wines produced from the Chinese grape species of V. amurensis Rupr., V. davidii Foex., and V. quinquangularis Rehd. and its hybrids were characterized in comparison to wines produced from European grapes (V. vinifera). The findings will help to the further understanding of the key aroma components in the different Chinese grapevine germplasm, and make further efforts to enrich the wine types in the marketplace.     

The effect of castration on the headspace aroma components of cooked lamb

Minced lamb samples (lean meat or adipose tissue) from 12-week-old ram lambs and wethers were fried in the absence of added fat. The headspace aroma components were isolated onto Tenax GC prior to thermal desorption. A total of 132 compounds were identified and a further 31 were partially characterised by GC-MS, 49 of which are reported here for the first time as components of sheep meat aroma. One of these, 4,6-dimethyl-1,3-oxathiane, which has not previously been reported in any meat, was associated with a ‘stale/wet animal’ odour. All aroma isolates were dominated by products of lipid degradation with aliphatic aldehydes present in the highest relative amounts. Certain branched-chain fatty acids have been implicated in the characteristic aroma of sheep meat, and 4-methyloctanoic and 4-methylnonanoic acids were identified at higher levels in the adipose tissue from entires than from wethers.     

云南临沧产区咖啡干香感官特征解析及杯品质量分析

以云南临沧产区咖啡为原料,利用顶空固相微萃取气相色谱-质谱联用技术和香气活度值（odor activity value,OAV）法确定咖啡干香特征组分,通过查询明确其风味感官特征,并邀请专业咖啡质量品鉴师团队评价杯品品质。结果表明：临沧咖啡中共有干香组成85 种,样品间组分含量差异不大;特征干香组分27 种（OAV＞1）,为临沧咖啡赋予蜂蜜、黑巧克力、奶油、焦糖、烤坚果的底香,同时具有枫糖浆、酸奶酪、热带水果、果酱和花香等风味;临沧咖啡杯测得分整体较高;同时可知杯品质量受区域环境影响较大。本实验结果可为临沧咖啡销售和推广提供理论参考。     

苹果沙棘复合果泥配方优化及品质分析

以苹果和沙棘原浆为原料,可溶性固形物、褐变度、感官评分为评价指标,通过单因素、Box-Behnken响应面设计优化苹果沙棘复合果泥配方。同时采用顶空固相微萃取-气相色谱-质谱联用技术分析苹果沙棘复合果泥的香气构成。试验优化果泥配方:苹果浆为基料,添加沙棘原浆7%、白砂糖12%、果胶0.3%(均为质量分数),该配方所制备果泥样品可溶性固形物为33%,pH值为3.35,亮度值(L^*)为50.45、红绿值(a^*)为3.93、黄蓝值(b^*)为24.83,感官评分87分,色泽金黄、口感细腻、酸甜适口。香气构成分析结果表明,苹果沙棘复合果泥样品中共定性定量57种组分,主要包括醇类、酯类、醛类、酮类、萜烯类。香气活性值(odor activity value,OAV)大于1的组分包括1-辛烯-3-醇、芳樟醇、正己醛、2-辛烯醛等22种香气化合物,可赋予产品青香、柠檬、苹果、紫丁香和茉莉香气。与苹果果泥相比,苹果沙棘复合果泥增加了12种主体香气(OAV>1),果香和花香更浓郁。     

啤酒酵母酿造葡萄酒及香气成分GC-MS分析研究

以宁夏贺兰山东麓产区酿酒葡萄为原料酿造葡萄酒,测定其感官指标、理化指标,并通过顶空固相微萃取-气质联用（HS- SPME-GC-MS）技术分析啤酒酵母单独发酵（SY）、葡萄酒酵母单独发酵（AY）及二者混菌（1∶1）发酵（MY）酿造葡萄酒的香气物质,并计算气味活力值（OAV）。结果表明,3个样品的感官评分顺序依次为MY＞SY＞AY,理化指标符合相关国标;MY、SY、AY样品GC-MS分析分别共检测出22种、20种、15种香气成分,其中含量最高的均为异戊醇,MY、SY样品中的酯类成分较AY样品种类多;OAV分析结果进一步显示,对3个样品香气贡献最大的物质均为酯类,MY样品OAV＞1的香气成分为4种。啤酒酵母酿造的葡萄酒风味独特,并且混菌发酵可以提升葡萄酒品质。     

Optimization of espresso machine parameters through the analysis of coffee odorants by HS-SPME-GC/MS

The aroma profile and the final quality of espresso coffee (EC) are influenced by such technical conditions as the EC machine extraction temperature and the pressure used. The effect of these two parameters on EC quality were studied in combination by headspace solid phase micro extraction-gas chromatography-mass spectrometry (SPME-GC-MS) and sensory profile. Moreover, 10 key odorants at the best EC machine settings were examined to compare the two coffee cultivars (Arabica and Robusta) and two EC machines [Aurelia Competizione (A) and Leva Arduino (B)]. The data obtained provides important information about espresso making technique, suggesting that the usual espresso machine temperature and pressure settings (i.e. 92°C and 9bar) are very close to those needed to obtain the best quality espresso. This confirms the traditional wisdom of coffee making, which judges 25ml, the typical volume of a certified Italian EC, to be ideal for very strong aroma intensity.