Volatile components of cooked tubers of the water yam (Dioscorea alata)

Volatile constituents were isolated from yams, during cooking, by concurrent steam distillation-solvent extraction. The essence which resulted was analysed by linked gasliquid chromatography-mass spectrometry (g.l.c.-m.s.) employing capillary columns and by gas-liquid chromatography coupled with sensory evaluation of the column effluent (nasal appraisal). In addition to hydrogen sulphide and a number of high-boiling fatty acids, 29 compounds, comprising seven hydrocarbons, eight alcohols, eight aldehydes, four ketones, a furan and a disulphide, were identified for the first time in yam. A further five components were tentatively identified by g.l.c.-m.s. and by thinlayer chromatography of derivatives. 4-Phenylbutan-2-one was the major constituent of the acid-free essence.     

Volatile constituents of horseradish roots

Essences of the volatile components of five samples of horseradish root, three fresh and two of dried flakes, have been prepared and examined by gas chromatography (g.c.) and combined gas chromatography-mass spectrometry (g.c.-m.s.). At least 17 compounds are involved. Five of these have been rigorously identified by comparison with authentic compounds, synthesised where necessary, through mass spectra and retention data and the identities of three others have been tentatively established. The compounds concerned are methyl, ethyl, isopropyl, 2-butyl, allyl, 4-pentenyl and 2-phenethyl isothiocyanate and allyl thiocyanate. The constituents of the five essences were assessed semi-quantitatively by g.c. and definite differences found. These were reinforced by examination of the headspace vapours over the coarsely grated root. Additional attention was devoted to the allyl isothiocyanate-thiocyanate interconversion and to the odour assessment of the volatile horseradish components.     

Volatile flavour components of brazil nuts Bertholletia excelsa (Humb. and Bonpl.)

Essences were prepared from solvent-extracted brazil nut oil, alternatively by means of a Likens and Nickerson apparatus and a high vacuum degassing unit. The relatively inexpensive degassing unit and its use are briefly described. Thirty-seven components were identified by g.c.-m.s. including most of the major components. The aroma of the components of each essence was evaluated on elution from a g.c. capillary column.     

Pyrazines in extruded malt

Green malt, partially dried, was processed by high-temperature short-time (HTST) extrusion cooking at three different temperatures. Volatile components of the product were analysed by gas chromatography (g.c.) using a headspace sampling technique, and identified by mass spectrometry (m.s.). The concentration of pyrazines increased when the temperature was increased from 130 to 160°C, but it fell at 190°C, probably as an effect of volatilisation. However, the influence of parameters such as water content, the milling of the raw material and its residence time in the extruder must also be taken into account. Extruded malt contained more total pyrazines than conventionally processed malt. 2-Vinyl-5-methylpyrazine and 2-vinyl-6-methylpyrazine were found only in extruded malt, especially at high processing temperature. The pyrazine content per colour unit was high, an observation which may lead to the production of a more flavourful beer of the lager-type.     

六款特种麦芽风味物质和感官特性分析

采用顶空固相微萃取(HS-SPME)方法,结合气相色谱-嗅闻-质谱联用仪(GC-O-MS),对六款不同色度的特种麦芽(高香麦芽、饼干麦芽、焦香麦芽、结晶麦芽、巧克力麦芽和黑麦芽)进行挥发性风味物质鉴定,从六款特种麦芽中一共鉴定出风味化合物41种,其中醛类20种、吡嗪类7种、醇类4种、酚类1种、杂环化合物类9种。采用Rate That All Apply(RATA)感官评价方法对特种麦芽的感官特性强度进行打分,结果表明,随着特种麦芽颜色的加深,其甜香果香逐渐降低,咖啡味和烟熏味逐渐增加。通过偏最小二乘回归法(PLSR)建立特种麦芽风味物质与感官特性的相关性,结果表明不同种类杂环化合物的协同作用解释了巧克力麦芽和黑麦芽的主体风味,不同种类吡嗪化合物的协同作用解释了饼干麦芽的主体风味,但该模型对高香麦芽、焦香麦芽、结晶麦芽的主体风味解释欠佳,有待下一步探索。     

Basic compounds contributing to beer flavour

Sixteen basic heterocyclic compounds have been identified by g.c.-m.s. after careful extraction of a flavour essence from an English beer. They include the following that have not previously been reported as beer constituents: pyridine, 2-acetylpyridine, 3-acetylpyridine, pyrazine, methylpyrazine, 2,3-dimethylpyrazine, 2,5-dimethylpyrazine, 2,6-dimethylpyrazine, 2-ethyl-5- (and/or 6-) methylpyrazine, trimethylpyrazine, 2-ethyl-3,5-dimethylpyrazine, 2-ethyl-3,6-dimethylpyrazine, 2-ethyl-5,6-dimethylpyrazine, 6,7-dihydro-5H-cyclopentapyrazine, 2-methyl-6,7-dihydro-5H-cyclopentapyrazine, and thiazole. The minimum total concentration of basic compounds in the beer was estimated to be 10 mg/kg.     

Volatile oil composition of greek mountain tea (Sideritis spp.)

The composition of the essential oils of two species of the genus Sideritis (Labiatae) was investigated by gas chromatography-mass spectroscopy (g.c.-m.s.). Ca50 components were identified. The smell of the diluted oils closely resembled that of a beverage prepared from it in the Balkans, the so-called ‘mountain tea'’.     

AROMA COMPOUNDS OF MALTED ACHA (DIGITARIA EXILIS, STAPF)

The flavor extract components of malted ‘acha’ (Digitaria exilis), which have not been studied prior to this report, were determined by gas chromatography with a mass selective detector. Volatile compounds were identified with a NBS 43 K.1 mass spectra library by Probability Based on Matching (PBM). A total of 14 peaks were detected and identified in the malted sample. The volatiles included, four aldehydes, one aromatic compound, an ester, a terpene, one aliphatic alcohol, five heterocyclic compounds of six membered rings. Quantitatively, heterocyclic compounds were the most abundant class of compounds identified. Six compounds, ethylacetate, 1-hydroxy-2-propanone, hexanal, pyrazine, 2, 5-dimethylpyrazine and 2, 3-dimethylpyrazine were identified as potential contributors to the flavor of malted acha. There was not a significant difference between the aroma quality of acha and crystal malt.     

The sensory analysis and identification of volatiles from walnut (Juglans regia L.) headspace

This paper has the two-fold aim of illustrating the application of techniques recently developed in this laboratory and of elucidating the nature of the compounds responsible for the aroma of a particular foodstuff. The volatile constituents of Chaberté walnuts (Juglans regia L.) headspace were investigated using charcoal capillary traps. By means of capillary columns and a g.c.-m.s. system some 37 compounds were identified, including six aldehydes, six alcohols, and five ketones. It was shown that the aroma of walnuts is composite in nature, since none of the components was found to possess a walnutty aroma on elution from g.c. columns, yet the total headspace, retrapped on a length of PLOT Celite capillary, was found to be extremely walnutty. Further sensory analysis using PLOT Celite traps revealed that the carbonyls present in a particular region of the chromatogram were important to the aroma of walnuts. A mixture in liquid paraffin of certain carbonyls identified in the headspace was found to possess a moderately walnutty aroma.     

Qualitative and quantitative analysis of petitgrain Eureka lemon essential oil by fused silica capillary column gas chromatography mass spectrometry

The identification of Algerian petitgrain Eureka lemon essential oil was carried out by gas liquid chromatography-mass spectrometry in electronic impact mode using a fused silica capillary column (FFAP). The results enabled a previous study on this oil to be completed where the relative retention data and chemical derivation reactions had been performed. A preparative gas chromatography was applied to give a better g.c.-m.s.analysis of minor compounds; thus, two new products (citronellyl n-propionate and cedrol) were revealed by this method. Only 80 compounds were identified after indexation of 137 mass spectra and after comparison with those in the literature because most mass spectra data banks are not well adapted for the identification of essential oils. A global comparison of the percentage composition of the major compounds of this oil with those in other petitgrain lemon essential oils has revealed distinct differences. From the mass spectra of nine monoterpenic hydrocarbons, it was shown that comparison of the intensity ratio of the characteristic fragment ions in EI mode, which has been suggested by some authors as a general method of identification of compounds with similar mass spectra, is not reliable.     

Tainting of pork meat by 1,4-dichlorobenzene

Pork meat rejected by consumers because of a nauseating taint was analysed by gas chromatography and mass spectrometry (g.c.-m.s.) and found to contain 5–20 mg kg^?1 of 1,4-dichlorobenzene. Trace amounts (10–35 μg kg^?1) of 1,4-dichlorobenzene were found in wood-shavings used as litter materials and in the feedstuffs, but were considered insufficient to be the main cause of contamination. Meat from the following batch of pigs from the same source contained only very small amounts, similar to those present in normal pork obtained elsewhere (<25 μg kg^?1). Examination of data recorded by g.c.-m.s. in the previous 2 years showed that 1,4-dichlorobenzene was present in trace quantity (>10μg kg^?1) in several samples of normal meat, and appeared to be widespread in its occurrence.     

Characterization of the aroma compounds in crystal malt

Crystal malt, the most popular type of specialty malt used in beer brewing, plays a vital role in forming complex flavor and color. Nevertheless, crystal malt is only defined based on the malting process, and there is not any standard to evaluate its quality. In the current study, the volatile aroma constituents of commercial crystal malt samples were analyzed with headspace solid-phase microextraction combined with gas chromatography–mass spectrometry, in order to explore the characteristic aroma compounds of crystal malt. The average concentration of volatile aroma compounds in 10 crystal malt samples is 587 µg L⁻¹, ranging from 347 to 1265 µg L⁻¹. A total of 38 aroma compounds were identified, 47% of which were existed in all the 10 samples. Based on principal component analysis and odor activity value, isobutyraldehyde, 2-methylbutanal, furfural, 2-acetyl-1H-pyrrole, oct-1-en-3-ol, 4-methyl-2-phenyl-2-pentenal, and (2E)-2-isopropyl-5-methyl-2-hexenal could be considered the characteristic aroma compounds of crystal malt. The results of this present study would help to establish a standard to assess the quality traits of crystal malt sample.     

Sensory and Chemical Analysis of ‘Shackleton's’ Mackinlay Scotch Whisky

Three cases of Mackinlay's Rare Highland Malt whisky were excavated from the ice under Sir Ernest Shackleton's 1907 expedition base camp hut at Cape Royds in Antarctica in January 2010. The majority of the bottles were in a pristine state of preservation and three were returned to Scotland in January 2011 for the first sensory and organoleptic analysis of a Scotch malt whisky distilled in the late 1890s. Sensory analysis and the higher alcohol and maturation congener profiles describe a lightly peated malt whisky matured in American white oak sherry or wine casks. Analysis of process related compounds together with combined gas chromatography (GC) mass spectrometry and GC‐olfactometry analysis of fermentation related congeners show a distinctly ‘modern’ style of malt whisky. While Scotch malt whisky at the end of the 19th century was generally regarded as heavily peated and harsh in character, Charles Mackinlay & Co. Distillers were producing a malt whisky with an altogether more subtle character at their Glen Mhor distillery near Inverness. The sensory and chemical analysis of this unique whisky artefact significantly changes our understanding of the quality and character of Scotch malt whisky produced by our distilling forefathers.     

Volatile aroma compounds of raw and roasted palm kernel

The volatile aroma compounds of raw and roasted palm kernel, isolated by hydrodistillation, were analysed by g.l.c. and g.c.-m.s. A number of compounds have been identified for the first time in this commodity. It was found that δ-lactones and ethyl esters were predominant in the flavour profile. In roasted palm kernels, flavour analysis showed the presence of a number of pyrazines formed during heating. Most of the lactones and esters identified in raw palm kernel were present in the roasted samples also. The flavour concentrate included a number of fatty acids in both the raw and roasted samples, in small amounts.     

玫瑰香型格瓦斯工艺优化及香气成分分析

以大麦芽、焦香麦芽和玫瑰花等为原料,研制玫瑰香型格瓦斯。利用单因素和正交试验对玫瑰香型格瓦斯的原料配比和发酵工艺进行优化,并采用顶空固相微萃取-气相色谱-质谱联用技术(SPME-GC-MS)分析其挥发性风味成分。试验结果表明,最佳发酵工艺为:大麦芽与焦香麦芽质量比9∶1、料水比1∶8(g/mL)、菌种添加量2%、接种体积比(酵母菌∶乳酸菌)2∶1、发酵时间16 h、玫瑰浸提液添加量18%,同时添加糖化酶2%、酒花0.2%、白砂糖1%、柠檬酸0.1%。玫瑰香型格瓦斯香气物质共有92种,其主体香气物质主要是苯乙醇、异戊醇、辛酸乙酯、丁香酚等。     

黑果枸杞风味品质的分析研究

摘要：目的 分析黑果枸杞风味物质的构成及对产品品质的影响。方法 采取顶空固相微萃取（headspace-solid phase microextraction,HS-SPME）结合气相色谱-质谱联用法（gas chromatography - mass spectrometry, GC-MS）对其挥发性成分进行分析,采用峰面积归一化法计算各成分的相对质量分数。采用高效液相色谱法对糖酸类化合物及氨基酸的含量进行了测定。结果 共鉴别出包括醇类、醛类、酮类、酯类、酸类、酚类、杂环化合物和含硫化合物等共99种挥发性物质,其中55种为食用香料,呈香物质中杂环化合物含量最高,其次是酯类和醇类。两种鲜味氨基酸和六种甜味氨基酸的含量分别为0.48 g/100g和0.50 g/100g,糖酸类化合物中苹果酸、柠檬酸、果糖和蔗糖的含量分别为0.011 g/100g、0.11 g/100g、0.0885 g/100g和0.0217 g/100g。结论 本研究明确了黑果枸杞中主要的风味物质,分析了影响其风味品质的香气成分、糖酸类物质和呈味氨基酸的组成和含量。     

LAGER-TYPE BEER MADE FROM EXTRUDED MALT; SENSORY AND CHEMICAL ANALYSES

A lager-type beer was brewed from a mixture of partially dried green malt and extruded green malt (9:1). Small flavour differences were observed in the beer made from the extruded malt when compared with two other types of beer, namely standard lager and beer made from 100% green malt which was partially dried. More than 90 flavour components were described upon sniffing of the GC eluate. Most of them were present in trace amounts which did not allow their identity to be established. However, in all beer samples several unidentified components were described as giving a “roasted”, “burnt”, “bread crust” or “biscuit” odour. These odour characteristics probably derive from the alkylpyrazines present. Positively identified pyrazines were only found in the “extruded” beer, namely methylpyrazine and 2,5 (and/or-2,6)-dimethylpyrazine. However, when the beer was tasted, no characteristics associated with a roasted or burnt flavour were registered. Among the identified flavour components esters and alcohols were abundantly represented.     

不同总酸含量的麦芽对啤酒理化特性及风味的影响

选用不同总酸含量的麦芽酿造啤酒,采用高效液相色谱(HPLC)法检测麦芽及酿造啤酒中的有机酸含量,以建立麦芽总酸和啤酒有机酸含量的相关性。采用顶空固相微萃取(HS-SPME)和气相色谱质谱联用(GC-MS)法检测啤酒中挥发性化合物成分,并对酿造的啤酒进行感官评价。结果显示,随着麦芽总酸含量的升高,麦汁pH值呈下降趋势,琥珀酸、苹果酸、乳酸和乙酸的含量呈上升趋势。麦芽总酸含量与啤酒中总酸、苹果酸、乳酸含量呈显著正相关,相关系数分别为0.94、0.94和0.92。不同总酸含量麦芽酿造啤酒特征香气物质不尽相同,且感官特征有差异。随着麦芽总酸含量的升高,酿造啤酒的酸味得分呈现升高趋势,花/果香、酚香、酒精刺激感得分呈下降趋势。     

FLAVOUR STABILITY OF ALES BREWED USING HYDROLYSED MAIZE SYRUP—SENSORY AND ANALYTICAL ASPECTS

Whereas ales brewed entirely from malt had flavour-lives of 12 weeks, those produced from 70% malt/30% hydrolysed maize syrup had flavour-lives of at least 25 weeks. The latter beers were of sound flavour and quality, and no difficulties were experienced during their production. Their initial flavour was similar to that of beers brewed using an all-malt grist. Analysis by gas chromatography coupled mass spectrometry showed that the all-malt beer underwent a greater degree of change during natural aging than did the beer brewed with maize syrup. A number of compounds, including a series of glycerol/acetaldehyde acetals, have been identified for the first time in beer; the latter compounds were found to increase in level during aging.     

Comprehensive evaluation of malt volatile compounds contaminated by Fusarium graminearum during malting

Fusarium graminearum is the most important filamentous fungi in the malting process, and greatly affects malting performance and malt quality. Analysis of the emitted volatiles from F. graminearum mycelium was used to evaluate the malt flavour contaminated by F. graminearum during malting based on solid‐phase microextraction combined with gas chromatography–mass spectrometry. GC–MS analysis of different mycelium samples revealed a broad spectrum of volatile compounds including aldehydes, ketones, alcohols, organic acids and aromatics, which were highly similar to those of barley and malt. Statistical assessment of the data via principal component analysis demonstrated that the major contributors to the time‐dependent dynamic changes in the volatiles were the volatile aldehyde, alcohol and ketone fractions in the contaminated malting process. The results showed that volatile concentration was modulated by the ‐metabolism of the green malt and F. graminearum. Volatile compounds from green malt were influenced by F. graminearum fungi contamination during malting, although some were probably generated by this fungus. Copyright © 2017 The Institute of Brewing & Distilling