Volatile flavour components of grapefruit juice (Citrus paradisi Macfadyen)

The qualitative analysis of volatile flavour components in grapefruit juice (Citrus paradisi Macfadyen) was performed using a gas chromatography/mass spectro-metry/computer system which allowed the identification of 58 components, 25 of them being reported for the first time. The aroma concentrates were obtained by an efficient simultaneous steam distillation/solvent extraction method which made it possible to identify many trace aroma components. Only quantitative differences were found in the aroma composition of fresh grapefruit juice extracted from different fruit batches of the same geographic origin during one season.     

Volatile flavour components of parsley leaves (Petroselinum crispum (mill.) nyman)

Fourteen compounds have been positively identified by gas chromatography mass spectrometry and a further seven tentatively identified in the headspace vapours above minced parsley leaves and petioles under very mild extraction conditions which closely simulate those occurring during mastication. By means of enzyme inhibitors it was shown that these components were present as such in the intact leaf tissue rather than in the form of an enzyme-non-volatile precursor system as in Allium species and the Cruciferae. The only sulphur-containing compound was methyl disulphide. The characteristic flavour and odour are due to the presence of monoterpene hydrocarbons.     

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 components of figs

Volatile essences of Calimyrna, Kadota, Black Mission and Adriatic figs were prepared by passing large volumes of headspace gas through porous polymer traps at room temperature. The essences were analysed by gas chromatography, utilising wall-coated open-tubular glass capillary columns; structural elucidations were based on gas chromatography-mass spectrometry. Differences between varieties appear to be quantitative rather than qualitative, and are not noticeably greater than differences between samples of the same variety. Compounds identified included acetaldehyde, dimethyl acetal, methyl acetate, ethyl acetate, ethyl alcohol, ethyl propionate, ethyl isobutyrate, propyl acetate, methyl butyrate, isobutyl acetate, ethyl butyrate, ethyl-2-methyl butyrate, 2-methyl butyl acetate, 2-ethyl-1,2-dihydrothiophene, ethyl valerate and 3-hydroxy-2-butanone.     

Volatile components of avocado leaves (Persea americana mill) from the Mexican race

The chemical composition of the volatile oil of avocado leaves from Mexican race (Persea americana Mill) grown in the highlands of Mexico was investigated by gas chromatography and gas chromatography-mass spectrometry. Thirty compounds were identified accounting for 92.45% of the oil. Estragol (78.12%), α-cubebene (3.58%), methyl eugenol (3.37%) and β-caryophyllene (2.10%) were the major components representing more than 87%. The oil has a characteristic aroma similar to anise-tobacco.     

Volatile components of jute sacks

The vacuum steam volatile oil from jute sacks has been analysed by capillary gas chromatography and mass spectrometry. Thirty-four compounds were characterised with some certainty, and some information obtained about an additional 36. The major volatile components were dimethylnaphthalenes. The odour thresholds of the volatile oil and some fractions were determined. These data and calculation of the amount transferred to a food contained in a sack, indicate that the jute sack could contribute an off-flavour to the food.     

Volatile components of baked potatoes

The vacuum steam volatile components of whole baked potatoes have been analysed by the direct combination of capillary gas-liquid chromatography and mass spectrometry. Forty-two compounds, mostly pyrazines and aliphatic aldehydes were characterised with some certainty. Some information was obtained about the identities of an additional 12. In the authors' opinion the components most important to baked potato aroma include 2-ethyl-3,6-dimethylpyrazine, 3-methyl-mercaptopropanal (methional), deca-trans,trans-2,4-dienal and possibly 2-ethyl-3,5-dimethylpyrazine. Qualitatively the pattern of components characterised is very similar to that found in potato chips (the English potato crisp). Comparison of the volatile oils obtained from the baked potato skins and the potato insides showed a considerably greater ratio of pyrazines to aldehydes in the skins indicating that the pyrazines are probably formed largely in the skins.     

Volatile flavour components of watercress

Using previously reported methods of sample preparation an essence of watercress was obtained which proved to contain only four major components. All are glucosinolate degradation products with 3-phenylpropionitrile the major compound, although the related 2-phenylethyl isothiocyanate is most important in flavour terms. The other compounds obtained are long chain ω-methylthioalkyl nitriles.     

Volatile flavour components of eggs

Using a modified Likens and Nickerson extraction apparatus and a gas entrainment method of concentration by low temperature—high vacuum distillation, approximately 115 volatile flavour components of the hen's egg were obtained. These were separated by gas chromatography and the majority were identified by combined gas chromatography-mass spectrometry. The odours of some of the separated components were described.     

Chemotaxonomy of wormwood (Artemisia absinthum L.)

Summary A series of essential oils obtained from samples ofArtemisia absinthium L. from various geographical origins and collected at different heights were analysed by means of glass-capillary gas chromatography. The main components were identified by means of GC, GC-MS, IR,¹HNMR and¹³CNMR.Several chemotypes were detected: in the western Alpine arc (Italy) the most important chemotype, above 1,000 m., was acis-epoxy-ocimene type, while at lower levels a-thujone type predominated.Plants originating from France could be divided into a chrysanthenyl acetate and a saßinyl acetate chemotype; plants from Siberia, Rumania and some from Valle d'Aosta belonged to a mixed type.

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Chemotaxonomie von Wermut (Artemisia absinthum L.)I. Zusammensetzung des ätherischen Öls einiger Chemotypen

Zusammenfassung Die ätherischen Öle des Wermuts, aus mehreren Herkunften und aus verschiedenen Höhen, wurden durch Capillargaschromatographie bestimmt und durch MS, IR,¹HNMR,¹³CNMR identifiziert.Dabei konnten verschiedene Chemotypen festgestellt werden. In den Westalpen ist der cis-Epoxycimen Typ über 1000 m der wichtigste Typ, während der-Thujon-Typ in niedrigeren Zonen vorherrscht.Französische Muster gehörten zu den Chrysanthenylacetat-und Sabinylacetat-Chemotypen, Muster aus Sibirien, Rumänien und dem Aostatal dagegen zu einem gemischten Typ.

     

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.     

Volatile flavour components of walnuts (Juglans regia L.)

The volatile components of walnut oil obtained by solvent extraction were investigated. Two essences were prepared, one using the Likens–Nickerson concurrent distillation–extraction apparatus and the other by high vacuum degassing. The essences were submitted both to g.c.–m.s. analysis and sensory evaluation of the components eluted from g.c. capillary columns. Twenty-nine compounds were identified, including 8 carbonyls, 4 alcohols, and 2 terpenes. The odour of walnuts appears to be due to the collective effect of a number of components.     

Volatile flavour components of dalieb (Borassus aethiopum L.)

The volatile components of dalieb fruit have been investigated by capillary column gas chromatography/mass spectrometry. The main components were C1 to C4 aliphatic alcohols and the corresponding acids together with esters derived from them. Acetic acid and ethanol were particularly abundant, the fruit pulp containing approximately 0.1% of each compound. Other volatiles present included the unsaturated ketone 6-methyl-5-heptene-2-one, the corresponding alcohol and the terpene, geranyl acetone.     

番茄籽油的挥发性成分分析

番茄籽油是具有开发潜力的植物油。采用顶空固相微萃取-气相色谱质谱联用技术分析新疆、内蒙古、甘肃和浙江4个不同产地低温压榨番茄籽油的风味,共鉴定出58种挥发性风味物质,包括20种醛类化合物、5种烯类化合物、12种酯类化合物、6种醇类化合物、5种酮类化合物、3种酸类化合物、6种杂环类化合物和1种苯酚类化合物。综合而言,番茄籽油的特征风味成分主要包括油脂氧化产物和来源于番茄本身固有的香气成分。     

Volatile flavour components of malt extract

The Likens-Nickerson concurrent steam distillation-solvent extraction apparatus was used to obtain an essence from malt extract. The essence was submitted to combined gas chromatography-mass spectrometry (g.c.-m.s.), to examination by sulphurspecific and nitrogen-specific detectors, and to sensory evaluation of the components eluted from gas chromatographic capillary columns. Some 33 compounds were identified by direct examination by g.c.-m.s., another 14 by trapping and re-injection, which provides an efficient method of concentration, and a further six, which had not been previously identified due to interference from the solvent peak, by the use of charcoal adsorption traps. Results indicate that several compounds need to be combined to simulate malt flavour. The odour contributions of several components are discussed.     

Volatile flavour components of garden cress

Using previously reported methods of sample preparation an essence of garden cress was obtained which proved to contain only 11 components. Eight have been identified, all glucosinolate degradation products (isothiocyanates and nitriles), and provide over 95% of the sample. Benzyl derivatives, from glucotropaeolin, are the most abundant. No thiocyanates were obtained.     

Volatile flavour components of coriander leaf

Using previously reported methods of sample preparation an essence of coriander leaf was obtained which proved to contain over 25 components. Most of these have been identified, with aliphatic aldehydes providing nearly 90% of the sample. C₁₂ aldehydes are the most abundant.     

Volatile components of Zalema white wines

The volatile composition of young white wines from Vitis vinifera cv. Zalema, an autochthonous grape variety in Huelva (southern Spain), has been studied by gas chromatography-olfactometry (GC-O) and techniques of quantitative analysis. This is the first time that an olfactometric analysis has been reported in wines made from this grape variety. The quantitative chemical study has shown 71 volatile compounds, of which 23 were in concentrations above their thresholds. On the basis of the odour activity values (OAVs), the most potent odorants were fermentative compounds, mainly fatty acids and their ethyl esters. Two norisoprenoids, β-damascenone and β-ionone, two alcohols (isoamyl alcohol and β-phenylethanol), three volatile thiols, 4-mercapto-4-methyl-2-pentanone, 3-mercaptohexyl acetate and 3-mercapto-1-hexanol, and two carbonyl compounds (acetaldehyde and phenylacetaldehyde) also exhibited OAVs > 1. The GC-O study corroborated these results, showing that five esters (isoamyl acetate, ethyl hexanoate, ethyl butyrate, ethyl isovalerate and ethyl octanoate), isoamyl alcohol and β-damascenone can be considered as the most powerful odorants of Zalema wines.