Volatile constituents of green and ripened pineapples were isolated and identified by gas chromatography and gas chromatography/mass spectrometry. The numbers of volatiles found were 144 and 127 in green and ripened pineapples, respectively. Among a total of 157 constituents identified, 50 were identified for the first time from pineapple. Esters constituted over 80% of total volatiles from both green and ripened pineapples. The major volatile constituents in green pineapples were ethyl acetate and ethyl 3-(methylthio)propanoate. In ripened pineapples, ethyl acetate and butane-2,3-diol diacetate were the main constituents. Diastereoisomers of butane-2,3-diol diacetate were satisfactorily separated by a gas chromatographic chiral column.Pineapple, one of the most popular tropical fruits in the world, has been cultivated in South America since the 15th century. However, it was not until the beginning of the 20th century that advanced canning technology made it possible to deliver green pineapple to people all over the world. People now enjoy the pineapple's unique sweet and sour flavor either as a green fruit or in processed form, such as in cake or pie.Volatile constituents of pineapple have been investigated by many researchers. Numerous reviews on pineapple flavors have been published in the past two decades (

Volatile chemicals formed from heated D-glucose, L-cysteine, or D-glucose/L-cysteine were collected in three traps (20, 0, and -78 "C) connected in series, recovered, and analyzed. A total of 130 chemicals was positively identified: 41 identified in the samples from D-glUCOSe heated alone, 52 in the samples from L-cysteine heated alone, and 93 in the samples from L-cysteine/D-glucose heated together. The heterocyclic compounds identified were 16 thiophenes, 16 furans, 11 pyridines, 10 pyrazines, 9 thiazoles, 8 thiazolidines, 7 pyrroles, 2 thiazolidines, and 1 oxazole. Thialdine and 3,5-dimethyl-1,2,4-trithiolane were also identified. Carbonyl compounds (14 ketones and 3 aldehydes) were produced from D-glucose alone. The L-cysteineh-glucose system produced 2-methylthiazolidine and thialdine as major volatile components; L-cysteine alone produced 2-methylthiazolidine as a major component. Pyridines and pyrroles were found both in the L-CySteine/D-glUCOSe system and in L-cysteine alone, whereas pyrazines and thiazoles were found mainly in the L-cysteine/D-glucose system.

Extracts from leaves of Japanese mugwort (Artemisia princeps Pamp.) were obtained using two methods: steam distillation under reduced pressure followed by dichloromethane extraction (DRP) and simultaneous purging and extraction (SPSE). A total of 192 volatile chemicals were identified in the extracts obtained by both methods using gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS). They included 47 monoterpenoids (oxygenated monoterpenes), 26 aromatic compounds, 19 aliphatic esters, 18 aliphatic alcohols, 17 monoterpenes (hydrocarbon monoterpenes), 17 sesquiterpenes (hydrocarbon sesquiterpenes), 13 sesquiterpenoids (oxygenated sesquiterpenes), 12 aliphatic aldehydes, 8 aliphatic hydrocarbons, 7 aliphatic ketones, and 9 miscellaneous compounds. The major volatile constituents of the extract by DRP were borneol (10.27 ppm), alpha-thujone (3.49 ppm), artemisia alcohol (2.17 ppm), verbenone (1.85 ppm), yomogi alcohol (1.50 ppm), and germacren-4-ol (1.43 ppm). The major volatile constituents of the extract by SPSE were 1,8-cineole (8.12 ppm), artemisia acetate (4.22 ppm), alpha-thujone (3.20 ppm), beta-caryophyllene (2.39 ppm), bornyl acetate (2.05 ppm), borneol (1.80 ppm), and trans-beta-farnesene (1. 78 ppm).

Extracts from leaves of aloe (Aloe arborescens Mill. var. natalensis Berger) were obtained using two methods: steam distillation under reduced pressure followed by dichloromethane extraction (DRP) and simultaneous purging and extraction (SPE). A total of 123 aroma chemicals were identified in the extracts obtained by both methods using gas chromatography and gas chromatography/mass spectrometry. There were 42 alcohols, 23 terpenoids, 21 aldehydes, 9 esters, 8 ketones, 6 acids, 5 phenols, and 9 miscellaneous compounds. The major aroma constituents of this extract by DRP were (Z)-3-hexenol (29.89%), (Z)-3-hexenal (18.86%), (E)-hexenal (7.31%), 4-methyl-3-pentenol (5.66%), and butanol (4.29%). The major aroma constituents of this extract by SPE were (E)-2-hexenal (45.46%), (Z)-3-hexenal (32.12%), hexanal (9.14%), (Z)-3-hexenol (1.60%), and 3-pentanone (1.41%). Terpenoids were also found as one of the major constituents. The fresh green note of aloe leaves is due to the presence of these C(6) alcohols and aldehydes as well as terpenoids.

Volatile compounds in the peel extract of Jabara (Citrus jabara Hort. ex Tanaka), a Japanese sour citrus, have been investigated using GC-FID, GC-MS and GC-olfactometry. The peel extract was obtained by solvent-assisted flavour evaporation after solvent extraction. The GC-FID and GC-MS analyses led to the identification of 49 compounds, including myrcene (46.8%), limonene (28.2%) and γ-terpinene (15.5%) as major constituents. Interestingly, the level of myrcene was much higher than that of limonene known as the main volatile constituent in citrus peel. This specific composition indicated that Jabara was a rare species among citrus fruits. Application of aroma extract dilution analysis revealed 22 odour-active compounds with the flavour dilution (FD) factor ranged from 8 to 16 384, and 19 of these compounds were identified. Myrcene, which showed the highest FD factor of 16 384, was regarded as the most character impact odorant in the Jabara peel extract. It should be noted that (3E,5Z)-1,3,5-undecatriene (FD = 512), (3E,5Z,8Z)-1,3,5,8-undecatetraene (FD = 256), 1,3,5,7-undecatetraene (unknown stereochemistry, FD = 256) and (6Z,8E)-6,8,10-undecatrien-3-one (FD = 16) were detected as potent odorants with green and fruity aroma, despite their trace levels in the extract. In addition to these, 7-methyl-1,6-octadien-3-one, having a metallic and mushroom-like odour, was identified as a further key contributor to the aroma of Jabara peel extract. This novel odorant has been reported for the first time as a volatile constituent in a natural product.