Predominant aromas

In general, microwave cake appeared to lack many of the nutty, brown, and caramel-type aromas observed in the conventional cake and was in fact more similar to the batter. Table 2 summarizes the predominant aranas noted from each extract in decreasing order. The predominant aromas in both batter and microwave cake were green vegetable notes. Brown, caramel, and potato notes were observed less frequently. The conventional cake profile contained more brown, caramel notes followed by butter, cucumber, potato, and finally, green vegetable aromas. 

Table 2. Predominant Aromas Associated With Batter, Microwave, and Conventionally Baked Cake...

In an earlier study we conducted AEDA for the determination of the predominant aroma-active components of C. sativum (1), in which we determined that a nonpolar DB-5 column gave superior results during AEDA to a polar DB-WAX column. Therefore, in the present study a DB-5 column was used for AEDA and for the determination of flavor dilution (FD)-factors. For... 

In E. foetidum a total of 13 aroma-active constituents with FD-factors > 9 were detected. These consisted of two n-aldehydes (nos. 2 and 6), seven 2-alkenals (nos. 3, 5, 7, 8, 9, 11, 28), (Z)-3-hexenal (no. 22) and three unknown compounds (nos. 29, 30 and 32)(Table V). All of these compounds were detected in C sativum with the exception of an unknown compound (no. 32) having a spicy, herbaceous note. ( )-2-Dodecenal was by far the predominant aroma component with an FD-factor of 2187. Unknown compound no. 30 had the second highest FD factor (=243). The musty, chlorine-like character of this compound may be important in the overall aroma of E. foetidum herb. Other aroma contributors include compounds with FD factors from 27 to 81, such as nos. 5, 6, 7, 11, 22, and 29. Despite having an FD factor of 27, (Z)-3-hexenal (no. 22) was probably derived via lipoxygenase action during sample preparation and may not be a characteristic aroma component of essential oil of E. foetidum herb. 

Based on the results of AEDA some general conclusions may be drawn about the characteristic aroma components of each herb. In most cases, the predominant aroma-active components determined for each herb follow closely its volatile aldehyde profile. With respect to its essential oil profile and the number of aroma-active constituents, P. odoratum herb may be the simplest of the herbs studied. In this herb the n-aldehydes decanal and dodecanal were the predominant aroma-active components, while the sequiterpene components... 

In the AEDA of UHT milk (Table 10.38), 5-decalactone, which contributes to the aroma of butter (Table 10.40) as well as unripened and ripened cheese (cf. 10.3.5), is the predominant aroma substance. Apart from other lactones, 2-acetyl-l-pyrroline, methional, 2-acetyl-2-thio-azoline and 4,5-epoxy-2-decenal are among the identified aroma substances. 

The predominant aroma-active components of the essential oil sample described and of fresh leaves of O. sanctum (purple type) obtained from a local market (Bangkok, Thailand) were compared by gas chromatography olfactometry and aroma extract dilution analysis. During the isolation of volatile constituents from the fresh herb, the influence of extraction... 

Citrus oils contain up to 95% monoterpene hydrocarbons (usually limonene, but others as well, e.g., lemon oil also contains a-terpinene and /3-pinene). The important aroma-determining components of citrus oils are functionalized terpenes and aliphatic compounds (predominantly carbonyl compounds and esters), present only in relatively low concentrations [358]. Thus, several methods are employed to concentrate citrus oils on an industrial scale. The monoterpene hydrocarbon... 

Davana oil is obtained by steam distillation of the herb Artemisia pallens Wall. (Asteraceae), grown in south India. It is an orange-brown liquid with a sweet tealike odor reminiscent of dried fruits. The composition of the oil is very complex its main components are furanoid sesquiterpenes [474-476a]. It is used predominantly for aroma compositions. FCT 1976 (14) p.737 [8016-03-3], [91844-86-9]. 

Sugars, acids and aroma compounds contribute to the characteristic strawberry flavour [85]. Over 360 different volatile compounds have been identified in strawberry fruit [35]. Strawberry aroma is composed predominately of esters (25-90% of the total volatile mass in ripe strawberry fruit) with alcohols, ketones, lactones and aldehydes being present in smaller quantities [85]. Esters provide a fruity and floral characteristic to the aroma [35,86], but aldehydes and furanones also contribute to the strawberry aroma [85, 87]. Terpenoids and sulfur compounds may also have a significant impact on the characteristic strawberry fruit aroma although they normally only make up a small portion of the strawberry volatile compounds [88, 89]. Sulfur compounds, e.g. methanethiol. 

Banana (Musa sapientum L.) is one of the most common tropical fruits, and one of Central America s most important crops. It is grown in all tropical regions and is one of the oldest known fruits [45]. From a consumer perspective, bananas are nutritious with a pleasant flavour and are widely consumed throughout the world [57]. Esters predominate in the volatile fraction of banana (Fig. 8.2). Acetates are present in high concentrations in the fruit and generally possess a low threshold. Isopentyl acetate and isobutyl acetate are known as the two most important impact compounds of banana aroma. Alcohols are the second most important group of volatiles in banana extracts. 3-Methyl-1-butanol, 2-pentanol, 2-methyl-1-propanol, hexanol, and linalool are the alcohols present in higher concentrations in the fresh fruit [45]. 

Later, the chemical characterisation of the volatiles from yellow passion fruit essence and from the juice of the fruit was done by GC-MS and GC-olfactom-etry (GC-O) [27]. Esters were the components found in the largest concentrations in passion fruit juice and essence extracted with methylene chloride. Analysis by GC-O yielded a total of 66 components which appeared to contribute to the aroma of passion fruit juice and its aqueous essence. Forty-eight compounds were identified in the pulp of Brazilian yellow passion fruits (Passiflora edulis f. flavicarpa) [48]. The predominant volatile compounds belonged to the classes of esters (59%), aldehydes (15%), ketones (11%), and alcohols (6%). 

Mixtures of gaseous or liquid hydrocarbons which can be vaporized represent the raw materials preferable for the industrial production of carbon black. Since aliphatic hydrocarbons give lower yields than aromatic hydrocarbons, the latter are primarily used. The best yields are given by unsubstituted polynuclear compounds with 3-4 rings. Certain fractions of coal tar oils and petrochemical oils from petroleum refinement or the production of ethylene from naphtha (aromatic concentrates and pyrolysis oils) are materials rich in these compounds. These aromatic oils, which are mixtures of a variety of substances, are the most important feedstocks today. Oil on a petrochemical basis is predominant. A typical petrochemical oil consists of 10-15% monocyclic, 50-60% bicyclic, 25-35% tricyclic, and 5-10% tetracyclic aroma tes. 

Only with practice is it possible to judge of the greater or less purity of the alcohol, of the nature of the predominant impurities and of the special aromas characteristic of the different products. 

With several foods it has now become evident that only a few compounds are actually involved in the aroma [4-6]. Therefore, the main goals of modern flavor chemistry are (i) to identify those compounds predominantly contributing to a food flavor (ii) to characterize their precursors in the raw materials and (iii) to clarify the reaction pathways governing their formation during food processing and storage. Such data are prerequisites for the improvement of food flavors as well as the inhibition of off-flavors by technological steps. 

C, no esters and furanones are found, but thiazoles, cyclopen-tenones and other heterocyclic compounds dominate. These data imply that esters and furanones are stable at mild temperatures while the formation of thiazoles, cyclopentenones and other heterocyclic compounds require a higher temperature. Also at 160°C, trithiolanes, thiophenones and 2,4-hexanedione predominate, indicating that formation of such compounds is favored by a medium temperature. Bread, crusty and caramel aromas were found in the 100°C sample, pot-roasted, roasted, meaty and clean aromas were found at 160°C, and roasted, roasted-meat, chemical and off-notes were produced at 200°C. 

A comparison of the most important aroma compounds present in the wheat bread crust (3 7) with those identified in the crumb (Table IV) revealed two striking differences 2-acetyl-l-pyrroline and 3-methylbutanal, which appeared as potent flavor compounds respectively responsible for the roasty and malty aroma note in wheat bread crust, showed low FD-factors in the wheat bread crumb and are not listed in Table IV. On the other hand, carbonyl compounds with fatty aroma notes like 2(E),4(E)-decadienal, 2(E)-nonenal and 2(Z)-nonenal predominated in the crumb (Table IV). 

The basic fraction of the volatiles identified in the fried pork bundle contained 16 alkylpryazines. Among them, methylpyrazine (nutty, roasted), 2,5-dimethylpyrazine (grilled chicken, roasted peanut), 2,6-dimethylpyrazine (ether-like), 2,3,5-trimethylpyrazine (nutty, roasted) and 2-ethyl-6-methylpyrazine (grassy) were predominant. The combination of these alkylpyrazines may cause the characteristic cooked meat aroma of Chinese fried pork bundle. Quantitative analyses showed that alkylpyrazine formed during the final frying stages, as shown in Table II. 

A problem common to many wineries in this area is an overabundance of new or almost new wood cooperage. It is often not possible to allow the wines to remain in wood to achieve the level of maturity desired by the winemaker. Rather, it is necessary to remove the wine prior to it becoming too astringent and having too predominant an oak aroma. In lieu of a long wood aging cycle, a number of wineries are bottle aging their wines for an extended period of time prior to release. 

As for coriander, in the unripe fruits and the vegetative parts of the plant, aliphatic aldehydes predominate in the steam-volatile oil and are responsible for the peculiar aroma. On ripening, the fruits acquire a more pleasant and sweet odour and the major constituent of the volatile oil is the monoterpene alcohol, linalool. Sotolon (also known as sotolone, caramel furanone, sugar lactone and fenugreek lactone) is a lactone and an extremely powerful aroma compound and is the major aroma and flavour component of fenugreek seeds (Mazza et al., 2002). 

Ginger oleoresin should contain predominantly the aroma and pungency contributed mainly by the volatile oils, gingerols and related compounds. 

Milk fat contains a number of different lipids, but is predominately made up of triacylglycerols (TAG) (98%). The remaining lipids are diacylglycerols (DAG), monoacylglycerols (MAG), phospholipids, free fatty acids (FFA) and sterols. Milk fat contains over 250 different fatty acids, but 15 of these make up approximately 95% of the total (Banks, 1991) the most important are shown in Table 19.1. The unique aspect of bovine, ovine and caprine milk fat, in comparison to vegetable oils, is the presence of high levels of short-chain volatile FFAs (SCFFA), which have a major impact on the flavor/aroma of dairy products. Most cheeses are produced from either bovine, ovine or caprine milk and the differences of their FFA profile are responsible for the characteristic flavor of cheeses produced from such milks (Ha and Lindsay, 1991). 

Aroma compounds originate from biosynthetic pathways inside an animal, a botanical body, and other life-forms as well as enzymes and thus frequently carry chiral components within the molecule. Determination of such enantiomeric properties can, in many cases, be accomplished using a GC column with a chiral stationary phase (CSP) application.75-79 These columns, usually called chiral GC column, will provide diastereometric interaction that could lead to resolution of enantiomers. Commercially available chiral GC columns predominantly utilize cyclodextrin derivatives as CSPs. Chiral columns consisting of multiple cyclodextrin derivatives intending synergic effect in resolution property80 are also successful in the market. In practice, these columns are mainly operated as secondary columns in MDGC technique. 

Fusel alcohols (1-propanol, 2-methyl-1-propanol, 2-methyl-1-butanol, 3-methyl-1-butanol, 1-hexanol, 2-phenyl-ethanol) were actually among the first aroma constituents studied, as early gas chromatographic research had indicated, erroneously, that these compounds represented the predominant volatile fraction in wines (28). Yeast-specific fusel alcohol production has been studied by a number of researchers (31,33,37-39), all of whom found production differences among yeast strains. Unfortunately yeast strains have not usually been replicated among studies an exception is the work of Delteil and Jarry (57) and Kunkee and Vilas (39). Their results for the fiisel alcohol isobutanol (2-methyl-1-propanol) are shown in Table I. Soufleros and Bertrand (55) studied fifty different yeast strains unfortunately their data do not allow for statistical analysis. Mateo and coworkers (38) examined ten... 

Esters, not fusel alcohols, actually comprise the most abundant group of volatile compounds in wines Rapp (26) has listed over 300 esters and lactones found in grapes, musts and wines. The esters are largely responsible for the fmity aromas associated with wine (52), especially young wine (27). Of the esters, ethyl acetate predominates by some two orders of magnitude (see 40) however, the low aroma thresholds of a number of the fatty acid ethyl esters makes them of sensory import nonetheless (27). 

Brett flavor in wine The question still remains what is "Brett" flavor Results from our initial work indicates that "Brett" aroma in wine is a complex mixture of odor-active compounds, including acids, alcohols, aldehydes, ketones, esters, and phenolics. Analysis by gas chromatography-olfactometry revealed two predominate odor-active compounds responsible for the Brett flavor in the wines studied isovaleric acid and a second unknown compound other identified odor-active compounds included 2-phenyl ethanol, isoamyl alcohol, cis-2-nonenal, trans-2-nonenal, B-damascenone, ethyl decanoate, guaiacol, 4-ethyl guaiacol, 4-ethyl phenol. Our findings are a snapshot into the much larger picture know as Brett flavor. Ultimately this preliminary investigation requires the descriptive analyses of many more wines to know what odor active compounds describe the flavor know as "Brett". 

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