Aroma-active components

The most common method for the separation and concentration of flavor chemicals before chromatography is solvent extraction. If the aroma active components in a sample are less than a microgram/liter then solvent extraction followed by fractional distillation can be used to concentrate the analytes above 1 4g/liter. This is done for two reasons (1) to remove the odorants from some of the interfering substances and nonvolatiles, and (2) to concentrate the sample for greater sensitivity. The choice of solvent(s) depends on a number of issues, but similar results can be obtained with many solvents. Table Gl.1.2 lists a number of solvents, their polarity, and physical properties. Pentane is the least polar and ethyl acetate the most. The sample must be an aqueous or dilute sample, dissolved or slurried into water to a final concentration of 80% to 90% water. Dilute aqueous samples will present the greatest polarity difference between the solvent and the sample, driving more volatiles into the extracting solvent. 

Jordan MJ, Margaria CA, Shaw PE, Goodner KL (2002) Aroma active components in aqueous Kiwi fruit essence and Kiwi fruit puree by GC-MS and multidimensional GC/GC-O. JAgric Food Chem 50, 5386-5390. 

Saffron, production, 66 Saffron flavor characterization using aroma extract dilution analysis aroma-active components, 74-78 detection of aroma-active component using OC-olfactometry, 67 experimental procedure, 67-68 volatile components, 68-74 Safranal, role in flavor, 66-78 Scmivolatile components in powdered turmeric, characterization using direct thermal extraction GC-MS, 80-96 Shallot, contribution of nonvolatile sulfur-containing flavor precursors to flavor, 53-63... 

There have been a number of reports on the essential oil composition of the above mentioned cilantro mimics however, there is limited information on the characteristic aroma-active components of the fresh herbs. The following investigation was undertaken to identify and compare the characteristic aroma components of fresh leaves of C sativum, E. foetidum, and P. odoratum. The essential oils from seeds of these plants differ significantly from that obtained from the green, leafy (herb) parts of the plant (the essential oil of the seeds of C sativum is contains mostly linalool) and will not be addressed in this investigation. 

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... 

Table IV. Aroma-Active Components Obtained from the Herb C. sativum L.

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... 

Aldehydes are highly reactive and typically have low aroma thresholds. Twelve of the 29 aroma active components observed in this study (Table I) were aldehydes. Approximately 40% of the total aroma impact (obtained from summing all GC-O aroma peak intensities for each oil) of both oils was due to aldehydes. This is perhaps why one of the oldest commercial measurements for oil quality has been total aldehydes (10), Total aroma intensities (total aroma... 

Table 1. Comparison of aroma active components in Valencia and Early-Mid season orange essence oils...

The detailed overview on the nutritional composition and health promoting components of hazelnut provided in this chapter summarizes the existing knowledge and appreciation for the use of hazelnut and its products in a variety of food and specialty products. Besides nutritional value and health aspects, the presence of taste- and aroma-active components contribute to the sensory characteristics of products. Thus, better taste and aroma/flavor of hazelnut may increase the consumption of this nutritionally important nut, as discussed in this chapter. In addition, characteristics of raw (natural) hazelnut as well as its health promotion and disease prevention aspects are given in detail. Aroma-active components of roasted hazelnut are also discussed. 

Volatile components of natural and roasted hazelnuts have been investigated by several researchers [7,88,90-98]. Among several volatile aroma-active compounds detected in roasted hazelnut, 5-methyl-( )-2-hepten-4-one (fllbertone) has been reported as the primary odorant (nutty-roasty and hazelnutlike) [88,93,94,96]. Alasalvar et al. [98] studied the comparison of natural and roasted Turkish Tombul hazelnuts and found a total of 39 compounds in natural hazelnut and 79 compounds in roasted hazelnut. These included ketones, aldehydes, alcohols, aromatic hydrocarbons, terpenes, furans, pyrroles, pyrazines, and acids. Pyrazines, pyrroles, terpenes, and acids are detected in roasted hazelnut only. The combination of several volatile aroma-active components that increases upon roasting may contribute to the distinctive and unique flavor of roasted hazelnut. Pyrazines together with ketones, aldehydes, furans, and pyrroles may contribute to the characteristic roasted aroma of hazelnut. Detail information about flavor and volatile compounds in major tree nuts are detailed in Chapter 7. 

Butter flavor. Aroma-active components in creamery butter are the 5- alkanolides Cg, C,o, and C,2, free... 

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... 

Q-X Zhou, CL Wintersteen, KR Cadwallader. Identification and quantification of aroma-active components that contribute to the distinct malty flavor of buckwheat honey. J Agric Food Chem 50 2016-2021, 2002. 

GC in combination with olfactometric techniques (GC-0) is a valuable method for the selection of aroma-active components from a complex mixture (7). Experiments based on human subjects sniffing GC effluents are described as GC-0. This technique helps to detect potent odorants, without knowing their chemical structures, which might be overlooked by the OAV concept (ratio of concentration to threshold) if the sensory aspect is not considered from the very beginning of the analysis. Experience shows that many key aroma compounds occur at very low concentrations their sensory relevance is due to low odor thresholds. Thus, the peak profile obtained by GC does not necessarily reflect the aroma profile of the food. 

Detection of odorous regions in a gas chromatogram is the first useful information that can be obtained from a single GC-0 run. In the first GC-O ran, all volatiles are detected whose concentrations in the GC effluent are higher than their odor thresholds. The corresponding volatiles are then characterized by their aroma quality and intensity as well as by their chromatographic properties, i.e., retention index (RI). The RI increments, obtained on stationary phases with different polarities, provide additional information about the nature of the aroma-active component, such as functional groups. Aroma qualities and intensities are very useful data for flavorists, who can then use these to create characteristic and complex aroma notes. 

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