Essential oil concentration

Skandamis, P.N. and Nychas, G.J. (2000) Development and evaluation of a model predicting the survival of Escherichia coli 0157 H7 NCTC 12900 in homemade eggplant salad at various temperatures, pHs, and oregano essential oil concentrations . Applied and Environmental Microbiology, 66, 1646-1653. 

Figure 6 Essential oil concentrations in top and bottom phases using a continuous feed.

No effect on pentobarbital-induced sleeping time was observed in rats exposed to air odorized with ylang ylang essential oil (concentration in air not reported) (Komori et al. 1997, 2006). 

Most essential oils contain a significant proportion of terpenes (monoterpenic and sesquiterpenic hydrocarbons). For example, their level in some citrus essential oils is 95% or more. These substances are not usually essential to the smell and aroma character of essential oils, as the most important odoriferous compounds are alcohols, aldehydes, ketones, esters and other compounds. Furthermore, terpenic hydrocarbons are a reason for the limited solubility of essential oils in diluted ethanol and are often the cause of deterioration of essential oils that easily oxidise or polymerise. By removing hydrocarbons from essential oils, concentrates are obtained. Monoterpene-free or sesquiterpene-free essential... 

Materials for flavoring may be divided into several groups. The most common groupings are either natural or artificial flavorings. Natural materials include spices and herbs essential oils and thek extracts, concentrates, and isolates fmit, fmit juices, and fmit essence animal and vegetable materials and thek extracts and aromatic chemicals isolated by physical means from natural products, eg, citral from lemongrass and linalool from hois de rose. 

Many essential oils are used for flavoting and perfumery, eg, neroH, geranium, and ylang (see Oils, essential). The whole fmit, cmshed fmit, and puree may be used directly in foods, ice cream, cakes, and confections. Fmit juices, concentrates, and essences are more commonly employed (see Fruit juices). 

One class of flavorings, known as tme fmit, is composed of fmit juices, their concentrates, and their essences. A second group, fmit flavor with other natural flavors (WONF), contains fmit concentrates or extracts that may be fortified with natural essential oils or extractives (isolates), or other naturally occurring plants (64,65). This class of flavor is employed when the manufacturer is compelled by regulation to use only natural products, as in wines and cordials in the United States. 

Many spices are processed (2) to produce essential oils, oleoresins, essences, tinctures, extracts, resinoids, etc. These processes separate nonflavor components and further concentrate the aromatic or pungent principles of the spices. Such products allow a wider variety of uses and appHcations of the vital spice components. 

Essences generally are stored separately from the bulk concentrates for stabiHty, and their addition prior to retail packaging is essential to restoring much of the natural fresh flavor of the starting juice otherwise lost during processing. Unlike citms, which affords both an aqueous and an oil-phase essence, only an aqueous-phase essence is obtained for deciduous fmit. Virtually no essential oil is present in the peel or juice in the latter. 

Flavors and Fragrances. SaUcylaldehyde is a starting material in the synthesis of coumatin, which finds extensive use in the soap (qv) and perfume (qv) industries and saUcylaldehyde can be used itself as a preservative in essential oils and perfumes (see Oils, essential). The antibacterial activity of sahcylaldehyde is strong enough to allow its use at very low concentrations (79). 

Pommade. These are botanical extracts prepared by the enfleurage method wherein flower petals are placed on a layer of fat which extracts the essential oil. This method is appHed to low odored flowers, which do not yield appreciable oil on steam or water distillation, or flowers of valuable but dehcate odor (such as jasmin), which are destroyed on such treatment. Pommades, as such, are seldom used by the industry at present (ca 1995), but are further processed to provide more concentrated extracts such as absolutes. Absolutes, being alcohol-soluble, are much more convenient forms for the perfumer. 

A number of other valuable aroma chemicals can be isolated from essential oils, eg, eugenol from clove leaf oil, which can also, on treatment with strong caustic, be isomerked to isoeugenol, which on further chemical treatment can be converted to vanillin (qv). Sometimes the naturally occurring component does not requke prior isolation or concentration, as in the case of cinnamaldehyde in cassia oil which, on dkect treatment of the oil by a retro-aldol reaction, yields natural ben2aldehyde (qv). This product is purified by physical means. 

Gum Elemi. This resin, tapped from trees in the Philippines, contains a higher concentration of essential oils than other natural resins. It is a soft, sticky, plastic material that can be deformed manually. Gum elemi [9000-75-3] contains 20—25% essential oils, 13—19% acids, 30—35% resenes (condensed decarboxylated resin acids), and 20—25% terpenic resinols (condensed terpene alcohols). It has an acid number of 20—35 and a saponification number of 20—40. Gum elemi is a film-forming plasticizing resin used in lacquers. 

The analysis of combustion products presents problems of complexity similar to that of feedstock and raw fuel analysis. A highly complex matrix of aliphatic material often exists (as unburnt fuel in the combustion exhaust), whilst the species of interest, for example, carcinogens or mutagens are often at very low concentrations. A classic example of multidimensional GC is its use in the analysis of flue-cured tobacco essential oil condensate. 

As part of a study of the secondary chemistry of members of Cistus (the rock-rose) in France, Robles and Garzino (1998) examined the essential oil of C albidus L. Plants were sampled from two areas in Provence characterized by different soil types, calcareous sites west of Marseille, and siliceous sites near Pierrefeu-du-Var and Bormes les Mimosas (PF and BM, respectively, in Fig. 2.23), which lie about 60 km and 80 km to the east, respectively, in the Massif les Maures. Regardless of the soil type, a-zingiberene [88] (Fig. 2.24) was the dominant component. Concentrations of other major components of the plants varied between the two soil types, as summarized in Table 2.6. Many other compounds were present in lesser amounts, but varied little between the two areas. A more recent paper by the same workers (Robles and Garzino, 2000) described an analysis of C. monspeliensis L. leaf oils, the results of which are summarized in Table 2.7. 

The plant is strongly aromatic on account of an essential oil which comprises cis-a-ocimene (25.11%), 3,7-dimethyl-l,6-octadien-3 ol (16.85%), and trans-nerolidol (13.89%), hence the use of the plant in aromatherapy. A methanolic extract of bark of Litsea cubeba (Lour.) Pers. and its fractions (0.01 mg/mL) from bark inhibit NO and PGE2 production in LPS-activated RAW 264.7 macrophages without significant cytotoxicity at less than 0.01 mg/mL concentration. The methanol extract decreased the enzymatic activity of myeloperoxidase (0.05 mg/mL). These findings suggest that L. cubeba is beneficial for inflammatory conditions and may contain compound(s) with anti-inflammatory properties (63). Can we expect the vasorelaxant laurotetanine (64) isolated from the plant to exert such activity ... 

The follicles are used to treat asthma and cough and to mitigate painful swollen breasts. A paste of the leave is applied to contusion. Essential oil distilled from the follicles induced apoptotic death in HepG2 human hepatoma cells in a concentration- and time-related manner, and inhibited tumor development of mice inoculated with Huh-7 human hepatoma cells (33). 

Other assays have been used to evaluate the antioxidant activity against H202 of several plant-based products, namely, fruit juices from different cultivars of berries (Wang and Jiao 2000), fractions rich in phenolics isolated from the aqueous by-products obtained during the milling of oil palm fruits (Balasundram and others 2005), cherry laurel fruit and its concentrated juice (Liyana-Pathirana and others 2006), and strawberries and blackberries treated with methyl jasmonate, allyl isothiocyanate, essential oil of Melaleuca alternifolia, and ethanol (Chanjirakul and others 2007). 

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