Citrus oils

Citrus Fix Citrus fragrances Citrus juices Citrus odor Citrus oils... 

Mondello et al. (2, 20-23) have used a multidimensional gas chromatographic system based on the use of mechanical valves which were stable at high temperatures developed in their laboratory for the determination of the enantiomeric distribution of monoterpene hydrocarbons (/3-pinene, sabinene and limonene) and monoterpene alcohols (linalol, terpinen-4-ol and a-terpineol) of citrus oils (lemon, mandarin, lime and bergamot). Linalyl acetate was also studied in bergamot oil. The system consisted of two Shimadzu Model 17 gas chromatographs, a six-port two-position valve and a hot transfer line. The system made it possible to carry out fully... 

Table 10.2 reports some results obtained for cold-pressed and distilled citrus oils. As can be seen, the values obtained are characteristic of the different oils, and can be used as references for the authenticity and quality of the oil. 

Table 10.2 Enantiomeric distribution of various components in cold-pressed and distilled citrus oils (2, 20-23)...

It has been found that the compound 8-geranoxy psoralen is present in citrus oils, particu-lariy lemon and lime oils. This compound can be isolated from the oil by a process which involves primarily absorption on an adsorbent material followed by elution with a suitable solvent. 

Yokohama Tire Corporation has combined citrus oil with NR to form super nanopower rubber (SNR) which is being used to reduce the use of petroleum products in the tire by 80%, [34]. Tires containing SNR are lighter than conventional equivalents, reduce rolling resistance by 18%, and are expected to hit the Japanese market later in 2007. 

A 10-g representative sample (5-g sample for citrus oil or cotton substrates) was extracted by adding 150 mL of acetonitrile-water (4 1, v/v) to the sample in an 8-oz bottle and homogenized with a Polytron at high speed for 2 min. The extract was filtered through a Whatman No. 1 filter-paper into a 500-mL side-arm flask. The extraction bottle was rinsed with 50 mL of acetonitrile-water (4 1, v/v) for citms and cottonseed oil (for molasses use lOmL of water followed by 40 mL of acetonitrile for rinsing). The extract was transferred to a 500-mL separatory funnel and partitioned twice, each time with 50 mL of hexane for 1 min. The hexane fractions... 

The average recoveries and standard deviations for the many citrus, pome fruit, tree nut, fruiting vegetables, and cotton substrate sample types were acceptable when fortified at concentration levels ranging from 0.01 to 4 mg kg. The LOQ of the method was 0.01 mgkg , except for citrus oil (0.02mgkg Q, and the LOD was 1.25 ng injected. 

Hexane-acetonitrile partition. Partition the sample between hexane and acetonitrile as described for fruit and vegetables to remove citrus oils. Evaporate the... 

In practice some natural flavours work very well any problems are financial rather than technical. Examples of satisfactory natural flavours are any citrus fruit or vanilla. Some other flavours are never very satisfactory when all natural. Notably, citrus oils are prepared from the skin rather than the fruit. 

Whether the flavour used is natural, nature identical, synthetic, or a mixture it has to be dosed into the product. Although some flavourings are very intense the volume added to the product has to be large enough for the equipment or the people to add it with sufficient accuracy. The flavour of course has to be uniformly distributed in the product. This normally means producing the flavour as a solution. Flavours are prepared for a particular use. As an example, citrus oil based flavours can be dissolved in various alcohols. 

Gum acacia is a unique polysaccharide, with some peptides as part of the structure and has a range of different uses. It was originally the gum in gum sweets although some gum sweets do contain modified starch as a substitute. The replacement of gum is not because the substitute performs better but because there have been supply problems with gum acacia. Gum acacia is likely to be encountered in bakeries in small quantities when it has been used to make emulsions of citrus oils as a bakery flavour. It is possible to use gum acacia in making dry flavours from oils such as citrus by making an emulsion and then spray drying it. 

The acceptable tolerance level of chlorpyrifos in meat and meat by-products destined for human consumption is 2.0 mg/kg fresh weight (Byford et al. 1986), and for agriculture products it usually ranges between 0.05 and 15.0 mg/kg FW and up to 25.0 mg/kg for citrus oil (USPHS 1995). The significance of these concentrations to animal health, or to consumers other than man, is unknown. More research is needed to establish maximum tolerable chlorpyrifos limits in tissues of sensitive fish and wildlife. Proposed air criteria for chlorpyrifos and human health include 200 pg/m3 in the workplace, and much lower concentrations of 0.48 to 3.3 pg/m3 in nonoccupational settings (USPHS 1995). No air criteria are currently available or proposed for protection of wildlife. 

A concentrated essential oil. Folding is a gravimctric/volumetric measure of the strength of a concentrated essential oil expressed as a multiple of a standard. A folded Citrus oil would be compared to the expressed oil (steam distilled oil in the case of distilled Lime oil), e.g. 5 x Orange oil. 

The three main platform molecules employed in terpene chemistry are a-pinene and / -pinene, which are extracted from turpentine oil (350000 t a-1) a co-product of paper pulp industry, and limonene extracted from citrus oil (30000 t a-1). 

FIGURE 4.8 Pigeons in Italy misorient when deprived of olfaction, while those in New York and Germany were unaffected. In Italy (left), anosmic birds headed into a direction different from home, while no such difference between anosmic and control birds was found in New York and Germany. (Anosmic birds had their nostrils plugged with citrus oil-soaked cotton until release, and an anesthetic was sprayed into their nostrils at the time of release. This renders the birds anosmic for 4-6 hours.) Dashed radius, home direction solid dots, individual anosmic birds open circles, control birds arrows mean directions for anosmic and control birds. (From Wiltschko and Wiltschko, 1992.)... 

Mosandl A, Juchelka D, Advances in the authenticity assessment of citrus oils. J Essent Oil Res 9 5—12, 1997. 

Example 1 Citrus oil or citrus root products can Indeed kill slugs if they are applied as a contact agent or act as a slug repellent. Although some patents have been issued on the use of citrus oil as a slug control agent, such control with a contact agent is difficult and the chemical compositions of citrus oil and root exudate are ill-defined. Other obstacles for commercialization of citrus oil are (1) market size is too small to justify the development cost, and (2) an effective delivery method has yet to be developed. 

Such a system has been used for the comprehensive 2D chromatography of proteins [9,14], synthetic polymers [16], oxygen heterocyclic fraction of cold-pressed citrus oils [22,29], carotenoids [39], triglycerides in fats and oils [18-21], pharmaceuticals [29], and acidic and phenolic compounds [27,28]. 

CH3(CH2)9CH0, C11H22O, Mr 170.29, bp2Ave 1°C, df 0.8251, ng 1.4325, occurs in citrus oils. It is a colorless liquid with a flowery-waxy odor that has aspects of freshness. Undecanal is the prototype of the perfumery aldehydes and is widely used in perfume compositions for imparting an aldehydic note. ... 

C15H22O, Mr 218.33, mp 35 °C, has been isolated from grapefruit peel and juice and identified in other citrus oils as well. The commercially available product is a colorless to yellowish liquid with a typical grapefruit odor. 

C8H9NO2, Mr 151.16, bp2w 135.5 °C, df 1.1682, ng 1.5815, occurs in a large number of blossom essential oils (e.g., neroli, ylang-ylang, and jasmin oils), grapes, and citrus oils. It occurs as white crystals mp 24-25 °C), or a yellowish liquid, that show blue fluorescence and have an orange blossom odor. Methyl anthranilate is prepared by esterification of anthranilic acid with methanol or by reaction of isatoic anhydride with methanol [163]. 

Oils isolated from other parts of citrus plants (blossoms and leaves) are not classified as citrus oils because the former show marked differences in composition and organoleptic properties, they are described in other sections (see Neroli Oil, and Petitgrain Oils). 

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... 

The characteristic odor of lemon oil differs from that of other citrus oils and is largely due to neral and geranial. The content of these compounds in Italian lemon oil generally exceeds 3% [369, 370a, 370d, 370e, 381-394e]. 

The oils have a high terpene hydrocarbon content (>90%, mainly (+)-limonene), but their content of oxygen-containing compounds differs and affects their quality. Important for aroma are aldehydes, mainly decanal and citral, and aliphatic and terpenoid esters. The sesquiterpene aldehydes a-sinensal [17909-77-2] and/3-sinensal [6066-88-8], which contribute particularly to the special sweet orange aroma, also occur in other citrus oils, although in lower concentration [369-370a, 370d, 394,421, 430-438]. 

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