Lemon peel oil

Enzymatic treatment in the extraction of cold-pressed lemon peel oils... 

Table 1. Material balance in the non-recycling and recycling lemon peel oil recovery systems...

Both recycled and non-recycled essential oils met the standards for specific gravity, angular rotation and refractive index of the Food Chemicals Codex [22] and United States Pharmacopeia [23] for cold-pressed lemon peel oil. Results of gas chromatography analysis show the same compounds and levels in both systems, specially for the oxygenated compounds as citral (neral and geranial). Therefore, recycling the aqueous discharges to the extractor does not cause undesirable modifications. 

Lemon peel oil is much more valuable than its juice therefore, extensive research efforts have been expended to determine its natural composition as a way to detect adulteration as well as to determine quality factors [6, 31, 32]. However, a few studies on lemon juice volatiles can be found [33-35]. Lemon oils are notable for possessing relatively low levels of limonene (more than 70%) and relatively high levels of a-pinene (1-2%), -pinene (6-13%), sabinene (1-2%) and y-terpinene (8-10%) [32]. The relatively high concentration of -pinene is thought to instil the green peely odour of lemon oil. The concentrations of aliphatic and monoterpenic aldehydes, (especially citral) as well as those of esters and alcohols are critical components in the perceived quality of the oil. As lemon oil is unstable, quality can deteriorate with improper storage, resulting in... 

Introducing adsorbents into a supercritical fluid extraction system is an alternative attractive method to improve the selectivity for the citrus oil processing. Several applications using silica gel as adsorbent have been reported in the last decade [1-3]. Yamauchi and Saito [3] fractionated lemon peel oil into 3 fractions with gradual increase in pressure by supercritical fluid chromatography, where terpene rich fraction, ester rich, and alcohol and aldehyde rich fraction were obtained at 10 MPa, 20 MPa, and 20 MPa with ethanol as a cosolvent,... 

Supercritical fluid extraction is also a suitable technique for enhancing the quality of essential oils obtained by conventional extraction methods, by means of fractionation and deterpenation. Thus, the separation of citrus oils into different clssses of substances by supercritical CO2 has been widely investigated. Temelli et al. reported a method for the extraction of terpene hydrocarbons from cold-pressed Valencia orange oil with supercritical CO2, using both static and dynamic flow approaches (65). Another article has reported the SFE of terpenes from cold-pressed orange oil in a temperature range from 40°C to 70°C and pressures from 83 to 124 bar (66). The determination and elimination of psoralens from lemon peel oil by SFE has also been conducted (67). The procedure included the increase of CO2 density in successive steps. 

While by definition, aroma compounds need to be volatile enough to be inhaled into the nose, flavor compounds can either be volatile or non-volatile. Volatile compounds typically have molecular weights below 300 Daltons. Nonvolatile flavor compounds can have molecular weights well over 300. Detection of non-volatiles requires the use of TLC or HPLC either alone or in tandem with an identification technique. HPLC-NMR can identify non-volatile coumarins, sterols, fatty acids and psoralens, in citrus oils, such as the substituted psoralen byakangelicol, found in lemon peel oil. Non-volatiles can act as odor fixatives, impacting the release of a perfume from the skin. Non-volatiles also serve as authentication markers that are difficult to adjust or circumvent (27). 

Allergic contact dermatitis due to lemon peel oil (among other products) was reported in perfume factory workers routinely exposed to essential oils and related compounds (Schubert 2006). A case of allergy to lemon peel essential oil has been reported and confirmed by patch testing (Audicana and Bernaola 1994). 

Lemon oil Lemon oil, coldpressed Lemon oil, expressed Lemon peel oil... 

Lemon peel extract. See Lemon (Citrus medica limonum) peel extract Lemon peel oil. See Lemon (Citrus medica limonum) oil... 

Yamauchi, Y. and M. Salto, 1990. Fractionation of lemon-peel oil by semi-preparative supercritical uld-chromatography. L Ouvnmto, 505 237-246. 

Molecular structures of monoterpenoids are present as three major types acyclic, monocyclic and bicyclic. Oxygenated derivatives of acyclic monoterpenes are more widespread in nature than acyclic monoterpenes themselves. Such derivatives are the monoterpene alcohols citronellol and geraniol, or the monoterpene aldehydes citronellal and geranial. Mononocyclic monoterpene hydrocarbons are exemplified by limonene, which is a major component of orange and lemon peel oils, and p-phellandrene, which is emitted by conifer trees under biotic stress. These compounds are relatively common in nature. Bicyclic monoterpenes are represented by the aforementioned a-pinene, one of the most abundant and important monoterpenes. 

Calame and Steiner [7] have previously pointed out that the composition of lemon peel oils extracted with carbon dioxide at 300 bar and 40°C differs from that of the oil obtained by cold pressing. The compositions of the extracts are given in Table 2.7. The C02-extracted oil contains less limonene and more alcohols than the pressed extract. This consequently leads to the possibility of producing of tailored and unique extracts for the flavour industry. 

Lemon oil is obtained by pressing peel from the fruits of Citrus limon (L.) Burm. (Rutaceae). It is a pale yellow or pale greenish-yellow to dark green liquid with a characteristic lemon peel odor. 

Main constituent of citrus fruit peels oils, common in many other essential oils. (+)-limonene orange, lemon, grape oils ... 

The flavor of lemon, contributed by the peel oil, is probably second only to orange flavor in overall popularity. The growth in market fcr the powdered soft drink mixes and the fruit drink mixes, particularly for lemon-flavored products, has increased the demand for lemon oil. Added to this is the increasing demand for lemon oils for use in the carbonated and noncar-bonated soft drinks that are increasing in popularity worldwide. 

Lemon Oil, Coldpressed, occurs as a pale to deep yellow or green-yellow liquid with the characteristic odor and taste of the outer part of fresh lemon peel. It is the volatile oil obtained by expression, without the aid of heat, from the fresh peel of the fruit of Citrus limon L. Burmann filius (Fam. Rutaceae) with or without the previous separation of the pulp and the peel. It is miscible with dehydrated alcohol and with glacial acetic acid. It may contain a suitable antioxidant. 

Citral A (Geranial) Citral B(Neral) = trans- cis-3,7-Dimethyl-2,6-octadienal) (monoterpene) Myrcia acris (bay oil) (Myrtaceae), Citrus Andropogon citratus (lemon grass oil) (Poaceae), Rosa spp. (rose oil) (Rosaceae), Citrus lirrwn (lemon peel), C. sinensis (orange) (Rutaceae) [flower], Verbena triphylla (verbena) (Verbenaceae) [antiseptic]... 

Citrus peel oils of very complex composition are contained in oval, balloon-shaped oil sacs, or vesicles, located in the outer rind, or flavedo, of the fmit (3). The oil is usually extracted by mechanical separation or hydrodistUlation. The five main types of citrus from which peel oils are recovered are orange, grapefruit, tangerine, lemon, and lime (4). Mechanical separation, known as cold-pressing of peel oils, does not use heat in order to avoid loss of volatile components. Swisher and Swisher (1) described three general commercial methods that are widely used in citrus industry to extract crude oils from fruit peels ... 

These structures are either found as globular or irregular spaces, as in Orange and Lemon Peel and Eucalyptus leaves, containing oil or oil and resin when they are called internal glands, or, as tube-like spaces filled with hydrocarbon principles such as are found in Pine leaves and stems, when they sometimes receive the name of secretion Digitized by Microsoft ... 

The enantiomeric ratio of limonene was used to discriminate genuine mandarin and lemon oils fi om the reconstituted ones [28, 29]. The enantiomeric excess of (+)-limonene in the lemon peel has been found between 97.1 and 97.4% [30]. Mondello et al. found small differences in the enantiomeric composition of monoterpenes between two varieties of lime oils Citrus aurantifolia Swingle (Key lime) and Citrus latifolia Tanaka (Persian lime) [31]. The enantiomeric ratio of limonene was the... 

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