Extraction citrus peel oils

Pesticide residues may contaminate citrus peel oils as well. Cultivation of citrus crops commonly involves the use of chemicals such as fertilizers and pesticides. Regulations are increasingly stricter in terms of residual levels of pesticides because of the application of citrus oils in food, pharmaceutical, and cosmetic industries (75). Citrus peel oils, extracted from citms peels, contain a higher concentration of pesticide residues than the fruits, due to the direct contact of the peels with pesticides. Organophosphorus and organochlorine pesticide residues in citrus peel oils have shown a steady decrease in recent years (76). 

For flavones in citrus peel oils, separations were accomplished with isocratic mobile phases of 38% and 40% acetonitrile in H20 (1). The extracts of peel and cold-pressed peel oils were diluted in ethanol and analyzed by reversed-phase on various C18 columns with good results. For the dilute citrus oils, gradient elution was preferred, to prevent the accumulation of terpenes on the column. With normal-phase chromatography, the elution order is reversed terpenes elute with the solvent front and are not a problem. 

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 ... 

The current citrus industry uses oil extraction machinery associated with the specific type of juice extractor in use. In general, peel oil extraction is carried out with Food... 

A simple way to obtain a clear soft drink is adding clear, water-soluble flavours, so-called essence flavours. The most popular products, usually derived from ethanol-extracted and distilled citrus peel oils, provide a subtle taste of lemon or lime. The dosage of these flavours is around 1 g per litre of final drink. Together with sweetener, acidifier and carbonation, one gets a fizzy clear and colourless drink with citrus taste. 

Citrus oil is present in small glands contained in the flavedo, which is the colored portion of the peel of the fruit. Cold-pressed citrus peel oil is obtained commercially by a process that starts with the rupture of these glands during juice extraction. For its recovery, the oil is washed away from the peel with water forming an... 

Most essential oils are obtained by distillation using one of the processes already described in this chapter dealing with herbs and spices, bnt essential oils may also be obtained via other methods (albeit, essential oils to the purest are obtained only via distillation). The other methods inclnde (i) enfleurage-extraction of floral oils using fats, (ii) solvent extraction, and (iii) mechanical pressing, particnlarly applied to the recovery of citrus peel oils. 

With the exception of lime oil, which is primarily recovered by distillation, the citrus peel oils are obtained by mechanical extraction that differs depending on the nature of the fruit to be handled. Other parts of the citrus plant also yield essential... 

Citrus peel oils for smaU-scale use may be obtained by hand-pressing. Fruits are sliced, and mesocarp and albedo layers are peeled from the flavedo before hand-pressing. Peel oils are collected in brine solution on ice, and oil extract is centrifuged at 4 C. Afterwards, the supernatant is dehydrated with anhydrous sodium sulfate and filtered (5). The total final oil extract is about 1% of the flavedo by weight (6). 

Juice Cloud. Mechanical extraction of citrus fruits yields a turbid suspension of wall fragments and cellular organelles in a serum composed primarily of cell vacuolar fluids. In most citrus juice products, such a suspension of fragments and organelles is a desirable component, since it provides most of the characteristic color and flavor (28). Essence and peel oils suspended in juice contribute desirable citrus notes to flavor, and these oils are rapidly adsorbed by juice particulate material shortly after extraction (29). 

Several types of Brown extractors are used in the citrus industry throughout the world. The Model 400 produces a juice that is low in peel oil content and high in juice quality. The fruit is halved and the juice removed by a rotating reamer that exerts pressure to effect extraction. 

Fresh Citrus Juice. Freshly extracted commercial orange juice may contain a high peel oil content making sensory evaluation of this product very difficult because of the overriding, biting and even bitter flavor effect of the peel oil. This is one of the reasons why in certain plants, minimal attention is paid to the flavor quality of the juice until the product is standardized either in retail or bulk form (2). 

Excessive pressure used in hand-reaming of citrus fruit can also result in juice containing high peel oil content and perhaps significant amounts of undesirable flavor constituents (primarily of a bitter nature) as well. Since high peel oil and undesirable flavor constituents would seriously affect sensory evaluation results in a negative way, care should be taken in hand-reaming citrus fruit to apply only as much pressure as necessary to extract most but not all of the juice. In this way the amounts of peel oil and undesirable flavor factors will be held to normal levels. 

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,... 

The most commonly used natural carotenoid extracts for foodstuffs are annatto, paprika, and saffron. Many other sources, including alfalfa, carrot, tomato, citrus peel, and palm oil, are also utilized. 

PBO synergizes (he activity of linalool, an oil extracted from citrus peel that is effective in controlling the cat flea, formulations with linalool and PBO can be used on both the pet to control adult lleas or applied to the carpet or bedding to control eggs, larvae and pupae (Hink et al 1988). 

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. 

A tliird byproduct from citrus processing is citrus molasses (CM). CM is obtained from tlie spent citrus peel after the juice and peel oils are extracted The peels are furtlier processed to squeeze out residual juice sugars and peel oils. This mixture is concentrated by distillation wliich removes water and many of the volatile oil components present. A sample of 33 Brix orange molasses was analyzed for PMF content to compare with our other results. The HPLC spectrum (Figure 6) shows a very different absorption spectrum from the typical juice sample. A large (unidentified) peak is seen eluting before 2.5 minutes with the PMF peaks eluting later. The total PMF content in this... 

L-(+)-Citrulline. See Citrulline Citrus amara. See Bitter orange (Citrus aurantium amara) flower extract Bitter orange (Citrus aurantium amara) extract Bitter orange (Citrus aurantium amara) peel extract Bitter orange (Citrus aurantium amara) oil Citrus aurantifolia. See Lime oil terpeneless Lime (Citrus aurantifolia) oil Lime (Citrus aurantifolia) extract Lime (Citrus aurantifolia) peel extract... 

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

---