Natural citrus oils, production

I.4. Polyterpene resins. Terpene resins are obtained from natural terpene monomers obtained from naval stores, paper pulp production, and citrus juice production. Terpenes are found in almost all living plants, and the turpentine oil from pine trees is the most important source. 

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. 

Hotrienol was found for the first time in Ho leaf oil as the S enantiomer [7], but has been found since then in many natural sources for instance, the R enantiomer was found in black tea and in green tea. The product can be used in many flavours, such as eldertlower, grape, berry and honey flavours. It can be prepared from linalool obtained from citrus oils or Chinese Ho oils, but most linalool is obtained by synthesis from isoprene from petrochemical sources. 

The use of terpenoids, usually as mixtures prepared from plants, dates from antiquity. The several essential oils produced by distillation of plant parts contained the plant essences. These oils have been employed in die preparation of perfumes, flavorings, and medidnals. Examples are oils of clove (local anesthetic in toothache), lemon (flavoring), lavender (perfume), and juniper (diuretic). Usually essential oil production depends on a simple technology which often involves steam distillation of plant material The perfume industry of Soudiem France uses somewhat more sophisticated procedures in the isolation of natural flower oils since these oils are heat sensitive. The separation of oils from citrus fruit residues m California and Florida is done by machine. 

In practice, some natural flavours work very well and any problems with them are financial rather than technical. Examples of satisfactory natural flavours are vanilla or any of the citrus fruits. Some other flavours, however, are never very satisfactory when all natural. (It should be noted that citrus oils are prepared from the skin rather than the fruit.) Some gum and jelly sweets contain fruit juice or pulp in addition to the fruit flavour. If a product is made with both fruit juice and fruit flavour, the experiment of leaving out the juice and adding the flavour, or leaving out the flavour and adding the juice, shows that the... 

Expression is the simplest of the three techniques. When odorants are forced out of the natural source by physical pressure, the process is referred to as expression and the product is called an expressed oil. If you squeeze a piece of orange peel, you will see the oil-bearing glands burst and eject a fine spray of orange oil. Many commercially available citrus oils are prepared in this way. 

Essential oil Product obtained from a natural vegetable raw material of plant origin, by steam distillation, by mechanical process from the epicarp of Citrus fruits, or by dry distillation, after separation of the aqueous phase—if any—by physical process. 

Various other natural extracts are used as feedstocks for the production of terpenoids as shown in Figure 5.35. Two of the most significant ones are clary sage and the citrus oils (obtained as by-products of the fruit juice industry). After distillation of the oil from clary sage, sclareol (203) is extracted from the residue and this serves as a starting material for naphthofuran (204), known... 

For use in ice cream, frozen confectionery and certain types of beverages, citrus fruits may be passed through a colloid mill to form a homogenous paste. These finely ground products are made from the whole fruit and may be further blended with juice or natural peel oil emulsion in order to achieve a desired flavor profile and some degree of standardization. Such products are generally aseptically processed and packaged. The process inactivates any enzyme systems and results in a shelf-stable product. 

The extraction of natural nootkatone from citrus oil and peel is too expensive, because the process is characterized by low yields and high biomass production, and it suffers from annual harvest fluctuations. The chemical oxidation of the sesquiterpene valencene extracted from orange peels often results in off-notes, and it has the disadvantage of employing heavy-metal salts as strong oxidants thus the final product cannot be labeled as natural. Therefore, biotechnological routes have been extensively studied in the last decade to find an economical and sustainable synthetic procedure to natural nootkatone. Most of them make use... 

Essential oil, also defined as essence, volatile oil, etheric oil or aetheroleum, is a complex mixture of volatile constituents biosynthesised by living organisms. Essential oils can be liberated from their matrix by water, steam and dry distillation, or expression in the case of citrus fruits [1-5]. Their occurrence and function in nature is still a question and the subject of ongoing research. However, there is evidence that organisms produce essential oils for defence, signalling or as part of their secondary metabolism. As a consequence essential oils comprise an important bio resource for renewable natural products [1-25]. 

Limonene (92) is the most widely distributed terpene in nature after a-pinene [68]. The (+)-isomer is present in Citrus peel oils at a concentration of over 90% a low concentration of the (-)-isomer is found in oils from the Mentha species and conifers [26]. The first data on the microbial transformation of limonene date back to the sixties. A soil Pseudomonad was isolated by enrichment culture technique on limonene as the sole source of carbon [69]. This Pseudomonad was also capable of growing on a-pinene, / -pinene, 1-p-menthene and p-cymene. The optimal level of limonene for growth was 0.3-0.6% (v/v) although no toxicity was observed at 2% levels. Fermentation of limonene by this bacterium in a mineral-salts medium resulted in the formation of a large number of neutral and acidic products. Dihydrocarvone, carvone, carveol, 8-p-menthene-1,2-cw-diol, 8-p-menthen-1 -ol-2-one, 8-p-menthene-1,2-trans-diol and 1 -p-menthene-6,9-diol were among the neutral products isolated and identified. The acidic compounds isolated and identified were perillic acid, /Msopropenyl pimelic acid, 2-hydroxy-8-p-menthen-7-oic acid and... 

There are many applications where the organic compounds are extracted from natural materials. Extraction is used for preparation of pure flavor essences from expressed oils of various citrus fruit. Pyrethrum is recovered from pyrethrum flowers by solvent extraction. A continuous saponification, glycol extraction, and splitting process for converting fat into finished soap base has been used in soap production. 

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