Citrus oils table

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)...

Duplicate and triplicate IFT aging curves were obtained at one or two temperatures for most of the interfaces characterized in this study. The replicate IFT data reported in Figures 1,3,4,7,8 and 10-14 show that many IFT aging curves for citrus oil/aqueous phase interfaces differ by a maximum of 1.7mJ/m2. Replicate curves often differ by less than lmJ/m2. Because each IFT aging experiment involved formation and separation of a new complex coacervate and supernatant phase, replicate IFT aging curves measure the combined effect that several factors have on reproducibility. These factors include variability of the complex coacervation procedure, protocol followed for separation of the coacervate and supernatant phases, and the IFT measurement process itself. The variability in solids content of replicate coacervate and supernatant phases shown in Table 1 could contribute to the observed IFT variability. 

Optical rotation measures the degree that light is rotated (see Table Gl.5.7 in Anticipated Results). In citrus oils, d-limonene is the major enantiomer in the sample. Since other optically active compounds are often present in racemic mixtures, there is no net rotation and thus they are ignored. If a compound is a racemic mixture, the polarimeter will not give a reading. Readings can be verified with known standards. 

Table G1.5.1 Protocol Modifications Based on Different Types of Citrus Oils"... 

For exact amounts of different citrus oils see Table Gl.5.1. 

The diversification and reactivity of oil components can decrease functionality and value. Table Gl.5.2 lists the market value for most citrus oils. Prices range from 0.45 per gallon for c/-limonene to 35.00 per gallon for Sicilian Mandarin. Figure Gl.5.6 presents chemical structures of compounds that are important to the flavor of citrus oils. 

Table G1.5.7 Physical and Chemical Properties of Citrus Oils"-6...

Table G1.5.7 lists the physical and chemical properties (specific gravity, SG refractive index, r optical activity, a) of citrus oils defined by the Food Chemicals Codex (NRC, 1981).

Table G1.5.10 Aldehyde Composition for Various Citrus Oils" ...

Table Gl.5.9 is a summary of the total available oil for various citrus cultivars. Table G1.5.10 is the aldehyde composition for orange and grapefruit oils.

Citrus oil dominates this class of essential oil. It is obtained by the cold press method with the exception of lime oil, which is also prepared by steam distillation of essential oil separated during the production of juice.106,107 Aside from bergamot, these oils are primarily monoterpene hydrocarbon mixtures of which (if)-limonene (3) is usually the dominant compound. Since odor contribution of this monoterpene compound is low, it is often removed by distillation or repeated solvent extraction. The resulting oil rich in odor-active compounds is called terpeneless oil and is used extensively. In the case of bergamot and lemon oils, psoralen derivates like bergaptene (64) causing photosensitivity are problematic, and those for fragrance use are rectified to remove it (Table 8). 

Table 8 Aroma extract from peel (citrus oil)...

Tocopherol was effective and ascorbic acid ineffective in the protection of citrus oils evaluated by aroma (13). In a typical study, 5 g of orange oil was oxidized in 75-mL open brown bottles at 45°C and was evaluated by a panel after 6 d, at which time it was ranked as off-odor, "terpeney. The peroxide value of the initial oil was zero the oxidized material had a PV of 100. As a result, days to reach 100 PV was used as an endpoint. Comparative antioxidant effects on a number of citrus oils and on D-limonene [cyclohexene, l-methyl-4-(l-methylethenyl)-(R)-5989-27-5] are presented in Table X. BHA is the most active while AP has no activity alone but does synergize with tocopherol. 

By volume (in tons) the most important essential oils used for flavours are the citrus oils (see 3.2.2.2), the mint oils, eucalyptus oils, clove oils and to a lesser extent some spice oils (Table 3.25). 

An interesting new aspect regarding the production of essential oils was highlighted by Verlet [2], who associated total production figures with cultivated plants, wild crafting, citrus oils and other tree crops (Table 3.26). 

For example, a combination of processes (1) and (2) in Table I could be combined to yield a more specific composition in the final extract. Unit process 1 if conducted by sequentially increasing the extraction density when coupled with a sequence of let down pressures (unit process 2) can anqilify the SFF effect. Likewise, by combining unit process 1 using SC-CX>2 followed Ity application of unit process 2 utilizing sidxritical H2O to deterpenate the extract from unit process 1, can yield a more specific final product from the starting citrus oil. To obtain a mote enriched and/or concentrated product fiom the latter process, one could add on unit process 6, a supercritical fluid membrane-based separation of the aqueous extiact/finctions firom unit process S as indicated below (Table I). 

Citrus oils are characterized by having a high percentage of terpenoid hydrocarbons and a relatively low content of oxygenated terpenoid compounds that are mainly responsible for their aromatic profiles (Table 8.13). 

Orange Flower (Neroli) Oil. "The rose we call the queen of flowers, the jasmin the fairest and prettiest princess, but the orange flower is the most fragile and dainty of out royal family of flowers. If the rose stirs our memories, the jasmin our hopes, the orange flower stirs sentiments—sentiments most romantic " (14). Commercial neroh oil [8016-38 J is obtained by steam distillation of the freshly picked blossoms of the bitter orange Citrus aurantium L. subspecies amara, which is cultivated in Mediterranean countries as well as in Haiti and several other tropical countries. More than 125 components have been identified in the oil the principal ones are shown in Table 4 and Figure 1. 

Lime Oil. This oil is obtained from the fmit Citrus aurantijolia Swingle the Key, Mexican, or West Indian lime or C latijolia Tanaka, the Persian lime, either by steam distillation or expression. Either the entire cmshed fmit or only the peel may be used, depending on the specific properties desired. A typical commercial distilled lime oil contains the constituents shown in Table 10 (25). 

---