Adulterated oils

Specimen F waa said to have bccu obtained Irom old and young leaves and to have been adulterated with kiiroseut. and therefore to he -of no use to the dealer price 200. When lironght into water, this oil formed a compact mass with a thick aurlace, partly of a whitish and striped appearance. (Ailour rather dark. The dealer slated that hft bad showed us this oil only as a specimuii of adulterated oil, that bo kept it ouly as a sample, and thai be had only a small amount of it, Conseqnently he could only sell us such a Small sample. 

Terpinyl acetate in the absence of esters of high molecular weight, or ethyl esters of the fatty acids of coconut oil, is indicated by a difference to be observed in the apparent ester value by different times of saponification. This ester is far more resistant to the action of caustic alkali than is linalyl acetate, and requires two hours at least for complete saponification. Hence, if the oil shows a difference in the saponification value in thirty minutes and in two hours, which amounts to more than from 1 to 2, terpinyl acetate is almost certainly present. The following table shows the effect of this partial-saponrfication on the two esters and on adulterated oils —... 

The author has recommended the examination of the last 10 per cent, left on evaporation of the oil on a water-bath, since the heavy artificial esters accumulate in this fraction. The refractive index of this 10 per cent, should not be below 1 5090, and the saponification value should not exceed 190. The following figures (see p. 317) represent nine samples of adulterated oil, all sold as genuine bergamot oil. 

Glyceryl acetate is so easily washed out with ordinary hot distilled water, that an adulterated oil when washed several times with hot water will show a distinctly lower ester value and refractive index than the original unwashed oil. 

P4 The hrst part of this study involved structurally differentiating between hazelnut oil and other oils and then detecting adulterating oils in hazelnut oil. For this purpose, the spectra of pure hazelnut oil were compared with the spectra of seven other oil types, as shown in Figure 1. (Adapted from Ozen and Mauer, 2002)... 

It is certain that not all of the oils consumed today are completely authentic with respect to all the descriptions on the label (Grob et al., 1994 Firestone, 2001 Working Party on Food Authenticity, 1996). Although there are published expected chemical compositions of the major edible oils (Codex Alimentarius Commission, 1997), the only oil that has a defined legal composition is olive oil (EC Council, 1991). This does not mean that adulterated oils cannot be identified, but it does mean that, in many cases, doing so is not an easy matter. 

Grob, K., Giuffre, A., Leuzzi, U. and Mincione, B. (1994) Recognition of adulterated oils by direct analysis of the minor components. Fat Sci. Technol., 96, 286-290. 

As has been emphasized, essential oils are made up of a mixture of a large number of chemicals. These chemicals are sometimes able to complement each other by having additive or synergetic effects influencing their properties. The combination of major components alone would not produce an oil resembling the natural product. The quality and characteristics rely on all components. This is one reason why the use of synthetic or adulterated oils is inappropriate for aromatherapy. 

Properties Colorless or yellowish oil characteristic penetrating odor bitterish burning taste. D 0.965-0.990 (15C), optical rotation —4 to —8 degrees, refr index 1.4740-1.4790 (20C). Soluble in 3-10 volumes of 70% alcohol (inferior and adulterated oils do not yield a clear solution). Chief known constituents Ascaridole (C10H16O2) o-cymene /-li-monene. 

Martinez Tello, F. J., Navas Palacios, J. J., Ricoy, J. R. et al., Pathology of a new toxic syndrome caused by ingestion of adulterated oil in Spain, Virchows Arch. (Pathol. Anat.), 397, 261, 1982. 

Cerrato Oliveros et al. (2002) selected array of 12 metal oxide sensors to detected adulteration in virgin olive oils samples and to quantify the percentage of adulteration by electronic nose. Multivariate chemometric techniques such as PCA were applied to choose a set of optimally discriminant variables. Excellent results were obtained in the differentiation of adulterated and non-adulterated olive oils, by application of LDA, QDA. The models provide very satisfactory results, with prediction percentages >95%, and in some cases almost 100%. The results with ANN are slightly worse, although the classification criterion used here was very strict. To determine the percentage of adulteration in olive oil samples multivariate calibration techniques based on partial least squares and ANN were employed. Not so good results were carried out, even if there are exceptions. Finally, classification techniques can be used to determine the amount of adulterant oil added with excellent results. 

Country, Target Compounds, Adulterant oils. Adulteration Detection Thresholds, and Multivariate Analysis Methods for Olive Oil Authentication... 

Country Extraction Method Target Compound Adulterant Oil Detection Threshold Method Multivariate Analysh... 

This chapter therefore presents the results of research to establish the fatty acid compositions (FACs) and 8 ( C) stable carbon isotope ratios (SCIRs) of 130 samples comprising a variety of edible oils. An attempt was made to link the SCIR with the FAC in such a way as to reduce the limit of detection (increase the sensitivity) of an adulterant oil in maize oil. 

Pa = amount of fatty acid in the adulterant oil as a percentage of total fatty acids ... 

The lightest fr-action which the author and Bennett obtained tiom the adulterated oils had a specific gravity of 0 798, an optical rotation of - 17, hnd commenced to distil at 112 C. In none of the fractions has any odour of paraffin been observed, nor any fluorescence—hence the conclusion that resin spirit is the adulterant. 

According to Dragendorff, the oil should not be quite soluble in an equal volume of 85 to 90 per cent, alcohol. He states that the chief adulterants are oils of pimento and cloves, which are much more soluble in alcohol. The ready solubility of samples of oil in all proportions of 80 per cent, alcohol is, therefore, probably indicative of adulteration. Oil of lemon and turpentine have also been used to sophisticate the pure oil. These will be indicated by the lowering of the specific gravity and the alteration in the optical rotation. 

From a comparison of these figures it will be seen that the highest boiling fractions of the adulterated oil have a high specific gravity, a high refractive index, and, further, do not crystallise. 

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