Olive oil authentication

Wherever it is considered useful there is the development of simple analytical and structural chemistry elements, as well as of reaction mechanisms, to explain the chemical properties and the induced or spontaneous transformation of the natural oil products. We do not pretend that the official methods presented, and commented on, in this section are the most important for the determination of olive oil authenticity, but we do hope that the methodologies illustrated will represent a foundation upon which the interested reader will achieve familiarity with some of the original classes of compounds and those of new formation that make up olive oil. 

Calvente, J.J. and Aparicio, R. (1995) A fuzzy filterfor removing interferences among membership grade functions. An application to pre-treatment of data in olive oil authentication. Anal. Chim. Acta., 312, 281-294. 

Gomez-Ariza, J.L., Arias-Borrego, A., Garcia-Barrera, T., and Beltran, R., Comparative study of electrospray ionization sources coupled to quadrupole time-of-flight mass spectrometer for olive oil authentication, Talanta, 70, 859-869, 2006. 

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

Arvanitoyannis, IS. and Vlachos, A. Implementation of physicochemical and sensory analysis in conjunction with multivariate analysis towards assessing olive oil authentication/adulteration. Critical Reviews in Food Science and Nutrition, 47, 441 98. 2007. 

Aparicio, R., Alonso, V. and Morales, M. T. (1996) Developments in olive oil authentication, in Food Authenticity 96, Norwich. 

Bohacenko, I. and Kopicova, Z. 2001. Detection of olive oils authenticity by determination of their sterol content using LC/GC. Czech J. Food Sci. 19 97-103. 

Alonso-Salces RM, Moreno-Rojas JM, Holland MV, Reniero F, Guillou C, Heberger K. Virgin olive oil authentication by multivariate analyses of H NMR fingerprints and and 8 H data. J Agric Food Chem 2010 58 5586-96. 

By the nature of the process by which olive oil is extracted from the olive, the oil is susceptible to contamination. The high price associated with olive oil of the highest purity— extra virgin olive oil — also leads to falsification by unscrupulous vendors who blend with less costly oils such as com, peanut, and soybean oil. Various analytical techniques have been devised to authenticate the purity of olive oil by detecting certain oil components. 

E. Bertran, M. Blanco, J. Coello, H. Iturriaga, S. Maspoch and I. Montoliu, Near infrared spectrometry and pattern recognition as screening methods for the authentication of virgin olive oils of very close geographical origins, J. Near Infrared Spectrosc., 8, 45-52 (2000). 

Cosio, M. S., Ballabio, D., Benedetti, S., and Gigliotti, C. (2006). Geographical origin and authentication of extra virgin olive oils by an electronic nose in combination with artificial neural networks. Anal. Chim. Acta 567(2), 202-210. 

El-Fizga (108) developed a simple, rapid method for the detection of oils high in linoleic acid in olive oil by RP-HPLC and a simple authenticity factor and a derived equation to determine the extent of adulteration with a one short chromatographic step, completed in less than 15 min. They used two 150 X 4.5-mm ID stainless steel columns packed with an octyl-bonded silica stationary phase (Supelcosil-LC 8) (Supelco. Bellefonte, PA, USA) and a differential reffactometric detector. The isocratic mobile phase was acetone-acetonitrile (70 30, v/v) (Table 5). 

The presence of vegetable oils of high linoleic acid content in olive oil can be detected by measuring its authenticity factor (Au) as follows ... 

Shaw AD, di Camillo A, Vlahov G, Jones A, Bianchi G, Rowland J, Kell DB (1996) Discrimination of Different Olive Oils using 13C NMR and Variable Reduction, in Food Authenticity 96. Norwich, UK... 

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. 

In the UK at least, the Adulteration Act of 1860, the result of the deliberations of the above committee, was the beginning of a more scientific approach to authentication of fats and oils. However, it was still being stated after the turn of the century (Sloane 1907) that, in the USA, butter was being adulterated by oleomargarine and lard, and cream by cottonseed oil and other fats. Indeed the USA equivalent of the UK Adulteration Act, the 1938 Federal Food, Drug and Cosmetic Act, was only passed after a series of even later cases of adulteration coconut and cottonseed replacing cocoa butter and milk-fat (1922), peanut oil in olive oil (1923), lard contaminating butter (1926) and sesame oil in olive oil used in tinned sardines (1936) (Kurtzweil, 1999). 

Aparicio, R., Morales, M.T. and Alonso, V. (1997) Authentication of European virgin olive oils by their chemical compounds, sensory attributes, and consumers attitudes. J. Agric. Food Chem., 45, 1076-1083. 

Spangenberg, J.E. and Ogrinc, N. (2001) Authentication of vegetable oils by bulk and molecular carbon isotope analysis with emphasis on olive oil and pumpkin seed oil. J. Agric. Food Chem., 49, 1534-1540. 

Official analytical methods provide data and results that give soundproof of the authenticity and quality of an olive oil, or, alternatively, elements that permit the uncovering of altered and sophisticated over-classified oils. This section is not to be regarded as a comprehensive presentation of olive oil chemistry and analysis but is intended only to give the reader an overall perspective of the origin and fate, and the chemico-physical properties, of the classes of compounds constituting olive oil. 

Flor et al. (1993) were the first to develop criteria for the authentication of olive oil based on vegetable oil HPLC data. They observed that corn, cottonseed, soyabean, sunflower and safflower oils, to mention the most important commercial products, have large peaks for LLL, LLO and LLP but generally smaller LOO and LOP peaks (abbreviations P, palmitic O, oleic S, stearic L, linoleic Ln, linolenic Po, palmitoleic). Additional typical peaks were observed LnLL peak (ca. 7%) in soyabean and LnLO peak (ca. 7%) in rapeseed oils, respectively. Other relevant compositional pictures were observed peanut oil displays a relatively small LLL peak (ca. 3.5%) but larger LLO and LLP peaks (ca. 18.2, 5.9%, respectively). 

Inter-esterification has many industrial applications such as the production of structured lipids and the manipulation of the physical properties of oils. This method is therefore intended to check the overall genuine authenticity of any commercial olive oil. 

Future authenticity testing of cocoa butter and chocolate products is likely to follow defined paths. To assure the authenticity of cocoa butters databases of the composition of the relevant fats will be required, constructed from a statistically significantly number of samples of proven provenance and processing history. Analyses must be carried out using internationally validated methods and characterized reference materials by a number of respected laboratories. Scientific co-operation within the European Union is beginning to develop such approaches in ensuring the authenticity of other foods such as olive oil. 

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