Olive oil volatiles

Virgin olive oil/ Wax and stigmastadienes Virgin olive oil/ Volatile carbonyls... 

Garcia-Gonzalez, D.L., Barie, N. Rapp, M., Aparicio, R. (2004) Analysis of virgin olive oil volatiles by a novel electronic nose based on a miniaturized SAW sensor array coupled with SPME enhanced headspace enrichment. J. Agric. Food Chem. 52 7475-7479. 

Flavor Components. Olive oil volatiles contain at least 100 compounds (33-37) in several categories hydrocarbons (5 compounds), aliphatic alcohols (13 compounds), terpenic alcohols (4 compounds), aldehydes (27 compounds), ketones (8 compounds), ethers (2 compounds), furans (3 compounds), thiophenes (6 compounds), and esters (29 compounds). 

Characterization of olive oil volatiles by multi-step direct thermal desorption-comprehensive gas chromatography-time-of-flight mass spectrometry using a programmed temperature vaporizing injector. Journal of Chromatography A, Vol.1186, pp. 228-235, ISSN 0021-9673... 

Vichi, S., Pizzale, L., Conte, L.S., Buxaderas, S. and Lopez-Tamames, E. Solid-phase microextraction in the analysis of virgin olive oil volatile fraction Modification induced... 

Properties APHA 100 max. cl. liq. sol. in acetone, castor oil. ethanol, celyl alcohol, ethyl acetate, IPM, liq. lanolin, oleic add, oleyl alcohol, olive oil, volatile silicone oil, hot wh. petrol, jelly insol. in water, propylene glycol acid no. 1 max. hyd. no. 60-70 0.2% max. water Use Level 5-15%... 

Common name Olive oil Chemical name NA Molecular weight NA Formula Mixture of natural products Density 0.909-0.915 gmU1 Volatility Very low... 

A widespread method for determining the induction period for autoxidation of oils and fats consists of passing a continuous stream of air through the heated sample and collecting the volatile acids evolved in a water trap, where they are determined on a real time basis. The time plot usually presents a flat appearance for a certain period and then takes off in an accelerated manner. This test is the basis of several national and international standards (e.g. AOCS Cd 12b-92—oil stability index" ISO 6886—accelerated oxidation test for oxidative stability of fats and oils ) and the design of the Rancimat equipment, where the end determination is based on conductivity measurements . In addition to oxidation stability as determined by the Rancimat method and POV, which negatively affects virgin olive oil stability, other nonstandard properties were proposed for better assessment of the quality of this oil, namely LC determination of Vitamin E (21), colorimetric determination of total polar phenols and UVD of total chlorophyll. ... 

There are few data on concentrations of ethylbenzene in foodstuffs. It has been identified as a trace component in the volatiles from honey, jasmine, papaya, olive oil and cheese flavour and in the neutral component of roast beef flavour isolate (Min et al., 1979 Fishbein, 1985). Trace quantities of ethylbenzene have been detected in split peas (13 ig/kg), lentils (5 ig/kg) and beans (mean, 5 pg /kg maximum 11 pg /kg (Lovegren et al., 1979). Concentrations of ethylbenzene in orange peel (23.6 ng/g dry weight) and in parsley leaves (0.257 pg/g dry weight) have been reported (Goma-Binjul etal., 1996). 

Various methods are used in extracting the oils from the plant tissue. Many are distilled with water or steam, Hie oil being carried over with the distillate. In others, as for example oil of bitter almonds, the oil develops in the tissues only after fermentation. It is then obtained by distillation. Anollter method, and one especially used for more delicate and valuable oils, is called enfleurage. In this method the flowers containing the oil are spread as a thin layer over a layer of lard or olive oil. The latter absorbs the delicate oil in the flowers, after which distillation may separate the volatile oil from the other. 

A second amendment, Directive 97/48/EEC, laid down the conditions of use of volatile solvents, e g. isooctane and ethanol, as test liquids in the fat test . It provided that these solvents may replace olive oil or the other fat simulants (HB 307, sunflower oil, etc.) if the fat test is not applicable in its basic version for technical reasons or in routine checking. These conditions are shown in Tables 12-10 and 12-11. 

Volatile test media are used up to a maximum temperature of 60 °C. It is a precondition for substitution testing that the material or article should withstand the test conditions applied with simulants D. Immerse a test specimen in olive oil in the appropriate conditions. If the physical properties are changed (e.g. melting or deformation), the material is considered to be unsuitable for use at that temperature. If the physical properties are not changed, carry out substitution tests using new specimens. 

Lipoxygenases play an important role in determining oil quality. The aromas typical of olive oil are due to complex mixtures of volatile compounds those especially abundant are saturated and unsaturated six carbon atom aldehydes, alcohols, and the esters of alcohols, the cited aldehydes and alcohols having sensory properties responsible for the so-called green odour (Hatanaka, 1996). 

Iodometry on peroxidized olive oils gives the peroxide value (PV), which is expressed as the milliequivalent of active oxygen in the peroxides present in 1 kg of olive oil. Experienced oil analysts can relate PV values with rancidity and oil stability. Typical reports are that a fresh genuine oil has a PV of 2-5, a fresh deodorized oil a PV near to zero and that PV values of 10 or more are for oils prone to produce off-flavour volatiles. 

This method has the main aim of detecting attributes and defects, and measuring their intensity, for the classification of the various categories of virgin olive oils (Angerosa, 2001). The sensory attributes perceived by the consumer arise from the stimulation of gustatory and olfactory receptors from a large number of volatile and some non-volatile compounds such as simple and combined phenols. The intensity of each sensation is related to the concentration of chemical compounds identified in the volatile fraction of the oil. 

Morales, M.T. and Aparicio, R. (1993) Characterising some European olive oil varieties by volatiles using statistical tools. Grasas Aceites, 44(2), 113-115. 

Morales, M.T., Aparicio, R. and Rios, J.J. (1994) Dynamic headspace gas chromatographic method for determining volatiles in virgin olive oil. J. Chromatogr. A, 668, 455-462. 

Most oils contain low levels of saturated and unsaturated hydrocarbons. In olive oil, the unsaturated hydrocarbon squalene can constitute up to 40% of the unsaponifiable fraction (Boskou, 1996). Other hydrocarbons commonly present in olive oil are straight chain alkanes and alkenes with 13 to 35 carbon atoms, along with very low amounts of branched chain hydrocarbons. Variations are found between different olive varieties but the main hydrocarbons are those with 23, 25, 27 and 29 carbon atoms (Guinda et al., 1996). Olive oil can clearly be differentiated from other vegetable oils on the basis of hydrocarbon components, and levels of 2.6% crude rapeseed oil or crude sunflower oil can be detected by hydrocarbon analysis (Webster et al., 1999). Terpenes have been identified in the volatile fraction of crude sunflower oil (Bocci and Frega, 1996). 

Figure 7.1 Authentication of monovarietal virgin olive oils results of applying clustering analysis to volatile compounds. The Mahattan (city block) distance metric and Ward s amalgamation methods were used in (a) the Squared Euclidean distance and (b) complete linkage amalgamation methods. Note A, cv. Arbequina (6) C, cv. Coratina (6) K, cv. Koroneiki (6) P, cv. Picual (6) 1, harvest 1991 2, harvest 1992. Olives were harvested at three levels of maturity (unripe, normal, overripe) (source SEXIA Group-Instituto de la Grasa, Seville, Spain).

In practice, there are no great differences among the methods for extracting factors. Thus, PCA could be suggested in authentication studies because it is simply a mathematical transformation of the raw data. Figure 7.2 illustrates the case of monovarietal virgin olive oils characterized by volatile compounds described in the cluster paragraph. 

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