Edible oils analysis

ECN (effective carbon number), 689, 690, 708 Edible oils analysis, 636, 701 autoxidation, 614, 623, 661-2 peroxide value, 657, 658, 660-3 EDTA... 

R 112 F.J. Hidalgo and R. Zamora, Edible Oil Analysis by High-Resolution Nuclear Magnetic Resonance Spectroscopy Recent Advances and Future Perspectives , p. 499... 

The composition of an oil and the progress of its hydrogenation is expressed in terms of its iodine value (IV). Edible oils are mixtures of unsaturated compounds with molecular weights in the vicinity of 300. The IV is a measure of this unsaturation. It is found by a standardized procedure. A solution of ICl in a mixture of acetic acid and carbon tetrachloride is mixed in with the oil and allowed to reac t to completion, usually for less than I h. Halogen addition takes place at the double bond, after which the amount of unreacted iodine is determined by analysis. The reaction is... 

The methods of analysis of polymer additives and chemicals, such as hydrocarbons, alcohols, etc., are not only restricted to the field of polymer chemistry but can also be applied for the analysis of such materials in the field of food chemistry. In addition, the analysis of polyaromatic hydrocarbons in edible oils has been of extreme importance. Polymeric packaging materials that are intended for food-contact use may contain certain additives that can migrate into the food products which are actually packaged in such products. The amounts of the additives that are permitted to migrate into food samples are controlled by government agencies in order to show... 

Figure 12.1 Analysis of Tinuvin 1577 in 30% virgin olive oil (in hexane), showing (a) the gas cliromatogram comparing the pure oil with a sample at the Tinuvin 1577 detection limit concentration, and (b) the coixesponding liquid chromatogram. Reprinted from Journal of High Resolution Chromatography, 20, A. L. Baner and A. Guggenberger, Analysis of Tinuvin 1577 polymer additive in edible oils using on-line coupled HPLC-GC , pp. 669-673, 1997, with pennission from Wiley-VCH.

A. L. Baner and A. Guggenberger, Analysis of Tinuvin 1577 polymer additive in edible oils using on-line coupled HPLG-GG , J. High Resolut. Chromatogr. 20 669 - 673 (1997). 

By late 1996, Monsanto had planned to divide itself into two entities Monsanto Life Sciences and a chemical entity (later given the name Solutia) (Reisch). This occurred within a year, during which Monsanto purchased a plant biotechnology company (Calgene) that held patents for improved fresh produce, cotton seeds, specialty industrial and edible oils (derived from seeds) and plant varieties (Anonymous, 1997). Based on analysis of 1995 sales, the life sciences products accounted for annual sales of S5.3 billion based on the major products of Round-up herbicide, Roundup-resistant soybeans, Bollguard insect-protected cotton, Nutrasweet sweetner, and prescription drugs for arthritis and insomnia. 

Edible oils are easily dissolved in benzene, but if a solid food is to be analyzed, the sample should be well ground first. A portion is accurately weighed, to which a known volume of benzene is added. The sample is mixed, centrifuged, and a 5.0-ml aliquot of this extract is used for the analysis. 

H Indyk, DC WooIIard. Antioxidant analysis in edible oils and fats by normal-phase high-performance liquid chromatography. J Chromatogr 356 401-408, 1986. 

Trace element analysis of foods can be carried out to check for contamination by toxic elements, such as lead and cadmium, or to determine beneficial micronutrients, or as an aid to distinguishing geographical origin. In fats, small numbers of trace elements are measured after digestion of the sample in acid followed atomic absorption spectrophotometry (AAS) or by direct graphite furnace vaporization. An AAS procedure for measuring lead in edible oils and fats has been collaboratively trialed with cocoa butter as a test material (Firestone, 1994). 

Mottram, H.R. (1999) The Application of HPLC-APCI MS to the Regiospecific Analysis of Triacylglycerols in Edible Oils and Fats. PhD thesis, Department of Chemistry, University of Bristol, UK. Movia, E. and Remoli, S. (1977) Application of enzymic hydrolysis to determine the genuineness of butter., Bollettino dei Chimici dei Laboratori Provinciali, 3, 187-192. 

Artho, A., Grob, K. and Mariani, C. (1993) Online LC-GC for the analysis of the minor components in edible oils and fats. Fett. Wissen. Technol., 95(5), 176-180. 

Communities in India may also be exposed to hazardous cotton pesticides through the contamination of cottonseed and cottonseed derivatives - an important source of edible oil. Because of the intensive use of hazardous pesticides in cotton production much of the cottonseed oil entering the Indian food chain may be heavily contaminated . One analysis of cottonseeds collected from 5 locations in Punjab found detectable residues of the cotton pesticides ethion (WHO II), cypermethrin (WHO II), endosulfan (WHO II), chlorpyrifos (WHO II) the latter being 2 of the most common pesticides applied to cotton in India ... 

Oxidation reactions are dramatically enhanced by US energy, as discussed in detail in Chapter 7. Analytically, US-assisted oxidation reactions are of enormous interest. Two cases in point are the determination of the oxidative stability of edible oils [35], where the analysis time is reduced from 129 h to only 50.5 min, and the degradation of highly contaminated organic compounds, which is typically 10000 times faster than natural aerobic degradation [36]. 

These methods are based on lipid (substrate) oxidation and specihc to the analysis of oxidation that occurs in food lipids. The tests employed strongly correlate to the conditions that oils and fats are subjected to during processing, food preparation, and storage. The substrate is a model compound that could be a pure triacylgly-cerol, fatty acid methyl ester, or an actual edible oil/lipid. Favorable conditions for substrate oxidation (e.g., high temperature) are provided to facilitate increased rate of oxidation reactions in a controlled environment. The end point is determined... 

Oxidative stability of edible oils depends primarily on their fatty acid composition and, to a lesser extent, in the stereospecific distribution of fatty acids in the triacyl-glycerol molecules. The presence of minor components in the oils also affects their oxidative stability. A detailed discussion of oxidative processes in fats and oils is provided elsewhere in this series. Oxidation may occur via different routes and includes autoxidation, photo-oxidation, thermal oxidation, and hydrolytic processes, all of which lead to production of undesirable flavor and products harmful to health. Flavor and odor defects may be detected by sensory analysis or by chemical and instrumental methods. However, chemical and instrumental procedures are often employed in the processing and during usage of edible oils. Indicators of oxidation are those that measure the primary or secondary products of oxidation as well as those from hydrolytic processes or from thermal oxidation, including polymers and polar components (15). 

Edible oils and fats are composed primarily of triacylglycerols (TAG), ester of one molecule of glycerol, and three molecules of fatty acids. Analysis of canola oils showed that TAGs constituted 94.4% to 99.1 % of the total lipid (2). The typical composition of canola, rapeseed, and soybean oils is presented in Table 1. 

The determination of sulfur compounds in the range of concentrations, which occur in edible oils, is difficult. The literature on concentrations found in rapeseed and canola oils can be confusing. Considering relevance to hydrogenation effects and speed of analysis, ICP spectroscopy for determining sulfur in canola oil is presently the most appropriate method. 

Anisidine Value. Anisidine value is a measure of secondary oxidation or the past history of an oil. It is useful in determining the quahty of crude oils and the efficiency of processing procedures, but it is not suitable for the detection of oil oxidation or the evaluation of an oil that has been hydrogenated. AOCS Method Cd 18-90 has been standardized for anisidine value analysis (103). The analysis is based on the color reaction of anisidine and unsaturated aldehydes. An anisidine value of less than ten has been recommended for oils upon receipt and after processing (94). Inherent Oxidative Stability. The unsaturated fatty acids in all fats and oils are subject to oxidation, a chemical reaction that occurs with exposure to air. The eventual result is the development of an objectionable flavor and odor. The double bonds contained in the unsaturated fatty acids are the sites of this chemical activity. An oil s oxidation rate is roughly proportional to the degree of unsaturation for example, linolenic fatty acid (C18 3), with three double bonds, is more susceptible to oxidation than linoleic (C18 2), with only two double bonds, but it is ten times as susceptible as oleic (C18 l), with only one double bond. The relative reaction rates with oxygen for the three most prevelent unsaturated fatty acids in edible oils are ... 

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