Identification in foods

According to P. Goodwin (81) for species content identification in foods, the preferred technique should be capable of testing processed meat, raw, cooked and heat-treated samples, dairy foods and other commodities in meat samples. Different immunoassay techniques have been used for meat specification (see Table 1). For more details one can refer to articles by Kangethe (82) and others (12,13). 

Meyer R, Hofelein C, Liithy J, Candrian U (1995). Polymerase chain reaction-restriction fragment length polymorphism analysis a simple method for species identification in food. J. AOAC Int., 78(6) 1542-1551. 

A food must have the expected or proper appearance and color before it will be readily consumed (7). There are many prepared foods in which artificial flavors and colors are used whose flavor is sufticientiy bland to make color essential for flavor identification, eg, margarine. The preservation of color in natural food during processing or the development of color by processing are aspects of primary importance in food acceptance. 

KITTS D D (1994) Bioactive substances in food identification and potential uses. Can J Physiol Pharmacol. 72 423-34. 

Knowledge of the identity of phenolic compounds in food facilitates the analysis and discussion of potential antioxidant effects. Thus studies of phenolic compounds as antioxidants in food should usually by accompanied by the identification and quantification of the phenols. Reversed-phase HPLC combined with UV-VIS or electrochemical detection is the most common method for quantification of individual flavonoids and phenolic acids in foods (Merken and Beecher, 2000 Mattila and Kumpulainen, 2002), whereas HPLC combined with mass spectrometry has been used for identification of phenolic compounds (Justesen et al, 1998). Normal-phase HPLC combined with mass spectrometry has been used to identify monomeric and dimeric proanthocyanidins (Lazarus et al, 1999). Flavonoids are usually quantified as aglycones by HPLC, and samples containing flavonoid glycosides are therefore hydrolysed before analysis (Nuutila et al, 2002). 

The total number of different anthocyanins reported to be isolated from plants was 539. However, the number of anthocyanins found in foods is much smaller. Although a large number of papers were published regarding anthocyanin composition in several foods, investigators in most studies used only chromatographic and chemical behaviors as bases for identification. In this chapter, we considered only papers in which identification was based at least on mass spectrometry (MS). In fact, the use of only MS and UV-visible information can easily lead to misidentifi-cation as the following example shows. 

Color plays a special role in the foods we eat. For example, when confronted with a food of an unattractive color, the consumer assumes the food is of poor quality or is spoiled. Similarly, a product with an atypical color, e.g., a green cheese or a blue drink, in most cases would be rejected by the consumer. Typically, one associates certain colors with certain food items such as cherry with red, lemon with yellow, and orange with carrot. Therefore, color can serve as a primary identification of food and also as a protective measure to prevent the consumption of spoiled food. Food colors create physiological and psychological expectations and attitudes that are developed by experience, tradition, education, and environment we inevitably eat with our eyes. ... 

High performance spectroscopic methods, like FT-IR and NIR spectrometry and Raman spectroscopy are widely applied to identify non-destructively the specific fingerprint of an extract or check the stability of pure molecules or mixtures by the recognition of different functional groups. Generally, the infrared techniques are more frequently applied in food colorant analysis, as recently reviewed. Mass spectrometry is used as well, either coupled to HPLC for the detection of separated molecules or for the identification of a fingerprint based on fragmentation patterns. ... 

The identification of synthetic colorants (pure or mixtures) in foods is usually carried out using spectrophotometry but the resolution of complex mixtures in food requires a previous separation of extract components by SPE and chromatographic techifiques. Dual wavelength, solid phase, and derivative spectrophotometric methods combined with chemometric approaches have been used. ... 

AOAC Official Method 988.13, FD C Color Additives in Foods, Rapid Cleanup for Spectrophotometric and Thin-Layer Chromatographic Identification, AOAC Official Method of Analysis, 46.1.05, 3, 2000. 

NOAEL (no-observed-adverse-effect level) is defined as the highest dose at which no adverse effects are observed in the most susceptible animal species. The NOAEL is used as a basis for setting human safety standards for acceptable daily intakes (ADIs), taking into account uncertainty factors for extrapolation from animals to humans and inter-individual variabilities of humans. The adequacy of any margin of safety or margin of exposure must consider the nature and quality of the available hazard identification and dose-response data and the reliability and relevance of the exposure estimations. In some cases, no adverse endpoint can be identified such as for many naturally occurring compounds that are widespread in foods. In that case, an ADI Not Specified is assigned. ... 

Wedzicha, B.L., Chemistry of Sulphur Dioxide in Foods, Elsevier, Amsterdam, 1984. Damant, A., Reynolds, S., and Macrae, R., The structural identification of a secondary dye produced from the reaction between sunset yellow and sodium metabisulphite, FoodAddit. Contam., 6, 273, 1989. 

B. van Lierop, L. Castle, A. Feigenbaum and A. Boenke, Spectra for the Identification of Additives in Food Packaging, Kluwer Academic Publishers, Dordrecht (1998). 

Ehret-Henry et al. [220] have shown that H NMR spectra can be used without chromatographic analysis, to shorten the total identification time necessary, and as a fingerprint of all the extractable nonvolatile compounds present in food packaging material (safety control). Figure 5.10 shows a H NMR spectrum (in CDCI3 with TMS as internal standard) of a Soxhlet extract of a 35 pirn PP film (after solvent evaporation). The assignments of the resonances of Irgafos 168 and its decomposition products were confirmed by a 31P- H 2D correlation NMR experiment [220],... 

Bureau Communautaire de Reference, Spectra for the Identification of Additives in Food Packaging, Geel... 

Absorption, Distribution, Metabolism, and Excretion. There are no data available on the absorption, distribution, metabolism, or excretion of diisopropyl methylphosphonate in humans. Limited animal data suggest that diisopropyl methylphosphonate is absorbed following oral and dermal exposure. Fat tissues do not appear to concentrate diisopropyl methylphosphonate or its metabolites to any significant extent. Nearly complete metabolism of diisopropyl methylphosphonate can be inferred based on the identification and quantification of its urinary metabolites however, at high doses the metabolism of diisopropyl methylphosphonate appears to be saturated. Animal studies have indicated that the urine is the principal excretory route for removal of diisopropyl methylphosphonate after oral and dermal administration. Because in most of the animal toxicity studies administration of diisopropyl methylphosphonate is in food, a pharmacokinetic study with the compound in food would be especially useful. It could help determine if the metabolism of diisopropyl methylphosphonate becomes saturated when given in the diet and if the levels of saturation are similar to those that result in significant adverse effects. 

Experiment 61 Identification of Amino Acids in Food by Paper Chromatography... 

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