Animal food analysis

Steyn PS, Thiel PG, Trinder DW (1991) Detection and quantification of mycotoxins in animal feeds by chemical analysis. In Smith JE, Henderson RS (eds) Mycotoxins and animal foods. CRC Press, Boca Raton, FL, pp 165-222... 

It is with the topic of analyte determination in foods by the technique of analytical AAS that this chapter is concerned. Analyte quantitation (d above) by this technique is thus the main thrust of this treatment, but of necessity, the intimately related procedures of sample treatment (b) and analyte separation and manipulation (c) will also be discussed insofar as they bear on quantitative measurement by AAS. Food for human consumption is the main concern of this chapter. Peripheral discussion, however, of allied commodities such as plants and animal feedstuffs, is included to make the treatment more comprehensive, especially in areas where there is a dearth of publications relating to food-analysis applications of atomic spectrometry. For detailed accounts of methodologies bearing on such related materials, the reader is referred to the other chapters in this volume. 

Changes in the focus of SFE can be easily followed through its reported applications. Thus, in 1993 [3], environmental applications prevailed (45.9% versus 21.9% devoted to foods and 11.6% to industrial analyses). By 1996, however, SFE applications to food analysis had risen to 38%, environmental uses fallen to 41% and industrial analyses levelled off at 11% [48]. More recently [17], the extraction of food components (particularly fat) has become one of the major applications of SFE, so much so that the current boom in SF extractor sales has been ascribed to it. The book by Luque de Castro et al. [3] contains comprehensive tables of SFE applications in various fields. Also, one review of SFE in food analysis [148] includes four tables with applications involving the extraction of fat from various types of sample (viz. meat and animal products, fish, cereal, seed and animal feed, plants and vegetables). On a more specific level, Eller and King reviewed determinations of the fat content in foods [149]. Finally, the Analytical Chemistry issues devoted to reviewing techniques provide periodic updates on SFE and SFC [150]. 

LC-MS plays an important role in the confirmation of identity of the veterinary residues of antibiotics in animal food products for human consumption [3-6]. LC with UV or UV-DAD detection is often apphed in quantitative determination, while confirmation of identity is performed by LC-MS. GC-MS is applicable to a limited number of compound classes after derivatization. The LC-MS characterization of various classes of antibiotics is discussed in this section, while residue analysis is discussed in Ch. 14.3. An overview of important classes of antibiotic and antibacterial compounds is given in Table 14.1. Typical examples of various compound classes are shown in Figure 14.1. Only a limited number of compound classes is discussed here. 

Brandsteterova, E. Kubalec, P. Bovanova, L. HPLC Determination of Antimicrobial Residues in Edible Animal Products. In Food Analysis by HPLC, 2nd Ed. Nollet, L.M.L., Ed. Marcel Dekker, Inc. New York, 2000 621-691. 

The oldest DNA technique in food analysis is based on labeled probes, which bind directly to DNA if complementary regions exist. This method, called Southern hybridization, is very time consuming. Further disadvantages are insufficient sensitivity for many questions, as well as the problem of nonspecific hybridization signals for closely related animal species (Behrens and Unthan, 1999). 

Gentili A, Perret D, Marchese S, Liquid chromatography tandem mass spectrometry for performing confirmatory analysis of veterinary drugs in animal food products. Trends Anal. Chem. 2005 24(7) 704-733. 

Ito Y, Oka H, Dcai Y, et al.. Application of ion-exchange cleanup in food analysis V. Simultaneous determination of sulphonamide antibacterials in animal liver and kidney using high performance liquid chromatography with ultra violet and mass spectrometric detection, J. Chromatogr. A 2000 898 95-102. 

One of the initial methods used for food analysis was DNA hybridization. The method was based on the principle that labeled DNA from an organism should hybridize to another DNA molecule from the same source. The use of nylon membranes was necessary to provide a solid attachment environment for the DNA molecules. This method was further improved with the use of satellite sequences to distinguish meat products from closely related animals, such as sheep and goat, even if they were heat processed [50]. 

Biological techniques encompass two methodological approaches live systems and biochemical techniques. Live systems employ (1) whole animal, (2) microorganisms, and (3) cell and tissue culture methods as tools in food analysis. Biochemical techniques include uses of enzymes and immunochemical techniques (Table 3). 

Among the different chemometric methods, exploratory data analysis and pattern recognition are frequently used in the area of food analysis. Exploratory data analysis is focused on the possible relationships between samples and variables, while pattern recognition studies the behavior between samples and variables [95]. Principal component analysis (PCA) and partial least-squares discriminant analysis (PLS-DA) are the methods most commonly used for exploratory analysis and pattern recognition, respectively. The importance of these statistical tools has been demonstrated by the wide number of works in the field of food science where they have been applied. The majority of the applications are related to the characterization and authentication of olive oil, animal fats, marine and vegetable oils [95], wine [97], fruit juice [98], honey [99], cheese [100,101], and so on, although other important use of statistical tools is the detection of adulterants or frauds [96,102]. 

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