Abstract
Food authenticity is a major necessity to meet the demands of conscious consumers and to reassure them regarding the origin and content of their food, and also to fulll the needs of manufacturers to enable them to comply with government regulations and labeling obligations for their products. The determination of food authenticity, particularly meat species identication, has great importance in food quality control and safety. Fraudulent substitution or undeclared adulteration of meat species in comminuted and highly processed meat products is a widespread problem in retail markets. Undesired practices in general include replacement of cheaper or undesired meats with higher commercial value meat species and the nondeclaring of proportion of meat species used in the production. These cases have led to the suggestion of some analytical techniques for the qualitative and quantitative determination of such replacements in meat mixtures. These methods include different protein-based techniques and related methods such as electrophoretic techniques, enzyme-linked immunosorbent assays (ELISA), and isoelectric focusing (IEF). However, these methods have been reported to be sometimes inadequate or less sensitive for the species identication of thermally processed foods due to the denaturation of proteins. DNA-based12.1 Introduction .................................................................................................................................. 249 12.2 Spectroscopic Techniques ............................................................................................................ 250 12.3 Chromatographic Techniques .......................................................................................................251 12.4 Electrophoretic Techniques .......................................................................................................... 25212.4.1 PAGE and SDS-PAGE ..................................................................................................... 252 12.4.2 Isoelectric Focusing ......................................................................................................... 252 12.4.3 Capillary Electrophoresis ................................................................................................ 25312.5 Immunoassays .............................................................................................................................. 254 12.6 DNA-Based Methods ................................................................................................................... 25512.6.1 DNA Hybridization ......................................................................................................... 255 12.6.2 PCR-Based Techniques ................................................................................................... 25612.6.2.1 Sequencing of PCR Products ........................................................................... 257 12.6.2.2 Species-Specic PCR ...................................................................................... 257 12.6.2.3 Species-Specic Multiplex PCR ...................................................................... 258 12.6.2.4 PCR-Restriction Fragment Length Polymorphism .......................................... 259 12.6.2.5 PCR-Random Amplied Polymorphic DNA .................................................. 259 12.6.2.6 PCR-Single-Strand Conformation Polymorphism .......................................... 26012.6.3 Real-Time PCR ................................................................................................................ 260 12.6.3.1 Intercalating Dyes .............................................................................................261 12.6.3.2 Oligoprobe-Based Chemistries ........................................................................ 26212.7 Conclusion .................................................................................................................................... 267 References .............................................................................................................................................. 268techniques could offer a potential to identify the animal species because of the higher stability of DNA molecules in thermal processing conditions compared to proteins and their high specicity to all types of cells. Polymerase chain reaction (PCR) is a fast, sensitive, and highly specic technique, and it could be an alternative to the protein-based methods. However, when a conventional PCR technique is used, it only allows qualitative identication of the species, not quantitative identication. Nowadays, real-time PCR technique is a very popular tool for the species identication and quantication because of its high sensitivity and specicity, larger dynamic detection range, and less carryover contamination. In this respect, real-time PCR method now appears to be the most effective and robust technique for the identi-cation and quantication of trace quantities of different animal species, even in complex foods. Consequently, advances in analytical techniques constantly offer new possibilities for meat species identication. However, the recognition of such techniques by food control laboratories is inuenced by several factors such as their sensitivity, specicity, cost, rapidity, reliability, etc. In this chapter, we will describe a wide range of techniques, some of which are currently in practice.
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