Polymerase chain reaction techniques for food allergen detection

Food allergies represent an important health problem in industrialized countries. Undeclared allergenic foods as contaminants in food products pose a major risk for sensitized persons. Reliable detection and quantification methods for food allergens are necessary to ensure compliance with food labeling and improve consumer protection. The methods currently used for the detection of potential allergens in foods are to target either the allergen itself or a marker that indicates the presence of the offending food. As markers for the presence of potentially allergenic foods or ingredients, specific proteins or DNA fragments are targeted. In routine food analysis, the enzyme-linked immunosorbent assay (ELISA) and the polymerase chain reaction (PCR) in the form of a real-time PCR or in combination with an ELISA have been used. The availability, the characteristics, and some future aspects of DNA-based methods in the rapid and sensitive detection of potentially allergenic food constituents or contaminations are discussed in this review.     

Food safety assurance using methods of chemical analysis

A review of state-of-the-art methods of sample preparation and chemical analysis for the control of contaminants in foodstuffs and food raw materials is presented. The main achievements and performance characteristics of methods for the determination of pesticides and veterinary drugs, their metabolites, natural toxins, trace amounts of chemical elements, first of all toxic, allergens, food additives, and contaminants from packaging materials in foodstuffs and for the identification of falsifications by methods of chemical analysis are considered.     

The frontiers of mass spectrometry-based techniques in food allergenomics

In the last years proteomic science has started to provide an important contribution to the disclosure of basic aspects of food-related diseases. Among these, the identification of proteins involved in food allergy and their mechanism of activation of toxicity. Elucidation of these key issues requires the integration of clinical, immunological, genomic and proteomic approaches. These combined research efforts are aimed to obtain structural and functional information to assist the development of novel, more reliable and powerful diagnostic protocols alternative to the currently available procedures, mainly based on food challenge tests. Another crucial aspect related to food allergy is the need for methods to detect trace amounts of allergenic proteins in foods. Mass spectrometry is the only non-immunological method for high-specificity and high-sensitivity detection of allergens in foods. Nowadays, once provided the appropriate sample handling and the correct operative conditions, qualitative and quantitative determination of allergens in foods and ingredients can be efficiently obtained by MALDI-TOF-MS and LC-MS/MS methods, with limits of detection and quantification in the low-ppb range. The availability of accurate and fast alternatives to immunological ELISA tests may also enable the development of novel therapeutic strategies and food processing technologies to aid patients with food allergy or intolerance, and to support allergen labelling and certification processes, all issues where the role of proteomic science is emerging.     

Food analysis on microchip electrophoresis: An updated review

From 2008 to date, basically, single-cross microchip electrophoresis (ME) design has been used for food analysis with electrochemicaland laser-induced fluorescencedetection being the most commonprinciples coupled. In the last 4 years, the main outlines were: (i) the exploration of new analytes such as heavy metals, nitrite, micotoxins, microorganisms, and allergens; (ii) the development of electrokinetic microfluidic (bio-) sensors into microchip format for the detection of toxins; and interestingly (iii) although sample preparation is still performed off-chip, an important increase in works dealing with complicated food samples has been clearly noticed. Although microchip technology based on electrokinetics is emerging from important fields such as authentication of foods, detection of frauds, toxics, and allergens; the marriage between micro- and nanotechnologies and total integration approaches has not reached the expected impact in the field but it is still a great promise for the development of ME of new generations for food analysis.     

Biosensors for the analysis of microbiological and chemical contaminants in food

Increases in food production and the ever-present threat of food contamination from microbiological and chemical sources have led the food industry and regulators to pursue rapid, inexpensive methods of analysis to safeguard the health and safety of the consumer. Although sophisticated techniques such as chromatography and spectrometry provide more accurate and conclusive results, screening tests allow a much higher throughput of samples at a lower cost and with less operator training, so larger numbers of samples can be analysed. Biosensors combine a biological recognition element (enzyme, antibody, receptor) with a transducer to produce a measurable signal proportional to the extent of interaction between the recognition element and the analyte. The different uses of the biosensing instrumentation available today are extremely varied, with food analysis as an emerging and growing application. The advantages offered by biosensors over other screening methods such as radioimmunoassay, enzyme-linked immunosorbent assay, fluorescence immunoassay and luminescence immunoassay, with respect to food analysis, include automation, improved reproducibility, speed of analysis and real-time analysis. This article will provide a brief footing in history before reviewing the latest developments in biosensor applications for analysis of food contaminants (January 2007 to December 2010), focusing on the detection of pathogens, toxins, pesticides and veterinary drug residues by biosensors, with emphasis on articles showing data in food matrices. The main areas of development common to these groups of contaminants include multiplexing, the ability to simultaneously analyse a sample for more than one contaminant and portability. Biosensors currently have an important role in food safety; further advances in the technology, reagents and sample handling will surely reinforce this position.     

Electrochemical Biosensors in Food Safety: Challenges and Perspectives

Safety and quality are key issues for the food industry. Consequently, there is growing demand to preserve the food chain and products against substances toxic, harmful to human health, such as contaminants, allergens, toxins, or pathogens. For this reason, it is mandatory to develop highly sensitive, reliable, rapid, and cost-effective sensing systems/devices, such as electrochemical sensors/biosensors. Generally, conventional techniques are limited by long analyses, expensive and complex procedures, and skilled personnel. Therefore, developing performant electrochemical biosensors can significantly support the screening of food chains and products. Here, we report some of the recent developments in this area and analyze the contributions produced by electrochemical biosensors in food screening and their challenges.     

Lateral-flow immunoassays for mycotoxins and phycotoxins: a review

Natural toxin (for example mycotoxin and phycotoxin) contamination of food is of safety and economic concern, so much effort is devoted to the development of screening methods which enable the toxins to be continuously and widely monitored in food and feed. More generally speaking, rapid and non-instrumental assays for detection of a variety of food contaminants are generating ever-increasing scientific and technological interest because they enable high-throughput, economical, on-site monitoring of such contaminants. Among rapid methods for first-level screening of food contaminants, lateral-flow immunoassay (LFIA), also named immunochromatographic assay or immune-gold colloid immunoassay, has recently attracted scientific and industrial interest because of its attractive property of enabling very rapid, one-step, in-situ analysis. This review focuses on new aspects of the development and optimization of lateral-flow devices for mycotoxin and phycotoxin detection, including strategies for management of matrix interference and, particularly, for investigation of the improvements achieved by signal-enhancing strategies or by application of non-gold nanoparticle signal reporters.

Detection of microbial food contaminants and their products by capillary electromigration techniques

This work reviews the different analytical strategies based on capillary electromigration techniques developed for detecting microbial contaminants and their products in food matrices. Namely, this work presents an exhaustive and critical review, including works published till March 2007, on CE methods developed to detect and identify contaminants of microbial origin that represent a hazard to humans in foods. First, an overview on the strategies adopted for the analysis of intact microorganisms is presented. Next, CE methodologies based on the analysis of microbial constituents, including those based on genomics and proteomics approaches, are described. Finally, CE methods developed for detecting microbial toxins are discussed.     

Bioanalytical methods for food contaminant analysis

Foods are complex mixtures of lipids, carbohydrates, proteins, vitamins, organic compounds, and other naturally occurring substances. Sometimes added to this mixture are residues of pesticides, veterinary and human drugs, microbial toxins, preservatives, contaminants from food processing and packaging, and other residues. This milieu of compounds can pose difficulties in the analysis of food contaminants. There is an expanding need for rapid and cost-effective residue methods for difficult food matrixes to safeguard our food supply. Bioanalytical methods are established for many food contaminants such as mycotoxins and are the method of choice for many food allergens. Bioanalytical methods are often more cost-effective and sensitive than instrumental procedures. Recent developments in bioanalytical methods may provide more applications for their use in food analysis.     

Combining targeted and nontargeted data analysis for liquid chromatography/high‐resolution mass spectrometric analyses

Increasing importation of food and the diversity of potential contaminants have necessitated more analytical testing of these foods. Historically, mass spectrometric methods for testing foods were confined to monitoring selected ions (SIM or MRM), achieving sensitivity by focusing on targeted ion signals. A limiting factor in this approach is that any contaminants not included on the target list are not typically identified and retrospective data mining is limited. A potential solution is to utilize high‐resolution MS to acquire accurate mass full‐scan data. Based on the instrumental resolution, these data can be correlated to the actual mass of a contaminant, which would allow for identification of both target compounds and compounds that are not on a target list (nontargets). The focus of this research was to develop software algorithms to provide rapid and accurate data processing of LC/MS data to identify both targeted and nontargeted analytes. Software from a commercial vendor was developed to process LC/MS data and the results were compared to an alternate, vendor‐supplied solution. The commercial software performed well and demonstrated the potential for a fully automated processing solution.     

Determination of organic contaminants in food by capillary electrophoresis

This review addresses recent advances in the analysis of organic contaminants, such as antibiotics, pesticides, biological toxins, and food-borne pathogens, in foods by capillary electrophoresis (CE). Special attention is paid to those aspects that increase sensitivity and/or selectivity, such as sample extraction and concentration, on-line preconcentration techniques (stacking), affinity capillaries or/and specific detectors (laser induced fluorescence (LIF), mass spectrometry (MS)). The various CE modes used to separate the compounds and the quantification strategies are also examined. As a result, this work presents an updated overview on the principal applications of CE, together with a discussion of their main advantages and drawbacks, and an outline of future trends in the analysis of organic contaminants in food.     

Sample preparation techniques for the determination of trace residues and contaminants in foods

The determination of trace residues and contaminants in complex matrices, such as food, often requires extensive sample extraction and preparation prior to instrumental analysis. Sample preparation is often the bottleneck in analysis and there is a need to minimise the number of steps to reduce both time and sources of error. There is also a move towards more environmentally friendly techniques, which use less solvent and smaller sample sizes. Smaller sample size becomes important when dealing with real life problems, such as consumer complaints and alleged chemical contamination. Optimal sample preparation can reduce analysis time, sources of error, enhance sensitivity and enable unequivocal identification, confirmation and quantification. This review considers all aspects of sample preparation, covering general extraction techniques, such as Soxhlet and pressurised liquid extraction, microextraction techniques such as liquid phase microextraction (LPME) and more selective techniques, such as solid phase extraction (SPE), solid phase microextraction (SPME) and stir bar sorptive extraction (SBSE). The applicability of each technique in food analysis, particularly for the determination of trace organic contaminants in foods is discussed.     

Analytical methods for the detection of viruses in food by example of CCL-3 bioagents

This critical review presents challenges and strategies in the detection of viral contaminants in food products. Adenovirus, caliciviruses, enteroviruses, and hepatitis A are emerging contaminant viruses. These viruses contaminate a variety of food products, including fruits, vegetables, shellfish, and ready-to-eat processed foods. The diversity of targets and sample matrices presents unique challenges to virus monitoring that have been addressed by a wide array of processing and detection methods. This review covers sample acquisition and handling, virus recovery/concentration, and the determination of targets using molecular biology and mass-spectrometric approaches. The concentration methods discussed include precipitation, antibody-based concentration, and filtration; the detection methods discussed include microscopy, polymerase chain reaction, nucleic acid sequence-based amplification, and mass spectrometry.     

Detection of cholera toxin in seafood using a ganglioside-liposome immunoassay

Microbiological contamination of foods continues to be a major concern in public health. Biological toxins are one class of important contaminants that can cause various human diseases. Outbreaks related to contamination by biological toxins or toxin-producing microorganisms have made it extremely important to develop rapid (approximately 20 min), sensitive and cost-effective analytical methods. This paper describes the development of a sensitive bioassay for the detection of cholera toxin (CT) in selected seafood samples, using ganglioside-incorporated liposomes. In this study, the assays were run with food samples spiked with various concentrations of CT. The limit of detection (LOD) increased by a factor of about 10–20 in most food samples, compared with the LOD in the buffer system previously reported. However, the LOD of toxins in food samples (8 × 10–3 × 10³ fg/mL for CT) was still comparable to, or lower than, that previously reported for other assays. The results from this study demonstrate that the bioassays using ganglioside-liposomes can detect the toxin directly in the field screening of food samples rapidly, simply and reliably, without the need for complex instrumentation.     

Multiplex bioanalytical methods for food and environmental monitoring

Recent advances in miniaturization of analytical systems and newly emerging technologies offer platforms with greater automation and multiplexing capabilities than traditional biological binding assays. Multiplexed bioanalytical techniques provide control agencies and food industries with new possibilities for improved, more efficient monitoring of food and environmental contaminants. This review deals with recent developments in planar-array and suspension-array technologies, and their applications in detecting pathogens, food allergens and adulterants, toxins, antibiotics and environmental contaminants.     

Application of capillary electrophoresis-mass spectrometry for determining organic food contaminants and residues

Food contamination continues to be a serious problem around the world. Surveillance of chemical contaminants in foods is important not only for public health but also because of the negative economic impact of contamination. From the analytical perspective, analysis of contaminants in food is an extremely challenging area. There is a wide variety of questions, ranging from the quantification of extremely low levels of individual components to the detailed assessment and evaluation of the analytical technique possibilities. This review considers the applications of CE coupled to MS detection (CE-MS) for the analysis of organic contaminants in food. Analytical information on sample concentration techniques, as well as on the CE separation conditions and recoveries obtained from water and food are provided. Different sections include several fields of application, such as pesticides, drug residues, or toxic formed during food processing in different matrices. A number of tables report a comprehensive listing of CE-MS applications. As a result, this work presents an update overview on the principal application of CE-MS together with a discussion of their main advantages and drawbacks, and an outline of future trends on analysis of organic contaminants.     

3-MCPD in food other than soy sauce or hydrolysed vegetable protein (HVP)

This review gives an overview of current knowledge about 3-monochloropropane-1,2-diol (3-MCPD) formation and detection. Although 3-MCPD is often mentioned with regard to soy sauce and acid-hydrolysed vegetable protein (HVP), and much research has been done in that area, the emphasis here is placed on other foods. This contaminant can be found in a great variety of foodstuffs and is difficult to avoid in our daily nutrition. Despite its low concentration in most foods, its carcinogenic properties are of general concern. Its formation is a multivariate problem influenced by factors such as heat, moisture and sugar/lipid content, depending on the type of food and respective processing employed. Understanding the formation of this contaminant in food is fundamental to not only preventing or reducing it, but also developing efficient analytical methods of detecting it. Considering the differences between 3-MCPD-containing foods, and the need to test for the contaminant at different levels of food processing, one would expect a variety of analytical approaches. In this review, an attempt is made to provide an up-to-date list of available analytical methods and to highlight the differences among these techniques. Finally, the emergence of 3-MCPD esters and analytical techniques for them are also discussed here, although they are not the main focus of this review.     

Determination of additives and organic contaminants in food by CE and CEC

The application of CE to the analysis of additives and organic contaminants in food since 2001 has been reviewed. Additives included in the review are dyes, preservatives, antioxidants and sweeteners. Organic contaminants included in the review are pesticides, antibiotics and those produced during processing or cooking food. The review highlights the strategies and approaches adopted in making CE suitable for the determination of analytes at residue level and in complicated matrices.     

Present and future of expert systems in food analysis

This paper presents an overview of the most relevant contributions in the field of expert system (ES) applications in chemical analysis of foods, along with a critical discussion of future, would-be developments. It illustrates the possibilities offered as well as the fact that quality control laboratories should be aware of the power of artificial intelligence that modern computer technology affords. It is worth noting that the applications described are straightforward with a certain versatility and can, therefore, be implemented for other analytes and/or food samples. Special attention is devoted to the promising distributed knowledge-based systems due to their potential advantages over the existing centralized approaches, as inferred from a recent example of application to the on-line monitoring of some key chemical parameters in the course of a food production process. Short and middle term predictions concerning the potential of ES in food analysis are also made.     

Characterization of nutraceuticals and functional foods by innovative HPLC methods

In recent years there is a growing interest in food and food ingredient which may provide health benefits. Food as well as food ingredients containing health-preserving components, are not considered conventional food, but can be defined as functional food. To characterise such foods, as well as nutraceuticals specific, high sensitive and reproducible analytical methodologies are needed. In light of this importance we set out to develop innovative HPLC methods employing reversed phase narrow bore column and high-performance anion-exchange chromatographic methods coupled with pulsed amperometric detection (HPAEC-PAD), which are specific for carbohydrate analysis. The developed methods were applied for the separation and quantification of citrus flavonoids and to characterize fructooligosaccharide (FOS) and fructans added to functional foods and nutraceuticals.