Food allergen analysis: A review of current gaps and the potential to fill them by matrix-assisted laser desorption/ionization.

Food allergy remains a public health, business, and regulatory challenge. Risk analysis (RA) and risk management (RM) of food allergens are of great importance and analysis for food allergens is necessary for both. The current workhorse techniques for allergen analysis (enzyme linked immunosorbent assay [ELISA] and real-time polymerase chain reaction) exhibit recognized challenges including variable and antibody specific responses and detection of species DNA rather than allergen protein, respectively. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) enables protein identification, with potential for multiplex analysis and traceability to the System of International units (SI), aiding global measurement standardization. In this review, recent literature has been systematically reviewed to assess progress in LC-MS/MS and define the potential and benefits of matrix-assisted laser desorption/ionization-time-of-flight MS (MALDI-ToF-MS) technology for allergen analysis. MALDI-ToF-MS of initially intact protein is already applied to verify in silico-derived peptide sequences for LC-MS/MS analysis. We describe the origins of MALDI and its future perspectives, including affinity bead-assisted assays coupled to MALDI. Based on the proliferation of reliable and reproducible MALDI-based clinical applications, the technique should emulate the detection capability (sensitivity) of established allergen detection techniques, whilst reducing technical support and having equivalent multiplexing potential to competing techniques, for example, LC-MS/MS and ELISA. Although unlikely to offer inherent SI traceability, MALDI-based allergen analysis will complement existing MS approaches for allergens. Affinity bead-MALDI appears capable of higher throughput at lower cost per sample than almost any existing technique, enabling repeated sub-sampling as a way to reduce representative sampling issues.

Critical Review of Analytical and Bioanalytical Verification of the Authenticity of Coffee.

BACKGROUND: The driving factors for the commercial adulteration of coffee are reviewed. OBJECTIVE: Methods have been assessed for the identification of the most common materials used to adulterate coffee by dilution, to establish the geographic origins, the genotypes of beans, and to assess the authenticity of Kopi Luwak coffee. METHOD: The literature was surveyed manually and electronically from 1820 to 2018. RESULTS: A flow diagram has been developed to summarize the best approaches to deal with the authentication of coffee. CONCLUSIONS: Encouragement is given to the interlaboratory validation of spectroscopic approaches, the exploration of civet cat deoxyribonucleic acid for the identification of Kopi Luwak, and the development of appropriately large and well-curated datasets of authenticity information across multiple techniques. HIGHLIGHTS: The current analytical difficulties in the authentication of coffee are highlighted and suggestions made to improve the situation.

Chondroitin Sulfate: A Critical Review of Generic and Specific Problems in Its Characterization and Determination-An Exemplar of a Material with an Unknown or Variable Composition (UVCB).

This review discusses the criteria for the selection of appropriate reference samples of chondroitin sulfate (CS) and the properties and specific problems of analytical methods for CS, namely titration with cetylpyridinium chloride; various separations; and UV-Vis, NMR, MS, and IR spectroscopies. Suggestions are put forward with regard to acceptable protocols for manufactures' and for official/referee analysts for the analysis of CS in products.

Towards absolute quantification of allergenic proteins in food--lysozyme in wine as a model system for metrologically traceable mass spectrometric methods and certified reference materials.

Current routine food allergen quantification methods, which are based on immunochemistry, offer high sensitivity but can suffer from issues of specificity and significant variability of results. MS approaches have been developed, but currently lack metrological traceability. A feasibility study on the application of metrologically traceable MS-based reference procedures was undertaken. A proof of concept involving proteolytic digestion and isotope dilution MS for quantification of protein allergens in a food matrix was undertaken using lysozyme in wine as a model system. A concentration of lysozyme in wine of 0.95 +/- 0.03 microg/g was calculated based on the concentrations of two peptides, confirming that this type of analysis is viable at allergenically meaningful concentrations. The challenges associated with this promising method were explored; these included peptide stability, chemical modification, enzymatic digestion, and sample cleanup. The method is suitable for the production of allergen in food certified reference materials, which together with the achieved understanding of the effects of sample preparation and of the matrix on the final results, will assist in addressing the bias of the techniques routinely used and improve measurement confidence. Confirmation of the feasibility of MS methods for absolute quantification of an allergenic protein in a food matrix with results traceable to the International System of Units is a step towards meaningful comparison of results for allergen proteins among laboratories. This approach will also underpin risk assessment and risk management of allergens in the food industry, and regulatory compliance of the use of thresholds or action levels when adopted.