A filtration-assisted approach to enhance optical detection of analytes and its application in food matrices

Enhancing analysis of neo-formed contaminants in two relevant food global commodities: Coffee and cocoa

Neo-formed contaminants (NFCs) are common in many foods, especially those subjected to high-temperature processing. Among these contaminants, products arising from the Maillard reaction, sugar reduction, thermal degradation of polyphenols and lipid oxidation, including acrylamide, furan, furfuryl alcohol, and hydroxymethylfurfural, are consistently linked to potential neoplastic effects. NFCs are found in globally traded commodities like coffee and cocoa, posing a significant risk due to their frequent consumption by consumers. A direct correlation exists between consumption frequency, exposure levels, and health risks. Hence, it's crucial to establish reliable methods to determine levels in both matrices, aiming to mitigate their formation and minimise risks to consumers. This review offers a comprehensive examination, discussion, and identification of emerging trends and opportunities to enhance existing methodologies for extracting and quantifying NFCs in coffee and cocoa. By presenting an in-depth analysis of performance parameters, we aim to guide the selection of optimal extraction techniques for quantifying individual NFCs. Based on the reviewed data, headspace extraction is recommended for furan, while solid and dispersive solid phase extractions are preferred for acrylamide when quantified using gas and liquid chromatography, respectively. However, it is worth noting that the reported linearity tests for certain methods did not confirm the absence of matrix effects unless developed through standard addition, leading to uncertainties in the reported values. There is a need for further research to verify method parameters, especially for determining NFCs like furfuryl alcohol. Additionally, optimising extraction and separation methods is essential to ensure complete compound depletion from samples. Ideally, developed methods should offer comprehensive NFC determination, reduce analysis time and solvent use, and adhere to validation parameters. This review discusses current methods for extracting and quantifying NFCs in coffee and cocoa, highlighting emerging trends and emphasising the need to improve existing techniques, especially for compounds like furfuryl alcohol.

Colorimetric Sensor Array for Identification of Proteins and Classification of Metabolic Profiles under Various Osmolyte Conditions

Rapid and efficient detection and identification of proteins hold great promise in medical diagnostics, treatment of different diseases, and proteomics. Here, we present a simple colorimetric sensor array for the differentiation of proteins in various osmolyte solutions. Osmolytes have different influences on the conformation of proteins, which have differential binding to silver nanoparticles, resulting in color changes. The sensor array shows unique color change patterns for each of the 19 proteins, allowing unambiguous identification. Very interestingly, the differentiation of 19 proteins is related to their molecular weight. Moreover, the sensor array can be used to identify protein mixtures, thermal denaturized proteins, and unknown protein samples. Finally, the sensor array can also analyze the plasma or liver samples of the four groups of salt-sensitive rats fed with different diets, indicating that it has the potential for the classification of metabolic profiles.

A portable kit based on thiol-ene Michael addition for acrylamide detection in thermally processed foods

Accurate, sensitive, and selective analysis of acrylamide generated in thermally processed foods is of great significance for food safety. Herein, a novel acrylamide sensing platform is designed for both sensitive on-site colorimetric analysis and accurate UV-vis spectroscopy quantification, by integrating thiol-ene Michael addition with gold nanoparticles-mediated catalytical oxidation. The Michael addition reaction between acrylamide and glutathione efficiently alleviates glutathione-induced catalytic activity inhibition of gold nanoparticles, evoking the chromogenic reaction of H₂O₂-mediated 3,3',5,5'-tetramethylbenzidine. With increasing the concentration of acrylamide, the oxidation of 3,3',5,5'-tetramethylbenzidine is accelerated, presenting a series of shades from colorless to blue. The sensing platform exhibits excellent detection performance of acrylamide in the range of 0.5-175 μM with a detection limit of 0.16 μM, and is successfully employed in food samples. Especially, a portable assay kit based on the proposed platform is developed for visual determination of acrylamide, opening an avenue for smart sensors of food safety hazards.

Nanomaterials Enabled and Bio/Chemical Analytical Sensors for Acrylamide Detection in Thermally Processed Foods: Advances and Outlook

Acrylamide, a food processing contaminant with demonstrated genotoxicity, carcinogenicity, and reproductive toxicity, is largely present in numerous prominent and commonly consumed food products that are produced by thermal processing methods. Food regulatory bodies such as the U.S. Food and Drug Administration (U.S. FDA) and European Union Commission regulations have disseminated various acrylamide mitigation strategies in food processing practices. Hence, in the wake of such food and public health safety efforts, there is a rising demand for economic, rapid, and portable detection and quantification methods for these contaminants. Since conventional quantification techniques like liquid chromatography-mass spectrometry (LC-MS) and gas chromatography-mass spectrometry (GC-MS) methods are expensive and have many drawbacks, sensing platforms with various transduction systems have become an efficient alternative tool for quantifying various target molecules in a wide variety of food samples. Therefore, this present review discusses in detail the state of robust, nanomaterials-based and other bio/chemical sensor fabrication techniques, the sensing mechanism, and the selective qualitative and quantitative measurement of acrylamide in various food materials. The discussed sensors use analytical measurements ranging from diverse and disparate optical, electrochemical, as well as piezoelectric methods. Further, discussions about challenges and also the potential development of the lab-on-chip applications for acrylamide detection and quantification are entailed at the end of this review.