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Quality checks, assessments, and the assurance of food products, raw materials, and food ingredients is critically important to ensure the safeguard of foods of high quality for safety and public health. Nevertheless, quality checks, assessments, and the assurance of food products along distribution and supply chains is impacted by various challenges. For instance, the development of portable, sensitive, low-cost, and robust instrumentation that is capable of real-time, accurate, and sensitive analysis, quality checks, assessments, and the assurance of food products in the field and/or in the production line in a food manufacturing industry is a major technological and analytical challenge. Other significant challenges include analytical method development, method validation strategies, and the non-availability of reference materials and/or standards for emerging food contaminants. The simplicity, portability, non-invasive, non-destructive properties, and low-cost of NIR spectrometers, make them appealing and desirable instruments of choice for rapid quality checks, assessments and assurances of food products, raw materials, and ingredients. This review article surveys literature and examines current challenges and breakthroughs in quality checks and the assessment of a variety of food products, raw materials, and ingredients. Specifically, recent technological innovations and notable advances in quartz crystal microbalances (QCM), electroanalytical techniques, and near infrared (NIR) spectroscopic instrument development in the quality assessment of selected food products, and the analysis of food raw materials and ingredients for foodborne pathogen detection between January 2019 and July 2020 are highlighted. In addition, chemometric approaches and multivariate analyses of spectral data for NIR instrumental calibration and sample analyses for quality assessments and assurances of selected food products and electrochemical methods for foodborne pathogen detection are discussed. Moreover, this review provides insight into the future trajectory of innovative technological developments in QCM, electroanalytical techniques, NIR spectroscopy, and multivariate analyses relating to general applications for the quality assessment of food products.

Volatile organic compounds (VOCs) that evaporate under standard atmospheric conditions are of growing concern. This is because it is well established that VOCs represent major contamination risks since release of these compounds into the atmosphere can contribute to global warming, and thus, can also be detrimental to the overall health of worldwide populations including plants, animals, and humans. Consequently, the detection, discrimination, and quantification of VOCs have become highly relevant areas of research over the past few decades. One method that has been and continues to be creatively developed for analyses of VOCs is the Quartz Crystal Microbalance (QCM). In this review, we summarize and analyze applications of QCM devices for the development of sensor arrays aimed at the detection of environmentally relevant VOCs. Herein, we also summarize applications of a variety of coatings, e.g., polymers, macrocycles, and ionic liquids that have been used and reported in the literature for surface modification in order to enhance sensing and selective detection of VOCs using quartz crystal resonators (QCRs) and thus QCM. In this review, we also summarize novel electronic systems that have been developed for improved QCM measurements.

The quartz crystal microbalance (QCM) has been widely used in laboratory settings as an analytical tool for recognizing and discriminating biological and chemical molecules of interest. As a result, recent studies have shown there to be considerable attention in practical applications of the QCM technique beyond the laboratory. However, most commercial QCM instruments are not suitable for off-laboratory usage. For field-deployable applications and in situ detection, the development of a portable QCM measurement system achieving comparable performance to benchtop instruments is highly desired. In this paper, we describe the development of a fully customizable, miniaturized, battery-powered, and cost-efficient QCM system employing a phase-locked loop (PLL) electronic circuit-based QCM measurement system. The performance of this developed system showed a minimum frequency resolution of approximately 0.22 Hz at 0.1 s measurement time. This novel, miniaturized system successfully demonstrated an ability to detect two common volatile organic compounds (VOCs), methanol and dichloromethane (DCM), and the obtained results were comparable to responses from a commercially available benchtop instrument.

Doc number: 19 Abstract Background: The cytochrome P450s are monooxygenases that insert oxygen functionalities into a wide variety of organic substrates with high selectivity. There is interest in developing efficient catalysts based on the \"peroxide shunt\" pathway in the cytochrome P450s, which uses H2 O2 in place of O2 /NADPH as the oxygenation agent. We report on our initial studies using cytochrome c peroxidase (CcP) as a platform to develop specific \"peroxygenation\" catalysts. Results: The peroxygenase activity of CcP was investigated using 1-methoxynaphthalene as substrate. 1-Methoxynaphthalene hydroxylation was monitored using Russig's blue formation at standard reaction conditions of 0.50 mM 1-methoxynaphthalene, 1.00 mM H2 O2 , pH 7.0, 25°C. Wild-type CcP catalyzes the hydroxylation of 1-methoxynaphthalene with a turnover number of 0.0044 ± 0.0001 min-1 . Three apolar distal heme pocket mutants of CcP were designed to enhance binding of 1-methoxynaphthalene near the heme, constructed, and tested for hydroxylation activity. The highest activity was observed for CcP(triAla), a triple mutant with Arg48, Trp51, and His52 simultaneously mutated to alanine residues. The turnover number of CcP(triAla) is 0.150 ± 0.008 min-1 , 34-fold greater than wild-type CcP and comparable to the naphthalene hydroxylation activity of rat liver microsomal cytochrome P450. While wild-type CcP is very stable to oxidative degradation by excess hydrogen peroxide, CcP(triAla) is inactivated within four cycles of the peroxygenase reaction. Conclusions: Protein engineering of CcP can increase the rate of peroxygenation of apolar substrates but the initial constructs are more susceptible to oxidative degradation than wild-type enzyme. Further developments will require constructs with increased rates and selectivity while maintaining the stability of wild-type CcP toward oxidative degradation by hydrogen peroxide.