Effects of cola drinks on the morphology and elastic modulus of dentin

The mechanical and morphological degradation that human dentin undergoes after prolonged exposure in cola drinks was examined using nanoindentation and AFM. The elastic modulus of the dentin prior cola exposure was 18.28 ± 1.7 GPa, while after exposure it had decreased to 4.25 ± 1.4 GPa on the surface that was in direct contact with the drink, and to 13.38 ± 2.9 GPa on the surface that was in indirect contact with the drink. AFM documented the corrosion effects of the cola through topography images and histograms of the RMS roughness.     

Combination of analyte protectants to overcome matrix effects in routine GC analysis of pesticide residues in food matrixes

Analyte protectants were previously defined as compounds that strongly interact with active sites in the gas chromatographic (GC) system, thus decreasing degradation, adsorption, or both of coinjected analytes. In this study, we evaluated various combinations of promising analyte protectants for the volatility range of GC-amenable pesticides using GC/quadrupole mass spectrometry (MS) and 1-microL hot splitless injection for sample introduction. A mixture of ethylglycerol, gulonolactone, and sorbitol (at 10, 1, and 1 mg/mL, respectively, in the injected samples) was found to be the most effective in minimizing losses of susceptible analytes and significantly improving their peak shapes (due to reduction of peak tailing). When added to final sample extracts and matrix-free calibration standards alike, these analyte protectants induced a similar response enhancement in both instances, resulting in effective equalization of the matrix-induced response enhancement effect even after a large number of fruit and vegetable extract injections. As compared to matrix-matched standardization, the analyte protectant approach offers a more convenient solution to the problems associated with calibration in routine GC/MS analysis of pesticide residues and possibly other susceptible analyte types in diverse samples. Moreover, the use of analyte protectants also substantially reduced another adverse matrix-related effect caused by gradual build-up of nonvolatile matrix components in the GC system, thus improving ruggedness and, consequently, reducing need for frequent maintenance.     

Genetic variability in the RAGE gene: possible implications for nutrigenetics, nutrigenomics, and understanding the susceptibility to diabetic complications

Complex chemical processes called nonenzymatic glycation and glycoxidation are one of the interesting examples of potentially harmful interaction between nutrition and disease. This review summarizes factors influencing the extent of glycoxidation in health and disease and especially focuses on the role of genetic variability in "glycoxidation-related genes" in a disease and diet-related pathogenesis. Possible interaction between genetic variability in relevant loci and dietary advanced glycation end products (AGEs) is considered. As AGEs possess a wide range of chemical and biological effects, the interindividual functional variability in systems dealing with glycoxidation could have a significant nutrigenomic and nutrigenetic consequences.     

Traceability of olive oil based on volatiles pattern and multivariate analysis

An automated head-space solid-phase microextraction (HS-SPME)-based sampling procedure, coupled to gas chromatography–ion trap mass spectrometry (GC–ITMS), was developed and employed for fast characterisation of olive oil volatiles. In total, 914 samples were collected, over three production seasons, in north-western Italy—Liguria (n = 210) and other regions—in addition to the rest of Italy, Spain, France, Greece, Cyprus, and Turkey (n = 704) with the aim to distinguish, based on analytical (profiling) data, the olive oils labelled as “Ligurian” (protected denomination of origin region, PDO) from all the others (“non-Ligurian”). For the chemometric analysis, linear discriminant analysis (LDA) and artificial neural networks with multilayer perceptrons (ANN-MLP) were tested. Employing LDA, somewhat lower recognition (81.4%) and prediction (61.7%) abilities were obtained. The classification model was significantly improved using ANN-MLP. Under these conditions, the recognition (90.1%) and prediction (81.1%) abilities were achieved. The diagnostic value of the data obtained by one-dimensional GC–ITMS were compared with those generated by two-dimensional gas chromatography–time-of-flight mass spectrometry (GC × GC–TOFMS), allowing a comprehensive analysis of olive oil volatiles.     

Assessment of chromium biostabilization in contaminated soils using standard leaching and sequential extraction techniques

The iron reducing microorganism Desulfuromonas palmitatis was evaluated as potential biostabilization agent for the remediation of chromate contaminated soils. D. palmitatis were used for the treatment of soil samples artificially contaminated with Cr(VI) at two levels, i.e. 200 and 500 mg kg^− 1. The efficiency of the treatment was evaluated by applying several standard extraction techniques on the soil samples before and after treatment, such as the EN12457 standard leaching test, the US EPA 3060A alkaline digestion method and the BCR sequential extraction procedure. The water soluble chromium as evaluated with the EN leaching test, was found to decrease after the biostabilization treatment from 13 to less than 0.5 mg kg^− 1 and from 120 to 5.6 mg kg^− 1 for the soil samples contaminated with 200 and 500 mg Cr(VI) per kg soil respectively. The BCR sequential extraction scheme, although not providing accurate estimates about the initial chromium speciation in contaminated soils, proved to be a useful tool for monitoring the relative changes in element partitioning, as a consequence of the stabilization treatment. After bioreduction, the percentage of chromium retained in the two least soluble BCR fractions, i.e. the “oxidizable” and “residual” fractions, increased from 54 and 73% to more than 96% in both soils.     

Application of Kluyveromyces marxianus, Lactobacillus delbrueckii ssp. bulgaricus and L. helveticus for sourdough bread making

The application of Kluyveromyces marxianus (IFO 288), Lactobacillus delbrueckii ssp. bulgaricus (ATCC 11842) and Lactobacillus helveticus (ATCC 15009) as starter cultures for sourdough bread making was examined. Production of lactic and acetic acids, bread rising, volatile composition, shelf-life and organoleptic quality of the sourdough breads were evaluated. The amount of starter culture added to the flour, the dough fermentation temperature and the amount of sourdough used were examined in order to optimise the bread making process. The use of mixed cultures led to higher total titratable acidities and lactic acid concentrations compared to traditionally made breads. Highest acidity (3.41 g lactic acid/kg of bread) and highest resistance to mould spoilage were observed when bread was made using 50% sourdough containing 1% K. marxianus and 4% L. delbrueckii ssp. bulgaricus. The use of these cultures also improved the aroma of sourdough breads, as shown by sensory evaluations and as revealed by GC–MS analysis.     

Quasi‐Bayesian Estimation of Time‐Varying Volatility in DSGE Models

We propose a novel quasi‐Bayesian Metropolis‐within‐Gibbs algorithm that can be used to estimate drifts in the shock volatilities of a linearized dynamic stochastic general equilibrium (DSGE) model. The resulting volatility estimates differ from the existing approaches in two ways. First, the time variation enters non‐parametrically, so that our approach ensures consistent estimation in a wide class of processes, thereby eliminating the need to specify the volatility law of motion and alleviating the risk of invalid inference due to mis‐specification. Second, the conditional quasi‐posterior of the drifting volatilities is available in closed form, which makes inference straightforward and simplifies existing algorithms. We apply our estimation procedure to a standard DSGE model and find that the estimated volatility paths are smoother compared to alternative stochastic volatility estimates. Moreover, we demonstrate that our procedure can deliver statistically significant improvements to the density forecasts of the DSGE model compared to alternative methods.     

Analysis of the fluorescence of mechanically processed defect-laden hexagonal boron nitride and the role of oxygen in catalyst deactivation

ABSTRACT

The use of hexagonal boron nitride (h-BN) as a non-metal heterogeneous catalyst has been a popular subject in research since the discovery of its catalytic properties in 2016. Previous work found that an activation step was necessary for producing an effective catalyst. Density functional theory (DFT) calculations indicate defect sites, such as nitrogen (V_N) and boron (V_B) vacancies, bind favourably to olefins, hydrogen, and oxygen. In particular, the visible fluorescence intensity of processed h-BN increased with the length of exposure to air. The fluorescence behaviour of dh-BN powders when exposed to air after exposure to species such as argon, propene, and carbon dioxide is presented. Density of state calculations for molecular and atomic oxygen bound to V_N and V_B show that this increase in fluorescence may be due to atomic oxygen binding to V_N. The fluorescence emission behaviour observed in dh-BN powders and its relationship to DOS of oxygen species bound to catalytically active defect sites provides a better understanding of potential deactivation modes for catalysts based on dh-BN.     

Dietary fibre from berry-processing waste and its impact on bread structure: a review

The structure and function of by-products of berry-processing industries are reviewed, with particular attention to dietary fibre (DF) and its effects in food products. The complex chemical composition and physicochemical characteristics of DF have been investigated and strategies for extraction of specific fractions that provide tailored technological and physiological functionality have been reviewed. The aim of this review is to describe in detail the structural composition and isolation methods of dietary fibre derived from berry by-products, and to explore their potential functionality in foods. The goal is to introduce DF from berry waste streams into the food chain, for which bread is a major vehicle. However, the appeal of bread lies in its aerated structure, for which DF is generally detrimental. The technological influence of DF on the formation and stabilization of the aerated structure of bread is therefore reviewed, in order to understand how to incorporate DF into bread while maintaining palatability. The aerated structure of bread is stabilized by two mechanisms: the gluten matrix and the liquid film surrounding bubbles. Incorporating DF successfully into bread requires understanding its interactions with both of these mechanisms. DF fractions from berries offer superior nutritional value compared to cereal fibre, potentially with less damage to bread structure, due to the higher proportion of soluble fibre. By-products from berry-processing industries could be used as a source of technologically and nutritionally distinctive DF to fabricate foods with enhanced nutritional value. © 2019 Society of Chemical Industry