 Many atmospheric chemicals occur in the gas phase as well as in liquid cloud droplets and aerosol particles Therefore, it is necessary to understand the distribution between the phases According to Henry's law, the equilibrium ratio between the abundances in the gas phase and in the aqueous phase is constant for a dilute solution Henry's law constants of trace gases of potential importance in environmental chemistry have been collected and converted into a uniform format The compilation contains 17 350 values of Henry's law constants for 4632 species, collected from 689 references It is also available at http://wwwhenrys-laworg 

/pdf/compilation-of-henry-s-law-constants-version-4-0-for-water-58il9q0ogv.pdf

Compilation of Henry's law constants (version 4.0) for water as solvent

Key odorants in various cheese types as determined by gas chromatography-olfactometry

Mycotoxins are fungal metabolites commonly occurring in food, which pose a health risk to the consumer. Maximum levels for major mycotoxins allowed in food have been established worldwide. Good agricultural practices, plant disease management, and adequate storage conditions limit mycotoxin levels in the food chain yet do not eliminate mycotoxins completely. Food processing can further reduce mycotoxin levels by physical removal and decontamination by chemical or enzymatic transformation of mycotoxins into less toxic products. Physical removal of mycotoxins is very efficient: manual sorting of grains, nuts, and fruits by farmers as well as automatic sorting by the industry significantly lowers the mean mycotoxin content. Further processing such as milling, steeping, and extrusion can also reduce mycotoxin content. Mycotoxins can be detoxified chemically by reacting with food components and technical aids; these reactions are facilitated by high temperature and alkaline or acidic conditions. Detoxification of mycotoxins can also be achieved enzymatically. Some enzymes able to transform mycotoxins naturally occur in food commodities or are produced during fermentation but more efficient detoxification can be achieved by deliberate introduction of purified enzymes. We recommend integrating evaluation of processing technologies for their impact on mycotoxins into risk management. Processing steps proven to mitigate mycotoxin contamination should be used whenever necessary. Development of detoxification technologies for high-risk commodities should be a priority for research. While physical techniques currently offer the most efficient post-harvest reduction of mycotoxin content in food, biotechnology possesses the largest potential for future developments.

/pdf/impact-of-food-processing-and-detoxification-treatments-on-2974len175.pdf

Impact of food processing and detoxification treatments on mycotoxin contamination.

Selenium is regulated in the body to maintain vital selenoproteins and to avoid toxicity. When selenium is limiting, cells utilize it to synthesize the selenoproteins most important to them, creating a selenoprotein hierarchy in the cell. The liver is the central organ for selenium regulation and produces excretory selenium forms to regulate whole-body selenium. It responds to selenium deficiency by curtailing excretion and secreting selenoprotein P (Sepp1) into the plasma at the expense of its intracellular selenoproteins. Plasma Sepp1 is distributed to tissues in relation to their expression of the Sepp1 receptor apolipoprotein E receptor-2, creating a tissue selenium hierarchy. N-terminal Sepp1 forms are taken up in the renal proximal tubule by another receptor, megalin. Thus, the regulated whole-body pool of selenium is shifted to needy cells and then to vital selenoproteins in them to supply selenium where it is needed, creating a whole-body selenoprotein hierarchy.

Regulation of Selenium Metabolism and Transport

Background As minerals have diverse functionalities and potentials in the body's metabolism and homeostasis, deficiency of these bioactive constituents can result in an abundant incidence of common disorders and disease symptoms. Maintenance knowledge of the mineral content in terms of safe food fortification and processing techniques can significantly increase their absorption and bioavailability rate. Scope and approach This overview mainly discusses current investigations about the identification of high-available sources and remarkable functions of mineral elements, quantification methods for the bioavailability assessment, and influence of different processing practices and usual fortification strategies on mineral content and quality of staple food products. Key findings and conclusions The most dominant minerals to fortify various food preparations are iron, calcium, zinc and iodine. Utilization of isotopic approaches can sensitively determine the bioavailability values of food minerals. Modern processing techniques (e.g., high pressure and sonication) compared with the conventional processes have lower negative impacts on the content of micro- and macro-minerals. Accumulation of mineral elements in the edible tissues of crops using agrobiotechnological techniques (e.g., gene overexpression and activation control) and their direct fortification into formulation of processed foods along with nanoencapsulation could enhance the concentration and bioaccessibility of these bioactive ingredients.

The importance of minerals in human nutrition: Bioavailability, food fortification, processing effects and nanoencapsulation

A new headspace-GC-sniffing method is proposed. Using a recently developed headspace cell, the vapor phase is collected under conditions that mimic well those of an aroma above a food. Data treatment is based on detection frequency, rather than on perceived intensity or successive dilutions as used in other approaches. Repeatability appears satisfactory, and independent panels are even able to generate similar aromagrams, without training prior to the analysis. Using a minimum of six assessors, this technique seems to be more reliable than classical ones. To compare detection frequencies between two aromagrams, an estimation of the least significant difference is given. A theoretical justification of this approach is suggested, on the basis of determination of detection thresholds. Keywords: Headspace-GC-sniffing; impact odorants; detection frequency

Hyphenated Headspace-Gas Chromatography-Sniffing Technique: Screening of Impact Odorants and Quantitative Aromagram Comparisons

As considerable inconsistencies are found in the literature regarding the influence of roasting and subsequent operations on the ochratoxin A (OTA) content of green coffee, experiments were undertaken to assess the evolution of OTA along an industrial soluble coffee manufacturing line. Both the variability and the amount of OTA naturally present in a lot of Thai Robusta green coffee were drastically reduced during soluble coffee manufacture. A small proportion of OTA was eliminated during green coffee cleaning, but the most significant reduction took place during roasting. The roast and ground coffee contained only 16% of the OTA originally present in the green coffee. Two phenomena are responsible for the elimination of OTA during roasting: a thermal degradation and a removal with chaff. Thermal degradation is the most important route of elimination, with <20% accounted for by the chaff. A further 20% reduction was observed during soluble coffee manufacture, so that the powder contained only 13% of the OTA initially present in the green beans.

Behavior of ochratoxin A during green coffee roasting and soluble coffee manufacture.

A survey of partition coefficient values reported in the literature showed numerous discrepancies. These could be attributed to technical problems encountered during headspace measurements. Consequently, a novel method based on a combination of static headspace sampling and dynamic headspace traps was developed. The new method also includes determination of partition coefficients independently of the concentration of the reference. Once the partition coefficient is known, a simple calibration of the gas phase constituents can be performed. This headspace quantification method does not require addition of a standard. Estimation of variance showed the method to be accurate (0.5-15%, depending on component and matrix). A model mixture of flavors was investigated by the new method. Varying the concentration of one compound had no effect on the rest of the aroma profile. Small differences in the aroma profile due to changes in the matrix were investigated as exemplified by alterations in flavor retention observed when water, lipids, or emulsions were used as the solvent.

Determination of Partition Coefficients and Quantitation of Headspace Volatile Compounds

The present study was designed to determine the apparent absorption and retention of the inorganic Se compounds SeO 3 2 and SeO 4 2- , which are commonly used for Se fortification of clinical nutrition products and infant formulas. Ten healthy men were fed a milk-based formula labelled with 40 μg Se as 74SeO32 or 76 SeO 4 2 on two consecutive days using a randomised crossover design. Se stable-isotope analysis of 9 d complete collections of urine and faeces was used to calculate apparent Se absorption and retention. Se retention from 74 SeO 3 2 (41.0 (SD 8.4) %) and from 76 SeO 4 2- (46.0 (SD 7.9) %) was not significantly different (P > 0.05). However, Se absorption was significantly higher from SeO 4 2 than from SeO 3 2 (91.3 (SD 1.4) % ν. 50.2 (SD 7.8) %, P < 0.05). Urinary excretion of the administered dose was 9.2 (SD 1.8) % for 74 SeO 3 2- and 45.3 (SD 8.2) % for 76 SeO 4 2- (P < 0.05). Urinary Se excretion kinetics differed significantly for the two Se compounds; 90 % of the total urinary Se was excreted after 121 h for 74 SeO 3 2 and after 40 h for 76 SeO 4 2 (P < 0.05). These results suggest that although Se absorption and urinary excretion differ for SeO 3 2- and SeO 4 2 both Se compounds are equally well retained when administered at a relatively low dose (40 μg Se). The nutritional impact of Se fortification of foods would thus be expected to be similar when SeO 4 2 or SeO 3 2 are used.

/pdf/selenium-absorption-and-retention-from-a-selenite-or-wkz3i3r7x8.pdf

Rafael Muñoz-Box

Papers

Hyphenated Headspace-Gas Chromatography-Sniffing Technique: Screening of Impact Odorants and Quantitative Aromagram Comparisons

Behavior of ochratoxin A during green coffee roasting and soluble coffee manufacture.

Determination of Partition Coefficients and Quantitation of Headspace Volatile Compounds

Selenium absorption and retention from a selenite- or selenate-fortified milk-based formula in men measured by a stable-isotope technique.

Hyphenated headspace-gas chromatography-sniffing technique