Exposure assessment of chemicals from packaging materials in foods: review

It is recognised that chemicals from packaging and other foodcontact materials can migrate into the food itself and thus be ingested by the consumer. The monitoring of this migration has become an integral part of ensuring food safety. This article reviews the current knowledge on the food safety hazards associated with packaging materials together with the methodologies used in the assessment of consumer exposure to these hazards. Special attention is given to the most promising approaches for exposure assessment and to the technical and other barriers which need addressing

Application of a liquid chromatographic method for the determination of phenolic compounds and furans in fortified wines

Fortified wines which suffer extended periods of wood ageing develop characteristics which in many cases define the product. An important component of this style is contributed by the specific phenolic compounds and furans which are either extracted from the wood or formed during the barrel ageing process. An HPLC method is presented here for the determination of phenolic compounds and furans in wood aged fortified wines. The method employed involved direct injection with no sample pre-treatment, separation on a RP C18 column in a single run and detection with a diode array detector. In this way up to 28 compounds from various phenolic groups (hydroxybenzoic acids, hydroxycinnamic acids, phenolic aldehydes, coumarins, ¯avan-3-ols, ¯avonol aglycones and other compounds involved in browning reactions in food systems (furans and pyranones) could be separated and determined. Of these, 10 phenolic compounds, gallic acid, protocatechuic acid, p-coumaric acid, ca eic acid, chlorogenic acid, ellagic acid, vanillic acid, syringic acid, p-hydroxybenzaldehyde, myricetin, and two furans; furfural, 5-hydroxymethyl-2-furaldehyde, were determined in forti®ed and similar wood aged wines. Three other compounds, a chlorogenic acid isomer, vanillin and resorcinol, were also tentatively identified in these wine type

Informação sobre nutrição e alimentação – o que devemos comer

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Enhancement of apparent resistance to ethanol in Lactobacillus hilgardii

The survival of Lactobacillus hilgardii, a highly ethanol-tolerant organism, after an ethanol challenge at 25% (v/v) for 10 min, increased by several log cycles when cells, grown in the absence of ethanol, were pre-treated with 10% (v/v) ethanol, 15% (v/v) methanol or 2% (v/v) butanol for 4 h. A temperature upshift (25 to 40°C) before ethanol challenge demonstrated a similar enhancement of apparent resistance to ethanol. Ethanol shock enhanced apparent resistance to methanol, butanol and heat challenges. The addition of chloramphenicol to cells prior to any pre-treatment did not significantly diminish the increase in ethanol tolerance, suggesting that de novo protein synthesis is not required for induced tolerance in this organis

Alcohols, esters and heavy sulphur compounds production by pure and mixed cultures of apiculate wine yeasts

Strains of Hanseniaspora uvarum, Hanseniaspora guilliermondii and Saccharomyces cerevisiae were used as pure or mixed starter cultures in commercial medium, in order to compare their kinetic parameters and fermentation patterns. In pure and mixed cultures, yeasts presented similar ethanol yield and productivity. Pure cultures of H. uvarum and S. cerevisiae showed a specific growth rate of 0.38 h⁻¹; however, this value decreased when these yeasts were grown in mixed cultures with H. guilliermondii. The specific growth rate of pure cultures of H. guilliermondii was 0.41 h⁻⁻¹ and was not affected by growth of other yeasts. H. guilliermondii was found to be the best producer of 2-phenylethyl acetate and 2-phenylethanol in both pure and mixed cultures. In pure cultures, H. uvarum led to the highest contents of heavy sulphur compounds, but H. guilliermondii and S. cerevisiae produced similar levels of methionol and 2-methyltetrahydrothiophen-3-one. Growth of apiculate yeasts in mixed cultures with S. cerevisiae led to amounts of 3-methylthiopropionic acid, acetic acid-3-(methylthio)propyl ester and 2- methyltetrahydrothiophen-3-one similar to those obtained in a pure culture of S. cerevisiae; however, growth of apiculate yeasts increased methionol contents of fermented media

Factors influencing the production of volatile phenols by wine lactic acid bacteria

This work aimed to evaluate the effect of certain factors on the production of volatile phenols from the metabolism of p-coumaric acid by lactic acid bacteria (LAB) (Lactobacillus plantarum, L. collinoides and Pediococcus pentosaceus). The studied factors were: pH, L-malic acid concentration, glucose and fructose concentrations and aerobic/anaerobic conditions. It was found that, in the pH range of 3.5 to 4.5, the higher the pH the greater the production of volatile phenols. This behaviour is correlated with the effect of pH on bacterial growth. Increasing levels of L-malic acid in the medium diminished the production of 4-vinylphenol (4VP) and stimulated the production of 4-ethylphenol (4EP) by L. plantarum NCFB 1752 and L. collinoides ESB 99. The conversion of 4VP into 4EP by the activity of the vinylphenol reductase may be advantageous to the cells in the presence of L-malic acid, presumably due to the generation of NAD(+), a cofactor required by the malolactic enzyme. Relatively high levels of glucose (20 g/L) led to an almost exclusive production of 4VP by L. plantarum NCFB 1752, while at low concentrations (<= 5 g/L), 4EP is mainly or solely produced. Part of the glucose may be diverted to the production of mannitol as an alternative pathway to regenerate NAD+. This is corroborated by the experiments done with fructose, a compound that can be used as an electron acceptor by some bacteria becoming reduced to mannitol. In anaerobiosis, the reduction of 4VP into 4EP is clearly favoured, which is consistent with the need to increase the availability of NAD(+) in these conditions. This study shows that the amount and the ratio 4VP/4EP produced by LAB are greatly affected by certain environmental and medium composition factors. The behaviour of the bacteria seems to be driven by the intracellular NAD(+)/NADH balance.info:eu-repo/semantics/acceptedVersio

Automated detection of galaxy-scale gravitational lenses in high resolution imaging data

Lens modeling is the key to successful and meaningful automated strong galaxy-scale gravitational lens detection. We have implemented a lens-modeling "robot" that treats every bright red galaxy (BRG) in a large imaging survey as a potential gravitational lens system. Using a simple model optimized for "typical" galaxy-scale lenses, we generate four assessments of model quality that are used in an automated classification. The robot infers the lens classification parameter H that a human would have assigned; the inference is performed using a probability distribution generated from a human-classified training set, including realistic simulated lenses and known false positives drawn from the HST/EGS survey. We compute the expected purity, completeness and rejection rate, and find that these can be optimized for a particular application by changing the prior probability distribution for H, equivalent to defining the robot's "character." Adopting a realistic prior based on the known abundance of lenses, we find that a lens sample may be generated that is ~100% pure, but only ~20% complete. This shortfall is due primarily to the over-simplicity of the lens model. With a more optimistic robot, ~90% completeness can be achieved while rejecting ~90% of the candidate objects. The remaining candidates must be classified by human inspectors. We are able to classify lens candidates by eye at a rate of a few seconds per system, suggesting that a future 1000 square degree imaging survey containing 10^7 BRGs, and some 10^4 lenses, could be successfully, and reproducibly, searched in a modest amount of time. [Abridged]Comment: 17 pages, 11 figures, submitted to Ap

Lowering costs of microbial cellulose

We have been conducting research with Acetobacter xylinium for microbial conversion of sugars to cellulose. A rotating disk biological contactor should lower costs considerably because its production rates are greater than for the usual method of surface culture. Another major cost saving comes from replacing expensive sugars in the medium with sugars derived from wastes. Extracts of spent grapes from wastes of Portuguese wine factories supply suitable sugars for good production of microbial cellulose

The antimicrobial effect of wine on Listeria innocua in a model stomach system

A model stomach, containing a food matrix and a synthetic gastric Xuid, was used to study the bactericidal eVect of ingested wine on Listeria innocua. Volumes of wine equivalent to the ingestion of one glass and half a bottle, led, over a period of less than 2 h, to a reduction of 3 and 4 logarithmic cycles of the initial population respectively. The inXuence of ethanol and organic acids, wine constituents with known antimicrobial properties, was investigated. Ethanol exhibited a higher bactericidal eVect than the mixture of the main wine organic acids. When testing the organic acids separately, malic and lactic acids were found to have the strongest eVect. The combination of ethanol with the organic acids acted synergistically but to a lesser extent than wine itself. The results suggest that the ingestion of wine during a meal may diminish the quantity of Listeria persisting further in the alimentary tract

Building on scientific excellence via sharing of scientific expertise - The case study of food safety

Many of the difficulties faced nowadays by society at large in maintaining a safe food supply can be effectively addressed by more and (preferably) better science. However, excellence in science will become more and more dependent on sharing of data and expertise - the nuclear idea emphasized in this viewpoint article, which conveys the major points presented and discussed by the senior author in the (invited) opening plenary lecture delivered at EFSA 5th anniversary scientific forum. Data and knowledge are usually shared within the scientific community itself - and are typically aimed at peers; however, the associated citing metrics do not often correlate with their applicability and usefulness. Funding bodies have for long recognized the value of networking and crossbreeding among scientists - in reinforcing complementarities and promoting synergies. Furthermore, these bodies have had a major effect in driving food scientists reach out of their cocooned, narrow communities toward embracing a wider spectrum of disciplines (e.g. in social and economic sciences). Web-supported databases of e.g. risk data and pathogen sequences have also revolutionized access to, and use of knowledge. Finally, a number of formal trans-European platforms have been launched by private stakeholders to promote sharing. In all cases, the thrust is to be put on trust - that what is shared is genuine and valid, and will not be subsequently adulterated or used inappropriately. Willingness to engage in free circulation of information and expertise will determine the extent of effective sharing on the long run, and of excellence of science derived therefrom - which is ultimately developed for the well-being and safety of the citizen, seen first of all as a food consumer