Flame retardants in the serum of pet dogs and in their food

A previous study from our laboratory showed that pet cats had much higher serum levels of flame retardants compared to humans, despite sharing the same household environment. Dogs, on the other hand, are expected to have lower serum levels of flame retardants because they are metabolically better equipped to degrade these compounds. Thus, we hypothesized that dogs might be more similar to humans in their response to these environmental stressors and be better indicators of human exposures to these contaminants. Serum samples and their food were collected from 18 dogs and analyzed for PBDEs and other emerging flame retardants. The concentrations of PBDEs in dog serum and dog food averaged 1.8 ± 0.4 ng/g wet weight (ww) and 1.1 ± 0.2 ng/g ww, respectively. While the dog serum samples were dominated by the tetra to hepta BDE congeners, BDE-209 was the most abundant congener in the dog food. This difference in congener pattern was analyzed in terms of half-lives. Assuming food as the main exposure source, the average half-life in dog serum was 450 ± 170 days for the less brominated congeners and 2.3 ± 0.5 days for BDE-209. Dust was also considered as an additional exposure source, giving unreasonable residence times. In addition to PBDEs, other flame retardants, including Dechlorane Plus, decabromodiphenylethane, and hexabromocyclododecane, were identified in these samples.     

Effect of storage on chemical and sensory profiles of peanut pastes prepared with high‐oleic and normal peanuts

BACKGROUND: Peanut paste and peanut butter have high oil contents and are thus susceptible to developing rancidity and off‐flavours through lipid oxidation. Preservation of the chemical and sensory quality of these products is one of the main problems in the peanut industry. The purpose of this study was to compare the chemical and sensory stability of peanut paste prepared with high‐oleic peanuts (cv. Granoleico, GO‐P) with that of peanut paste prepared with normal peanuts (cv. Tegua, T‐P) from Argentina. RESULTS: Chemical (peroxide and p‐anisidine values and conjugated dienes) and sensory (roasted peanutty, oxidised and cardboard flavours) indicators of lipid oxidation were measured in peanut pastes stored at 4, 23 and 40 °C. Chemical indicator values and oxidised and cardboard flavours showed lower increments in GO‐P than in T‐P during storage. T‐P had significantly higher peroxide value than GO‐P. Roasted peanutty flavour showed a lower decrease in GO‐P. Peanut paste prepared with high‐oleic peanuts had four (at 4 °C), two (at 23 °C) and three (at 40 °C) times longer shelf‐life than peanut paste prepared with normal peanuts. CONCLUSION: These results indicate that high‐oleic Granoleico kernels provide peanut paste with higher protection against lipid oxidation. Copyright © 2010 Society of Chemical Industry     

Functionality of enterococci in meat products

The presence of enterococci in meat fermentation is a constant as reported in the literature. Despite the concern about pathogenicity of enterococci, recent studies point out that food and meat enterococci, especially Enterococcus faecium have a much lower pathogenicity potential than clinical strains. Enterococci possess a competitive advantage over other microbiota in meat fermentations, and many enterococci isolated from sausages have the ability to produce enterocins harbouring antimicrobial activity against pathogens and spoilage microorganisms of meat concern. The application of enterocins producing enterococci or their purified metabolites, as extra hurdles for preservation in sausage fermentation and in sliced-vacuum packed cooked meat products can be beneficial, preventing the outgrowth of Listeria monocytogenes and slime-producing lactic acid bacteria. Enterocins and bacteriocinogenic enterococci hold considerable promise as alternatives to traditional chemical preservatives and they could be exploited for the control of emergent pathogens in meat products. Their inhibitory effect can be increased when used in conjunction with particular physical and chemical processes, but current regulation is hampering the application of purified bacteriocins.     

Bacterial composition of commercial probiotic products as evaluated by PCR-DGGE analysis

The use of Polymerase Chain Reaction-Denaturing Gradient Gel Electrophoresis (PCR-DGGE) technique in identifying the microorganisms present in commercial probiotic yoghurts and lyophilised products was evaluated. Two reference ladders were assembled constituted by PCR-amplified V2-V3 regions of 16S rDNA from bacterial species generally used as probiotics. Identification was achieved comparing the PCR-DGGE patterns obtained from the analysed products with the ladder bands. Bands from members of the same species showed the same migration distance in denaturing gel, hence supporting the identificative value of the method. The validity of the technique was also proven confirming the PCR-DGGE identification results by sequence data analysis and by species-specific PCR. General congruence between microorganisms declared on the label and those revealed by PCR-DGGE was found for probiotic yoghurts. Conversely, some discrepancies were observed for probiotic lyophilised preparations, i.e. the incorrect identification of some Bifidobacterium and Bacillus species and the presence of not declared microorganisms. PCR-DGGE turned out to be an appropriate culture-independent approach for a rapid detection of the predominant species in mixed probiotic cultures.     

Biosurfactant- and biodegradation-enhanced partitioning of polycyclic aromatic hydrocarbons from nonaqueous-phase liquids

A study was conducted on the effect of two different biological factors, microbial surfactants and biodegradation, on the kinetics of partitioning of polycyclic aromatic hydrocarbons (PAHs) from nonaqueous-phase liquids (NAPLs). The effect of rhamnolipid biosurfactants on partitioning into the aqueous phase of naphthalene, fluorene, phenanthrene, and pyrene, initially dissolved in di-2-ethylhexyl phthalate (DEHP) or 2,2,4,4,6,8,8-heptamethylnonane (HMN), was determined in multiple-solute experiments. Biosurfactants at a concentration above the CMC enhanced the partitioning rate of fluorene, phenanthrene, and pyrene but were ineffective with naphthalene. Enhancement of partitioning was also observed in the presence of suspended humic acid-clay complexes, which simulated the solids often present in the subsurface. Biosurfactants sorbed to the complexes modified PAH partitioning between the NAPL and these solids, increasing the fraction of solid-phase PAH. Biodegradation-driven partitioning was estimated in mineralization experiments with phenanthrene initially present in HMN and three representative soil bacterial strains, differing in their potential adherence to the NAPL. In the three cases, the rates of mineralization were very similar and significantly higher than the abiotic rate of partitioning. Our study suggests that in NAPL-polluted sites, partitioning of PAH may be efficiently enhanced by in situ treatments involving the use of biosurfactants and biodegradation.     

Relationships between biochemical characteristics and meat quality of Longissimus thoracis and Semimembranosus muscles in five porcine lines

Five porcine genetic lines which represent a high proportion of European pig production were fully characterized for meat quality parameters and muscle biochemical characteristics (Longissimus thoracis, LT, and Semimembranosus, SM). The line characterisation was based on 100 animals each representing Large White, Landrace, Duroc, Piétrain (Halothane negative) and Meishan (a Meishan/Large White crossbred line) prevalent genetic backgrounds. Different meat quality parameters (pH 45min, pH ultimate, electrical conductivity, and colour measurements), as well as muscle water holding capacity, muscle metabolic and contractile traits, fibre type, size and frequencies were measured and their relationships studied. The main differences in the LT were found between the Meishan and Piétrain genetic lines, in relation to the muscle fibre size (larger in Piétrain). The Duroc line was characterized by the muscle oxidative traits and the Landrace by the high percentage of fast glycolytic fibres. In SM, Duroc and Piétrain were distinguished from Landrace and Meishan according to the metabolic and contractile characteristics of this muscle. Large White tended to lie between the other breeds for many of the traits. The measured muscle characteristics were related to differences in drip loss and marbling values and could thereby influence the eating quality of pork. Overall the results show differences between the genetic lines for a number of muscle traits which could have impact on consumer appeal and eating quality. The present findings should serve to emphasise the importance of including eating quality as a trait in breed selection.     

Quality of live packaged mussels during storage as a function of size and oxygen concentration

The commercialization of live mussels is limited by their capacity to resist the adverse conditions associated with their removal from the natural environment. Packaging under modified atmospheres has been proposed as an alternative method for the stabilization of mussels and shelf life extension. This study investigates how different concentrations of oxygen (20, 75 and 85%) influence the percentage mortality and quality of packaged Mediterranean mussels (Mytilus galloprovincialis) of different sizes (30 and 44 units/kg). In general, mussels packaged with oxygen-rich atmospheres had a higher organoleptic rating and lower percentage mortality. The decrease in pH of both the tissues and intervalval fluid was less pronounced in the larger mussels compared to the smaller mussels. Mussel size and packaging atmosphere also influenced the metabolic survival strategies. The smaller mussels produced more ammonium and volatile fatty acids, which decreased as initial oxygen increased. After 10 days of storage no consumption of glycogen was detected in any of the samples analyzed. The marketable period for the mussels, defined as a 20% mortality threshold, was reached earlier in the packages displaying a greater accumulation of acidic and basic metabolites.     

Mercury‐Mediated Organic Semiconductor Surface Doping Monitored by Electrolyte‐Gated Field‐Effect Transistors

Surface doping allows tuning the electronic structure of semiconductors at near‐surface regime and is normally accomplished through the deposition of an ultrathin layer on top or below the host material. Surface doping is particularly appealing in organic field‐effect transistors (OFETs) where charge transport takes place at the first monolayers close to the dielectric surface. However, due to fabrication restrictions that OFET architecture imparts, this is extremely challenging. Here, it is demonstrated that mercury cations, Hg²⁺, can be exploited to control doping levels at the top surface of a thin film of a p‐type organic semiconductor blended with polystyrene. Electrolyte‐ or water‐gated field‐effect transistors, which have its conductive channel at the top surface of the organic thin film, turn out to be a powerful tool for monitoring the process. A positive shift of the threshold voltage is observed in the devices upon Hg²⁺ exposure. Remarkably, this interaction has been proved to be specific to Hg²⁺ with respect to other divalent cations and sensitive down to nanomolar concentrations. Hence, this work also opens new perspectives for employing organic electronic transducers in portable sensors for the detection of an extremely harmful water pollutant without the need of using specific receptors.