Lipolysis, proteolysis and physico-chemical modifications during ripening of dry-cured duck breast

Chemical traits related to dry-curing process (pH, moisture, water activity total and chlorides), color and textural properties and changes of free fatty acid and amino acid compositions during the processing of dry-cured duck breast were quantified. For this purpose, 25 male ducks from crossbred mule were used in this study and samples at 0 days (raw breast) and after 7, 14, 21 and 28 days of ripening were taken. The results showed that all physico-chemical parameters suffered significant differences during the manufacture of dry-cured duck breast. A decrease in all variables was observed with the exception of chlorides and textural properties due to dehydration process. Concerning free fatty acids, a significant increase (P < 0.05) from 299.57 mg/g of fat in the raw breast to 380.43 mg/g of fat at the end of the drying–ripening stage was recorded. Finally, a significant increase (P < 0.001) in the total free amino acids was observed from raw breast (1,059.17 mg/100 g of DM) to the end of dry-ripening (2,792.48 mg/100 g of DM).     

Multi-scale coupling between two dynamical models for PEMFC aging prediction

In this paper, an approach allowing connecting two numerical models for the simulation of the PEMFC operation and durability at different physical scales is presented. After explaining the interest of coupling them to study the interactions between the fuel cell system and the fuel cell itself, along with lifetime concerns, the feasibility of the task is assessed. Then the numerical approach to achieve this coupling is presented. Finally the response of the coupled models is examined to check its validity, and first results are presented. Predicted fuel cell lifetime trends when changing the stack operation conditions are shown, which highlight the presence of optima concerning temperature, demanded current, pressure and O₂ stoichiometry. Two operation modes are then compared in terms of their impact on the fuel cell performance decay, showing that power cycles are more damaging the fuel cell than nominal operation.     

What are the costs and benefits of biodiversity recovery in a highly polluted estuary?

Biodiversity recovery measures have often been ignored when dealing with the restoration of degraded aquatic systems. Furthermore, biological valuation methods have been applied only spatially in previous studies, and not jointly on a temporal and spatial scale. The intense monitoring efforts carried out in a highly polluted estuary, in northern Spain (Nervión estuary), allowed for the economic valuation of the costs and the biological valuation of the benefits associated with a 21 years sewage scheme application. The analysis show that the total amount of money invested into the sewage scheme has contributed to the estuary’s improvement of both environmental and biological features, as well as to an increase in the uses and services provided by the estuary. However, the inner and outer parts of the estuary showed different responses. An understanding of the costs and trajectories of the environmental recovery of degraded aquatic systems is increasingly necessary to allow policy makers and regulators to formulate robust, cost-efficient and feasible management decisions.     

Growth potential of Salmonella spp. and Listeria monocytogenes in nine types of ready-to-eat vegetables stored at variable temperature conditions during shelf-life

Growth potential (δ) is defined as the difference between the population of a microorganism at the end of shelf-life of specific food and its initial population. The determination of δ of Salmonella and Listeria monocytogenes in RTE vegetables can be very useful to determine likely threats to food safety. However, little is known on the behavior of these microorganisms in several RTE vegetables. Therefore, the aim of this study was to determine the δ of both pathogens in nine different types of RTE vegetables (escarole, collard green, spinach, watercress, arugula, grated carrot, green salad, and mix for yakisoba) stored at refrigeration (7°C) and abuse temperature (15°C). The population of aerobic microorganisms and lactic acid bacteria, including those showing antimicrobial activity has been also determined. Results indicated that L. monocytogenes was able to grow (δ≥0.5 log(10)) in more storage conditions and vegetables than Salmonella. Both microorganisms were inhibited in carrots, although a more pronounced effect has been observed against L. monocytogenes. The highest δ values were obtained when the RTE vegetables were stored 15°C/6days in collard greens (δ=3.3) and arugula (δ=3.2) (L. monocytogenes) and arugula (δ=4.1) and escarole (δ=2.8) (Salmonella). In most vegetables and storage conditions studied, the counts of total aerobic microorganisms raised significantly independent of the temperature of storage (p<0.05). Counts of lactic acid bacteria were higher in vegetables partially or fully stored at abuse temperature with recovery of isolates showing antimicrobial activity. In conclusion, the results of this study show that Salmonella and L. monocytogenes may grow and reach high populations in RTE vegetables depending on storage conditions and the definition of effective intervention strategies are needed to control their growth in these products.     

Effect of annealing on the semicrystalline structure of normal and waxy corn starches

The influence of amylose and amylopectin on structural reorganization occurred during annealing was studied for normal and waxy corn starches. Annealing caused an increase in crystallinity in the waxy corn starch, whereas the number of pores on the granule surface, observed by SEM, increased especially for normal corn starch. Amylose and amylopectin chains of the annealed normal corn starch were degraded to greater extension during enzymatic hydrolysis than those of the native starch. On contrary, the annealing caused a protective effect on waxy corn starch amylopectin toward the enzymatic reaction suggesting that this treatment promoted a better interaction between amylopectin chains of waxy corn starch. The amylose molecules of normal corn starch may have impaired the mobility of amylopectin molecules and restricted the reorganization of the crystalline structure during the annealing. The major increase in pores number on the granule surface of annealed normal corn starch, resulted of the endogenous amylase action during annealing, could facilitate the exogenous enzymes’ role in the degradation of the starch granules’ amorphous area.     

Optimization of Chitosanase Production by <Emphasis Type="Italic">Trichoderma koningii</Emphasis> sp. Under Solid-State Fermentation

This study aimed at the optimization of the production of chitosanase in solid culture. Trichoderma koningii sp., an entomopathogenic fungus, was used to produce chitosanase under solid-state fermentation using a mixture of wheat bran and chitosan. The incubation period; addition of moistening water and culture medium composition were optimized. The protocol to extract the enzyme was also optimized. The optimal conditions for chitosanase production by T. koningii were obtained using a mixture of 3.0 g of wheat bran and 1.5 g of chitosan, with the addition of 2.5 mL of moistening water (pH 5.5) and of 2.5 mL of saline solution (pH 5.5) containing NaNO₃ (1.0 g/L), (NH₄)₂HPO₄ (1.0 g/L), MgSO₄.7H₂O (1.0 g/L), and NaCl (1.0 g/L). Optimal enzyme extraction was carried out adding 20 mL of sodium acetate buffer (200 mM, pH 5.5) at 30 °C under orbital agitation at 150 rpm for 6 min. The optimized production yielded 4.84 IU/gds.     

Optimum selection of capacitive array for multibit Sigma-Delta modulators without DEM

A method for a smart selection and sequencing of unity capacitors in a multibit digital-to-analog converter (DAC) that improves the linearity is proposed. The approach, suitable for the DAC nonlinearity correction in Sigma-Delta modulators, obtains better results than dynamic element matching. The key of the proposed technique is an off-line self-measurement of mismatches with the available hardware. The results significantly improve when redundant DAC capacitors are introduced. Hence, the capacitors are selected from a set that is larger than required. An affordable silicon area overhead introduced by the redundant capacitors avoids extra power consumption, that is unavoidable in other methods during the normal operation of the converter.     

Numerical and experimental analysis of polarization properties from hybrid PCFs across different photonic bandgaps

This work presents a numerical and experimental characterization of polarization properties from hybrid photonic crystal fibers (hybrid PCFs or HPCFs) across different bandgaps. Very high extinction ratio over at least three wide bands and single-mode and single-polarization operation over more than 320 nm have been obtained by using only one fiber. Furthermore, it is reported, for the first time, a multi- and broadband fiber-based optical polarizer. Numerical simulations and experiments of modal, birefringence and polarization properties have been carried out to demonstrate the remarkable performance of the proposed device.     

Pyrogenic inputs of anthropogenic Pb and Hg to sediments of the Hood Canal, Washington, in the 20th century: source evidence from stable Pb isotopes and PAH signatures

Combustion-derived PAHs and stable Pb isotopic signatures ((206)Pb/(207)Pb) in sedimentary records assisted in reconstructing the sources of atmospheric inputs of anthropogenic Pb and Hg to the Hood Canal, Washington. The sediment-focusing corrected peak fluxes of total Pb and Hg (1960-70s) demonstrate that the watershed of Hood Canal has received greater atmospheric inputs of these metals than its mostly rural land use would predict. The tight relationships between the Pb, Hg, and organic markers in the cores indicate that these metals are derived from industrial combustion emissions. Multiple lines of evidence point to the Asarco smelter, located in the Main Basin of Puget Sound, as the major emission source of these metals to the watershed of the Hood Canal. The evidence includes (1) similar PAH isomer ratios in sediment cores from the two basins, (2) the correlations between Pb, Hg, and Cu in sediments and previously studied environmental samples including particulate matter emitted from the Asarco smelter's main stack at the peak of production, and (3) Pb isotope ratios. The natural rate of recovery in Hood Canal since the 1970s, back to preindustrial metal concentrations, was linear and contrasts with recovery rates reported for the Main Basin which slowed post late 1980s.