Stability of casein micelles cross-linked by transglutaminase

In this study, caseins micelles were internally cross-linked using the enzyme transglutaminase (TGase). The integrity of the micelles was examined on solubilization of micellar calcium phosphate (MCP) or on disruption of hydrophobic interactions and breakage of hydrogen bonds. The level of monomeric caseins, determined electrophoretically, decreased with increasing time of incubation with TGase at 30°C; after incubation for 24 h, no monomeric β- or κ-caseins were detected, whereas only a small level of monomeric α_S1-casein remained, suggesting near complete intramicellar cross-linking. The ability of casein micelles to maintain structural integrity on disruption of hydrophobic interactions (using urea, sodium dodecyl sulfate, or heating in the presence of ethanol), solubilization of MCP (using the calcium-chelating agent trisodium citrate) or high-pressure treatment was estimated by measurement of the L*-value of milk; i.e., the amount of back-scattered light. The amount of light scattered by casein micelles in noncross-linked milk was reduced by >95% on complete disruption of hydrophobic interactions or complete solubilization of MCP; treatment of milk with TGase increased the stability of casein micelles against disruption by all methods studied and stability increased progressively with incubation time. After 24 h of cross-linking, reductions in the extent of light scattering were still apparent in the presence of high levels of dissociating agents, possibly through citrate-induced removal of MCP nanoclusters from the micelles, or urea- or sodium dodecyl sulfate-induced increases in solvent refractive index, which reduce the extent of light-scattering.     

Cold storage of porcine plasma treated with microbial transglutaminase under high pressure. Effects on its heat-induced gel properties

The objective of this work was to study the heat-induced gelling properties, at acid pH, of porcine plasma previously treated with microbial transglutaminase (MTGase) under high pressure (HP), when kept under refrigeration conditions for different times (setting time). The results indicated that, although the cross-linking activity of MTGase was enhanced under pressure, consequently, improving the thermal gel texture, the most significant effects, particularly on gel hardness, were obtained by keeping the treated plasma solutions under refrigeration for at least 2 h before gelation. On the whole, under such conditions, increases of approximately 60% of this textural parameter, calculated on the basis of the values corresponding to the heat-induced non-treated plasma gels at pH 5.5, were achieved. However, from the SDS–PAGE profiles, it can be suggested that mechanisms other than polymerisation by MTGase explain the beneficial effects of the treated plasma cold storage on gel texture. In contrast, the setting time had no effects on the water-holding capacity of heat-induced plasma gels at acid pH value, although this gel property was slightly enhanced by submitting porcine plasma solutions to the combined treatment (MTGase plus HP), with improvements being in accordance with the better-structured network of these heat-induced plasma gels.     

Increasing mercury in yellow perch at a hotspot in Atlantic Canada, Kejimkujik National Park

In the mid-1990s, yellow perch (Perca flavescens) and common loons (Gavia immer) from Kejimkujik National Park and National Historic Site (KNPNHS), Nova Scotia, Canada, had among the highest mercury (Hg) concentrations across North America. In 2006 and 2007, we re-examined 16 lakes to determine whether there have been changes in Hg in the loon's preferred prey, yellow perch. Total Hg concentrations were measured in up to nine perch in each of three size classes (5-10 cm, 10-15 cm, and 15-20 cm) consumed by loons. Between 1996/97 and 2006/07, polynomial regressions indicated that Hg in yellow perch increased an average of 29% in ten lakes, decreased an average of 21% in three, and were unchanged in the remaining three lakes. In 2006/07, perch in 75% of the study lakes had Hg concentrations (standardized to 12-cm fish length) equal to or above the concentration (0.21 μg·g(-1) ww) associated with a 50% reduction in maximum productivity of loons, compared with only 56% of these lakes in 1996/97. Mercury contamination currently poses a greater threat to loon health than a decade ago, and further reductions in anthropogenic emissions should be considered to reduce its impacts on ecosystem health.     

Packaging under pressure: Effects of high pressure, high temperature processing on the barrier properties of commonly available packaging materials

High pressure thermal (HPT) processing has the potential to deliver quality benefits to a range of processed foods. By exploiting the rapid temperature increase/decrease that accompanies pressurization/depressurization, commercial sterilization of foods can potentially be achieved by HPT with an overall reduced thermal exposure compared with conventional thermal processing technologies. High pressure thermal sterilization (HPTS) of foods is yet to be commercialized, but during development of the technology some potential limitations have been raised about the suitability for HPTS of commercially available packaging materials developed for retort processing. Key requirements of packaging materials for thermally processed foods are the preservation of oxygen and water barriers during processing and for the duration of the shelf life of the food. We examined the barrier properties after HPT processing of eleven commercially available packaging materials developed for conventional thermal sterilization processes. We found that the barrier properties of vapor-deposited oxide and nylon containing films were compromised by the combination of high pressure (600 MPa) and high temperature ( 110 °C) which would be reasonably expected to be required to render food commercially sterile by HPT processing. However, the barrier properties of aluminium foil and PVDC–MA containing films were not significantly affected by HPT processing. All materials suffered cosmetic deformation of the outer surface to some degree and mechanisms for these changes are proposed.

Industrial relevance

Information on the barrier properties of flexible packaging suitable for foods sterilized by HPT processing has been scarcely reported. This study provides information on the barrier properties of commercially available, retortable films processed under high pressure/high temperature conditions and identifies candidate packaging based on barrier performance.     

The effect of by-product inclusion and concentrate feeding rate on milk production and composition,pasture dry matter intake,and nitrogen excretion of mid-late lactation spring-calving cows grazing a perennial ryegrass-based pasture

Interest is growing in the use of by-products as economical sources of nutrients that complement grazed grass, particularly at times when grass supply is insufficient to meet the nutritional demands of lactating dairy cattle. The objective of this research was to assess the effect of the amount of by-product inclusion and concentrate feeding rate on pasture dry matter intake, milk production and composition, and N excretion from spring-calving cows grazing summer pasture during mid-late lactation. Forty-eight Holstein Friesian dairy cows were randomly assigned to 1 of 4 dietary treatments in a 2 × 2 factorial design. Cows were grazed in one group on a perennial ryegrass-based sward, with pelleted concentrates offered twice daily during milking over a 63-d experimental period. The dietary treatments were 3 kg of concentrate containing 35% by-products; 6 kg of concentrate containing 35% by-products; 3 kg of concentrate containing 95% by-products; and 6 kg of concentrate containing 95% by-products on a fresh matter basis. The by-products used were soybean hulls, palm kernel expeller, and maize dried distillers grains with solubles, included in equal proportions on a dry matter basis. Pasture dry matter intake (14.5 kg/d) was not affected by the amount of by-product inclusion or feeding rate. By-product inclusion had no effect on milk yield (27.1 kg/d) or milk solids (MS) yield (2.0 kg/d). Cows offered 6 kg of concentrate had a greater milk (+1.6 kg/d) and MS (+0.13 kg/d) yield, consumed more N (+0.08 kg/d), and excreted a lower proportion of N in the milk (0.25 vs. 0.27) and feces (0.39 vs. 0.41) and a higher proportion in the urine (0.39 vs. 0.32) compared with cows offered 3 kg of by-product-based concentrate. In conclusion, by-products can be included at up to 95% of the concentrate fed to cows grazing pasture without affecting pasture dry matter intake, milk production or composition, or N excretion. Cows offered 6 kg of concentrates produced more milk and MS than cows offered 3 kg but had higher urinary N excretion. Economics of this yield response will depend on milk and concentrate prices.     

Invited review: Whey proteins as antioxidants and promoters of cellular antioxidant pathways

Oxidative stress contributes to cell injury and aggravates several chronic diseases. Dietary antioxidants help the body to fight against free radicals and, therefore, avoid or reduce oxidative stress. Recently, proteins from milk whey liquid have been described as antioxidants. This review summarizes the evidence that whey products exhibit radical scavenging activity and reducing power. It examines the processing and treatment attempts to increase the antioxidant bioactivity and identifies 1 enzyme, subtilisin, which consistently produces the most potent whey fractions. The review compares whey from different milk sources and puts whey proteins in the context of other known food antioxidants. However, for efficacy, the antioxidant activity of whey proteins must not only survive processing, but also upper gut transit and arrival in the bloodstream, if whey products are to promote antioxidant levels in target organs. Studies reveal that direct cell exposure to whey samples increases intracellular antioxidants such as glutathione. However, the physiological relevance of these in vitro assays is questionable, and evidence is conflicting from dietary intervention trials, with both rats and humans, that whey products can boost cellular antioxidant biomarkers.     

Evaluation of the electrical integrity of E-textiles subjected to environmental conditions

E-textiles contain electrically conductive elements and electronic devices that are integrated in textile substrate. Wearable e-textiles are expected to perform like textiles in terms of breathability, conformability, and comfort despite the presence of the electrically conductive elements and electronics. E-textiles are also expected to provide reliable data and signal processing like electronic devices while they are subjected to normal wear and tear under different environmental conditions. The goal of this research was to investigate the electrical integrity of e-textiles while they are subjected to environmental conditions. Different woven samples of electronic-improved outer tactical vest with two narrow conductive traces woven in the warp direction were subjected to range of temperatures and humidity, including extreme conditions. The effects of formation parameters (e-yarn type, number of e-yarns/trace, and weldability), temperature, and humidity on the integrity of the e-textiles were studied. It was found that resistance of networks was affected by changes in air temperature and humidity and the quality of the weld had the greatest impact on electrical integrity of the conductive network. This impact was pronounced in more extreme environmental conditions, which revealed that there was a strong interaction between the weldability, temperature, and humidity.     

Catalyzing strategic transformation to a low-carbon economy: A CCS roadmap for China

China now faces the three hard truths of thirsting for more oil, relying heavily on coal, and ranking first in global carbon dioxide (CO₂) emissions. Given these truths, two key questions must be addressed to develop a low-carbon economy: how to use coal in a carbon-constrained future? How to increase domestic oil supply to enhance energy security? Carbon Capture and Storage (CCS) may be a technological solution that can deal with today's energy and environmental needs while enabling China to move closer to a low-carbon energy future. This paper has been developed to propose a possible CCS roadmap for China. To develop the roadmap, we first explore major carbon capture opportunities in China and then identify critical CCS-enabling technologies, as well as analyze their current status and future prospects. We find that coal gasification or polygeneration in combination with CCS could be a nearly unbeatable combination for China's low-carbon future. Even without CCS, gasification offers many benefits: once coal is gasified into syngas, it can be used for many different purposes including for alternative fuels production, thereby increasing the domestic oil supply and the flexibility of the energy system.     

Exploring the impact of technology development and adoption for sustainable hydroelectric power and storage technologies in the Pacific Northwest United States

A wide range of literature streams and methods were examined for this research, including sustainability, integrated resource planning, and construction of portfolios of electricity generation technologies. The research then focused on current and emerging HPSTs (hydropower generation and storage technologies), and technical, economic, social, and environmental sustainability objectives associated with those technologies in the PNW (Pacific Northwest) region of the United States. Candidate technologies obtained from the literature were examined using the Delphi Method, and then rated according to their perceived impacts using the AHP (Analytical Hierarchy Process). GP (Goal Programming) was then used to determine an optimal mix of technologies to achieve sustainability objectives, using these weightings and assumptions related to specific scenarios regarding technology development, adoption, and availability. This research is important because few previous studies have systematically considered multiple objectives and criteria from multiple stakeholder experts for creating portfolios of sustainable electricity generation technologies. Previous research has also not comprehensively investigated the manner in which changing scenarios of technology development and availability rates may lead to various technological, economic, environmental, and social sustainability impacts with regard to planning of regional electrical generation and storage systems.     

Preliminary Developments of Miniplate-Type Fuel of U-2.5Zr-7.5Nb Alloy Dispersed and Cladded in Zircaloy

Nuclear fuel based on uranium metal alloys is utilized in research and test reactors. For the purpose of the reduction of fuel enrichment, high densities of uranium-235 in this kind of fuel are needed. This can be achieved when uranium alloys are used containing elements such as Zr, Mo and Nb. The construction of fuel element with high-uranium density requires materials with low cross sections for neutron absorption, stability under irradiation and absence of the chemical interactions between the fuel and cladding elements. In case of U-Zr-Nb alloys, Zry （zircaloy） cladding is a better option due to the fact that they have a higher chemical compatibility when compared with the use of aluminum alloys. This study aims to develop plate type nuclear fuel using the U-2.5Zr-7.5Nb alloy dispersed in Zry. Powders of this uranium based alloy and Zry were obtained by hydriding-dehydriding process. These powders were homogenized, compacted in pellet that was sandwiched in plates and frame of Zry. This assembly was hot rolled forming the dispersion fuel miniplate.