Whey proteins: Musings on denaturation, aggregate formation and gelation.

Whey proteins are globular milk proteins with numerous functional properties and a broad potential for usage in food and supplement-pharmaceutical products. Under various denaturing conditions, whey proteins unfold, form aggregates, microparticles, while at sufficiently high concentrations, gel networks are created. The continuously growing research interest makes it necessary to discuss the recent advances and achievements in this area, including the basic principles of the structural assembly's kinetics along with the different approaches undertaken to fabricate whey protein gels as well as the means to modulate the gel physical properties. This article also focuses on the use of ethanol to modify the structure and functionality of whey proteins, as an alternative way to change the protein conformation and thereby gelation phenomena and functionality.

Investigation of the post mortem zinc protoporphyrin IX fluorescence with respect to its protein-bound and unbound occurrence in aqueous meat extracts.

Zinc protoporphyrin IX (ZnPP) is known to accumulate in most meat products during storage. However, the pathway of its formation is not yet completely clarified. To gain more insights into the specificity of ZnPP occurrence, a SEC-HPLC-UV-fluorescence setup was established to screen the proteins in aqueous meat extracts for their ZnPP fluorescence during incubation. In accordance with previous studies it was identified by SDS-PAGE and MALDI-TOF-MS that ZnPP formation takes place in myoglobin. In this study, valuable new insights into the ZnPP forming pathway were gained, as our results indicated that a significant part of ZnPP - after being formed within the protein - is transitioned into free ZnPP during incubation. Additionally, the obtained results implied that ZnPP may also occur in proteins of higher molecular weight (>100 kDa).

Factors affecting migration kinetics from a generic epoxy-phenolic food can coating system.

This study investigated how the properties of a polymeric can coating film, such as thickness and crosslink density as well as the type of migrant, influence the migration kinetics of model migrants in an attempt to better understand, model and control the migration process. Four model migrants were used BADGE (bisphenol A diglycidyl ether), BADGE·H2O, cyclo-diBADGE and Uvitex OB, that differ in size and polarity. Fatty and aqueous food simulants were used at high temperatures (70-130°C). The apparent diffusion coefficients were found to decrease with increasing crosslink density, while they increased with increasing film thickness. The apparent activation energy of BADGE and BADGE-related compounds was calculated from the diffusion data and were high, in the range of 250-264kJmol-1. The polarity of the simulant and the polarity of the migrant were found to influence migration. The results can be used to improve existing migration models, and thereby help to reduce migration from packaging into food by using safety-by-design approaches in new product development.

[Comparison of Different Mechanical Insufflator-Exsufflator Systems by Measurement of the Peak Exspiratory Flow (PEF)]. / Vergleich verschiedener mechanischer Hustenhilfen durch Messung der exspiratorischen Spitzenflüsse.

Background The management of pulmonary secretion in patients with respiratory muscle weakness using mechanical insufflator-exsufflator systems (MIE) is an established treatment option. There are significant differences in the efficiency of different devices in practical use. The intention of this study was to evaluate the peak exspiratory flow (PEF) values of different devices with and without use of equipment. Methods PEFs of ten MIE were investigated in vitro using different equipment. Results The efficiency of the devices showed significant differences. The use of two bacterial filters showed a significant reduction of 13 % compared to one filter, the use of a catheter mount revealed a significant reduction of 10 %, with an elbow connector additionally 15 %. With a commonly used equipment (1800 mm tube, one filter, catheter tube with elbow) there was a difference of 58 % between the devices Nippy (2,86 l/s) and Pulsar (1,2 l/s). Conclusion There are significant differences in PEF of different MIE and use of different equipment. That could be of therapeutic relevance. Further studies are needed to investigate the clinical relevance of these findings. Recommendations for the use of devices and equipment are necessary to ensure the efficacy of the elimination of pulmonary mucus.

Timing and deciphering mitochondrial DNA macro-haplogroup R0 variability in Central Europe and Middle East.

BACKGROUND: Nearly half of the West Eurasian assemblage of human mitochondrial DNA (mtDNA) is fractioned into numerous sub-lineages of the predominant haplogroup (hg) R0. Several hypotheses have been proposed on the origin and the expansion times of some R0 sub-lineages, which were partially inconsistent with each other. Here we describe the phylogenetic structure and genetic variety of hg R0 in five European populations and one population from the Middle East. RESULTS: Our analysis of 1,350 mtDNA haplotypes belonging to R0, including entire control region sequences and 45 single nucleotide polymorphisms from the coding region, revealed significant differences in the distribution of different sub-hgs even between geographically closely located regions. Estimates of coalescence times that were derived using diverse algorithmic approaches consistently affirmed that the major expansions of the different R0 hgs occurred in the terminal Pleistocene and early Holocene. CONCLUSION: Given an estimated coalescence time of the distinct lineages of 10-18 kya, the differences in the distributions could hint to either limited maternal gene flow after the Last Glacial Maximum due to the alpine nature of the regions involved or to a stochastic loss of diversity due to environmental events and/or disease episodes occurred at different times and in distinctive regions. Our comparison of two different ways of obtaining the timing of the most recent common ancestor confirms that the time of a sudden expansion can be adequately recovered from control region data with valid confidence intervals. For reliable estimates, both procedures should be applied in order to cross-check the results for validity and soundness.

alpha-Dicarbonyl compounds--key intermediates for the formation of carbohydrate-based melanoidins.

The Maillard reaction of carbohydrates and amino acids is the chemical basis for flavor and color formation in many processed foods. Dicarbonyl compounds, such as 1-, 3-deoxyosones and 1,4-dideoxyosones, as well as short-chain dicarbonyls, such as methylgyoxal or glyoxal, are key compounds of the Maillard browning reaction. The alpha-dicarbonyls are also starting materials for polymerization reactions which lead to formation of carbohydrate-based melanoidins. With regard to the dicarbonyl compound, different possible chemical structures of melanoidins will be discussed. The analysis by size-exclusion chromatography revealed that those colored compounds differ in their molecular size and are directly associated with reactions having specific alpha-dicarbonyl compounds.