Temperature-induced changes in dough elasticity as a useful tool in defining the firmness of cooked pasta

Semolina with high protein content and strong gluten is recognized as the best raw-material for pasta-products with a good cooking quality, while little consideration has been given to semolina dough elasticity when heating is applied. In this research, a new technique was developed by adapting the Glutograph (Brabender GmbH&Co., Duisburg, Germany) to measure the changes in elasticity induced by heating on a sheeted dough. The information obtained by this procedure was related to the firmness of cooked pasta. Starting from semolina of four durum wheat varieties with differences in protein quantity and quality, dough samples were prepared in a Farinograph at a hydration level of 35 %. Each dough was sheeted by a home-made pasta machine, obtaining disks of 5 cm diameter and 2.1 mm thickness. Stretching (10 s) and relaxation (30 s) cycles were applied repeatedly during the test time, while dough temperature was increased from 30 to 90 °C at 1.2 °C/min. For each peak recorded, stretching and recovery values were calculated and plotted against sample temperature. Both stretching and recovery curves were integrated and the loss of elasticity was calculated. Results showed as high elasticity loss during heating is related to low firmness of the related cooked pasta.     

Gut: A key player in the pathogenesis of type 2 diabetes?

The gut regulates glucose and energy homeostasis; thus, the presence of ingested nutrients into the gut activates sensing mechanisms that affect both glucose homeostasis and regulate food intake. Increasing evidence suggest that gut may also play a key role in the pathogenesis of type 2 diabetes which may be related to both the intestinal microbiological profile and patterns of gut hormones secretion. Intestinal microbiota includes trillions of microorganisms but its composition and function may be adversely affected in type 2 diabetes. The intestinal microbiota may be responsible of the secretion of molecules that may impair insulin secretion/action. At the same time, intestinal milieu regulates the secretion of hormones such as GLP-1, GIP, ghrelin, gastrin, somatostatin, CCK, serotonin, peptide YY, GLP-2, all of which importantly influence metabolism in general and in particular glucose metabolism. Thus, the aim of this paper is to review the current evidence on the role of the gut in the pathogenesis of type 2 diabetes, taking into account both hormonal and microbiological aspects.     

C and N isotope fractionation during biodegradation of the pesticide metabolite 2,6-dichlorobenzamide (BAM): potential for environmental assessments

2,6-Dichlorobenzamide (BAM) is a metabolite of the herbicide 2,6-dichlorobenzonitrile (dichlobenil), and a prominent groundwater contaminant. Observable compound-specific isotope fractionation during BAM formation-through transformation of dichlobenil by Rhodococcus erythropolis DSM 9685-was small. In contrast, isotope fractionation during BAM degradation-with Aminobacter sp. MSH1 and ASI1, the only known bacterial strains capable of mineralizing BAM-was large, with pronounced carbon (ε(C) = -7.5‰ to -7.8‰) and nitrogen (ε(N) = -10.7‰ to -13.5‰) isotopic enrichment factors. BAM isotope values in natural samples are therefore expected to be dominated by the effects of its degradation rather than formation. Dual isotope slopes Δ (=Δδ(15)N/Δδ(13)C ≈ ε(N)/ε(C)) showed only small differences for MSH1 (1.75 ± 0.03) and ASI1 (1.45 ± 0.03) suggesting similar transformation mechanisms of BAM hydrolysis. Observations are in agreement with either a tetrahedral intermediate promoted by OH(-) or H(3)O(+) catalysis, or a concerted reaction mechanism. Therefore, owing to consistent carbon isotopic fractionation, isotope shifts of BAM can be linked to BAM biodegradation, and may even be used to quantify degradation of this persistent metabolite. In contrast, nitrogen isotope values may be rather indicative of different sources. Our results delineate a new approach to assessing the fate of BAM in the environment.     

Global metabolite analysis of yeast: evaluation of sample preparation methods

Sample preparation is considered one of the limiting steps in microbial metabolome analysis. Eukaryotes and prokaryotes behave very differently during the several steps of classical sample preparation methods for analysis of metabolites. Even within the eukaryote kingdom there is a vast diversity of cell structures that make it imprudent to blindly adopt protocols that were designed for a specific group of microorganisms. We have therefore reviewed and evaluated the whole sample preparation procedures for analysis of yeast metabolites. Our focus has been on the current needs in metabolome analysis, which is the analysis of a large number of metabolites with very diverse chemical and physical properties. This work reports the leakage of intracellular metabolites observed during quenching yeast cells with cold methanol solution, the efficacy of six different methods for the extraction of intracellular metabolites, and the losses noticed during sample concentration by lyophilization and solvent evaporation. A more reliable procedure is suggested for quenching yeast cells with cold methanol solution, followed by extraction of intracellular metabolites by pure methanol. The method can be combined with reduced pressure solvent evaporation and therefore represents an attractive sample preparation procedure for high-throughput metabolome analysis of yeasts.     

Characterization of different promoters for designing a new expression vector in Saccharomyces cerevisiae

The widely used pESC vector series (Stratagene, La Jolla, CA, USA) with the bidirectional GAL1/GAL10 promoter provides the possibility of simultaneously expressing two different genes from a single vector in Saccharomyces cerevisiae. This system can be induced by galactose and is repressed by glucose. Since S. cerevisiae prefers glucose as a carbon source, and since its growth rate is higher in glucose than in galactose‐containing media, we compared and evaluated seven different promoters expressed during growth on glucose (pTEF1, pADH1, pTPI1, pHXT7, pTDH3, pPGK1 and pPYK1) with two strong galactose‐induced promoters (pGAL1 and pGAL10), using lacZ as a reporter gene and measuring LacZ activity in batch and continuous cultivation. TEF1 and PGK1 promoters showed the most constant activity pattern at different glucose concentrations. Based on these results, we designed and constructed two new expression vectors which contain the two constitutive promoters, TEF1 and PGK1, in opposite orientation to each other. These new vectors retain all the features from the pESC–URA plasmid except that gene expression is mediated by constitutive promoters. Copyright © 2010 John Wiley & Sons, Ltd.     

Reliability of thermal interface materials: A review

Thermal interface materials (TIMs) are used extensively to improve thermal conduction across two mating parts. They are particularly crucial in electronics thermal management since excessive junction-to-ambient thermal resistances can cause elevated temperatures which can negatively influence device performance and reliability. Of particular interest to electronic package designers is the thermal resistance of the TIM layer at the end of its design life. Estimations of this allow the package to be designed to perform adequately over its entire useful life. To this end, TIM reliability studies have been performed using accelerated stress tests. This paper reviews the body of work which has been performed on TIM reliability. It focuses on the various test methodologies with commentary on the results which have been obtained for the different TIM materials. Based on the information available in the open literature, a test procedure is proposed for TIM selection based on beginning and end of life performance.     

Effects of Fusarium infection on the amino acid composition of winter wheat grain

Winter wheat (susceptible cultivar Ritmo) was grown in 2006 near Kiel and in 2007 near Heide in northern Germany. Plants were inoculated at anthesis using a Fusarium graminearum macroconidial suspension. The percentage of Fusarium-damaged kernels (FDK) ranged from 0 ± 2% to 28 ± 2%. The contents of the Fusarium mycotoxin deoxynivalenol (DON) and wheat amino acids were determined in the grain. Levels of the amino acids alanine, lysine, and tyrosine increased with the percentage of FDK or DON contents whereas glutamic acid contents decreased. Aspartic acid and threonine were not related to the percentage of FDK or DON contents. Effects of Fusarium infection on other amino acids were significant only at the sampling site with the higher degree of Fusarium-damage. Interestingly, those amino acids that increased consistently and significantly with the degree of Fusarium-damage are derived from phosphoenolpyruvate or pyruvate, suggesting that pathogen-induced changes in the glycolytic input for amino acid biosynthesis play a significant role for the amino acid composition of Fusarium-damaged winter wheat grain. On average, amino acid contents decreased by 0.13% compared to the amino acid content of sound kernels upon an increase of 1% of FDK.     

Colour formation in fermented sausages by meat-associated staphylococci with different nitrite- and nitrate-reductase activities

Three Staphylococcus strains, S. carnosus, S. simulans and S. saprophyticus, selected due to their varying nitrite and/or nitrate-reductase activities, were used to initiate colour formation during sausage fermentation. During fermentation of sausages with either nitrite or nitrate added, colour was followed by L^*a^*b measurements and the content of nitrosylmyoglobin (MbFe^IINO) quantified by electron spin resonance (ESR). MbFe^IINO was rapidly formed in sausages with added nitrite independent of the presence of nitrite reducing bacteria, whereas the rate of MbFe^IINO formation in sausages with added nitrate depended on the specific Staphylococcus strain. Strains with high nitrate-reductase activity showed a significantly faster rate of pigment formation, but other factors were of influence as well. Product stability for the sliced, packaged sausage was evaluated as surface colour and oxidation by autofluorescence and hexanal content, respectively. No significant direct effect of the Staphylococcus addition was observed, however, there was a clear correspondence between high initial amount of MbFe^IINO in the different sausages and the colour stability during storage. Autofluorescence data correlated well with hexanal content, and may be used as predictive tools. Overall, nitrite- and nitrate-reductase activities of Staphylococcus strains in nitrite-cured sausages were of limited importance regarding colour development, while in nitrate-cured sausages strains with higher nitrate reductase activity were crucial for ensuring optimal colour formation during initial fermentation stages.     

A comparison of MAGIC and paleolimnological predictions of preindustrial pH for 55 Swedish lakes

Two fundamentally different approaches to define reference conditions for acidification assessments are hydrogeochemical modeling and paleolimnological reconstructions. Both methods have been applied to calculate the preindustrial chemistry for 55 Swedish lakes in two independent studies. This paper investigates whether these methods give similar reconstructions of the preindustrial pH for these lakes. Special focus has been attached to the importance of total organic carbon concentrations and CO2 partial pressure (pCO2) in the conversion from ANC to pH in the hydrogeochemical modeling. With a uniform pCO2 value for all the lakes of 0.63 matm, the mean absolute difference between pH from the hydrogeochemical model and the paleolimnological pH was +0.23 units (mean absolute difference 0.36 units). If instead a lake specific preindustrial pCO2 is assumed, equal to contemporary pCO2, the mean difference in the predicted preindustrial pH between the two methods was reduced to +0.03 units (mean absolute difference 0.22 units). Statistical analyses indicated that with a lake specific pCO2, the difference between the reconstructions is smaller than 0.13 pH-units at a 95% level of significance. The results of this study build confidence in the reliability of both methods, providing that lake-specific estimates of pC02 are used.     

Offshore wind resource assessment with WAsP and MM5: comparative study for the German Bight

In this study, two different approaches to estimate the wind resource over the German Bight in the North Sea are compared: the mesoscale meteorological model MM5 and the wind resource assessment program WAsP. The dynamics of the atmosphere of the year 2004 was simulated with the MM5 model, with input from the NCEP global model, without directly utilizing measurement data. WAsP estimations were calculated on the basis of six measurement stations: three on islands, two offshore and one onshore. The annual mean wind speed at onshore, offshore and island sites is estimated by both models. The predictions are compared both with each other and with measured data. A spatial comparison of the wind resource calculated by the two models is made by means of a geographical information system. The results show that the accuracy of the WAsP predictions depends mainly on the measurement station used as input. Small differences are shown in the estimations performed by the three island stations, despite the large geographical distance between them. Compared with the measurements of the offshore sites, they seem to be suitable for estimating the offshore wind resource from measurements on land. The two offshore stations show differences when predicting each other's mean wind speed with the WAsP method, while the MM5 calculations show a similar deviation for both sites. The largest differences between the two models are found at distances of 5–50km from the coast. While in WAsP the increase occurs in the first 10km from the coast, MM5 models an increase due to coastal effects for at least 50km. Copyright © 2006 John Wiley &Sons, Ltd.