Acid-base balance of dairy cows and its relationship with alcoholic stability and mineral composition of milk

This study aimed to associate the occurrence of acid-base disorders with the alcoholic stability of milk from animals in the field, and to evaluate differences between the mineral composition of milk that was both stable and unstable in alcohol. The sample comprised 96 dairy cows, where the milk and blood of each corresponding animal was collected. The mineral composition of stable and unstable milk in alcohol was different and may be related to acid-base disturbances. The average amount of phosphate was lower in the milk that was unstable in alcohol, while potassium was greater. Frequency of the alcoholically unstable milk cases was higher in the cows with acid-base disturbances. Respiratory alkalosis was the disorder that was most observed.

Curving simulation and stability of a creep-controlled wheelset for high speed rail-vehicles

Higher travel speeds of rail vehicles will be possible by developing sophisticated top performance bogies having creep-controlled wheelsets. In this case the torque transmission between the right and the left wheel is realized by an actively controlled creep coupling. To investigate hunting stability and curving capability the linear equations of motion are written in state space notation. Simulation results are obtained with realistic system parameters from industry and various controller gains. The advantage of the „creep-controlled wheelset" is discussed by comparison the simulation results with the dynamic behaviour of the special cases „solid-axle wheelset" and „loose wheelset" (independent rotation of the wheels). The stability is also investigated with a root-locus analysis.

Infestation maps and spatial stability of main weed species in maize culture

A study on the spatial distribution of the major weeds in maize was carried out in 2007 and 2008 in a field located in Golegã (Ribatejo region, Portugal). The geo-referenced sampling focused on 150 points of a 10 x 10 m mesh covering an area of 1.5 ha, before herbicide application and before harvest. In the first year, 40 species (21 botanical families) were identified at seedling stage and only 22 during the last observation. The difference in species richness can be attributed to maize monoculture favouring reduction in species number. Three of the most representative species were selected for the spatial distribution analysis: Solanum nigrum, Chenopodium album and Echinochloa crus-galli. The three species showed an aggregated spatial pattern and spatial stability over both years, although the herbicide effect is evident in the distribution of some of them in the space. These results could be taken into account when planning site-specific treatments in maize.

Effect of sigma factor S (sigmaS) on the stability of penicillin-binding protein 3 (PBP3) of Escherichia colt K12

The stability of penicillin-binding protein 3 (PBP3), a cell septum synthesizing protein, was analyzed at different incubation temperatures in three Escherichia coli K12 strains carrying a PBP3-overproducing plasmid. The stability of PBP3 was significantly reduced in stationary phase cells shifted to 42°C for 4 h, compared to samples incubated at 28 or 37°C. The half-life of PBP3 in the C600 strain was 60 min at 42°C, while samples incubated at 28 or 37°C had PBP3 half-lives greater than 4 h. Analysis of the PBP3 content in mutants deficient in rpoS (coding for the stationary phase sigma factor, sigmaS) and rpoH (coding for the heat shock sigma factor, sigma32) genes after shift to 42°C showed that stability of the protein was controlled by sigmaS but not by sigma32. These results suggest that control of the PBP3 levels in E. coli K12 is through a post-transcriptional mechanism regulated by the stationary phase regulon. We demonstrated that stability of PBP3 in E. coli K12 involves degradation of the protein. Moreover, we observed that incubation of cells at 42°C significantly reduces the stability of PBP3 in early stationary phase cells in a process controlled by sigmaS.

Insights into the role of hydration in protein structure and stability obtained through hydrostatic pressure studies

A thorough understanding of protein structure and stability requires that we elucidate the molecular basis for the effects of both temperature and pressure on protein conformational transitions. While temperature effects are relatively well understood and the change in heat capacity upon unfolding has been reasonably well parameterized, the state of understanding of pressure effects is much less advanced. Ultimately, a quantitative parameterization of the volume changes (at the basis of pressure effects) accompanying protein conformational transitions will be required. The present report introduces a qualitative hypothesis based on available model compound data for the molecular basis of volume change upon protein unfolding and its dependence on temperature.

Stability of relative oxygen pulse curve during repeated maximal cardiopulmonary testing in professional soccer players

During cardiopulmonary exercise testing (CPET), stroke volume can be indirectly assessed by O2 pulse profile. However, for a valid interpretation, the stability of this variable over time should be known. The objective was to analyze the stability of the O2 pulse curve relative to body mass in elite athletes. VO2, heart rate (HR), and relative O2 pulse were compared at every 10% of the running time in two maximal CPETs, from 2005 to 2010, of 49 soccer players. Maximal values of VO2 (63.4 ± 0.9 vs 63.5 ± 0.9 mL O2•kg-1•min-1), HR (190 ± 1 vs188 ± 1 bpm) and relative O2 pulse (32.9 ± 0.6 vs 32.6 ± 0.6 mL O2•beat-1•kg-1) were similar for the two CPETs (P > 0.05), while the final treadmill velocity increased from 18.5 ± 0.9 to 18.9 ± 1.0 km/h (P < 0.01). Relative O2 pulse increased linearly and similarly in both evaluations (r² = 0.64 and 0.63) up to 90% of the running time. Between 90 and 100% of the running time, the values were less stable, with up to 50% of the players showing a tendency to a plateau in the relative O2 pulse. In young healthy men in good to excellent aerobic condition, the morphology of the relative O2 pulse curve is consistent up to close to the peak effort for a CPET repeated within a 1-year period. No increase in relative O2pulse at peak effort could represent a physiologic stroke volume limitation in these athletes.

Stability of XIST repression in relation to genomic imprinting following global genome demethylation in a human cell line

DNA methylation is essential in X chromosome inactivation and genomic imprinting, maintaining repression of XIST in the active X chromosome and monoallelic repression of imprinted genes. Disruption of the DNA methyltransferase genes DNMT1 and DNMT3B in the HCT116 cell line (DKO cells) leads to global DNA hypomethylation and biallelic expression of the imprinted gene IGF2 but does not lead to reactivation of XIST expression, suggesting thatXIST repression is due to a more stable epigenetic mark than imprinting. To test this hypothesis, we induced acute hypomethylation in HCT116 cells by 5-aza-2′-deoxycytidine (5-aza-CdR) treatment (HCT116-5-aza-CdR) and compared that to DKO cells, evaluating DNA methylation by microarray and monitoring the expression of XIST and imprinted genes IGF2, H19, and PEG10. Whereas imprinted genes showed biallelic expression in HCT116-5-aza-CdR and DKO cells, the XIST locus was hypomethylated and weakly expressed only under acute hypomethylation conditions, indicating the importance ofXIST repression in the active X to cell survival. Given that DNMT3A is the only active DNMT in DKO cells, it may be responsible for ensuring the repression of XIST in those cells. Taken together, our data suggest that XIST repression is more tightly controlled than genomic imprinting and, at least in part, is due to DNMT3A.

Enhanced production and organic solvent stability of a protease fromBrevibacillus laterosporus strain PAP04

A bacterial strain (PAP04) isolated from cattle farm soil was shown to produce an extracellular, solvent-stable protease. Sequence analysis using 16S rRNA showed that this strain was highly homologous (99%) to Brevibacillus laterosporus. Growth conditions that optimize protease production in this strain were determined as maltose (carbon source), skim milk (nitrogen source), pH 7.0, 40°C temperature, and 48 h incubation. Overall, conditions were optimized to yield a 5.91-fold higher production of protease compared to standard conditions. Furthermore, the stability of the enzyme in organic solvents was assessed by incubation for 2 weeks in solutions containing 50% concentration of various organic solvents. The enzyme retained activity in all tested solvents except ethanol; however, the protease activity was stimulated in benzene (74%) followed by acetone (63%) and chloroform (54.8%). In addition, the plate assay and zymography results also confirmed the stability of the PAP04 protease in various organic solvents. The organic solvent stability of this protease at high (50%) concentrations of solvents makes it an alternative catalyst for peptide synthesis in non-aqueous media.

STABILITY OF OILS HEATED BY MICROWAVE: UV - SPECTROPHOTOMETRIC EVALUATION

The effects of microwave heating on the oxidative stability of refined canola, corn and soybean oils were determined by absorptivity in the UV spectrum and by chemical analysis (peroxide and acid values). Samples were heated in a microwave oven (800 W, 2,450 MHz) for 0 to 36 min. Microwave heating produced oxidative degradation in the three oils. Absorptivity at 232 and 270 nm increased gradually with an increase in microwave exposure time (0-36 min) for canola, corn and soybean oils. Values of absorptivity at 232 nm increased from 4.812, 3.568 and 4.183 to 10.579, 12.874 and 15.950 after 36 min of heating canola, corn and soybean oil, respectively. The absorptivity at 232nm, due to the formation of conjugated dienes, was a good index for measuring the degradation of microwaved samples. UV scanning (220 - 320 nm) detected alterations in the spectrum of microwaved samples. Acid value also increased within 36 min of heating for all oils. Peroxide value showed a significant difference (P<0.05) in the initial stage of heating (0-6 min) for all oils. After this period it could not be correlated with absorptivity at 232 nm, due to the instability of hydroperoxides at high temperatures.

Storage stability of cashew apple juice preserved by hot fill and aseptic processes

Cashew (Anacardium occidentale L.) apples from Pacajus, Ceará State, Brazil, were processed into high pulp content juice. The juice was packed either by hot fill or an aseptic process and evaluated for physical, physical-chemical, and sensorial changes during a 12-month storage period at room temperature. The results indicated that pH, soluble solids, total acidity, total sugar content and color did not change significantly during storage nor were affected by the type of filling. The sensorial analysis showed that juice acceptance remained high throughout the storage period regardless of the filling system. Differences in juice viscosity persisted between both processes.

Determining economical TBHQ doses for corn oil stability

Corn oil obtained from a Brazilian industry, free from antioxidants and citric acid, added of different tertiary butylhydroquinone (TBHQ) concentrations, was submitted to accelerated oxidation in the Schaal oven test at 63°C for 120 hours and for 168 hours in a photooxidation chamber. Peroxide and absorptivity values at 232nm and 270nm were determined for this oil. From the Schaal oven test results, the best and the economical TBHQ doses were determined to this oil. Afterwards, a shelf life experiment was conducted and confirmed 115mg.kg-1 TBHQ as the best and economical dose for that oil.

Storage stability of snacks with reduced saturated and trans fatty acids contents

Partially hydrogenated vegetable oil has been used in snack flavoring for its ability to entrap hydrophobic aroma compounds. However, increasing concerns about the health risks of saturated and trans fatty acids (TFA) consumption led to the development of alternative agents for this use. We studied the use of rapeseed oil (O) as a replacement for partially hydrogenated vegetable oil (F) in snack flavoring. Products with several different rapeseed oil contents were designed, packed, and then stored for twenty weeks at room temperature. Fatty acids compositions, TBA reactive substances (TBARS), shear strength and sensory acceptability were assessed throughout storage time. Total replacement reduced saturated fat by 72.5% in relation to market available snacks. TFA were initially absent in these products, but their production occurred spontaneously on the 8th week with gradual increase during storage up to levels still lower than those observed in commercially available snacks. Low TBARS levels and stability of shear strength during the twenty-week of storage were also observed. Snacks flavored with F or O were equally well accepted during the storage period. It is feasible to develop a storage stable snack with reduced saturated and trans fatty acid contents while maintaining the high sensory acceptability typical of this food product.

Rheological behavior and color stability of anthocyanins from Merlot (Vitis vinifera L.) and Bordô (Vitis labrusca L.) grapes in a jam model system

Anthocyanins are the pigments responsible for the color of most red grapes and are easily degraded following various reaction mechanisms affected by oxygen, enzymes, pH, and temperature among other variables. In this study, a jam model system was developed using Merlot and Bordô grape extracts and polysaccharides (xanthan and locust bean gums) and different temperatures (45, 55 and 65 °C). The stability of the anthocyanin pigments and the rheological behavior of the jam model system were studied. For the determination of the stability, the half-life time and first-order reaction rate constants for the anthocyanin pigments were calculated. The rheological behavior was determined through the Power law model. The jam model system produced using a temperature of 45 °C showed the best results for the anthocyanin half-life time. The first-order reaction rate constants for the 45, 55, and 65 °C treatments were not significantly different among each other (p > 0.05). It was observed that with an increase in the jam model system temperature there was an increase in the index of consistency.

Stability studies and shelf life estimation of a soy-based dessert

This work is aimed at evaluating the physicochemical, physical, chromatic, microbiological, and sensorial stability of a non-dairy dessert elaborated with soy, guava juice, and oligofructose for 60 days at refrigerated storage as well as to estimate its shelf life time. The titrable acidity, pH, instrumental color, water activity, ascorbic acid, and physical stability were measured. Panelists (n = 50) from the campus community used a hedonic scale to assess the acceptance, purchase intent, creaminess, flavor, taste, acidity, color, and overall appearance of the dessert during 60 days. The data showed that the parameters differed significantly (p < 0.05) from the initial time, and they could be fitted in mathematical equations with coefficient of determination above 71%, aiming to consider them suitable for prediction purposes. Creaminess and acceptance did not differ statistically in the 60-day period; taste, flavor, and acidity kept a suitable hedonic score during storage. Notwithstanding, the sample showed good physical stability against gravity and presented more than 15% of the Brazilian Daily Recommended Value of copper, iron, and ascorbic acid. The product shelf life estimation found was 79 days considering the overall acceptance, acceptance index and purchase intent.