Long‐Term Storage Effect in Frozen Dough by Spectroscopy and Microscopy

Storage of dough at low temperatures (‐20°C) has a considerable effect on the final quality of baked bread; this is most obviously reflected in lowered specific volumes. In this study, a suite of structural characterization techniques is applied to examine the underlying mechanism of storage damage at the molecular, microstructural, and macroscopic level. By using infrared spectroscopy, the dehydration of the gluten component could be established at the molecular level, and its kinetics could be monitored in time. Time‐domain nuclear magnetic resonance (NMR) showed increased water mobility, which could be attributed to a release of water from the gluten matrix. At the microstructural level, the growth of ice crystals could be monitored by means of cryogenic scanning electron microscopy (cryo‐SEM). These ice crystals are preferably formed in gas cells with kinetics that are slower than those during infrared spectroscopy but similar to those in time‐domain NMR. At the macroscopic level, ice crystals are not evenly distributed over the molded dough, nor are the gas cells homogeneously distributed over the dough. This has implications for the macroscopic water distribution during frozen storage, which could be substantiated by magnetic resonance imaging (MRI) measurements.     

Effect of mitratapide on body composition, body measurements and glucose tolerance in obese Beagles

The objective of this study was to confirm that weight loss after treatment with mitratapide (Yarvitan®) is loss of adipose tissue. Obese dogs were treated with the recommended treatment schedule of mitratapide. Dual-energy X-ray absorptiometry (DEXA) was done before and after the treatment schedule. Body weight, feed consumption and pelvic circumference were recorded and a glucose tolerance test was performed. Dual-energy X-ray absorptiometry measurements showed an impressive loss of fat tissue, corresponding to a mean loss of approximately 41.6% of the body fat mass recorded before treatment. After treatment with mitratapide, the mean body fat percentage had returned within the normal range. At the end of the study, the dogs had lost on average 14.2% of their body weight and 15.2% of their pelvic circumference compared to baseline. The results also suggest that losing weight with mitratapide might help to reverse insulin resistance.     

In vitro antimicrobial activity of miconazole and polymyxin B against canine meticillin-resistant Staphylococcus aureus and meticillin-resistant Staphylococcus pseudintermedius isolates

Background – Meticillin‐resistant Staphylococcus aureus (MRSA) and meticillin‐resistant Staphylococcus pseudintermedius (MRSP) infections are increasingly reported in dogs, and these bacteria may be isolated from ear infections. Hypothesis/Objectives – The main aim of the present study was to investigate the in vitro antimicrobial activity of miconazole, polymyxin B and a combination of both against 24 canine MRSA and 50 canine MRSP isolates. The minimal inhibitory concentration (MIC) values of 12 other antimicrobial agents were also determined. Methods – All MIC values were determined according to a broth microdilution assay. Results – Acquired resistance was found to all tested agents, except for linezolid, miconazole and polymyxin B. The MIC values for miconazole and polymyxin B against MRSA were in the range of 4–8 and 8–64 μg/mL, respectively, while the MIC values for miconazole and polymyxin B against MRSP were in the range of 1–2 and 0.25–4 μg/mL, respectively. Using a combination of miconazole and polymyxin B, there was no evidence for enhanced in vitro activity of the combination (i.e. synergy) of both products. Nevertheless, MIC₉₀ values of the combination of these antimicrobial agents and of a commercial product containing both agents were at least 1000 times lower than the concentration present in the commercial product. Conclusions and clinical importance – These results indicate that the topical use of a combination of miconazole and polymyxin B in a 43.5:1 ratio may have potential for the treatment of MRSA‐mediated and MRSP‐associated otitis externa in dogs.     

Time-delayed influence of urban landscape change on the susceptibility of koalas to chlamydiosis

Context

Infectious diseases are important in the dynamics of many wildlife populations, but there is limited understanding of how landscape change influences susceptibility to disease.

Objectives

We aimed to quantify the time-delayed influence of spatial and temporal components of landscape change and climate variability on the prevalence of chlamydiosis in koala (Phascolarctos cinereus) populations in southeast Queensland, Australia.

Methods

We used data collected over 14 years (n = 9078 records) from a koala hospital along with time-lagged measures of landscape change and rainfall to conduct spatial and temporal analyses of the influence of landscape and environmental variables on prevalence of chlamydiosis and koala body condition.

Results

Areas with more suitable habitat were associated with higher levels of disease prevalence and better body condition, indicating that koalas were less likely to be impacted by chlamydiosis. More intact landscapes with higher proportions of total habitat are associated with a reduction in prevalence of chlamydiosis and a decrease in body condition. Increased annual rainfall contributed to a decrease in prevalence of chlamydiosis and an increase in body condition. Urbanization was associated with an increase in disease, however the effects of urban landscape change and climate variability on chlamydiosis may not manifest until several years later when overt disease impacts the population via effects upon body condition and reproductive success.

Conclusions

Our study highlights the importance of effects of landscape change and climate variability on disease prevalence in wildlife. This recognition is essential for long-term conservation planning, especially as disease often interacts with other threats.

     

Dynamics of senescence-related QTLs in potato

The study of quantitative trait’s expression over time helps to understand developmental processes which occur in the course of the growing season. Temperature and other environmental factors play an important role. The dynamics of haulm senescence was observed in a diploid potato mapping population in two consecutive years (2004 and 2005) under field conditions in Finland. The available time series data were used in a smoothed generalized linear model to characterize curves describing the senescence development in terms of its onset, mean and maximum progression rate and inflection point. These characteristics together with the individual time points were used in a Quantitative trait loci (QTL) analysis. Although QTLs occurring early in the senescence process coincided with QTLs for onset of senescence, the analysis of the time points made it difficult to study senescence as a continuous trait. Characteristics estimated from the senescence curve allowed us to study it as a developmental process and provide a meaningful biological interpretation to the results. Stable QTLs in the two experimental years were identified for progression rate and year-specific QTLs were detected for onset of senescence and inflection point. Specific interactions between loci controlling senescence development were also found. Epistatic interaction between QTLs on chromosomes 4, 5 and 7 were detected in 2004 and pleiotopic effects of QTLs on chromosomes 3 and 4 were observed in 2005.     

Predicting the chemical composition of fibre and core fraction of hemp (Cannabis sativa L.)

Summary Fibre formation in hemp (Cannabis sativa L.) is a dynamic process. In order to follow this process, the chemical composition of the hemp stem was studied during plant development using the acid and neutral detergent fibre and lignin methods. Additionally, near infra-red spectroscopy was carried out. To predict the chemical composition of the stem samples partial least square (PLS) analysis was carried out. The developed PLS models can predict the level of %ADF and %NDF in the hemp bast and core samples. For %ADL, the models are only suited for either core or bast tissues and can not be used for both tissues simultaneously.     

Performance of spring barley (Hordeum vulgare) varieties under organic and conventional conditions

Organic agriculture needs spring barley varieties that are adapted to organic growing conditions and have good and stable grain yield across years, even under less favourable growing conditions. The aim of this study was to compare how varieties differ in yield and yield stability under conventional and organic management conditions. The results help to decide under which growing conditions selection of genotypes for organic farming can be most effective. Grain yield and yield components of 10 varieties were estimated in field trials for three years at four sites: two conventionally and two organically managed sites. Varieties differed in stability: some varieties had high yield under conventional conditions and relatively high and stable yield under organic conditions. Heritabilities for yield and yield components were lower under organic (especially in the field with low weed control) than under conventional conditions. Heritabilities for yield components were lower than those for yield itself. Selection for yield components, therefore, may be less effective than selection directly for grain yield. Our data showed that generally the top performing cultivars under conventional conditions also performed as the best under organic conditions, but there were also exceptions. Therefore we conclude that selection of genotypes for organic farming may take place under conventional conditions, but that a final testing should be conducted under organic conditions to confirm the suitability of the selected varieties for cultivation on organic farms.     

Towards an Optimized Protocol for Measuring Global Dehydrogenase Activity in Storm-Water Sediments (10 pp)

Background, Aim and Scope   Microorganisms play an important role in the biogeochemical cycles of soils and sediments; hence the microbiological quality of these environments can be evaluated by measuring microorganism population densities, diversity and enzyme activity. For example, dehydrogenase activity is known to be sensitive to pollutants, such as heavy metals, and to correlate with the carbon cycle. This article presents an optimized protocol for measuring dehydrogenase in a range of different sediments and, more precisely, in urban storm-water sediments. The influence of blank preparation, ratio substrate/sediment and time of formazan extraction was studied on sediments coming from urban sewage works, or lakes and rivers. Materials and Methods   After a microbial and chemical characterization of the sediments studied, the initial protocol of dehydrogenanse measurement consited in incubating 2 g of dry sediment with 2 μmol of INT (the substrate) at 37°C for 24 hrs. It was carried out on three different urban storm-water sediments. Once an optimum dehydrogenase activity was obtained, the new protocol was tested on six other sediment materials. Results   The results for all the sterilized samples were significantly different to those obtained for the corresponding, non-sterilized sample, with the exception of the St Vallier sediment, which was treated with formaldehyde or the maximum dose of gamma radiation. Sediments that are rich in organic matter must be treated with high concentrations of INT in order to reach, or approach, substrate excess, especially if it is intended to compare formazan measurements. In order to more easily achieve excess substrate, we investigated the possibility of reducing the quantity of solid matter used for the tests. For the two samples tested, and especially for the road basin sample, tests carried out using a ratio of sediment mass (in g) to INT quantity (in μmol) of 0.05 (0.5 g of sediment/10 μmol INT) produced values of 2000-2200 μg of formazan/g of sediment/24 hrs. Activities are much lower (between 1.5 and 3 times lower) when the ratio is equal to 0.2. Sonication should increase formazan extraction as it separates aggregates, thereby improving the contact between the acetone and the sediment. Sonication has an effect on the extraction of formazan. For sample EC2, 30% more formazan was extracted with sonication than without. Discussion   Sterilization by formaldehyde and by autoclaving demonstrated very different levels of activity. Autoclaving is the least satisfactory sterilization method, as the modifications it causes, especially to the sediment texture, are too great (Trevors 1996). The main advantage of sterilization by irradiation is the minimal disturbance of the sediment structure (Trevors 1996, McNamara et al. 2003). The quickest and most economic sterilization method is the use of formaldehyde. Therefore, blanks sterilized using formaldehyde were used in the tests of the different methods. Organic matter absorbs INT salts, so they are no longer bioavailable for the microorganisms. Sediments that are rich in organic matter must be treated with high concentrations of INT in order to reach, or approach substrate excess, especially if it is intended to compare formazan measurements. Based on our results, the results reported in the literature and practical considerations, such as the solubility of INT and the toxicity of INT with respect to bacteria (Hatzinger et al. 2003), we decided to use a quantity of INT equivalent to 10 μmol (i.e. 2.5 mM in a final concentration in the test) for our subsequent experiments, even though we realized this would not produce saturation conditions for the highly organic sediments. In order to more easily achieve excess substrate, we investigated the possibility of reducing the quantity of solid matter used for the tests. The literature shows that previous work has often been carried out using 1 g samples of dry soil or dry sediment (Merlin et al. 1995, Taylor et al. 2002, Benitez et al. 2004, Plaza et al. 2004). Here, we find a direct relation between the amount of sample and the reduction of the substrate. To ensure that samples remained representative, it was decided not to test samples of less than 0.5g dry weight. Acetone was chosen as the extractant, as it has been used by many other workers (Brohon 1998, Engelen et al. 1998). Sonication has an effect on the extraction of formazan. Kruskal and Wallis tests, at p=0.05, show that the increase of INT extraction is significant for EC2 at 10 minutes, but not for EC1. EC2 is much coarser (around 75% sand and 25% silt) than EC1 (40% sand and 60% silt) (data not shown). This difference in grain size distribution may be one explanation for the different behavior of the two matrices when subjected to sonication .This pretreatment is known to destroy aggregates. Therefore, in order to measure the maximum activity, the acetone extraction time, with or without ultrasound, must be chosen to suit the matrices being studied. So, depending on the characteristics of the sediment (mostly the grain size distribution), it may be useful to use ultrasound in order to achieve a good level of formazan extraction. The method to be used must be determined for each sediments. Conclusions   When tested on different types of sediment (river, urban sewage, etc.) the optimized protocol (0.5 g sediment and 10 μmol of INT) gave higher activity measurements than the initial protocol and appears to provide a useful test method for comparative studies or for monitoring sediment quality. The organic matter content appeared to be one the most important parameter controlling the measurement and playing an important part on the different contact and extraction steps of the experiment. The best method for preparing blanks is sterilization using gamma radiation, as this has the lowest impact on sediment structure. However, if cost and time considerations render this method impracticable, samples can be sterilized using formaldehyde. Recommendations and Perspective  : The final protocol can be used to monitor the spatial (in terms of the different vertical and horizontal zones at the surface) and temporal (monitoring changes in activity over time using surface samples taken after different rain events) evolution of this activity within sediment samples from rainwater infiltration basins.     

Impact of Industrial Dough Processing on Structure: A Rheology,Nuclear Magnetic Resonance,and Electron Microscopy Study

Dough processing is an important factor determining the quality of bread. The most important mechanical steps in industrial dough processing are kneading, extrusion, and molding. In all of these processing steps, considerable changes in the structure and properties of the dough can occur. On a laboratory‐scale level, these (structural) effects are well characterized but, so far, no systematic study has been performed at the level of a large‐scale industrial dough processing line. The molecular and microstructural changes that can take place during industrial dough processing were studied with the help of nuclear magnetic resonance (NMR), fundamental rheology, and scanning electron microscopy (SEM). After the kneading step, the dough shows a well‐developed gluten network with a homogeneous dispersion of starch particles (at optimum kneading time). After the extrusion step (a sheeting procedure), the structure of the dough becomes coarser and the dough gluten network is oriented and partially disrupted. This is accompanied with an increase in both rheological stress and water mobility. After molding, the network structure is restored and both the rheological stress and the mobility of water decrease. These findings provide a novel microstructurally‐lead approach to make recommendations for optimization of industrial dough processing lines.