Microwave Convective Drying of Plant Foods at Constant and Variable Microwave Power

Microwave convective drying of plant foods is a promising process due to the shorter drying time and better product quality. High microwave power decreases the drying time but causes charring of the product. In this work, microwave drying under constant and variable microwave power were compared. Temperature-sensitive products, such as plant foods, are especially affected by microwave power during the final drying period. Therefore, drying at variable microwave power was found to be a more suitable drying process. Air (temperature and velocity) has an important role during microwave drying, not only as carrier of evaporated moisture but also as it contributes to a more homogeneous and faster drying.     

4‐Alkylated Silver–N‐Heterocyclic Carbene (NHC) Complexes with Cytotoxic Effects in Leukemia Cells

Computational chemistry has shown that backbone‐alkylated imidazoles ought to be efficient ligands for transition metal catalysts with improved carbene‐to‐metal donation. In this work, such alkylated imidazoles were synthesized and complexed with silver(I) by means of an eight/nine‐step synthetic pathway we devised to access a new class of biologically active silver complexes. The synthesis involves selective iodination of the imidazole backbone, followed by Sonogashira coupling to replace the backbone iodine. The installed alkyne moiety is then subjected to reductive hydrogenation with Pearlman’s catalyst. The imidazole N1 atom is arylated by the palladium‐catalyzed Buchwald N‐arylation method. The imidazole N3 position was then methylated with methyl iodine, whereupon the synthesis was terminated by complexation of the imidazolium salt with silver(I) oxide. The synthetic pathway provided an overall yield of ≈20 %. The resulting complexes were tested in vitro against HL60 and MOLM‐13 leukemic cells, two human‐derived cell lines that model acute myeloid leukemia. The most active compounds exhibiting low IC₅₀ values of 14 and 27 μM , against HL60 and MOLM‐13 cells, respectively. The imidazole side chain was found to be essential for high cytotoxicity, as the imidazole complex bearing a C₇ side chain at the 4‐position was four‐ to sixfold more potent than the corresponding imidazole elaborated with a methyl group.     

Composition of the bacterial population of refrigerated beef, identified with direct 16S rRNA gene analysis and pure culture technique

The composition of the dominating population of freshly cut beef, and beef stored at 4 degrees C for 8 d, was studied by direct analysis of the 16S rRNA gene (PCR amplification, cloning and sequencing) and compared with pure culture technique where the isolates picked from the viable plate count were identified by sequencing of the 16S rRNA gene. The composition of the bacterial population was recorded at two different time points, at the start when the viable plate count of the meat was 4 x 10(2) colony forming unit (cfu) per cm(2) and when it was 5 x 10(7) cfu per cm(2). Direct gene analysis by PCR amplification generated 30 clones, and 79 isolates were picked from the plate count, and identified by 16S rRNA gene sequencing. At the low initial bacterial load of the beef, the two sampling strategies showed variations in the composition of species. Direct 16S rRNA gene analysis revealed a domination of Bacillus-like sequences while no such sequences were found in isolates from the viable plate count. Instead the population of the plate count was dominated by Chryseobacterium spp. In contrast, the two sampling strategies matched on the multiplying beef population, where both methods indicated Pseudomonas spp. as the dominating group (99% of the population-sequences), irrespectively of sampling strategy. Pseudomonas panacis/Pseudomons brennerii was the dominating taxon (99% similarity to type strain), but sequences with highest similarity to Pseudomonas lundensis (99%), Pseudomonas beteli (99%) and Pseudomonas koreensis (100%) were also found.     

Casein‐Based Powders: Characteristics and Rehydration Properties

Casein‐based powders are gaining industrial interest due to their nutritional and functional properties, but they are also known to have poor rehydration abilities. The fundamental physical and chemical mechanisms involved in the rehydration of these powders are essential for determining the critical steps in the manufacturing processes and for developing casein powders with improved rehydration properties. A number of analytical methods have been developed to measure the rehydration ability of powders, but criteria for the selection of methods for casein‐based powders have not been provided. This review article provides an overview of the characteristics and methods for the production of casein‐based powders, methodologies to measure their rehydration properties, and it summarizes the current state of understanding regarding rehydration. Advancements have been made in the field; however, a fundamental understanding enabling improvement of the rehydration properties of these powders is still lacking.     

Application of indigenous strains of lactic acid bacteria for semi‐industrial production of autochthonous Montenegrin Njeguši cheese

Most of the traditional dairy products of south‐eastern Europe are produced from unpasteurised milk without addition of selected starter cultures. These artisanal products have an interesting biodiversity of indigenous microbiota. In Montenegro, one of the most popular traditional cheeses is Njegu?i cheese, belonging to the group of hard cheeses. Most of the cheeses are produced from ewes' milk, but cows' milk is also widely used. In Montenegro, there are no existing legal regulations defining the specificities of the production or the raw material used for the production of autochthonous food products. Therefore, the producers make the decision about what type of milk to use for cheese production. One of the priorities of the food producers in Montenegro is to obtain a larger scale, standardised production of traditional food products, which are of good quality and considered safe for the consumers. Therefore, in this study, indigenous strains of lactic acid bacteria isolated from various Montenegrin artisanal dairy products were tested as starter cultures for the production of Njegu?i cheese. Three isolates were selected and used as starter cultures in pilot plant experiments for the production of Njegu?i cheese. When applying an adequate combination of added bacterial strains as starters, the flavour of Njegu?i cheese, produced under pilot plant conditions, was comparable to that of the artisanal origin.     

Lipolysis and the distribution of lipase activity in bovine milk in relation to stage of lactation and time of milking

The increase in levels of free fatty acids (FFA) in morning and afternoon milk after 48 h cold storage at 5 degrees C was determined at two stages of lactation in milk from 96 cows. Lipolysis was positively correlated to day of lactation (r = 0.6, P less than 0.001), while the correlations between lipolysis and milk yield and fat content respectively were due to these factors being related to day of lactation. In afternoon milk the level of FFA increased almost three times above that in morning milk. Lipolysis was closely related to the lipoprotein lipase (LPL) activity associated with the cream fraction (r = 0.8, P less than 0.001). Afternoon milk had higher LPL activity in the cream fraction than morning milk. Lipase activity in the cream increased with increasing stage of lactation. Cooling of milk increased LPL activity associated with the fat phase. This effect was greater in afternoon milk from late lactation than in morning milk from early lactation. When heparin was added to milk the LPL activity associated with the fat increased substantially; again, this effect was greater in afternoon milk from late lactation than in morning milk from early lactation. Lipolysis was higher in heparinized milk than in normal milk, and there was a close correlation between lipolysis and LPL activity associated with the fat (r = 0.82, P less than 0.001). Characteristics of the milk fat globule influencing the attraction of LPL were found to be fundamentally important to lipolysis.     

Enhancing security requirements engineering by organizational learning

More and more software projects today are security-related in one way or the other. Requirements engineers without expertise in security are at risk of overlooking security requirements, which often leads to security vulnerabilities that can later be exploited in practice. Identifying security-relevant requirements is labor-intensive and error-prone. In order to facilitate the security requirements elicitation process, we present an approach supporting organizational learning on security requirements by establishing company-wide experience resources and a socio-technical network to benefit from them. The approach is based on modeling the flow of requirements and related experiences. Based on those models, we enable people to exchange experiences about security-relevant requirements while they write and discuss project requirements. At the same time, the approach enables participating stakeholders to learn while they write requirements. This can increase security awareness and facilitate learning on both individual and organizational levels. As a basis for our approach, we introduce heuristic assistant tools. They support reuse of existing experiences that are relevant for security. In particular, they include Bayesian classifiers that issue a warning automatically when new requirements seem to be security-relevant. Our results indicate that this is feasible, in particular if the classifier is trained with domain-specific data and documents from previous projects. We show how the ability to identify security-relevant requirements can be improved using this approach. We illustrate our approach by providing a step-by-step example of how we improved the security requirements engineering process at the European Telecommunications Standards Institute (ETSI) and report on experiences made in this application.     

Stability of SrFeO3 based materials in the presence of SiOx species in humid atmosphere at high temperatures and pressures

Strontium silicate was found on the surface of La_0.2Sr_0.8Fe_0.79Cr_0.2Mg_0.01O₃ exposed to hydrogen containing humid atmospheres at 1000 °C and 30 bars. Silica originated from the furnace tube material and was transported via the gas phase as a gaseous silica hydrate. Fe and Sr were initially preferentially expelled from the perovskite grain boundaries to give Sr₂SiO₄ at the surface, along with a secondary Fe-rich phase and a LaCrO₃-rich grain boundary region. Eventually, Fe and Sr were drawn from the grains, leaving a porous structure. This investigation highlights the importance of avoiding Si sources near Sr-rich membranes in humid atmospheres at high temperatures.     

Stability of SrFeO3-Based Materials in H2O/CO2-Containing Atmospheres at High Temperatures and Pressures

The chemical stability of SrFeO₃-based perovskites in H₂O- and CO₂-containing atmospheres at high temperatures and pressures has been examined. The extent of reaction as a function of p CO₂, p H₂O, temperature, and time has been determined. Either strontium carbonate or Sr(OH)₂·H₂O was observed on sample surfaces after exposure. Observation of two different reaction-rate behaviors could be explained by the formation of different products. The stability of the perovskite has been found to increase when the activity of Sr is decreased. Chemical stability in H₂O/CO₂ is important to understand in order to use these membrane materials for syngas production.