Predictive modelling of the growth and survival of Listeria in fishery products

Predictive microbiology provides a powerful tool to aid the exposure assessment phase of 'quantitative microbial risk assessment'. Using predictive models changes in microbial populations on foods between the point of production/harvest and the point of eating can be estimated from changes in product parameters (temperature, storage atmosphere, pH, salt/water activity, etc.). Thus, it is possible to infer exposure to Listeria monocytogenes at the time of consumption from the initial microbiological condition of the food and its history from production to consumption. Predictive microbiology models have immediate practical application to improve microbial food safety and quality, and are leading to development of a quantitative understanding of the microbial ecology of foods. While models are very useful decision-support tools it must be remembered that models are, at best, only a simplified representation of reality. As such, application of model predictions should be tempered by previous experience, and used with cognisance of other microbial ecology principles that may not be included in the model. Nonetheless, it is concluded that predictive models, successfully validated in agreement with defined performance criteria, will be an essential element of exposure assessment within formal quantitative risk assessment. Sources of data and models relevant to assessment of the human health risk of L. monocytogenes in seafoods are identified. Limitations of the current generation of predictive microbiology models are also discussed. These limitations, and their consequences, must be recognised and overtly considered so that the risk assessment process remains transparent. Furthermore, there is a need to characterise and incorporate into models the extent of variability in microbial responses. The integration of models for microbial growth, growth limits or inactivation into models that can predict both increases and decreases in microbial populations over time will also improve the utility of predictive models for exposure assessment. All of these issues are the subject of ongoing research.     

Information systems in food safety management

Information systems are concerned with data capture, storage, analysis and retrieval. In the context of food safety management they are vital to assist decision making in a short time frame, potentially allowing decisions to be made and practices to be actioned in real time. Databases with information on microorganisms pertinent to the identification of foodborne pathogens, response of microbial populations to the environment and characteristics of foods and processing conditions are the cornerstone of food safety management systems. Such databases find application in: Identifying pathogens in food at the genus or species level using applied systematics in automated ways. Identifying pathogens below the species level by molecular subtyping, an approach successfully applied in epidemiological investigations of foodborne disease and the basis for national surveillance programs. Predictive modelling software, such as the Pathogen Modeling Program and Growth Predictor (that took over the main functions of Food Micromodel) the raw data of which were combined as the genesis of an international web based searchable database (ComBase). Expert systems combining databases on microbial characteristics, food composition and processing information with the resulting "pattern match" indicating problems that may arise from changes in product formulation or processing conditions. Computer software packages to aid the practical application of HACCP and risk assessment and decision trees to bring logical sequences to establishing and modifying food safety management practices.In addition there are many other uses of information systems that benefit food safety more globally, including: Rapid dissemination of information on foodborne disease outbreaks via websites or list servers carrying commentary from many sources, including the press and interest groups, on the reasons for and consequences of foodborne disease incidents. Active surveillance networks allowing rapid dissemination of molecular subtyping information between public health agencies to detect foodborne outbreaks and limit the spread of human disease. Traceability of individual animals or crops from (or before) conception or germination to the consumer as an integral part of food supply chain management. Provision of high quality, online educational packages to food industry personnel otherwise precluded from access to such courses.     

Reconstruction of polarization-shaped laser pulses after a hollow-core fiber using backreflection

We present a method to reconstruct the pulse shape of polarization-shaped femtosecond laser pulses after a hollow-core photonic crystal fiber by reflecting the pulses back through the fiber. First, a procedure is introduced to receive the optical fiber properties and generate parametrically shaped pulses after propagation through the fiber. Changes of the fiber's birefringence by mechanical stress are examined to investigate the correlation between the pulse shapes after one and two passes through the fiber. Finally, we demonstrate the characterization of the pulse after one pass through the fiber by calculating the pulse shape from the measured pulse after two passes.     

Ultrasound- and microwave-assisted intermittent drying of red beetroot

Abstract

A drying technique using a combination of high power airborne ultrasound, microwaves and hot air was applied to investigate the effect of intermittent drying on the process kinetics and several quality indicators of red beetroot. An innovative hybrid dryer was used in drying experiments. Six sets of drying programs were carried out. Ultrasound and microwaves were applied in convective drying continuously (hybrid processes) or periodically (hybrid intermittent processes). The drying processes were assessed in terms of drying time, drying rate, and energy consumption. Moreover, the total color change, retention of natural dye (betanin), water activity, texture, and microstructure of dry product were examined. The drying kinetics was well-fitted with the use of the Midilli-Kucuk model. It was found that hybrid intermittent drying reduces the total drying time and energy consumption, enhances both the drying rate and product quality. Furthermore, it was demonstrated that the hybrid intermittent drying can serve as an alternative to traditional hot air drying that could produce a more porous, nice color, and crispy vegetable product.     

Thawed Chilled Barents Sea Cod Fillets in Modified Atmosphere Packaging-Application of Multivariate Data Analysis to Select Key Parameters in Good Manufacturing Practice

The purpose of the present study was to select key parameters in good manufacturing practice for production of thawed chilled modified atmosphere packed (MAP) cod (Gadus morhua) fillets. The effect of frozen storage temperature (−20 and −30 °C), frozen storage period (3, 6, 9 and 12 mo) and chill storage periods up to 21 d at 2 °C were evaluated for thawed MAP Barents Sea cod fillets. Sensory, chemical, microbiological and physical quality attributes were evaluated and multivariate data analysis (principal component analysis and partial least-squares regression) applied for identification of key parameters in good manufacturing practice for this product. Frozen storage of up to 12 mo had no significant effect on quality attributes and shelf-life at 2 °C was above 14 d irrespective of the time of frozen storage. As compared to a previous study with Baltic Sea, cod drip losses during chill storage was low for thawed MAP Barents Sea cod and this fish raw material seemed the more appropriate for production of thawed chilled MAP products. Frozen storage inactivation of the spoilage bacteria of Photobacterium phosphoreum was modest in Barents Sea cod, possibly due to high trimethylamine oxide (TMAO) and NaCl contents.     

Synthesis and structure-activity relationships of 3,7-dimethyl-1-propargylxanthine derivatives, A2A-selective adenosine receptor antagonists

A series of 8-substituted derivatives of 3,7-dimethyl-1-propargylxanthine (DMPX) was synthesized and investigated as A2A adenosine receptor antagonists. Different synthetic strategies for the preparation of DMPX derivatives and analogues were explored. A recently developed synthetic procedure starting from 3-propargyl-5,6-diaminouracil proved to be the method of choice for the preparation of this type of xanthine derivatives. The novel compounds were investigated in radioligand binding studies at the high-affinity adenosine receptor subtypes A1 and A2A and compared with standard A2A adenosine receptor antagonists. Structure-activity relationships were analyzed in detail. 8-Styryl-substituted DMPX derivatives were identified that exhibit high affinity and selectivity for A2A adenosine receptors, including 8-(m-chlorostyryl)-DMPX (CS-DMPX, Ki A2A = 13 nM, 100-fold selective), 8-(m-bromostyryl)-DMPX (BS-DMPX, Ki A2A = 8 nM, 146-fold selective), and 8-(3,4-dimethoxystyryl)-DMPX (Ki A2A = 15 nM, 167-fold selective). These and other novel compounds are superior to the standard A2A adenosine receptor antagonists KF17837 (4) and CSC (5) with respect to A2A affinity and/or selectivity.     

Visualization techniques to support CCTV operators of smart city services

Multimedia Tools and Applications - In this paper visualization techniques for modern closed circuit television (CCTV) smart city services are discussed with application to prevention of threats....     

Photoinduced transient spectroscopy of defect centers in GaN and SiC

The potentialities of photoinduced transient spectroscopy in terms of investigation of defect centers in wide-band-gap semiconductors are presented. An experimental system dedicated to measurements of the photocurrent transients at temperatures 20–800 K is described and a new approach to extraction of trap parameters from the photocurrent relaxation waveforms recorded in a selected temperature range is presented. The approach is based on the two-dimensional analysis of the waveforms as a function of time and temperature using the correlation procedure. As a result, three-dimensional images showing the temperature changes of the emission rate for detected defect centers are produced and a neural network method is applied to determine the parameters of defect centers. The new approach is exemplified by studies of defect centers in high-resistivity GaN: Mg and semi-insulating 6H-SiC: V. The text was submitted by the authors in English.