Judith Kreyenschmidt

Determination of the shelf life of sliced cooked ham based on the growth of lactic acid bacteria in different steps of the chain

Aims:  Development of a predictive model for the determination of the shelf life of modified atmosphere‐packed (MAP) cooked sliced ham in each step of the cold chain.

Mathematical modelling for predicting the growth of Pseudomonas spp. in poultry under variable temperature conditions.

A dynamic growth model under variable temperature conditions was implemented and calibrated using raw data for microbial growth of Pseudomonas spp. in poultry under aerobic conditions. The primary model was implemented using measurement data under a set of fixed temperatures. The two primary models used for predicting the growth under constant temperature conditions were: Baranyi and modified Gompertz. For the Baranyi model the maximum specific growth rate and the lag phase at constant environmental conditions are expressed in exact form and it has been shown that in limit case when maximal cells concentration is much higher than the initial concentration the maximum specific growth rate is approximately equal to the specific growth rate. The model parameters are determined in a temperature range of 2-20 degrees C. As a secondary model the square root model was used for maximum specific growth rate in both models. In both models the main assumption, that the initial physiological state of the inoculum is constant and independent of the environmental parameters, is used, and a free parameter was implemented which was determined by minimizing the mean square error (MSE) relative to the measurement data. Two temperature profiles were used for calibration of the models on the initial conditions of the cells.

Study on the antimicrobial effect of silver-containing inner liners in refrigerators

Aims:  To investigate the effect of silver‐based antimicrobial material incorporated in the inner liners of refrigerators on food safety and quality.

Temperature monitoring in meat supply chains

Purpose – An optimal temperature monitoring is a prerequisite for cold chain management and thus for the production and supply of high quality and safe products as well as for the reduction of waste and economic losses. The aim of this paper is to identify and compare already existing temperature monitoring solutions in operation and novel temperature monitoring solutions with a view to their use for optimal temperature monitoring in meat supply chains. A special focus is placed on the identification and specification of challenges by the implementation of temperature monitoring systems which allow an optimal control of the temperature conditions in meat supply chains, as required by the new European food law.Design/methodology/approach – The paper is a literature review of existing and novel temperature monitoring systems and challenges faced by the practical implementation of monitoring systems which allow continuous control of the temperature conditions in meat supply chains. First, the relevant litera...

Comparison of argon-based and nitrogen-based modified atmosphere packaging on bacterial growth and product quality of chicken breast fillets

Poultry fillets were packaged under 6 different gas atmospheres (A: 15% Ar, 60% O2, 25% CO2; B: 15% N2, 60% O2, 25% CO2; C: 25% Ar, 45% O2, 30% CO2; D: 25% N2, 45% O2, 30% CO2; E: 82% Ar; 18% CO2; F: 82% N2, 18% CO2) and stored at 4°C. During storage, the growth of typical spoilage organisms (Brochothrix thermosphacta, Pseudomonas spp., Enterobacteriaceae, and Lactobacilli spp.) and total viable count were analyzed and modeled using the Gompertz function. Sensory analyses of the poultry samples were carried out by trained sensory panelists for color, odor, texture, drip loss, and general appearance. No significant difference in microbiological growth parameters was observed for fresh poultry stored under an argon-enriched atmosphere in comparison with nitrogen, except the B. thermosphacta stored under 82% argon. The sensory evaluation showed a significant effect of an argon-enriched atmosphere, particularly on color of meat stored under 15% argon (P < 0.05). In contrast, 25 and 82% argon concentrations in place of nitrogen showed no beneficial effect on sensory parameters.

Effect of high-oxygen and oxygen-free modified atmosphere packaging on the spoilage process of poultry breast fillets

A comparison was made of the effect of atmospheres containing high oxygen (70% O2 and 30% CO2) or high nitrogen (70% N2 and 30% CO2) on the spoilage process during storage (at 4°C) of poultry fillets. Four samples of each gas atmosphere were analyzed at 7 sample points during storage. For this analysis, the growth of typical spoilage organisms (Brochothrix thermosphacta, Pseudomonas spp., Enterobacteriaceae, and Lactobacilli spp.) and total viable count (TVC) were analyzed and modeled by using the Gompertz function. Sensory analyses of the poultry samples were carried out by trained sensory panelists to analyze color, odor, texture, drip loss, and general appearance. The composition of the spoilage flora differed between the oxygen-free atmosphere and the high-oxygen atmosphere. Anaerobic conditions favored the growth of Lactobacilli spp., whereas aerobic gas composition favored the growth of B. thermosphacta. However, no significant difference (P<0.05) in TVC and sensory parameters were observed for poultry samples stored under a high-oxygen atmosphere in comparison to a high-nitrogen atmosphere. These results indicate that high-oxygen packaging has no additional beneficial effect on the quality maintenance and shelf life of fresh poultry fillets.

Quality tracing in meat supply chains.

The aim of this study was the development of a quality tracing model for vacuum-packed lamb that is applicable in different meat supply chains. Based on the development of relevant sensory parameters, the predictive model was developed by combining a linear primary model and the Arrhenius model as the secondary model. Then a process analysis was conducted to define general requirements for the implementation of the temperature-based model into a meat supply chain. The required hardware and software for continuous temperature monitoring were developed in order to use the model under practical conditions. Further on a decision support tool was elaborated in order to use the model as an effective tool in combination with the temperature monitoring equipment for the improvement of quality and storage management within the meat logistics network. Over the long term, this overall procedure will support the reduction of food waste and will improve the resources efficiency of food production.

Development of a New Monomer for the Synthesis of Intrinsic Antimicrobial Polymers with Enhanced Material Properties

The use of biocidal compounds in polymers is steadily increasing because it is one solution to the need for safety and hygiene. It is possible to incorporate an antimicrobial moiety to a polymer. These polymers are referred to as intrinsic antimicrobial. The biocidal action results from contact of the polymer to the microorganisms, with no release of active molecules. This is particularly important in critical fields like food technology, medicine and ventilation technology, where migration or leaching is crucial and undesirable. The isomers N-(1,1-dimethylethyl)-4-ethenyl-benzenamine and N-(1,1-dimethyl-ethyl)-3-ethenyl-benzenamine (TBAMS) are novel (Co-)Monomers for intrinsic anti-microbial polymers. The secondary amines were prepared and polymerized to the corresponding water insoluble polymer. The antimicrobial activity was analyzed by the test method JIS Z 2801:2000. Investigations revealed a high antimicrobial activity against Staphylococcus aureus and Escherichia coli with a reduction level of >4.5 log10 units. Furthermore, scanning electron microscopy (SEM) of E. coli. in contact with the polymer indicates a bactericidal action which is caused by disruption of the bacteria cell membranes, leading to lysis of the cells.

Continuous temperature monitoring along the chilled food supply chain.

Abstract: This chapter addresses the need for continuous temperature monitoring along the entire food supply chain to ensure food quality and safety. In the first part, the needs and expectations as well as barriers of supply chain actors regarding novel technologies are discussed. In the second part, novel technologies for the continuous control of temperature conditions in chilled food chains are presented. These include temperature monitoring systems based on radio frequency identification (RFID) and smart labels, such as time temperature indicators (TTIs). Finally, solutions are presented which show how temperature monitoring systems can be linked with product characteristics to improve food quality and safety.

Potential of the polymer poly-[2-(tert-butylamino) methylstyrene] as antimicrobial packaging material for meat products.

The objective of the study was to investigate the antimicrobial potential of a new SAM® polymer poly(TBAMS) as packaging material for meat products.