Reduction Of Microbiological Contamination Research Articles

Training in tools to develop quantitative microbial risk assessment of ready-to-eat food with a comparison between the Romanian and Spanish food supply chains.

The prevention and control of bacterial contamination on ready-to-eat (RTE) fresh produce is an essential task to ensure food safety. Therefore, the development of novel and effective decontamination technologies to ensure microbiological safety of fruits and vegetables has gained considerable attention and new sanitisation methods are needed. The antimicrobial activity of essential oils (EOs) is well documented, but their application in fresh produce remains a challenge due to their hydrophobic nature. Thus, nanoemulsions efficiently contribute to support the use of EOs in foods by enhancing their dispersibility, their contact area and facilitating the introduction into bacterial cells. The combination of these factors ultimately increases their antimicrobial activity. Quantitative microbial risk assessment (QMRA) is gaining more attention as an effective tool to assess and prevent potential risks associated with food-borne pathogens. In this context, the current project aims to study the effectiveness of different washing methods based on nanoemulsified EOs, comparing them against traditional methods, using a QMRA model for Escherichia coli O157:H7 on cherry tomatoes. Different simulations within a stochastic risk assessment model were implemented using the biorisk package for R, aiming to describe microbial behaviour and biological risk along the Romanian and Spanish food supply chains of RTE fresh produce. Nanoemulsions were prepared using oregano and rosemary EOs, each from Romania and Spain. The four nanoemulsions were evaluated as decontamination treatments to control the growth of E. coli O157:H7 on artificially contaminated cherry tomatoes. The decontamination treatments showed encouraging results, comparable to commonly used chlorine solutions. Therefore, oregano and rosemary nanoemulsions are promising and could be a feasible alternative for chlorine solutions in the reduction of microbiological contaminants.

Application of Enzyme Indicators in Hydrogen Peroxide Biodecontamination Cycle Development: A Critical Evaluation of Indicator Variability and Correlation to Biological Indicator Results.

An important prerequisite for aseptic production of pharmaceuticals is the appropriate reduction of microbiological contamination. Hydrogen peroxide is commonly applied as decontamination agent for such processes in barrier systems. The development and validation of the barrier decontamination cycles is usually performed with the use of biological indicators (Geobacillus stearothermophilus). However, these indicators inherit certain drawbacks. A new type of indicators became available lately, based on the use of enzyme as a substance decomposed by hydrogen peroxide. There is no broad experience on the practical application of these enzyme indicators yet. Therefore, we investigated the practical use of enzyme indicators in comparison with biological indicators. To broaden the understanding on how these indicators might be used in practice, we provided an evaluation of indicator response variability and the correlation of enzyme indicator results to biological indicator results. In this study, we found the variability of the quantitative enzyme indicator reading to be < 30%, which is much smaller than the variability for spore enumeration of biological indicators (-50% to +300%). Further, we introduced a universal normalization approach to enable convenient comparison and evaluation of different enzyme indicator results. Finally, we discussed a new approach to establish a quantitative correlation between enzyme indicators and biological indicators with the use of threshold values to extrapolate theoretical biological indicator group results. We take the findings of this study as a basis for a suggestion on the practical application of enzyme indicators. We expect that the discussed possibilities of correlating enzyme indicator results to biological indicator results will allow the combined practical use of both indicator types. This would enable the continued application of proven approaches in new ways. Beyond this, the fast reading of enzyme indicators with the gain of significant quantitative information might result in faster and safer qualification and validation of pharmaceutical production equipment in the future.

Technology of fish semi-finished products using antimicrobial compositions with organic acids and salts

The actual problem of business is the low quality of fish raw materials due to the delay in deliveries from the manufacturer. The search for new technological solutions to extend the shelf life of fish raw materials due to the reduction of microbiological contamination is relevant. A technology is proposed for the production of natural fish semi-finished products using antimicrobial compositions based on organic acids and salts. Chilled carcasses, semi-finished products of trout (fillet with skin) and antimicrobial agents based on organic acids and salts (Dilactopolydon (DLP) and Dilactin Forte Plus (DFP) were used as objects of research. The choice of the most effective concentration of the DLP solution for processing trout carcasses was carried out using the mathematical method of a single-factor experiment and the Statgraphics Centurion computer program. Regression equations with high correlation coefficients are obtained. The most effective concentration of DLP during processing of trout carcasses before cutting into a piece of fillet with peel was set at 2% when the ratio of raw material to the additive solution was 1: 1 and aged for 20 minutes. This reduces the risk of re-contamination of fish carcasses during cutting due to the retention of the active components of DLP on the surface of the capillaries of the muscle tissue of the fish. A method for processing fish raw materials and natural semi-finished products with antimicrobial compounds DLP and DFP has been developed, which allows maintaining the quality of cooled semi-finished products for 13 days. This ensures a shelf life of 10 days. The developed technology has been tested under production conditions..

Effects of Chlorine Concentrations and Washing Conditions on the Reduction of Microbiological Contamination in Lettuce

We established optimum washing and sanitizing conditions for fresh-cut lettuce using sodium hypochlorite to reduce microbial hazards. Reduction of microbial hazards, including total aerobic bacteria, Escherichoa coli, and Staphylococcus aureus at different sodium hypochlorite concentrations (0-500 ppm), immersion times (0–20min), temperatures (0–30°C), and washing times (0–4 min) was evaluated. The optimum washing and sanitizing conditions using sodium hypochlorite for lettuce were determined as immersion at more than 50 ppm for 1min at 20°oC and washing twice for 30 sec after dipping. Application of these optimum conditions will improve safety and added value of lettuce as a fresh-cut-food without detrimental effects on sensory characteristics.

Modelling microbiological water quality in the Seine river drainage network: past, present and future situations

Abstract. The Seine river watershed is characterized by a high population density and intense agricultural activities. Data show low microbiological water quality in the main rivers (Seine, Marne, Oise) of the watershed. Today, there is an increasing pressure from different social groups to restore microbiological water quality in order to both increase the safety of drinking water production and to restore the possible use of these rivers for bathing and rowing activities, as they were in the past. A model, appended to the hydro-ecological SENEQUE/Riverstrahler model describing the functioning of large river systems, was developed to describe the dynamics of faecal coliforms (FC), the most usual faecal contamination indicator. The model is able to calculate the distribution of FC concentrations in the whole drainage network resulting from land use and wastewater management in the watershed. The model was validated by comparing calculated FC concentrations with available field data for some well-documented situations in different river stretches of the Seine drainage network. Once validated, the model was used to test various predictive scenarios, as, for example, the impact of the modifications in wastewater treatment planned at the 2012 horizon in the Seine watershed in the scope of the implementation of the european water framework directive. The model was also used to investigate past situations. In particular, the variations of the microbiological water quality in the Parisian area due to population increase and modifications in wastewater management were estimated over the last century. It was shown that the present standards for bathing and other aquatic recreational activities are not met in the large tributaries upstream from Paris since the middle of the 1950's, and at least since the middle of the XIXth century in the main branch of the Seine river downstream from Paris. Efforts carried out for improving urban wastewater treatment in terms or organic matter and nutrient loading resulted in a sensible reduction of microbiological contamination, but were not specific enough toward bacteriological contamination for achieving the objective of restoring levels compatible with bathing activities in the Parisian area.

Inhibition of the peroxidase catalysed oxidation of thiocyanate by ionising radiation

Abstract The lactoperoxidase (LP) system and its components were irradiated to increasing doses. The yield of OSCN− (as measured by the formation of 5-thio-2-nitrobenzoic acid from DTNB) decreased exponentially and the D37 (the dose required to reduce the yield of OSCN− to 37% of its original value) was estimated. The D37 for the LP system prepared using (i) irradiated lactoperoxidase, and (ii) a mixture of irradiated lactoperoxidase and thiocyanate were identical, numerically equal to 1·1 kGy, whereas the D37 measured when the entire LP system was irradiated was 0·05 kGy, possibly due to the reaction of OSCN− with HO• radicals. The results may be of significance since irradiation may be used for the reduction of microbiological contamination (e.g. listeria or salmonella) in some foods.