Ann Dumoulin

Performance of food safety management systems in poultry meat preparation processing plants in relation to Campylobacter spp. contamination.

A diagnostic instrument comprising a combined assessment of core control and assurance activities and a microbial assessment instrument were used to measure the performance of current food safety management systems (FSMSs) of two poultry meat preparation companies. The high risk status of the companys contextual factors, i.e., starting from raw materials (poultry carcasses) with possible high numbers and prevalence of pathogens such as Campylobacter spp., requires advanced core control and assurance activities in the FSMS to guarantee food safety. The level of the core FSMS activities differed between the companies, and this difference was reflected in overall microbial quality (mesophilic aerobic count), presence of hygiene indicators (Enterobacteriaceae, Staphylococcus aureus, and Escherichia coli), and contamination with pathogens such as Salmonella, Listeria monocytogenes, and Campylobacter spp. The food safety output expressed as a microbial safety profile was related to the variability in the prevalence and contamination levels of Campylobacter spp. in poultry meat preparations found in a Belgian nationwide study. Although a poultry meat processing company could have an advanced FSMS in place and a good microbial profile (i.e., lower prevalence of pathogens, lower microbial numbers, and less variability in microbial contamination), these positive factors might not guarantee pathogen-free products. Contamination could be attributed to the inability to apply effective interventions to reduce or eliminate pathogens in the production chain of (raw) poultry meat preparations.

Survival of Campylobacter spp. in poultry meat preparations subjected to freezing, refrigeration, minor salt concentration, and heat treatment

The survival of Campylobacter spp. under defined conditions of freezing (-22 degrees C) was studied in naturally contaminated chicken skin and minced chicken meat. A decline of approximately one log(10) cfu/g was observed after 1 day of freezing. No further significant reduction was achieved by prolonged storage in the freezer, although a tendency for further gradual reduction of the numbers of Campylobacter spp. present was noted. Campylobacter spp. could still be detected qualitatively (per 0.1g) after 84 days. In a second part of this study, the survival of Campylobacter spp. in a typical minced meat preparation (minced meat supplemented with 1.5% salt (NaCl)) stored at refrigeration (4 degrees C) or frozen (-22 degrees C) was studied. No significant reduction of the pathogen was observed if the minced chicken meat was kept at 4 degrees C for 14 days, opposite to approximately one log(10) cfu/g reduction after 1 day when the minced meat preparation was stored in the freezer (-22 degrees C) for 14 days. The latter reduction is imputed to the effect of freezing as mentioned above and not due to the supplementation of NaCl to minced meat or the combination of NaCl and freezing, because similar reductions of Campylobacter spp. were noticed when minced meat (without addition of NaCl) was frozen. Finally, in a third part of the study, the survival of Campylobacter spp. subjected to a heat treatment, conform to consumer-based pan-frying, in inoculated (4.5+/-0.2 cfu/g) as well as naturally contaminated chicken burgers (2.1+/-0.1 cfu/g) was studied. The Campylobacter spp. numbers declined after 2 min (internal temperature reached circa 38 degrees C), where after 4 min (internal temperature reached circa 57.5 degrees C) they dropped below detectable levels (<10 cfu/g).

Processing practices contributing to Campylobacter contamination in Belgian chicken meat preparations

The aim of this study was to obtain insight into processing practices in the poultry sector contributing to the variability in Campylobacter contamination in Belgian chicken meat preparations. This was achieved by company profiling of eleven food business operators, in order to evaluate variation of processing management, in addition to statistical modelling of microbiological testing results for Campylobacter spp. contamination in 656 end product samples. Almost half (48%) of chicken meat preparation samples were positive for Campylobacter spp. Results revealed a statistically significant variation in Campylobacter contamination between 11 chicken meat producers across Belgium at both quantitative and qualitative detection levels. All producers provided Campylobacter-positive samples, but prevalence ranged from 9% up to 85% at single producer level. The presence or addition of skin during production of chicken meat preparations resulted in almost 2.2-fold increase in the probability of a sample being positive for Campylobacter, while chicken meat preparations made from frozen meat, or partly containing pre-frozen meat, had a significant (Odds Ratio=0.41; CI 95% 0.18:0.98) lower probability of being positive for Campylobacter. However, the quantitative results indicated that the positive freezing effect on Campylobacter count was compromised by the presence and/or adding of skin.

Thermo-chemical pre-treatment to solubilize and improve anaerobic biodegradability of press mud

Different pre-treatment severities by thermo-alkaline conditions (100°C, Ca(OH)2) on press mud were evaluated for different pre-treatment time and lime loading. COD solubilization and the methane yield enhancement were assessed. The biochemical methane potential was determined in batch assays under mesophilic conditions (37±1°C). The best pre-treatment resulted in a surplus of 72% of methane yield, adding 10g Ca(OH)2 100g(-1)TS(-1) for 1h. Pre-treatment also increased the COD solubilization, but the optimal severity for COD solubilization as determined by response surface methodology did not ensure the highest methane production. Inhibitory effects on anaerobic digestion were noticed when the severity was increased. These results demonstrate the relevance of thermo-alkaline pre-treatment severity in terms of both lime loading and pre-treatment time to obtain optimal anaerobic biodegradability of lignocellulosic biomass from press mud.

Removal of atrazine in water by combination of activated carbon and dielectric barrier discharge

Efficiency of modern wastewater treatment plants to remove or decompose persistent contaminants in low concentration is often insufficient to meet the demands imposed by governmental laws. Novel, efficient and cheap methods are required to address this global issue. We developed a new type of plasma reactor, in which atrazine decomposition by atmospheric dielectric barrier discharge (DBD) in dry air is combined with micropollutant adsorption on activated carbon textile and with extra bubbling of generated ozone. Investigation of reaction kinetics and by-product analysis shows that increasing input power with a factor 3.5 leads to deeper atrazine oxidation without significantly changing energy yield of atrazine removal. By-products of first and later generations are detected with HPLC-MS analysis in water and adsorbed on the activated carbon textile. Our reactor is compared in energy efficiency with reactors described in literature, showing that combination of plasma discharge with pollutant adsorption and ozone recycling is attractive for future applications of water treatment.

Performance analysis and optimization of autotrophic nitrogen removal in different reactor configurations: a modelling study.

The autotrophic nitrogen removal process (partial nitritation combined with the Anammox process) is a new and sustainable nitrogen removal technique for nitrogen‐rich streams. A modelling study has been performed to define optimal process conditions (temperature, oxygen supply, pH and biomass retention) and to investigate the influence of chemical oxygen demand, nitrogen loading rate and hydraulic retention time on three alternative reactor configurations: a single oxygen‐limited partial nitritation reactor, a single Anammox reactor, and a combination of partial nitritation and Anammox in a single reactor. The model applied was compared to experimental data from the literature and gave good agreement for all three reactor configurations. The simulations revealed that a system with separated partial nitritation and Anammox offered a wider range of optimal process conditions than a one‐reactor system. The key factors in the successful operation of partial nitritation were found to be control of aeration, ammonium loading rate and temperature. Heterotrophs remained present in all three reactor systems and it was confirmed that interaction between heterotrophs and Anammox and between heterotrophs and ammonium oxidizers was possible.

Calibration and statistical analysis of a simplified model for the anaerobic digestion of solid waste

Modelling is increasingly used for optimizing environmental treatment processes such as anaerobic digestion. It allows problems such as instability of the process to be solved by predicting various scenarios. The anaerobic digestion model No. 1 (ADM1) is accepted worldwide as the standard model for the description of anaerobic digestion. However, it is sophisticated and complex, so it is not user friendly. Therefore, a mathematical method was developed that allows the calculation of the reactor pH, as well as the biogas flow rate (Q) and composition (expressed as the CO2 partial pressure, pCO2), based on a small number of widely available analyses such as chemical oxygen demand and total organic carbon. Furthermore, the ADM1 model was originally designed for anaerobic digestion of wastewater. In this work, the ADM1 model is evaluated for the first time for application in the modelling of solid waste digestion. This evaluation was performed in two steps. First, a list of experimentally available lab‐scale data (pH and Q) was grouped according to the composition and origin of the treated solid waste (e.g. manure or vegetable waste). For each group the developed model for the calculation of pH, Q and pCO2 was calibrated with this lab‐scale data. After calibration, the model was validated with additional experimental results. It could be demonstrated statistically that the model was able to predict the experimental results, although the confidence region was rather large.

N-alkylamide profiling of Achillea ptarmica and Achillea millefolium extracts by liquid and gas chromatography-mass spectrometry

Achillea millefolium and Achillea ptarmica are both plants belonging to the Asteracea family and are traditionally used for their medicinal properties. It has already been shown that some N-alkylamides (NAAs) are responsible for these pharmacological actions. Therefore, in the present study, the NAA content of the two plants was analytically characterised. Different extracts were prepared from the roots, the leaves, the stems and the flowers. The structures of NAAs have been assigned in ethanolic extracts of Achillea millefolium and Achillea ptarmica using high performance liquid chromatography – electrospray ionisation – mass spectrometry (HPLC–ESI–MS) and gas chromatography – electron impact – mass spectrometry (GC–EI–MS). Using both analytical techniques, the structures of 14 and 15 NAAs have been assigned in Achillea ptarmica and Achillea millefolium, respectively. Structures of two new NAAs, previously never observed in Achillea ptarmica, were assigned: deca-2E,6Z,8E-trienoic acid 2-methylbutylamide (homospilanthol) or a related isomeric compound and deca-2E,4E-dienoic acid N-methyl isobutylamide. The structure of homospilanthol or a related isomeric compound was also assigned in Achillea millefolium for the first time.