Effect of Plant Antimicrobial Agents Containing Marinades on Storage Stability and Microbiological Quality of Broiler Chicken Cuts Packed with Modified Atmosphere Packaging.

The food industry, including the meat industry, is currently looking for natural preservatives to prevent the growth of harmful microbes in foods. The potential of plant-derived antimicrobial extracts to increase the shelf life and to delay the microbiological spoilage of marinated broiler chicken cuts in modified atmosphere packages during cold storage was investigated in this study. We evaluated the impact of aqueous ethanolic extracts of Finnish sea buckthorn berries and lingonberries and supercritical CO2-extracted herbal extracts from an antimicrobial blend and oregano leaves on the shelf life of broiler meat. The commercial antimicrobial blend extract and the oregano extract inhibited the growth of lactic acid bacteria (LAB) and Brochothrix thermosphacta in the marinated samples. The antimicrobial blend extract also reduced the growth of psychrotrophic aerobic bacteria, whereas the sea buckthorn and lingonberry extracts did not. Only minor antimicrobial activity against Enterobacteriaceae by all the extracts was observed. Plate count analysis, denaturing gradient gel electrophoresis, and quantitative real-time PCR indicated that LAB, which are the major spoilage group in marinated modified atmosphere-packaged poultry products, were not significantly affected by the berry extracts studied. During this shelf-life study, LAB isolates of Lactobacillus and Leuconostoc were identified in the marinated samples. Antimicrobial blends and oregano leaf extracts can act as antimicrobial agents in marinade blends, although tailoring of the dose is needed because of their strong taste. Further studies for exploiting synergistic effects of plant extracts could contribute to the development of potential and more effective antimicrobial blends. Studies are needed in meat matrices and in product applications to demonstrate the efficacy of these compounds.

Molybdenum doped titanium dioxide photocatalytic coatings for use as hygienic surfaces: the effect of soiling on antimicrobial activity.

Titanium dioxide (TiO2) surfaces doped with molybdenum (Mo) were investigated to determine if their photocatalytic ability could enhance process hygiene in the brewery industry. Doping TiO2 with Mo showed a 5-log reduction in bacterial counts within 4 to 24 h and a 1-log reduction in yeast numbers within 72 h. The presence of a dilute brewery soil on the surface did not interfere with antimicrobial activity. The TiO2-Mo surface was also active in the dark, showing a 5-log reduction in bacteria within 4 to 24 h and a 1-log reduction in yeast numbers within 72 h, suggesting it could have a novel dual function, being antimicrobial and photocatalytic. The study suggests the TiO2-Mo coating could act as a secondary barrier in helping prevent the build-up of microbial contamination on surfaces within the brewery industry, in particular in between cleaning/disinfection regimes during long production runs.

Quorum sensing signalling and biofilm formation of brewery-derived bacteria, and inhibition of signalling by natural compounds.

Bacteria use quorum sensing signalling in various functions, e.g. while forming biofilms, and inhibition of this signalling could be one way to control biofilm formation. The aim of this study was to evaluate the production of signalling molecules and its correlation with the biofilm formation capability of bacteria isolated from brewery filling process. A further aim was to study berry extracts and wood-derived terpenes for their possible quorum sensing inhibitory effects. Out of the twenty bacteria studied, five produced short-chain and five long-chain AHL (acyl homoserine lactone) signalling molecules when tested with the Chromobacterium violaceum CV026 reporter bacterium. Production of AI-2 (autoinducer-2) signalling molecules was detected from nine strains with the Vibrio harveyi BB170 bioassay. Over half of the strains produced biofilm in the microtitre plate assay, but the production of AHL and AI-2 signalling molecules and biofilm formation capability did not directly correlate with each other. Out of the 13 berry extracts and wood-derived terpenes screened, four compounds decreased AHL signalling without effect on growth. These were betulin, raspberry extract and two cloudberry extracts. The effect of these compounds on biofilm formation of the selected six bacterial strains varied. The phenolic extract of freeze-dried cloudberry fruit caused a statistically significant reduction of biofilm formation of Obesumbacterium proteus strain. Further experiments should aim at identifying the active compounds and revealing whether quorum sensing inhibition causes structural changes in the biofilms formed.

Effect of photocatalytic and hydrophobic coatings on brewery surface microorganisms.

The aim of this study was to determine whether process hygiene in the beverage industry could be improved by applying new coating techniques to process surfaces. Photocatalytic titanium dioxide (TiO(2)) and hydrophobic coatings applied to stainless steel with or without added antimicrobial compounds were studied in laboratory attachment tests and in a 15-month process study. No clear reductions in numbers of attached microbes were obtained with photocatalytic coatings, except for coatings to which silver had been added. These TiO(2)+Ag coatings reduced microbial coverage in laboratory studies and in some process samples. Hydrophobic coatings reduced the area coverage of microorganisms in 4-h laboratory studies but did not affect colony counts in laboratory or process studies. The surfaces had changed from hydrophobic into hydrophilic during the process study. The coatings did not mechanically fully withstand process conditions; part of the hydrophobic coatings had peeled off, most of the precipitated Ag had dissolved, and some of the TiO(2) coatings were damaged. In conclusion, functional coatings have potential for reducing microbial loads on beverage industry surfaces, but these coatings need further development.

Evaluation of ITS PCR and RFLP for Differentiation and Identification of Brewing Yeast and Brewery 'Wild' Yeast Contaminants.

A reference library of ITS PCR/RFLP profiles was collated and augmented to evaluate its potential for routine identification of domestic brewing yeast and known 'wild' yeast contaminants associated with wort, beer and brewing processes. This library contains information on band sizes generated by restriction digestion of the ribosomal RNA-encoding DNA (rDNA) internal transcribed spacer (ITS) region consisting of the 5.8 rRNA gene and two flanking regions (ITS1 and ITS2) with the endonucleases CfoI, HaeIII, HinfI and includes strains from 39 non-Saccharomyces yeast species as well as for brewing and non-brewing strains of Saccharomyces. The efficacy of the technique was assessed by isolation of 59 wild yeasts from industrial fermentation vessels and conditioning tanks and by matching their ITS amplicon sizes and RFLP profiles with those of the constructed library. Five separate, non-introduced yeast taxa were putatively identified. These included Pichia species, which were associated with conditioning tanks and Saccharomyces species isolated from fermentation vessels. Strains of the lager yeast S. pastorianus could be reliably identified as belonging to either the Saaz or Frohberg hybrid group by restriction digestion of the ITS amplicon with the enzyme HaeIII. Frohberg group strains could be further sub-grouped depending on restriction profiles generated with HinfI.

Treatment of lower respiratory tract infections with ceftazidime.

The aim of this study was to evaluate the efficacy and tolerance of ceftazidime in the treatment of patients with lower respiratory tract infection. Fifty patients were included. Most of the patients received 1.0 g ceftazidime im three times daily. Thirty-seven patients were cured and eight improved (90%). A pathogen was isolated in 19 cases, (sputum 14, blood 4 and pleural fluid 1). The micro-organism was eradicated from the sputum in all but two cases. The result was unassessable in one. One or more side-effects probably related to the drug were found in 15 patients (30%), pain at injection site (10), an allergic rash (2), diarrhoea (2), pyrexia (1) and dyspnoea (1). Abnormal laboratory tests were seen in seven patients, an elevation in liver enzymes (4), an elevation in urea (1), leucopenia and granulocytopenia (1) and haemolytic anaemia (1). Most of the side-effects were mild and transient but the drug was stopped in five cases. The diarrhoea was severe in one case and the granulocytopenia was noted at a check-up four months after the treatment.

Clinical experience in the treatment of lower respiratory tract infections with ceftazidime.

In this study we report our results on the efficacy of ceftazidime in the treatment of 15 patients with lower respiratory tract infections. Most patients were elderly and had underlying diseases. Eleven patients were cured and one improved. In two cases the treatment was stopped after a few days because of local pain and in one patient a bacteriological failure was noted. Possible side-effects were noted in four cases: skin rash in one, local pain in two and transient rise in liver enzymes in one.