Hladíková Z., Kejlová K., Sosnovcová J., Jírová D., Vavrouš A., Janoušek A., Syčová M., Špelina V. (2015): Microbial contamination of paper-based food contact materials with different contents of recycled fiber. Czech J. Food Sci., 33: 308-312.Recycled paper is commonly used in food packaging industry, especially for disposable products. The material coming into direct contact with food products must not represent a source of contamination for food in accordance with the Framework Regulation (EC) No. 1935 containing the general requirements on all food contact materials. In the present study, the microbial purity of 31 paper-based materials with different contents of recycled matter (0-100%) was evaluated using a standard method based on the disintegration of paper. The results of the present study indicate the existing relation between the use of recycled fibers and the content of microorganisms. The increased amount of recycled fibers significantly increased the amount of bacteria in the paper samples. The highest content of microorganisms was observed in the case of paper with the highest recycled fiber content. Total counts of bacteria ranged from 5.0 × 10 1 to 1.2 × 10 5 CFU/g. Moulds were detected only in three paper samples. As the microorganisms present in food packaging may penetrate into foodstuffs (particularly those with high contents of water or fat) and have an adverse effect on end-consumers' health, microbial criteria for food packaging should be included into the EU legislation.Keywords: bacteria; disposable materials; health safety; microbial purity; recycled paper Disposable paper-based materials such as boxes, bags, plates, cups, sacks, containers, and napkins have been used in food packaging for many years. The greatest benefit of these materials in comparison to plastic materials is their comparatively minimal impact on our environment and biodegradability. Cellulose and hemicellulose contained in papers and boards are fast biodegradable products, while lignin is biodegraded more slowly by microorganisms because of its structure. Adding cellulosic packaging to traditionally composted products may improve the compost structure while no negative or inhibitory effects on the plant germination and growth have been observed (Ottenio et al. 2004). Paper recycling represents another advantage, as cellulosic fibres can be used several times in the paper production.The recycled paper and paperboard products are made from used papers such as newspapers, magazines and milk cartons, pulped with water and also cleaned and deinked with surfactants (Ozaki et al. 2004). Food grade paper with different pulp percentages of the recycled matter is commonly used in direct contact with foods. Food contact materials, including recycled fiber-based paper, have to be in compliance with general safety principles set up in Article 3 of the Framework Regulation. This Article requires that food contact materials must not transfer their components into food in quantities 309Czech J. Food Sci., 33, 2015 (4): 30...

Houška M., Kýhos K., Landfeld A., Průchová J., Schlemmerová L., Šmuhařová H., Špelina V., Novotná P. (2007): Dry heat inactivation of Bacillus cereus in rice. Czech J. Food Sci., 25: 208-213.The aim of this work was to validate the method of decontamination of rice at the temperature of 120°C (determined as optimal in previous experiments). Bacillus cereus was selected as the marker micro-organism for the monitoring of decontamination. The spores of Bacillus cereus are moderately heat resistant. In order to show the efficacy of our decontamination process, we artificially contaminated the rice under study with B. cereus. Decontamination was carried out in a homogenising steriliser about 20 h after contamination. The sample was first heated to 90°C and held at this temperature for 70 minutes. Then the temperature was increased to 120°C and held for 3 hours. Five samples were taken for microbiological analyses as follows: before the experiment, on reaching 120°C, and then after 1, 2, and 3 h of decontamination. Decontamination of rice from vegetative forms and spores of B. cereus present at the level of 400 CFu/ml was effected by heating to 120°C and holding for 1 hour.

Landfeld A., Strohalm J., Kýhos K., Průchová J., Houška M., Novotná P., Schlemmerová L., Šmuhařová H., Špelina V., Čermák P., Pavlišová K., Měřička P. High-pressure inactivation data were obtained for model working suspensions of Enterococcus faecium in saline solutions in pH range from 5.5 to 6.8, at water activity 0.99 (corresponding to the saline solution). The data were predicted for the pressure range of 450 MPa to 550 MPa, at the initial model suspension temperature 6-7°C prior to pressurising. The results indicate that E. faecium is a highly resistant organism under physiological pH values. With decreasing the substrate pH, the tolerance to the inactivation effects of high pressure decreased. The high-pressure inactivation proved ineffective for the above organism in the range of physiological pH values. The values for high-pressure inactivation model were specified and the calculated parameters of high-pressure inactivation were compared to the experimental data for the working suspensions of E. faecium in cow and human milks. As to cow milk, the predicted data showed some deviation from the model experimental results, while with human milk the model failed completely. High-pressure inactivation of E. faecium in human milk proved to be significantly more effective than that predicted by a model based on the saline solution.

Schlemmerová L., Houška M., Špelina V., Strohalm J., Landfeld A., Šmuhařová H., Němcová I., Kýhos K., Průchová J., Novotná P., Měřička P.

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