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...

Three wild strains of Lactobacillus plantarum were investigated for their growth and ability to produce lactic acid, acetic acid and ethanol under aerobic and anaerobic conditions. They were tested at three different temperatures (30 °C, 37 °C and 45 °C). The growth of lactobacilli was studied by measuring optical density (OD) at λ = 600 nm and pH value at the following times. With increasing temperature difference of cell yield was observed. The fi nal cell yield under aerobic conditions was higher. Organic acids and ethanol were analysed using an HPLC RID method. Formation of lactic acid (as the major metabolite) was the slowest during cultivation at 30 °C, but the fi nal amount of lactic acid showed the highest values. Concentrations of metabolites produced by lactobacilli after 48th hours of cultivation were: 9.18-11.48 g.dm -3 (lactic acid), 0.84-1.65 g.dm -3 (acetic acid) and 2.51-4.03 g.dm -3 (ethanol). No signifi cant differences (p = 0.05) were found in production of lactic acid and ethanol by different bacterial strains under aerobic and anaerobic conditions. Statistically signifi cant differences (p = 0.05) were observed in production of acetic acid by 2L2 under aerobic and anaerobic conditions and for production of ethanol under anaerobic conditions by strains 1L5 and 2L2.

Antimicrobial activity of selected lactic acid cocci and production of organic acidsAntimicrobial activity and production of organic acids by selected lactic acid bacteria were monitored in this study. The largest antimicrobial activity against indicator microorganisms showed Pediococcus sp. G5, whereasStreptococcus thermophilushad no inhibitory effect. The inhibitory effect ofPediococcussp. G5 was strongest againstBacillus subtilis(17.78 %). Lactococci inhibited the growth ofEscherichia coli, Pseudomonas aeruginosaandStaphylococcus aureus(% of inhibition ≤ 5.25). The growth ofAsperglillus flavus, Penicillium funiculosumandRhizopus oryzaewas not inhibited by all of tested cocci. Cocci produced varying quantities of organic acids (lactic acid, acetic acid, succinic acid, etc.). Lactic acid was in large amounts and phenyllactic acid was produced only byPediococcussp. G5 (49.65 mg/L).

Smetanková J., Hladíková Z., Zimanová M., Greif G., Greifová M. (2014): Lactobacilli isolated from lump sheep's cheeses and their antimicrobial properties. Czech J. Food Sci., 32: 152-157.A total of 34 strains of lactobacilli were isolated from the lump sheep's cheeses produced from raw sheep milk. The strains were identified by MALDI-TOF MS, and 20 of them demonstrating the best fermentation and sensoric properties in milk were chosen and tested for their antimicrobial activity. All selected strains were active against the indicator bacteria and moulds. The highest inhibitory effect was observed with the strains lactobacillus paracasei 314, l. paracasei 316, l. plantarum K816, l. plantarum L718, and l. plantarum 2L2. The subsequent research was focused on the metabolites causing this inhibition. The production of lactic and acetic acids was studied under different cultivation conditions (0, 2, 4, and 6.5% NaCl addition; cultivation at 15, 30, 37, and 45°C; and pH value of the broth before sterilisation 5 and 9). l. plantarum L718 produced the highest concentration of lactic and acetic acids under most of the cultivation conditions. Antimicrobial substances such as phenyllactic acid (62.54-101.62 mg/dm 3 ), H 2 O 2 (0.78-2.30 μg/cm 3 ), and diacetyl (produced by l. plantarum K816 and L718) were studied as well. Keywords: lactobacillus plantarum; lactobacillus paracasei; antimicrobial potentialIt is known that the natural microflora, present in the traditional biotechnological processes during manufacturing, participates in the production of the characteristic aroma, taste, and texture of different cheeses. At first, only artisanal starters were used for the dairy although fermentations. Although they are still used in certain cases, their microbiological instability promoted the evolution of more precisely defined mixtures of lactic acid bacteria (LAB). As cheesemaking became more industrialised, pasteurised milk and standardised bacterial and fungal inocula were introduced with the aim of obtaining a more stable acidifying activity and consistent quality of the products (Carminati et al. 2010). In spite of this trend, the production of raw milk cheeses is still significant, as consumers seek organic foods or traditional sensory characteristics. However, the diversity of microbial populations that have developed in the original cheesemaking environments is largely undefined and is a valuable source of new strains for commercial uses (Laurenčík et al. 2008). For example, non-starter LABs with the potential to inhibit the undesirable microflora are used in the biopreservation of foods (Rodríguez et al. 2000).As far as the technology is concerned, several characteristic properties of the bacterial strains of LAB (acid production in different media and at different temperatures, proteinase and peptidase activities, autolysis, production of volatile compounds, resistance to bacteriophages, production of inhibitory compounds) are important for their use as starters or adjuncts and have been evaluated in the sc...

<p><em>Lactococcus lactis</em> species is one of the most important groups of lactic acid bacteria that are used in the dairy industry. <em>Lactococci </em>are generally found on plants and the skins of animals. Special interest is placed on the study of <em>Lactococcus lactis</em> ssp. <em>lactis</em> and <em>Lactococcus lactis</em> ssp. <em>cremoris</em>, as they are the strains used as starter cultures in industrial dairy fermentation. The major functions of this species in dairy fermentation are the production of lactic acid, formation of flavour and aroma compounds, development of ripened cheese texture and antimicrobial activity against spoilage bacteria and moulds.<br /><br /><strong>doi:10.5219/162</strong></p>