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Milk is a complex physiological liquid that simultaneously provides nutrients and bioactive components that facilitate the successful postnatal adaptation of the newborn infant by stimulating cellular growth and digestive maturation, the establishment of symbiotic microflora, and the development of gut-associated lymphoid tissues. The number, the potency, and the importance of bioactive compounds in milk and especially in fermented milk products are probably greater than previously thought. They include certain vitamins, specific proteins, bioactive peptides, oligosaccharides, organic (including fatty) acids. Some of them are normal milk components, others emerge during digestive or fermentation processes. Fermented dairy products and probiotic bacteria decrease the absorption of cholesterol. Whey proteins, medium-chain fatty acids, and in particular calcium and other minerals may contribute to the beneficial effect of dairy food on body fat and body mass. There has been growing evidence of the role that dairy proteins play in the regulation of satiety, food intake and obesity-related metabolic disorders. Milk proteins, peptides, probiotic lactic acid bacteria, calcium and other minerals can significantly reduce blood pressure. Milk fat contains a number of components having functional properties. Sphingolipids and their active metabolites may exert antimicrobial effects either directly or upon digestion.

Lactic acid bacteria (LAB) isolated from poultry carcasses were added to BHI broth along with Salmonella spp. and Listeria monocytogenes in order to determine their antagonistic activity against the pathogens. There was a statistically significant reduction in Salmonella population on the 5th day that varied from 0.41 to 1.12 log CFU/ml. The reduction in L. monocytogenes population was also statistically significant and varied from 0.77 to 1.48 log CFU/ml. The LAB strain with the best inhibitory activity was chosen to examine its action against the same pathogens on the chicken skin and meat. On the chicken skin, the growth reduction on the 6th day caused by L. salivarius was lower and did not exceed the 0.54 log CFU/square cm for Salmonella spp. and 0.71 log CFU/square cm for L. monocytogenes. The reduction on the chicken meat was slightly lower for both pathogens. The results of the experiments suggest that L. salivarius (strain LAB 59) has a potential to be used as a protective culture to improve the safety and extend the shelf life of chicken products.

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 deg 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/cubic dm), H2O2 (0.78-2.30 microg/cubic cm), and diacetyl (produced by L. plantarum K816 and L718) were studied as well.

Yogurt was prepared from goat's milk supplemented with aronia juice and blueberry juice. The dynamics of acidification, number of lactic acid bacteria, and fatty acids composition were investigated. Yogurt from goat's milk supplemented with aronia juice and blueberry juice coagulated at a lower acidity and faster than natural yogurt. The numbers of lactic acid bacteria in supplemented yogurts were higher than in control samples. The addition of aronia and blueberry juices increased the amount of unsaturated fatty acids in yogurt by 6.9% and 8.5%, respectively. Polyunsaturated fatty acids increased by 11.2% in yogurt with aronia juice in comparison with natural yogurt.

Eight individual bacteriocin-producing lactic acid bacteria (LAB) strains and three bacteriocin-non-producing cheese starter cultures were evaluated for their ability to inhibit the growth of six Listeria monocytogenes strains, originating from the guinea-pig lymph nodes, raw cow milk, and manufacturing dairy equipment. Results showed that either live cells or cell-free neutralised supernatant (CFNS) and/or heated CFNS of six individual LAB strains (Lcc. lactis subsp. lactis CCDM 416 and NIZO R5, Lbc. plantarum HV 11 and DC 1246, P. acidilactici HV 12, and Ent. mundtii CCM 1282) and one starter culture (DELVO-ADD 100-X DSF) were effective in the suppression of at least one listeria strain. Neither any individual LAB strain nor starter culture was antagonistic toward all studied L. monocytogenes strains, indicating diverse sensitivity/resistance among L. monocytogenes strains to antimicrobial compounds of LAB. The significant susceptibility of listerias isolated from raw milk and dairy equipment together with the strong antilisterial activity of DELVO-ADD 100-X DSF could be applied in dairy technology, where commonly used starter cultures could play both the biopreservative and fermentation role.

The influence of different storage temperatures (5 deg C and 15 deg C) on the quality of vacuum-packed dry fermented sausage Polican was determined. The salami mixture, finished salamis (the maturing period of 30 days), and salamis stored for 30, 60, 90, and 120 days were analysed. The analyses performed (physical/chemical, sensory, microbiological) found no differences in sensory properties or basic physical/chemical and microbiological characteristics in the products after storage under different temperature conditions for 120 days. When stored at 15 deg C, the total content of biogenic amines in samples was significantly higher than that for samples stored at 5 deg C. If the principles of good manufacturing practice are observed at all phases of the technological process, the storage temperature of 15 deg C does not represent a risk as the consequent concentration of biogenic amines and polyamines remains extremely low.

Introducción. Los embutidos crudos se componen de carne fragmentada y otros ingredientes no cárnicos (sal, especias, fosfatos, nitritos) pero cuya formulación varía según el país; son productos altamente perecederos y podrían representar un riesgo para el consumidor. Objetivo. Los embutidos frescos son de alto consumo en varios países de Latinoamérica, por ello, el objetivo de esta revisión bibliográfica es compilar la información disponible sobre la calidad microbiológica de este tipo de productos en la región. Materiales y métodos. Se realizó una búsqueda de literatura (desde el 2006 a la fecha) en las principales bases de datos. Resultados. Se determinó que la calidad microbiológica de los embutidos crudos latinoamericanos no es adecuada según la reglamentación. Las bacterias más estudiadas son los microorganismos totales aerobios mesófilos (MTAM), y las bacterias ácido-lácticas (BAL); estos dos grupos son los referentes para determinar la vida útil. Los patógenos más analizados son Salmonella spp. y Listeria monocytogenes y llama la atención que Staphyloccoccus aureus no se utiliza como indicador de malas prácticas de higiene o de inocuidad. Conclusiones. En general se confirma que los embutidos frescos podrían ser un riesgo para la salud pública ya que presentan recuentos microbiológicos altos, en ocasiones no regulados. Algunos agentes antimicrobianos como los compuestos etanólicos de propóleos (EEP), compuestos fenólicos y bacteriófagos han sido estudiados. Sin embargo, no está claro si a nivel artesanal este tipo de ingredientes son utilizados del todo. Finalmente, destaca la necesidad de armonizar las metodologías de estudio y la normativa vigente en los distintos países.

Soymilk was fermented with probiotic culture ABT5 and yoghurt culture with the addition of bifidobacteria at different temperatures (37 deg C and 42 deg C) with the aim of shortening the fermentation time and producing a probiotic fermented soymilk. During the fermentation and storage of the fermented soymilk (28 days at 4 deg C), the changes in pH value and viable cells count were observed. Incubation temperature did not affect significantly fermentation time (7 h at 42 deg C and 8 h at 37 deg C, respectively), with ABT5 culture (Lactobacillus acidophilus, Bifidobacterium spp., and Streptococcus thermophilus). However, Lactobacillus acidophilus survived poorly during cold storage and the viable cells counts were under the probiotic minimum as soon as after the first week of storage. Therefore, in the consequent phase of the experiment, soymilk was fermented at 42 deg C with yoghurt culture YCX11 enriched with Bifidobacterium animalis subsp. lactis Bb12. Consequently, the fermentation time was shortened to 4 hours whereby the viable cells counts of bifidobacteria increased during fermentation for the half of the logarithm scale approximately. During 28 days of cold storage, bacterial counts remained constant and above 10,000,000 CFU/mL.

Nine lactic acid bacteria from artisanal-made cheeses were investigated for their ability to inhibit Listeria monocytogenes and Staphylococcus aureus. Both extracellular and surface-bound bacteriocins were recovered. While Lb. plantarum molecule was present only extracellularly, all the other strains displayed interference in both compartments. Maximum bacteriocin production was observed at the end-logarithmic phase, with the exception of Lb. plantarum (late stationary) and L. lactis subsp. cremoris (very early exponential). Lactobacillus and Lactococcus strains inhibited both List. monocytogenes and S. aureus. On the contrary, both E. faecium strains were active only on List. monocytogenes, and the enterocin A amount was enhanced under oxygen stress. All L. lactis strains (including L. lactis subsp. cremoris EL3 generally producing nisin Z) biosynthesised nisin A, while Lb. plantarum caused interference because of its very high lactic acid production. All these results suggest that artisanal-made cheeses can contain promising strains for food biosafety: these strains can be employed in toto directly in the food matrix or the purified bacteriocins can be incorporated into food packaging.

Halloumi cheese blocks, packaged in vacuum polyamide-polyethylene laminate bags, were stored at 5, 15, and 25°C. The changes in total bacterial count, lactic acid bacteria, total anaerobic bacteria, yeasts and molds, pH, and titratable acidity were monitored during the storage. The appearance of the packaged Halloumi cheese exhibited significant correlations with the counts of the different microbial populations inhabiting the cheese. The shelf-life of the stored Halloumi cheese was determined using survival analysis and considering consumer rejection as a failure index. The nominal shelf-lives of Halloumi cheese were 79.6, 37.8, and 2.6 days when stored at 5, 15, and 25°C, respectively. The Q10 values (shelf-life at T °C-shelf-life at T + 10°C) at 5°C and 15°C were 2.1 and 14.5, respectively. The increase in the counts of different microbial populations during storage highlights the need for adherence to good manufacturing practices and maintenance of low temperatures during the storage and distribution of the packaged Halloumi cheese. © Czech J. Food Sci. 2012.