Application of bacteriocinogenic Enterococcus mundtii CRL35 and Enterococcus faecium ST88Ch in the control of Listeria monocytogenes in fresh Minas cheese

Several strains of Enterococcus spp. are capable of producing bacteriocins with antimicrobial activity against important bacterial pathogens in dairy products. In this study, the bacteriocins produced by two Enterococcus strains (Enterococcus mundtii CRL35 and Enterococcus faecium ST88Ch), isolated from cheeses, were characterized and tested for their capability to control growth of Listeria monocytogenes 426 in experimentally contaminated fresh Minas cheese during refrigerated storage. Both strains were active against a variety of pathogenic and non-pathogenic microorganisms and bacteriocin absorption to various L. monocytogenes, Enterococcus faecalis ATCC 19443 and Lactobacillus sakei ATCC 15521 varied according to the strain and the testing conditions (pH, temperature, presence of salts and surfactants). Growth of L. monocytogenes 426 was inhibited in cheeses containing E. mundtii CRL35 up to 12 days at 8 degrees C, evidencing a bacteriostatic effect. E. faecium ST88Ch was less effective, as the bacteriostatic affect occurred only after 6 days at 8 degrees C. In cheeses containing nisin (12.5 mg/kg), less than one log reduction was observed. This research underlines the potential application of E. mundtii CRL35 in the control of L. monocytogenes in Minas cheese. (c) 2012 Elsevier Ltd. All rights reserved.

Epidemiologia molecular aplicada ao monitoramento de estirpes de Staphylococcus aureus na produção de queijo Minas frescal

We studied the molecular epidemiology of Staphylococcus aureus strains potentially toxigenic, isolated from the production process of Minas frescal cheese in a small dairy plant in the state of São Paulo. For this, samples were taken during the period from June 2008 to July 2009. Samples were collected from the surface of the receiving and storage tanks of raw milk, the surface of the balance tank of pasteurized milk, the water supply system, the pipes and equipments, the hands of the handler and from the packaged cheese, totaling 140 samples. The colonies isolated on Baird-Parker Agar confirmed as Gram positive and positive for catalase, coagulase and acetoin production, were submitted to extraction of bacterial DNA using the Invitek - Uniscience® kit. Confirmation of the isolated species and enterotoxins SEA, SEB, SEC, SED and TSST-1 toxin was carried out through the amplification of specific fragments of chromosomal DNA. Among the 74 strains of isolated coagulase-positive staphylococci, only 41 (55.4%) strains were confirmed as Staphylococcus aureus, of which 25 (61.0%) were positive to the presence of staphylococcal toxins. The most frequently identified enterotoxin was SEA. The toxigenic strains of Staphylococcus aureus were more frequently isolated from hands of the handler (16.0%), raw milk receiving tank (12.0%), pasteurized milk for cheese making (12.0%) and fresh white cheese ready for consumption (12.0%).

Potencialidades de desarrollo y movilización local: un estudio SIAL en Santa Cruz de Turrialba

El queso fresco blanco, conocido como queso Turrialba en Costa Rica, es un producto de mucho valor económico  y social, que ha despertado un interés particular en el análisis de sus estructuras de producción y las redes interrelaciónales entre los diferentes actores involucrados en su elaboración y comercio local y regional.  Se comprobó la existencia de un SIAL en Santa Cruz de Turrialba que cuenta con organizaciones con objetivos y metas comunes que han dado origen a acciones colectivas operativas. Este SIAL ha generado también acciones operativas individuales que han diversificado, entre otras, la comercialización de su producto. En el plano colectivo, la planificación y priorización de sus proyecciones futuras están afectando no solamente el área de la producción agroindustrial sino también otros campos como el turismo agroecológico.   ABSTRACT The fresh White cheese in Costa Rica is well known as “Turrialba cheese”. This cheese has high economic and social value and its production structure and its local and regional relations networks became a very interesting fact of analysis. It has been proved the occurrence of a local Agrofood System (SIAL) in Santa Cruz of Turrialba, where organizations with specific common purposes and goals were present. This situation originated individual operative action  as in order to diversity their products and markets. On the collective side, the planification and priorization of their future projects and ideas, have influenced not only the production, but also another fields like the development of agro ecological tourism in the region.

Preference of dairy cows for ryegrass, white clover and red clover, and its effects on nutrient supply and milk quality

Two experiments were conducted with 30 dairy cows each, to study the preference for fresh (Experiment 1) and ensiled (Experiment 2) ryegrass, white and red clover. Both experiments consisted of three choice diets with white or red clover or both, offered with ryegrass, and two diets with ryegrass mixed with white or red clover (40% clover). Cows consumed diets with 37.7% fresh white and 45.9% red clover, and no preference was observed when the cows were offered all three forages. By contrast, cows preferred white and red clover silage (73.0 and 69.2%, respectively) over ryegrass silage (of lower nutritive quality). When offered three forages, cows preferred white (59.8%) over red clover (17.5%) and ryegrass (22.7%). Choice diets resulted in diets similar (fresh forages) or higher in nutrient content and digestibility (silages). Treatments did not affect feed intake and performance. Choices compared to mixed diets with red clover silage were preferable regarding the fatty acid composition of the milk fat. Obviously, only large differences in nutrient and energy concentration facilitate preferences for clovers over ryegrass, which could, depending on clover type, be beneficial in terms of the milk's fatty acid composition.

Prevalence of anti-Toxoplasma gondii antibodies in dairy cattle, dogs, and humans from the Jauru micro-region, Mato Grosso state, Brazil

In order to determine the prevalence of anti-Toxoplasma gondii antibodies, 2000 serum samples from female dairy cattle belonging to 50 farms in the southwest of Mato Grosso state were analyzed by the indirect fluorescent antibody test (IFAT >= 64). Serum samples from 61 dogs (IFAT >= 40) and 116 humans (IFAT = 40), all from the same farm, were also tested. Among these samples, 1420 (71.0%) cattle, 54 (88.5%) dogs, and 113 (97.4%) humans were seropositive for the infection. No significant differences (P >= 0.05) were observed for risk factors associated with the occurrence of toxoplasmosis in humans due to contaminated sources such as fresh milk, cheese/sausage, and contact with felines or other animals. The presence of felines can indicate the likelihood of a contaminated environment, posing a risk to the human population and other animals. The work presented herein is the first report to evaluate the seroprevalence of T gondii in bovines from the Southwest region of the Mato Grosso state, Brazil. (C) 2009 Elsevier B.V. All rights reserved.

Textural and microstructural properties of urfa cheese (a white-brined Turkish cheese)

The texture and microstructure of white-brined cheeses similar to urfa (a traditional Turkish cheese) were studied. One batch of cheeses was made in the traditional manner and one batch was made from ultrafiltered (UF) milk. Samples from each batch were either ripened in brine after production or scalded in whey for 3 min at 90degreesC prior to ripening. The results showed only marginal differences in the ripening profiles of both batches of unscalded cheeses, but scalding slowed down the extent of proteolysis in both batches. The scalded cheeses had a firmer texture than the unscalded ones, and the unscalded UF cheese had a more 'springy' body than the unscalded traditional cheese. Overall, scalding resulted in a more homogeneous structure, but the unscalded UF cheese had a close texture that resembled the scalded samples. It was concluded that, with respect to texture and structure, cheeses made with UF milk do not need to be scalded after production.

Effect of chymosin reduction and salt substitution on the properties of white salted cheese

A whey salts mixture was used as a partial substitute for sodium chloride to provide a modified Na:K ratio (1:3.4) in the manufacture of white salted cheese using ultrafiltration. Reduction of chymosin addition from 20 to 8 mu L kg(-1) of cheese was also investigated. Variation of salt and chymosin levels did not result in any significant differences in composition and physicochemical properties. The rates of proteolysis in terms of water-soluble nitrogen (WSN) and nitrogen soluble in 12% trichloroacetic acid (TCA-SN) were affected by chymosin levels but not by salt treatment. Urea-PAGE electrophoretic analysis of caseins from the cheeses manufactured using three levels of chymosin and two salt types showed that the hydrolysis of alpha(s1)-casein was higher than for beta-caseins but the differences between the cheeses were not significant (P > 0.05). The chymosin level did not have a significant effect (P > 0.05) on hardness and fracturability, suggesting that any variation in hardness due to the initial hydrolysis was being confounded by other variables. Cheeses including the whey salts product were harder and more fracturable (P < 0.01) than the cheese treated with NaCl only. Both hardness and fracturability values decreased (P < 0.05) over the maturation period. The scores for bitterness were low; neither the effects of salt nor chymosin levels were significant (P > 0.05). (c) 2005 Elsevier Ltd. All rights reserved.

Effect of chymosin and salt reduction on the quality of ultrafiltrated white-salted cheese

This study demonstrated that both chymosin and salt-in-moisture (SM) were important factors for proteolysis in the manufacture of ultrafiltrated white-salted cheese, with significant effects on water-soluble nitrogen and nitrogen soluble in trichloroacetic acid. In contrast, the levels of free amino acids were not significantly affected by chymosin and salt treatments. The cheeses made using high levels of chymosin with low SM had lower levels of residual α(s1)- and β-casein at the end of ripening. On texture profile analysis, the hardness and fracturability of the cheeses significantly increased with SM and decreased during ripening. Increases in chymosin significantly contributed to the overall weakening of the structure throughout ripening. Bitter flavour was detected after 12 weeks in the cheese made with the higher chymosin level and lower SM, which could be the result of accumulation of γ-casein fractions. The sensory data indicated that the hedonic responses for low chymosin with low SM cheeses were good and acceptable in flavour, which may be due to the moderate levels of proteolysis products.

Effect of temperature and salt on the maturation of white-salted cheese

White-salted cheeses were prepared from ultrafiltered (UF) cows' milk and salted to give final salt-in-moisture (SM) levels of 2.5, 3.2 and 4.0%. The cheeses were stored at 5degreesC and 10degreesC for up to 15 weeks. The microflora was dominated by lactic acid bacteria (LAB) but some mould growth was evident within 15 weeks at all SM levels and both temperatures. Levels of water-soluble nitrogen (WSN), attributed to chymosin activity, increased significantly with time, the rate being inversely proportional to the SM level and increasing with storage temperature. Similar effects were noted for trichloroacetic acid-soluble nitrogen (TCA-SN) and free amino acid (FAA) levels, both of which would also be affected by bacterial protease activity. The proteolytic activity was reflected by changes in the hardness and fracturability of the cheeses.

Ultrasonic assessment of fresh cheese composition

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Effect of octenyl succinylated waxy starch as a fat mimetic on texture, microstructure and physicochemical properties of Minas fresh cheese

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Characterization of fresh cheese with addition of probiotics and prebiotics

Sensorial and microbiological characteristics of a Brazilian fresh cheese samples with Bifidobacterium animalis subps. lactis as well as samples with this probiotic and polydextrose, a prebiotic ingredient, were evaluated. The addition of this microorganism was studied as: (1) lyophilized probiotic added to cheese curd and (2) by using milk previously fermented by this probiotic to produce the cheese. Cheese samples were microbiologically characterized after 0, 7, 14, 21 and 28 days of storage at a temperature of 4 °C. The microbiological analyses conducted were quantification of total lactic acid bacteria, mesophilic microorganisms, Bif. animalis subps. lactis, coliforms at 30 °C and 45 °C. Affective sensory test was conducted for two different cheese samples (with probiotic and with probiotic and prebiotic) as well as for control one week after manufacturing date. Cheese samples provided acceptable results for coliform counts at 30 °C and 45 °C in compliance with legislation. The cheese samples produced using milk fermented by probiotic showed counts of 107 -108 CFU/g after 28 days of storage, which assures functional property for this product to be claimed.

Humorous health messages : "a fresh approach" for road safety advertising campaigns?

Theoretical Background and research questions/hypothesis: Recently, throughout Australasia, humorous appeals have become implemented increasingly in health advertising despite limited evidence regarding the persuasiveness of different types of humour. Of those studies available which have examined the persuasiveness of humorous messages, the type of humour is often not defined so it is unclear what type of humour is being examined. Speck’s (1991) typology includes five types of humour; comic wit, sentimental humour, satire, sentimental comedy, and full comedy. Each type of humour is based on one or more humour generation processes; namely, incongruity-resolution, disparagement humour, and arousal-safety. It has been acknowledged that more research is needed to determine the relative persuasiveness of these different types of humour and to identify those types which may be most effective for health advertising. The current research explored individuals’ thoughts about, and their responses to some different types of, humorous messages addressing the serious health topic of road safety. Methods: A preliminary qualitative, study was conducted involving discussions with licensed drivers (N = 18) regarding their thoughts and feelings about humorous road safety messages in general as well as in response to some (5 in total) pre-existing advertisements. Men (n = 10) and women of younger and older age groups (17-24 or 25+ years) participated in one of six discussions. Participants were recruited from an existing community-based database held by the authors’ Research Centre or were approached directly on the university campus. Ethical approval was gained for the study. Each participant was offered $AUD40. A semi-structured interview schedule guided the discussion (e.g., was it humorous?, would this ad influence you?). Audio-recordings of the discussions were professionally transcribed and the transcripts were analysed using thematic analysis. Results: The findings revealed that, irrespective of age and gender, humour that was clever, incorporated something unexpected and contrasting with the everyday, was a preferred and relevant approach, thus aligning with incongruity-based theories of humour generation and humour types, such as comic wit and satire. As a persuasive function, humorous messages were considered likely to be talked about (and relatively more so than traditional fear-based approaches). Participants also felt that humorous messages would need to be used cautiously as humour that was considered inappropriate and/or associated with serious occurrences, such as a crash, would be unlikely to persuade. Conclusions: The findings highlight some of the potential benefits of using humour, such as increasing the extent to which an advertisement is talked about as well as the types of humour which may be effective in this context. Implications for research and/or practice: While this research has provided important insight, future research which quantitatively assesses the persuasive effects of different types of humorous road safety messages within a larger, representative sample is needed. This current study has highlighted some humorous approaches which may hold persuasive promise in encouraging individuals to adopt safer attitudes and behaviours not only on the road, but in relation to serious health issues more broadly.