Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal.

Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal

Made available in DSpace on 2015-03-26T13:47:15Z (GMT). No. of bitstreams: 1 texto completo.pdf: 1110105 bytes, checksum: a122255067a39d8df06f289ce636ff42 (MD5) Previous issue date: 2013-07-25 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / Monitoring the populations of probiotic organisms such as Lactobacillus casei in food is required by food industries in order to assure that a minimum concentration of these organisms will be ingested by consumers. In this context, Petrifilm AC plates can be used along with selective culture media to allow the enumeration of specific groups of lactic acid bacteria. The present study aimed to assess chemical substances as selective agents for Lb. casei in order to propose a selective culture medium to be used with Petrifilm AC plates as an alternative protocol for the enumeration of this probiotic organism in fermented milk. Twenty-six probiotic and starter cultures (including 6 strains of Lb. casei) were plated on de Man Rogosa and Sharpe (MRS) agar with distinct concentrations of nalidixic acid, bile, lithium chloride, metronidazole, sodium propionate, and vancomycin. Vancomycin at 10 mg/L demonstrated selective activity for Lb. casei. In addition, 2,3,5-triphenyltetrazolium chlorine was identified as a compound that did not inhibit Lb. casei, and Petrifilm AC plates used with MRS and vancomycin at 10 mg/L (MRS-V) demonstrated more colonies of this organism when incubated under anaerobic conditions than aerobic conditions. Acidophilus milk and yoghurt were prepared, added to Lb. casei strains, and stored at 4 °C. Lb. casei populations were monitored using MRS-V and MRTLV by conventional plating and associated with Petrifilm AC plates. All correlation indices between counts obtained by conventional plating and Petrifilm AC were significant (p < 0.05), but the best performance was observed for growth on MRS-V. The obtained data indicate the efficiency of using MRS-V associated with Petrifilm AC plates for the enumeration of Lb. casei strains in fermented milk. / Micro-organismos da espécie Lactobacillus casei são os probióticos mais estudados, uma vez que são capazes de promover efeitos benéficos para a saúde humana. Além disso, os micro-organismos dessa espécie são ácido-tolerantes, sendo capazes de sobreviver ao ambiente gastrointestinal sem serem inativados. Quando adicionados em alimentos, devem se apresentar numa concentração mínima (maior que 106 UFC/mL ou g) para exercerem efetivamente a atividade probiótica. Por essas características, é necessário o monitoramento das populações dessas culturas quando adicionadas em alimentos, apesar da ausência de um protocolo oficial com esta finalidade. O sistema Petrifilm AC pode representar uma alternativa para enumeração de culturas starter e probióticas, desde que associado com meios de cultura seletivos. O presente estudo teve como objetivo a avaliação de substâncias químicas como agentes seletivos para Lb. casei, a fim de propor um meio de cultura seletivo para ser associado a placas Petrifilm AC, a ser avaliado como um protocolo alternativo de enumeração deste probiótico em leites fermentados. Vinte e seis culturas probióticas e starter (incluindo 6 cepas de Lb. casei) foram plaqueadas em ágar MRS com diferentes concentrações de ácido nalidíxico, bile, cloreto de lítio, metronidazol, propionato de sódio e vancomicina; somente vancomicina (10 mg/L) apresentou atividade seletiva para Lb. casei. Cloreto de 2,3,5-trifeniltetrazólio foi identificado como não inibitório para Lb. casei e placas de Petrifilm AC associadas a MRS adicionado de vancomicina a 10 mg/L (MRS-V) apresentaram contagens mais elevadas quando incubadas sob anaerobiose que em aerobiose. Leites fermentados acidificados e iogurtes foram preparados, adicionados de cepas de Lb. casei, estocados a 4 °C e as populações de Lb. casei foram monitoradas usando MRS-V e MRTLV por plaqueamento convencional e pelo sistema Petrifilm AC. Todos os índices de correlação entre as contagens obtidas por plaqueamento convencional e pelo sistema Petrifilm AC foram significativos (p < 0.05), mas o melhor desempenho foi observado para MRS-V. Os dados obtidos indicaram a adequação do uso do MRS-V associado às placas Petrifilm AC para enumeração de Lb. casei em leites fermentados.

Submitted by Marco Antônio de Ramos Chagas (mchagas@ufv.br) on 2015-11-04T10:40:44Z No. of bitstreams: 1 texto completo.pdf: 943889 bytes, checksum: 2c73252c1e6bb98d5e7d98fa75eb15c3 (MD5) / Made available in DSpace on 2015-11-04T10:40:44Z (GMT). No. of bitstreams: 1 texto completo.pdf: 943889 bytes, checksum: 2c73252c1e6bb98d5e7d98fa75eb15c3 (MD5) Previous issue date: 2014-07-21 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / As principais culturas starter utilizadas para produção de derivados cárneos fermentados são micro-organismos do grupo das bactérias láticas (BAL) e Staphylococcus coagulase negativa. Os gêneros Pediococcus e Lactobacillus possuem como principal característica a acidificação dos produtos e produção de compostos responsáveis pela determinação de aroma e sabor. Staphylococcus coagulase negativa contribuem para o desenvolvimento e a estabilidade da cor vermelha e para o desenvolvimento de outras propriedades sensoriais, como textura e aroma. O monitoramento adequado dessas populações é indispensável para manutenção da qualidade e inocuidade desses produtos. Porém, as metodologias convencionais de enumeração de culturas starter em alimentos possuem limitações quanto a praticidade e seletividade. Com isso, placas PetrifimTM AC tem sido empregadas para enumeração de culturas starter em produtos lácteos fermentados, desde que associadas a meios de cultura com agentes seletivos para grupos microbianos específicos. Considerando a escassez de dados científicos que demonstrem a pertinência de utilização de placas PetrifimTM AC associadas a meios de cultura seletivos para enumeração de BAL em produtos cárneos fermentados, o presente estudo tem como objetivo avaliar o uso de placas PetrfilmTMAC associado ao caldo MRS e vermelho de clorofenol para enumeração de culturas starter adicionadas em salames. Quatorze culturas puras e dois mix de culturas starter foram enumerados em seis protocolos diferentes: 1) PetrifilmTM AC associados ao caldo MRS adicionado de vermelho de clorofenol incubado em aerobiose e 2) em anaerobiose, 3) ágar MRS associado a vermelho de clorofenol, 4) MRS associado a púrpura de bromocresol, 5) MRS pH 5,7, e 6) ágar All Purpose Tween. Em seguida, amostras de salame foram obtidas e suas culturas starter enumeradas pelos protocolos 1, 2, 3 e 5. A análise de variância indicou ausência de diferenças significativas entre os protocolos de enumeração, independente dos tempos de incubação considerados (24, 48 e 72 horas). De maneira geral as contagens de culturas puras e culturas starter não apresentaram diferenças significativas considerando os diferentes tempos de incubação (exceto para AS 308 e S. xylosus em MRS com pH 5.7). Houve correlação significativa entre os protocolos, indicando a equivalência entre as contagens de culturas puras e culturas starter obtidas em aerobiose e em anaerobiose (p < 0,05). Os parâmetros de regressão linear também indicam correlações adequadas entre as contagens obtidas após 24, 48 e 72 h de incubação, indicando a confiabilidade dos resultados obtidos em um menor tempo de análise (24 h). Considerando os resultados obtidos na enumeração de culturas starter em salames, não foram observadas diferenças significativas entre os protocolos, independente dos tempos e condições de incubação e todas as correlações foram significativas (p < 0,05), indicando equivalências entre os protocolos independente das condições (aerobiose ou anaerobiose) e tempos (24, 48, 72h) de incubação. Após análise morfológica e identificação molecular de isolados obtidos das amostras de salame pelos protocolos avaliados, verificou-se uma seletividade adequada dos mesmos, que permitiram a formação de colônias apenas por micro-organismos dos gêneros Lactobacillus e Pediococcus, bem como Staphylococcus coagulase negativa, tipicamente utilizados como culturas starter para a produção de salame. Esses resultados confirmam a viabilidade da utilização de PetrifilmTM AC associado ao caldo MRS e vermelho de clorofenol para enumeração de culturas starter isoladas e em amostras de salame, em diferentes condições de aerobiose e em um reduzido período de incubação, representando vantagens a serem consideradas no monitoramento desses micro- organismos. / The main starter cultures used for the production of fermented meat products are microorganisms from the group of lactic acid bacteria (LAB) and Staphylococcus coagulase negative. Pediococcus and Lactobacillus present as main technological characteristic the acidification of products and production of compounds responsible for determining aroma and flavor. Staphylococcus coagulase negative contributes to the development and stability of the red color and the development of others sensory properties such as flavor and texture. Monitoring the populations is essential for maintaining the quality and safety of these products. However, conventional methods for enumeration of starter cultures in foods have limitations, due to poor selectivity and handling. Thus, PetrifilmTM AC plates have been used for enumeration of starter cultures in fermented dairy products, since associated with culture media with selective agents for specific microbial groups. Considering the lack of scientific data demonstrating the relevance of using PetrifilmTM AC plates associated with selective culture media for LAB enumeration in fermented meat products, the present study aimed to assess alternative protocols for the enumeration of starter culture in salami. Fourteen reference strains and two mix of starter cultures were plated on six different protocols: 1) PetrifilmTM AC added to MRS broth and chlorophenol red incubated in aerobiosis and 2) in anaerobiosis 3) agar MRS added to chlorophenol red 4) MRS added to bromocresol purple 5) MRS pH 5.7 and 6) agar All Purpose Tween. Then, samples of salami were obtained and their starter cultures enumerated by plating using protocols 1, 2, 3 and 5. The analysis of variance showed no significant differences between the enumeration protocols, independent of the incubation time: 24, 48 and 72 h. Generally, the counts of pure cultures of microorganisms and reference starter cultures showed no significant differences considering the different incubation times (except for AS 308 and S. xylosus in MRS at pH 5.7). The results indicated a significant correlation between the protocols, indicating equivalence between the counts of reference cultures and starter cultures in aerobiosis and anaerobiosis (p < 0.5). The linear regression parameters also indicate appropriate correlations between the counts obtained after 24, 48 and 72 h of incubation, indicating a reliability of the results obtained in a shorter analysis time (24 h). Considering the results obtained in the enumeration of starter cultures in salami, no significant differences were observed among the protocols considered, independent of time and incubation conditions, and all correlations were significant (p < 0.05), indicating equivalence between the protocols independent the conditions (aerobiosis and anaerobiosis) and time (24, 48 and 72 h) of incubation. After morphological and molecular identification of isolates obtained from samples of salami by the tested protocols, it was observed an adequate selectivity, which allowed the formation of colonies only by microorganisms of the genera Lactobacillus, Pediococcus and Staphylococcus coagulase negative, typically considered as starter cultures for the salami production. These results confirm the feasibility of using PetrifilmTM AC associated to MRS broth and chlorophenol red for enumeration of isolated starter cultures and starter cultures from salami samples, in different aerobic conditions and in a reduced incubation period, representing advantages to be considered during the monitoring of these microorganisms.

El presente trabajo de investigación está basado en una empresa que se dedica a la elaboración de productos medicinales y que viene recibiendo diversos reclamos que perjudican la imagen y calidad de sus productos, por lo que el objetivo es analizar sus problemáticas y tomar acciones para revertir la situación de la empresa. En el análisis del problema encontramos que la empresa acumula muchos reprocesos, y al mismo tiempo la demanda de la empresa creció en un 8% al año y por lo tanto es necesario mejorar el proceso productivo.Los problemas encontrados están muy relacionados con los métodos de trabajo, utilización de algunas máquinas, entre otros recursos que se detallan en el presente trabajo. El uso de las diferentes herramientas de ingeniería industrial sumándole un modelo del proceso de producción nos dará una mejor visión de cómo distribuir los recursos y métodos de trabajo en la empresa, teniendo en cuenta los principios y aportes de la gestión de la calidad y la inocuidad de alimentos que con su aporte podremos incrementar la productividad y a futuro la rentabilidad de la empresa. / The present research work is based on a company that is dedicated to the elaboration of medicinal products and that has been receiving various claims that damage the image and quality of its products, so the objective is to analyze their problems and take actions to reverse the situation of the company. In the analysis of the problem we find that the company accumulates many reprocesses, and at the same time the demand of the company grew by 8% per year and therefore it is necessary to improve the productive process. The problems encountered are very related to the working methods, the use of some machines, among other resources that are detailed in the present work. The use of the different tools of industrial engineering adding a model of the production process will give us a better vision of how to distribute the resources and methods of work in the company, taking into account the principles and contributions of the management of the quality and the innocuity of food that with its contribution we can increase productivity and future profitability of the company. / Tesis

No description available.

Le traitement sélectif (TS) des vaches laitières au tarissement (où seuls les quartiers ou les vaches infectées sont traités avec des antimicrobiens) constitue une alternative potentielle au traitement universel (TU, où tous les quartiers de toutes les vaches reçoivent des antimicrobiens, quel que soit leur statut infectieux), pour une utilisation plus judicieuse des antimicrobiens. L'objectif de cette thèse était d’apporter plus de lumière sur les décisions de traitement antimicrobien ciblant les quartiers ou vaches infecté(e)s au tarissement. Différents devis et méthodologies ont été utilisés pour répondre à cet objectif. Un essai contrôlé randomisé a été conçu et 569 vaches (2,251 quartiers) provenant de 9 troupeaux laitiers du Québec avec un comptage de cellules somatiques (CCS) du réservoir <250 000 cellules/mL ont été systématiquement enrôlées et réparties au hasard dans 4 groupes : 1) traitement antimicrobien seul pour tous les quartiers ; 2) traitement antimicrobien combiné avec un scellant interne à trayon pour tous les quartiers ; 3) traitement antimicrobien sélectif seul basé sur les résultats de la culture bactériologique du lait sur Petrifilm® ; et 4) traitement antimicrobien sélectif combiné avec un scellant interne à trayon basé sur les résultats de la culture du lait sur Petrifilm®. Dans les groupes de TS, les quartiers non infectés n'ont reçu qu'un scellant interne à trayon. Aucune différence significative n'a été détectée entre le TS par quartier et le TU des vaches laitières au tarissement, en termes d'élimination des infections intramammaires (IIM) et de prévention de nouvelles IIM pendant la période de tarissement, de risque d'un premier cas de mammite clinique (MC), de production laitière moyenne quotidienne et de CCS au cours des 120 premiers jours de la lactation suivante. Un TS reposant sur les résultats d'une culture de lait de quartier sur Petrifilm® au tarissement a permis de réduire l'utilisation d'antimicrobiens de 52% (IC à 95%: 39 – 64) par rapport à un TU. En plus de cet essai contrôlé randomisé, la culture du lait par quartier à l'aide de Petrifilm® a été comparée à l'historique du CCS par une estimation bayésienne de leur précision pour identifier les quartiers ou les vaches qui devraient être traités avec des antimicrobiens dans des protocoles de TS au tarissement. Compte tenu de la disponibilité des données de CCS, de la facilité d'utilisation du dernier test de CCS pré-tarissement et de la valeur prédictive négative élevée qui pourrait être obtenue, les producteurs pourraient envisager d'utiliser uniquement le dernier test de CCS pré-tarissement comme outil potentiel pour identifier les vaches qui devraient être traitées avec des antimicrobiens au tarissement. Le dernier test de CCS pré-tarissement peut être utilisé seul ou en combinaison avec la culture de lait par quartier sur Petrifilm® sur les vaches avec un CCS élevé pour identifier encore plus spécifiquement les quartiers qui doivent être traités. L'ajout d'une culture de lait par quartier à la ferme sur Petrifilm® pour les vaches identifiées comme infectées à l'aide des données du CCS améliorerait la précision du test (principalement la valeur prédictive positive) et réduirait davantage l'utilisation d'antimicrobiens. Également, une revue systématique et une série de méta-analyses ont été menées pour étudier l'efficacité du TS par rapport au TU, afin de guider les décideurs et les utilisateurs qui s'engagent dans une utilisation plus efficace et judicieuse des antimicrobiens au moment du tarissement. Treize articles représentant 12 essais contrôlés, randomisés ou non, étaient disponibles pour les analyses. Le TS a permis de réduire de 66% (IC à 95%: 49 – 80) l'utilisation d'antimicrobiens au moment du tarissement. Les résultats appuient fortement l'idée que le TS réduirait l'utilisation d'antimicrobiens au moment du tarissement, sans effet négatif sur la santé du pis ou la production laitière au cours des premiers mois de la lactation subséquente, si, et seulement si, les scellant internes à trayons sont utilisés pour les quartiers non traités avec des antimicrobiens. Enfin, le suivi de l'utilisation d'un scellant interne à trayon a été effectué pour déterminer la proportion de quartiers qui ont conservé le bouchon de scellant jusqu’à la première traite après le vêlage et la persistance de résidus de scellant dans le lait après le vêlage. Un bouchon de scellant était présent jusqu'à la première traite pour 83% des quartiers, et nous pourrions émettre l'hypothèse que la perte du bouchon s'est produite près du vêlage secondaire à la tétée ou pour une autre raison (ex., la pression hydrostatique du lait), étant donné que les associations observées entre la présence ou non d'un bouchon de scellant observable et les chances de nouvelles IIM étaient relativement faibles. Les résidus de scellant pouvaient être observés dans le lait jusqu'à 12 jours après le vêlage, quoique 75% des quartiers n’excrétaient plus de scellant au bout de 5 jours en lait. / Selective dry cow therapy (SDCT, in which only infected quarters or cows are treated with antimicrobials) represents an alternative to blanket dry cow therapy (BDCT, in which all quarters of all cows at dry off are treated with antimicrobials, regardless of their infection status), for a more judicious use of antimicrobials. The objective of this thesis was to shed more light on targeted antimicrobial treatment decisions of infected quarters or cows at dry-off. Different study designs and methodologies were used to meet this objective. A randomized controlled trial was designed and a total of 569 cows (2,251 quarters) from 9 dairy herds in Québec with bulk tank somatic cell count (SCC) <250,000 cells/mL were systematically enrolled and randomly allocated to 4 groups: 1) antimicrobial treatment alone of all quarters; 2) antimicrobial treatment combined with an internal teat sealant (ITS) of all quarters; 3) selective antimicrobial treatment alone based on milk bacteriological culture results on Petrifilm®; and 4) selective antimicrobial treatment combined with an ITS based on milk culture results on Petrifilm®. In the selective antimicrobial treatment groups, uninfected quarters received only an ITS. No significant differences were detected between quarter-based selective and blanket dry cow therapies, in terms of elimination of intramammary infections (IMI) and prevention of new IMI during the dry period, risk of a first case of clinical mastitis (CM), daily average milk yield and somatic cell count in the first 120 days of the subsequent lactation. A selective antimicrobial treatment relying on results of quarter milk culture using Petrifilm® at dry off enabled a reduction in antimicrobial use of 52% (95% CI: 39 – 64) as compared to blanket dry cow treatment. In addition to this randomized controlled trial, quarter milk culture using Petrifilm® was compared with SCC history through a Bayesian estimation of diagnostic accuracy to identify quarters or cows that should be treated with antimicrobials in selective treatment protocols at dry off. Considering the availability of SCC data, the easiness of using just the last Dairy Herd Improvement (DHI) test before dry off, and the high negative predictive value that could be achieved, producers may consider using just the last DHI test before dry off results as a potential tool to identify cows that should be treated with antimicrobials at dry off. The last SCC test before 7 dry off may be used alone or in combination with quarter-level on-farm Petrifilm® milk culture on high SCC cows to more specifically identify quarters that need to be treated. Adding quarter-level milk culture using Petrifilm® to cows identified as unhealthy using cow-level SCC data could improve the test accuracy (mainly the positive predictive value) and further reduced the use of antimicrobials. Also, a systematic review and a series of meta-analyses were conducted to investigate the efficacy of SDCT compared with BDCT, to guide decision-makers and users to engage in a more effective and judicious use of antimicrobials at dry-off. Thirteen articles representing 12 controlled trials, randomized or not, were available for analyses. SDCT reduced the use of antimicrobials at dry off by 66% (95% CI: 49 – 80). Evidences strongly support that SDCT would reduce the use of antimicrobials at dry off, without any detrimental effect on udder health or milk production during the first months of the subsequent lactation, if, and only if, ITS are used for healthy quarters untreated with antimicrobials. Finally, a follow up on the use of ITS was performed to determine the proportion of quarters that had retained the sealant plug until the first milking after calving and the persistence of ITS residues in milk after calving. A sealant plug was present at first milking after calving for 83% of the quarters, and we could hypothesize that the loss of the plug occurred closely around calving due to suckling or for another reason (e.g., milk hydrostatic pressure), since the observed associations between the presence or not of an observable sealant plug and the odds of new IMI were relatively small. The sealant residues could be observed in milk up to 12 days in milk, although 75% of the quarters had expelled the last ITS residues by 5 days in milk.