1,720,978 research outputs found
Filmes poliméricos com adição de agente antimicrobiano a base de prata: desenvolvimento, caracterização e aplicação em cortes de carne bovina
Full text linkTese (doutorado) - Universidade Federal de Santa Catarina, Centro Tecnológico, Programa de Pós-Graduação em Engenharia Química, Florianópolis, 2009.Embalagens ativas, especialmente os filmes antimicrobianos vêm sendo estudados e avaliados como método auxiliar de conservação de alimentos, principalmente por aumentar a vida-de-prateleira e reduzirem os níveis de conservantes adicionados diretamente ao alimento. Neste trabalho, foram desenvolvidos filmes antimicrobianos de Polietileno de Baixa Densidade (PEBD), preparados por extrusão industrial, adicionados de antimicrobiano à base de prata (AlphaSan®) a concentrações de 0, 0,1, 0,5 e 1,0% (m/m). Os filmes extrusados foram avaliados quanto à espessura, distribuição da partícula de prata nos filmes e propriedades de tração, resistência a perfuração e barreira ao oxigênio (TPO2). O potencial antimicrobiano in-vitro de cada filme em relação aos microrganismos patogênicos Staphylococcus aureus spp.e Salmonella spp. foi testado. Amostras de carne bovina (contrafilé) foram acondicionadas em embalagens a vácuo elaboradas com os filmes nas concentrações citadas, para verificação da ação antimicrobiana em relação à Contagem Bacteriana Total-CBT e bactérias do gênero Pseudomonas por 10 dias, em condições de refrigeração comercial (3±1ºC). Adicionalmente, foi realizada a análise de cor utilizando colorímetro e metodologia digital, além da avaliação do teor de prata no alimento. O aditivo a base de prata inserido nos filmes de PEBD não modificou de forma significativa as propriedades de tração, resistência à perfuração e barreira ao oxigênio, mostrando dispersão homogênea das partícula de prata nos filmes. As embalagens com as três concentrações de antimicrobiano estudadas mostraram-se eficientes na inibição do crescimento in-vitro de Staphylococcus aureus., porém, apenas o filme com maior concentração de prata (1%) apresentou inibição de Salmonella spp. Este filme também mostrou melhor desempenho na redução de microrganismos Contagem bacteriana total-CBT e contagem de Pseudomonas, apresentando, ao final de um tempo de avaliação de 10 dias, uma redução de 2 ciclos logarítmicos para CBT e 1 ciclo para Pseudomonas, em relação à carne acondicionada no filme sem adição de agente antimicrobiano. A cor da carne acondicionada nos filmes antimicrobianos contendo 0,5 e 1% adquiriu coloração vermelho-cereja, enquanto que as amostras acondicionadas a 0,1% de prata e no filme controle mostraram intensificação da coloração marrom referente à formação de metamioglobina, cor típica de carne embalada a vácuo. O método digital para obtenção dos parâmetros de cor mostrou ser mais fiel à observação visual do produto quando comparado com os resultados obtidos pelo colorímetro. Foi observado um teor máximo de prata presente no alimento de 0,0375 ± 0,0028 mg de Ag.kg-1, correspondente ao filme com adição 1% de prata. Este valor, porém, não excedeu a quantidade determinada pela legislação vigente, que é de 0,05 mg.kg-1.Abstract : Active packages, specially antimicrobial films, are being studied and evaluated as auxiliary methods of food conservation, mainly for increasing shelf-life and reducing the levels of addictives added directly in the foods. In this work, antimicrobial films made of Low Density Polyethylene Films (LDPE), prepared by industrial extrusion with silver addition (AlphaSan®). The films produced were evaluated regarding to thickness, silver particle distribution and traction properties, resistance to perforation and oxygen barrier (O2PT). The in-vitro microbial potential of each film related to the pathogenical microorganisms Staphylococcus aureus spp.and Salmonella spp. were tested. Samples of beef, Striploin (m. Longissimus dorsi) were packed for microbial action verification on Total Bacterial Counting (TBC) and growth of Pseudomonas for 10 days in chilled commercial conditions (3±1 ºC). Additionally, a meat color study in each treatment was done by traditional colorimetric methods, using a colorimeter, and by digital and computational method. Determination of the silver content was evaluated in the meat. The addition of the silver-based addictive has not significantly modified (p>0,05) the traction properties, perforation resistance and oxygen barrier, showing also a good homogeneity in the silver particle distribution and thickness of the film. The antimicrobial films in the three concentrations were evaluated and considered efficient on the in-vitro growth inhibition of Staphylococcus aureus. Considering the other microorganisms tested, just the 1% silver-based film F3 film (film with greater concentration of silver (1%)) showed inhibition against Salmonella spp. It The F3 film also had a better performance on the psychotrophic microorganism reduction and counting of Pseudomonas reducing 2 logarithmic cycles for TBC and 1 cycle for Pseudomonas in ten days, the end of the evaluation time. The color of meat packaged using 0,5% and 1% antimicrobial films showed to keep the bright red coloration, while the samples packed in the Control or 0,1% silver films showed a brownish color,characteristic of the metamioglobina formation, a typical compound found in vacuum packed meat. The digital color meter method gave better informations about the meat color in the storage time. Colorimetric measures given by a colorimeter did not correspond to the meat color as observed by eyes. Silver maximum contents detected in meat packed using films with 0,5 and 1% m:m silver amount was 0,0375 ± 0,0028 mg Ag.kg-1, and.did not exceeded that one determined by Brazilian Food Law (0,05mg.kg-1), in the evaluated times
Estudos das potencialidades do reuso de água em uma indústria frigorífica
Full text linkDissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico. Programa de Pós-graduação em Engenharia de AlimentosA crescente preocupação com o uso racional da água no Brasil e no mundo impulsionou as empresas a aderirem a tecnologias e processos que procurem reduzir os rejeitos gerados, e a demanda de água sobre os mananciais. A redução do volume de efluentes, através da recirculação e reaproveitamento da água, constitui um dos desafios enfrentado pela indústria de alimentos. No processamento de carne bovina, que compreende as operações de recebimento, banho, atordoamento, sangria, esfola, evisceração até a operação final de divisão e lavagem das carcaças, é constatado um grande volume de água consumido e também de efluente gerado. Por este motivo, este trabalho teve por principal objetivo a caracterização das águas utilizadas nas várias etapas do processo e de seus respectivos efluentes e o estudo de possibilidades de reuso de água dentro do mesmo. Foram determinados os parâmetros: Temperatura, pH, alcalinidade total e parcial, série de sólidos (ST e SV) e demanda química de oxigênio (DQO) das correntes de processo de uma indústria frigorífica de grande porte do estado de Santa Catarina. Foi estabelecida uma estratégia para o reuso de água oriundo dos rejeitos da operação do processamento de lavagem de carcaças, o que representa 28,6% do total da vazão de água utilizada pela empresa. O impacto do reuso desta corrente na estação de tratamento de efluentes também foi verificado
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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