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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Caracteriza??o das propriedades funcionais de filmes ativos antimicrobianos aditivados com ?leos essenciais e plastificante / Characterization of the functional properties of antimicrobial active films additivated with essential oils and plasticizer

Gon?alves, Sheyla Moreira 23 February 2016 (has links)
Submitted by Sandra Pereira (srpereira@ufrrj.br) on 2016-10-13T12:25:00Z No. of bitstreams: 1 2016 - Sheyla Moreira Gon?alves.pdf: 3716146 bytes, checksum: eaee6e62414cd3d497528f597f1abab5 (MD5) / Made available in DSpace on 2016-10-13T12:25:00Z (GMT). No. of bitstreams: 1 2016 - Sheyla Moreira Gon?alves.pdf: 3716146 bytes, checksum: eaee6e62414cd3d497528f597f1abab5 (MD5) Previous issue date: 2016-02-23 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior - CAPES / The use of active packaging incorporated with natural antimicrobials as essential oils (EOs) for food preservation is a modern concept for the food industry. The objective of this study was to characterize cellulose acetate film (CA) incorporated with EOs and their combinations and/or added plasticizer, evaluating the influence of additives on the behavior of these materials. It is characterized as the thickness of the films, visual aspect, chemical structure, surface, mechanical strength, water vapor rate of transmission (WVRT) and antimicrobial activity. Through technique "casting" were obtained films incorporated with 50% (w/v) of EOs oregano or cinnamon or sweet fennel or combinations thereof and/or glycerol (5, 10, 20 and 30% (w/v)). Having as controls only films containing 50% (w/v) glycerol, and CA pure film, a total 41 treatments. The incorporation of EOs did not change the thickness and transparency of the films, but it reduced the WVRT. The color parameters L *, a* and b* were affected by the incorporation with EOs and/or glycerol the films exhibited clear with different colors compared with the AC pure film. Incorporating the most EOs cause increased tensile strength (TS) of the modulus of elasticity (ME) and reduced elongation at break (EB), except for the film with fennel EO (FEO) who presented plasticizer power differing from the other for all the evaluated mechanical parameters. The drilling force (DF) has increased to most films EOs incorporated with the exception of the film incorporated with the three EOs. The scanning electron microscopy (SEM) images revealed that most of the EOs and their combinations did not cause changes in the surface and cross-sectional area of the films, except the film with FEO. In the spectra of infrared spectroscopy with Fourier transform (FTIR), it observed that the interactions between the polymer matrix and most EOs were similar except for the film with FEO. As for the antibacterial efficiency in vitro, only the film incorporated with FEO showed no efficacy against Staphylococcus aureus (Gram +) and Escherichia coli (Gram +). It was observed that glycerol causes increased thickness and WVRT the AC films, however, the active films with EOs does not modify the parameter to most treatments. Transparency was not affected for most films. The addition of glycerol for most films incorporated with EOs caused reduction of TS, the ME and increased EB and DF. From the SEM pictures it can be observed that the glycerol promoted the emergence of porous structures, networked or compact, depending on the EO concentration and glycerol. The FTIR spectral showed that glycerol has different interactions, depending on the embedded EOs. The antibacterial efficiency of films with EO oregano or cinnamon or oregano more cinnamon has been improved with the presence of glycerol, while the others were not affected. In the face of changes in functional properties observed, it appears that with the additivation materials it is necessary to characterize them to define their applicability / O emprego de embalagens ativas incorporadas com antimicrobianos naturais, como os ?leos essenciais (OEs) para conserva??o de alimentos, representa um conceito moderno para a ind?stria aliment?cia. Objetivou-se neste trabalho caracterizar filmes de acetato de celulose (AC) incorporados com OEs e suas combina??es e/ou adi??o de plastificante, avaliando as influ?ncias da aditiva??o no comportamento f?sico e mec?nico destes materiais. Caracterizou-se os filmes quanto ? espessura, aspectos visuais, estrutura qu?mica, superf?cie, resist?ncia mec?nica, taxa de transmiss?o ao vapor de ?gua (TTVA) e atividade antimicrobiana. Atrav?s da t?cnica ?casting? foram obtidos filmes incorporados com 50% (p/v) de OEs de or?gano, canela, funcho doce ou suas combina??es e/ou glicerol (5, 10, 20 e 30% (p/v)). Tendo como controles filmes contendo somente 50% (p/v) de glicerol, e filme de AC puro, totalizando 41 tratamentos. A incorpora??o de OEs n?o modificou a espessura e transpar?ncia dos filmes, por?m causou redu??o da TTVA. Os par?metros de cor L*, a* e b* foram afetados pela incorpora??o de OEs e/ou glicerol tendo os filmes apresentado-se claros com diferentes cores em compara??o com o filme de AC puro. A incorpora??o da maioria dos OEs causou aumento da resist?ncia ? tra??o (RT), do m?dulo de elasticidade (ME) e redu??o do alongamento na ruptura (AR), com exce??o para o filme com OE de funcho (OEF) que apresentou poder plastificante diferindo dos demais para todos os par?metros mec?nicos avaliados. A for?a de perfura??o (FP) aumentou para a maioria dos filmes incorporados com OEs, a exce??o do filme incorporado com os tr?s OEs. As imagens de microscopia eletr?nica de varredura (MEV) revelaram que a maioria dos OEs e suas combina??es n?o causaram mudan?as na superf?cie e regi?o transversal dos filmes, a exce??o do filme com OEF. Nos espectros da espectroscopia no infravermelho com transformada de Fourier (FTIR), notou-se que as intera??es entre a matriz polim?rica e a maioria dos OEs foram semelhantes, com exce??o para o filme com OEF. Quanto ? efici?ncia antibacteriana in vitro, somente o filme incorporado com OEF n?o apresentou efetividade contra Staphylococcus aureus (Gram +) e Escherichia coli (Gram -). Foi observado que o glicerol causou aumento da espessura e TTVA nos filmes de AC, por?m, nos filmes ativos com OEs n?o modificou o par?metro para maioria dos tratamentos. A transpar?ncia n?o foi afetada para a maioria dos filmes. A adi??o de glicerol para a maioria dos filmes incorporados com OEs causou redu??o da RT, do ME e aumento do AR e FP. Pelas imagens do MEV observa-se que o glicerol promoveu o surgimento de estruturas porosas, em rede ou compactas, dependendo do OE e concentra??o de glicerol. Os espectros da FTIR demonstraram que o glicerol apresentou diferentes intera??es, dependendo do OE incorporado. A efici?ncia antibacteriana dos filmes com OE de or?gano ou canela ou or?gano mais canela foi melhorada com a presen?a de glicerol, enquanto os demais n?o sofreram influ?ncia. Diante das varia??es nas propriedades funcionais observadas, verifica-se que com a aditiva??o dos materiais ? necess?rio caracteriza??o para definir sua aplicabilidade

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