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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

Chemical and sensory investigations on the processing and preservation of a lamb product

Silva, Elisabeth Mary Cunha da January 1997 (has links)
No description available.
2

Clostridium botulinum toxin development in refrigerated reduced oxygen packaged Atlantic croaker (Micropogonias undulatus)

Rheinhart, Courtney Elizabeth 25 May 2007 (has links)
The purpose of this study was to determine the effects of storage temperature and film oxygen transmission rate (OTR) on toxin development by Clostridium botulinum in refrigerated raw vacuum packaged croaker fillets, and to determine if toxin development precedes microbiological and/or organoleptic spoilage. Raw croaker fillets were vacuum packaged in oxygen-permeable films (OTR of 10,000 cc/m2/24hr or 3,000 cc/m2/24hr) and stored at either 4ºC or 10ºC. Type 83F, 17 Type B, Beluga, Minnesota, and Alaska nonproteolytic strains of C. botulinum were used to inoculate fish prior to vacuum packaging. At both temperatures, microbial spoilage preceded toxin production in fillets vacuum packaged in both film types. At 4ºC microbial spoilage occurred after approximately 7 days for fillets vacuum packaged in the 10,000 cc/m2/24hr OTR film and after 8 days for fillets vacuum packaged in the 3,000 cc/m2/24hr OTR film. However, toxin was not detected until day 8. At 10ºC microbial spoilage occurred after approximately 3 days for fillets vacuum packaged in the 10,000 cc/m2/24hr OTR film, while toxin production occurred on day 5. For fillets vacuum packaged in the 3,000 cc/m2/24hr OTR film microbial spoilage occurred after 4 days. However toxin production did not occur until day 6. In contrast, at both temperatures toxin production preceded or coincided with organoleptic spoilage in fillets vacuum packaged in both film types. At 4ºC organoleptic spoilage occurred after 10 days for fillets packaged in the 10,000 cc/m2/24hr OTR film and after 9 days in the 3,000 cc/m2/24hr OTR film, while toxin production occurred on day 8. At 10ºC organoleptic spoilage occurred after 6 days for fillets packaged in the 10,000 cc/m2/24hr OTR film, and toxin was detected on day 5. For fillets packaged in the 3,000 cc/m2/24hr OTR film and stored at 10ºC, organoleptic spoilage occurred after 6 days, while toxin production occurred on day 6. Although toxin production preceded or coincided with organoleptic spoilage in both film types, this may have been because samples were presented on ice, which could have masked potential odors. This study shows that there are not significant differences between these film types when it comes to microbial and organoleptic spoilage. Therefore lower OTR films, such as 3,000 cc/m2/24hr film, may be used to vacuum package Atlantic croaker. / Master of Science in Life Sciences
3

Estabilidade da carne de cordeiro em diferentes condições de armazenamento / Stability of lamb meat at different storage conditions

Rafaella de Paula Paseto Fernandes 15 April 2011 (has links)
Atualmente no Brasil a carne ovina é comercializada quase exclusivamente congelada. No entanto, praticamente não existem estudos no país sobre alterações na qualidade desta carne durante seu armazenamento. Com a crescente demanda do consumidor por produtos de maior conveniência, surge a necessidade de maiores estudos em relação à estabilidade de cortes cárneos ovinos estocados sob refrigeração, principalmente em decorrência de sua curta vida útil. Os objetivos deste trabalho foram avaliar a estabilidade da carne ovina quando estocada sob refrigeração e congelamento e se diferentes sistemas de acondicionamento em atmosfera modificada poderiam aumentar a estabilidade desta carne quando armazenada sob refrigeração. Foram realizados dois experimentos. No primeiro, lombos ovinos foram embalados a vácuo e armazenados sob refrigeração (4±1ºC) por 28 dias e congelamento (-18±1ºC) por 12 meses. No segundo, os cortes foram acondicionados individualmente em 3 diferentes sistemas de embalagem com atmosfera modificada: 1) Á vácuo (sistema tradicional); 2) Com injeção de gases na proporção 75% O2 e 25% CO2 e 3) Com injeção de 100% de CO2). Neste segundo experimento as carnes foram armazenadas sob refrigeração (1±1ºC) por um período de 28 dias. A estabilidade dos cortes foi avaliada por meio de análises físicas, químicas, microbiológicas e sensoriais, sendo que no segundo estudo, além destas análises também foi acompanhada a composição gasosa no espaço-livre. Foram realizadas três repetições de cada um dos estudos. A carne de cordeiro, nas diferentes temperaturas de estocagem e nos três sistemas de embalagens, apresentou-se estável ou com índices aceitáveis em relação à maioria dos parâmetros físicos e químicos avaliados e dentro dos padrões estabelecidos pela legislação brasileira para microrganismos patogênicos durante todo o período. No primeiro estudo, mesmo com uma redução significativa da maciez (de 3 para 8 Kg), a carne congelada continuou sensorialmente aceitável, com todos os atributos, inclusive a textura, recebendo notas em torno de 7 (\"gostei moderamente\"). Portanto, é possível afirmar que a carne de cordeiro apresenta vida de prateleira de no mínimo 12 meses quando armazenada à -18ºC. Em relação à avaliação da estabilidade do lombo ovino refrigerado, detectou-se um aumento elevado das contagens de psicrotróficos anaeróbios, atingindo valores da ordem de 107 UFC/g amostra já aos 14 dias. Esta carne foi avaliada sensorialmente apenas em relação aos atributos cor, aparência geral e aroma. Mesmo considerando as elevadas contagens de microrganismos psicrotróficos, os consumidores não detectaram alterações significativas nos atributos avaliados durante os 28 dias de armazenamento refrigerado. No segundo trabalho, os sistemas de embalagem com injeção de gases foram eficientes em reduzir a proliferação de microrganismos deterioradores quando comparados com o sistema tradicional de embalagem à vácuo. Em relação às diferentes composições gasosas, o sistema com 100% de CO2 apresentou menores contagens microbiológicas do que aquele com 75% O2 e 25% CO2, sendo possível concluir que o sistema de embalagem contendo 100% CO2 garantiu uma maior estabilidade durante 28 dias de armazenamento. No entanto, o lombo de cordeiro acondicionado nesta condição apresentou uma menor preferência sensorial da aparência em relação aos demais tratamentos durante todo o período avaliado. / Nowadays, in Brazil, sheep meat is mainly commercialized as frozen meat. However, in the country studies on possible quality meat changes during frozen storage are scarce. In addition, the increasing consumer demand for higher convenience products supports the need of more studies on of sheep meat cuts stability stored under refrigeration, mainly due to its short shelf life. The objectives of this work were to evaluate the stability of sheep meat when stored under refrigeration and freezing as well as to evaluate different packaging systems under modified atmosphere and the effect of this technology on the meat stability when stored under refrigeration. In order to achieve these objectives, two experiments were performed. In the first study, sheep loins were vacuum packaged and stored under refrigeration (4±1ºC) for 28 days and freezing (-18±1ºC) for 12 months. For the second study, cuts were individually packed in three different atmospheres: 1) vacuum (traditional system), 2) With 75% O2 and 25% CO2 and 3) With 100% CO2. For second experiment, meat was stored under refrigeration (1±1ºC) for a period of 28 days. Stability of the cuts was evaluated by means of physical, chemical, microbiological and sensory analysis, while for the second study, there were also performed headspace gas composition along the storage. Three replications of each study were carried out. The lamb meat at different storage temperatures and the three packaging systems, presented good stability or acceptable indexes in relation to most physical and chemical parameters evaluated. Samples showed good microbiological stability according to standards established by Brazilian legislation for pathogenic microorganisms throughout the storage period. In the first study, there was a significant reduction in tenderness (3 to 8 kg), nevertheless, the frozen meat continued sensory acceptable, showing texture scores around 7 (like moderately). Therefore, it is clear that the lamb meat has a shelf life of at least 12 months when stored at -18ºC. In relation to evaluation of the stability of chilled lamb loin, it was detect a high increase counts of anaerobic psychrotrophic, reaching around 107 CFU/g at 14 days storage. For thies reason, this meat was sensory evaluated only in relation to attributes color, overall appearance and flavor. Even considering the high counts of psychrotrophic, the consumers did not detect significant changes in the attributes evaluated during the 28 days of refrigerated storage. For he second work, it was verified that the gas compositions applied were more effective in reducing the proliferation of deteriorative microorganisms when compared with the traditional vacuum packaging. The system with 100% CO2 presented lower microbiological counts than that with 75% O2 and 25% CO2. Thus the packaging system containing 100% CO2 assured greater stability during 28 days storage. However, the lamb loin packed in this condition presented a lower preference sensory appearance compared to other treatments during the evaluated period.
4

Efeito da temperatura de estocagem sobre a estabilidade de carne bovina (M. Gluteus medius) embalada a vacuo / Effect of storage temperature on stability of vacuum packaged beef

Nishi, Luciene Marie 22 February 2008 (has links)
Orientador: Jose de Assis Fonseca Faria / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-09T22:23:12Z (GMT). No. of bitstreams: 1 Nishi_LucieneMarie_M.pdf: 860304 bytes, checksum: 4f40e930a46695dc3a9db8bcf94cf746 (MD5) Previous issue date: 2008 / Resumo: Este trabalho estudou um sistema comercial de embalagem a vácuo para carne bovina resfriada, alcatra (M. Gluteus medius) com relação à influência da temperatura de estocagem nos atributos de qualidade. As transformações na qualidade da carne foi avaliada com relação aos microrganismos deteriorantes (contagem padrão de mesófilos, bactérias láticas, psicrotróficos aeróbios e anaeróbios), coliformes fecais, Salmonella sp. e estafilococos coagulase positiva; aspectos físico-químicos (pH, exsudação, composição gasosa, nível de vácuo, cor, textura e perda na cocção) e aspectos sensoriais (aparência, aroma, sabor, maciez, suculência, impressão global e intenção de compra). Verificou-se que a temperatura (0, 2, 4, 7 e 10°C) interferiu em vários aspectos de qualidade da carne, afetando diretamente sua vida útil. A carne estocada a 0°C apresentou sinais nítidos de deterioração após 63 dias de armazenamento. O corte estocado a 2°C apresentou as mesmas características aos 49 dias, enquanto as estocadas a 4, 7 e 10ºC deterioram-se em 35, 21 e 15 dias, respectivamente. Não se detectou a presença de microrganismos estabelecidos pela RDC 12 (BRASIL, 2001), mas o desenvolvimento dos deteriorantes apresentou diferente perfil com o aumento da temperatura que, consequentemente, afetou outros parâmetros de qualidade. Foi observada uma tendência de queda nos valores de pH, possivelmente, provocada pela produção de ácidos orgânicos e de CO2, sendo que tal queda foi mais acentuada no exsudato. Observou-se, também, uma perda do vácuo ao longo da estocagem, devido à produção de CO2. A alteração de cor foi maior na superfície do que na parte interna do corte, notando-se uma regeneração da cor da carne, mesmo estando deteriorada. A exsudação, produção de CO2 e perda de massa por cocção aumentaram com o tempo e à temperatura de estocagem. Houve uma redução na força de cisalhamento, sendo essa inversamente proporcional ao tempo e temperatura de estocagem / Abstract: The objective of this research was to evaluate the efficiency of a commercial vacuum packaging system on the quality of beef (M. Gluteus medius) as affected by refrigeration temperature at 0, 2, 4, 7, and 10°C. The evaluation of the beef quality changes were based on: deteriorant microbial counts (aerobic plate, lactic bacteria, psychrotrophic aerobic, and anaerobic bacteria); fecal coliforms, Salmonella sp, and coagulase positive staphylococci; physicochemical characteristics (pH, exudation, gas composition, vacuum level, color, and texture, and cooking loss) and sensory (appearance, flavor, tenderness, juiciness, overall impression and purchase intention). It was not found any bacteria established by RDC 12 (BRASIL, 2001), but the deteriorant increased as a function of temperature and storage time, which consequently affected the beef quality. The changes caused by high microbial counts defined the end of shelflife of meat samples in 63, 49, 35, 21, and 15 days, respectively to 0, 2, 4, 7, and 10°C. The physicochemical changes also increased as function of temperature and storage time, but the sensory quality decreased accordingly. The typical red color changed to darker more at the surface than in the inner part of the beef and the blooming phenomenon happened even on the microbial spoiled beef. The production of CO2 by the microorganisms caused a decrease on the beef pH and more intensive on the exsudate. The CO2 evolution inside the package caused the loss of vacuum. The shear force value decreased within the time and storage temperature / Mestrado / Mestre em Tecnologia de Alimentos
5

Viabilidade de cistos de Toxoplasma gondii em carnes suínas processadas por maturação provenientes de animais experimentalmente infectados / Viability of Toxoplasma gondii cysts in dry-aged pork from experimentally infected pigs

Bruna Farias Alves 21 July 2017 (has links)
O objetivo do presente estudo foi avaliar a viabilidade de cistos de Toxoplasma gondii em carnes suínas processadas por maturação úmida por 14, 21 e 28 dias a 0º (±1), assim como avaliar a distribuição dos cistos em órgãos e cortes comerciais de suínos experimentalmente infectados. Para tanto, dois experimentos foram conduzidos e em ambos, os suínos foram infectados com 3.000 oocistos do isolado TgCkBr57 (BrII). O lombo foi o corte muscular escolhido para sofrer o processo de maturação por ser o corte convencionalmente utilizado para o processo. O lombo direito de cada suíno foi submetido ao processo de maturação e o esquerdo foi mantido como controle, sem processamento. No Experimento 1 três suínos foram infectados. Dos lombos processados por maturação (n=3) e controle (n=3) realizou-se bioensaio em gatos e em camundongos e o período de maturação foi de 14 dias. Nesse ensaio também avaliou-se a distribuição de cistos teciduais pelo bioensaio em camundongos do cérebro, retina, língua, diafragma e coração e de cortes musculares: lombo (m. longissimus), copa (m. longissimus, spinalis dorsi, rhomboideus), filé mignon (m. psoas major), coxão-duro (m. biceps femoris), coxão mole (m. semimembranosus) e alcatra (m. gluteos medius). No Experimento 2 seis suínos foram infectados e foi realizado o bioensaio em camundongos dos lombos que ficaram sob maturação por 14 (n=2), 21 (n=2) e 28 (n=2) dias. Em ambos os experimentos, cistos de T. gondii presentes nos lombos permaneceram viáveis após 14 dias de maturação úmida, com confirmação pelo bioensaio em gatos e em camundongos. Nos períodos de 21 e 28 dias, pelo bioensaio observou-se que os camundongos não se infectaram, indicando que o processo inviabilizou os cistos. Quanto à distribuição dos cistos, estes foram isolados da copa, coração, diafragma e língua dos três suínos; do filé mignon, coxão duro e cérebro de dois suínos e da alcatra e lombo de um suíno. Nenhum camundongo infectou-se no bioensaio com o coxão mole e com a retina. Os resultados demonstram que a maturação em embalagem a vácuo por 14 dias em temperatura controlada (0ºC) não foi eficaz para inativação dos cistos de T. gondii, porém, o processo se mostrou eficiente quando a maturação foi feita por período igual ou superior a 21 dias. Cistos de T. gondii foram encontrados em praticamente todos os órgãos e cortes avaliados, demonstrando a ampla distribuição do parasita em suínos e a importância dessa espécie como fonte de infecção para o homem. / The objective of the present study was to evaluate the viability of Toxoplasma gondii cysts in pork processed by dry-aged for 14, 21 and 28 days at 0º (± 1), as well as to evaluate the distribution of T. gondii cysts in organs and commercial cuts of experimentally infected pigs. For that, two experiments were conducted ans in both the pigs were infected with 3.000 oocysts of the isolate TgCkBr57 (BrII). The loin was the muscle chosen to undergo the dry-aged because it is the cut conventionally used for the process. The right loin of each pig was submitted to the dry-aged and the left was kept as control, without processing. In Experiment 1, three pigs were infected. From the loins processed by dry-aged (n=3) e controle (n=3), the bioassay was performed on cats and mice and the aged period of the loins was 14 days. This study, also avaluated the distribution of T. gondii tissue cysts by bioassay in mice of brain, retina, tongue, diaphragm and hear and of the muscles: loin (m. longissimus), coppa (m. longissimus, spinalis dorsi, rhomboideus), tender loin (m. psoas major), outside flat (m. biceps femoris), topside (m. semimembranosus) and top sirloin (m. gluteos medius) was evaluated. In Experiment 2, six pigs were infected and the bioassay was performed in mice of the loins aged for 14 (n=2), 21 (n=2) and 28 (n=2) days. In both experiments, T. gondii cysts of the loins remained viable after 14 days of dry-aged, confirmed by bioassay in cats and mice. At 21 and 28 days, the bioassay showed that the mice did not become infected, indicating that the process made the cysts unfeasible. As to the distribution of the cysts, T. gondii was isolated from the coppa, heart, diaphragm and tongue of the three pigs, to the tender loin, outside flat and brain of two pigs and to the top sirloin and loin of one pig. No mice were infected in the bioassay with the topside and with the retina. The results demonstrate that the dry-aged for 14 days at controlled temperature (0ºC) was not effective for inactivation of T. gondii cysts, however, the process was efficient when the dry-aged was done for a period egual or righter than 21 days. Toxoplasma gondii cysts were found in practically all organs and cuts evaluated, demonstrating the wide distribution of the parasite in pigs and the importance of this species as a source of infection for man.
6

Viabilidade de cistos de Toxoplasma gondii em carnes suínas processadas por maturação provenientes de animais experimentalmente infectados / Viability of Toxoplasma gondii cysts in dry-aged pork from experimentally infected pigs

Alves, Bruna Farias 21 July 2017 (has links)
O objetivo do presente estudo foi avaliar a viabilidade de cistos de Toxoplasma gondii em carnes suínas processadas por maturação úmida por 14, 21 e 28 dias a 0º (±1), assim como avaliar a distribuição dos cistos em órgãos e cortes comerciais de suínos experimentalmente infectados. Para tanto, dois experimentos foram conduzidos e em ambos, os suínos foram infectados com 3.000 oocistos do isolado TgCkBr57 (BrII). O lombo foi o corte muscular escolhido para sofrer o processo de maturação por ser o corte convencionalmente utilizado para o processo. O lombo direito de cada suíno foi submetido ao processo de maturação e o esquerdo foi mantido como controle, sem processamento. No Experimento 1 três suínos foram infectados. Dos lombos processados por maturação (n=3) e controle (n=3) realizou-se bioensaio em gatos e em camundongos e o período de maturação foi de 14 dias. Nesse ensaio também avaliou-se a distribuição de cistos teciduais pelo bioensaio em camundongos do cérebro, retina, língua, diafragma e coração e de cortes musculares: lombo (m. longissimus), copa (m. longissimus, spinalis dorsi, rhomboideus), filé mignon (m. psoas major), coxão-duro (m. biceps femoris), coxão mole (m. semimembranosus) e alcatra (m. gluteos medius). No Experimento 2 seis suínos foram infectados e foi realizado o bioensaio em camundongos dos lombos que ficaram sob maturação por 14 (n=2), 21 (n=2) e 28 (n=2) dias. Em ambos os experimentos, cistos de T. gondii presentes nos lombos permaneceram viáveis após 14 dias de maturação úmida, com confirmação pelo bioensaio em gatos e em camundongos. Nos períodos de 21 e 28 dias, pelo bioensaio observou-se que os camundongos não se infectaram, indicando que o processo inviabilizou os cistos. Quanto à distribuição dos cistos, estes foram isolados da copa, coração, diafragma e língua dos três suínos; do filé mignon, coxão duro e cérebro de dois suínos e da alcatra e lombo de um suíno. Nenhum camundongo infectou-se no bioensaio com o coxão mole e com a retina. Os resultados demonstram que a maturação em embalagem a vácuo por 14 dias em temperatura controlada (0ºC) não foi eficaz para inativação dos cistos de T. gondii, porém, o processo se mostrou eficiente quando a maturação foi feita por período igual ou superior a 21 dias. Cistos de T. gondii foram encontrados em praticamente todos os órgãos e cortes avaliados, demonstrando a ampla distribuição do parasita em suínos e a importância dessa espécie como fonte de infecção para o homem. / The objective of the present study was to evaluate the viability of Toxoplasma gondii cysts in pork processed by dry-aged for 14, 21 and 28 days at 0º (± 1), as well as to evaluate the distribution of T. gondii cysts in organs and commercial cuts of experimentally infected pigs. For that, two experiments were conducted ans in both the pigs were infected with 3.000 oocysts of the isolate TgCkBr57 (BrII). The loin was the muscle chosen to undergo the dry-aged because it is the cut conventionally used for the process. The right loin of each pig was submitted to the dry-aged and the left was kept as control, without processing. In Experiment 1, three pigs were infected. From the loins processed by dry-aged (n=3) e controle (n=3), the bioassay was performed on cats and mice and the aged period of the loins was 14 days. This study, also avaluated the distribution of T. gondii tissue cysts by bioassay in mice of brain, retina, tongue, diaphragm and hear and of the muscles: loin (m. longissimus), coppa (m. longissimus, spinalis dorsi, rhomboideus), tender loin (m. psoas major), outside flat (m. biceps femoris), topside (m. semimembranosus) and top sirloin (m. gluteos medius) was evaluated. In Experiment 2, six pigs were infected and the bioassay was performed in mice of the loins aged for 14 (n=2), 21 (n=2) and 28 (n=2) days. In both experiments, T. gondii cysts of the loins remained viable after 14 days of dry-aged, confirmed by bioassay in cats and mice. At 21 and 28 days, the bioassay showed that the mice did not become infected, indicating that the process made the cysts unfeasible. As to the distribution of the cysts, T. gondii was isolated from the coppa, heart, diaphragm and tongue of the three pigs, to the tender loin, outside flat and brain of two pigs and to the top sirloin and loin of one pig. No mice were infected in the bioassay with the topside and with the retina. The results demonstrate that the dry-aged for 14 days at controlled temperature (0ºC) was not effective for inactivation of T. gondii cysts, however, the process was efficient when the dry-aged was done for a period egual or righter than 21 days. Toxoplasma gondii cysts were found in practically all organs and cuts evaluated, demonstrating the wide distribution of the parasite in pigs and the importance of this species as a source of infection for man.
7

Estabilidade da carne de cordeiro em diferentes condições de armazenamento / Stability of lamb meat at different storage conditions

Fernandes, Rafaella de Paula Paseto 15 April 2011 (has links)
Atualmente no Brasil a carne ovina é comercializada quase exclusivamente congelada. No entanto, praticamente não existem estudos no país sobre alterações na qualidade desta carne durante seu armazenamento. Com a crescente demanda do consumidor por produtos de maior conveniência, surge a necessidade de maiores estudos em relação à estabilidade de cortes cárneos ovinos estocados sob refrigeração, principalmente em decorrência de sua curta vida útil. Os objetivos deste trabalho foram avaliar a estabilidade da carne ovina quando estocada sob refrigeração e congelamento e se diferentes sistemas de acondicionamento em atmosfera modificada poderiam aumentar a estabilidade desta carne quando armazenada sob refrigeração. Foram realizados dois experimentos. No primeiro, lombos ovinos foram embalados a vácuo e armazenados sob refrigeração (4±1ºC) por 28 dias e congelamento (-18±1ºC) por 12 meses. No segundo, os cortes foram acondicionados individualmente em 3 diferentes sistemas de embalagem com atmosfera modificada: 1) Á vácuo (sistema tradicional); 2) Com injeção de gases na proporção 75% O2 e 25% CO2 e 3) Com injeção de 100% de CO2). Neste segundo experimento as carnes foram armazenadas sob refrigeração (1±1ºC) por um período de 28 dias. A estabilidade dos cortes foi avaliada por meio de análises físicas, químicas, microbiológicas e sensoriais, sendo que no segundo estudo, além destas análises também foi acompanhada a composição gasosa no espaço-livre. Foram realizadas três repetições de cada um dos estudos. A carne de cordeiro, nas diferentes temperaturas de estocagem e nos três sistemas de embalagens, apresentou-se estável ou com índices aceitáveis em relação à maioria dos parâmetros físicos e químicos avaliados e dentro dos padrões estabelecidos pela legislação brasileira para microrganismos patogênicos durante todo o período. No primeiro estudo, mesmo com uma redução significativa da maciez (de 3 para 8 Kg), a carne congelada continuou sensorialmente aceitável, com todos os atributos, inclusive a textura, recebendo notas em torno de 7 (\"gostei moderamente\"). Portanto, é possível afirmar que a carne de cordeiro apresenta vida de prateleira de no mínimo 12 meses quando armazenada à -18ºC. Em relação à avaliação da estabilidade do lombo ovino refrigerado, detectou-se um aumento elevado das contagens de psicrotróficos anaeróbios, atingindo valores da ordem de 107 UFC/g amostra já aos 14 dias. Esta carne foi avaliada sensorialmente apenas em relação aos atributos cor, aparência geral e aroma. Mesmo considerando as elevadas contagens de microrganismos psicrotróficos, os consumidores não detectaram alterações significativas nos atributos avaliados durante os 28 dias de armazenamento refrigerado. No segundo trabalho, os sistemas de embalagem com injeção de gases foram eficientes em reduzir a proliferação de microrganismos deterioradores quando comparados com o sistema tradicional de embalagem à vácuo. Em relação às diferentes composições gasosas, o sistema com 100% de CO2 apresentou menores contagens microbiológicas do que aquele com 75% O2 e 25% CO2, sendo possível concluir que o sistema de embalagem contendo 100% CO2 garantiu uma maior estabilidade durante 28 dias de armazenamento. No entanto, o lombo de cordeiro acondicionado nesta condição apresentou uma menor preferência sensorial da aparência em relação aos demais tratamentos durante todo o período avaliado. / Nowadays, in Brazil, sheep meat is mainly commercialized as frozen meat. However, in the country studies on possible quality meat changes during frozen storage are scarce. In addition, the increasing consumer demand for higher convenience products supports the need of more studies on of sheep meat cuts stability stored under refrigeration, mainly due to its short shelf life. The objectives of this work were to evaluate the stability of sheep meat when stored under refrigeration and freezing as well as to evaluate different packaging systems under modified atmosphere and the effect of this technology on the meat stability when stored under refrigeration. In order to achieve these objectives, two experiments were performed. In the first study, sheep loins were vacuum packaged and stored under refrigeration (4±1ºC) for 28 days and freezing (-18±1ºC) for 12 months. For the second study, cuts were individually packed in three different atmospheres: 1) vacuum (traditional system), 2) With 75% O2 and 25% CO2 and 3) With 100% CO2. For second experiment, meat was stored under refrigeration (1±1ºC) for a period of 28 days. Stability of the cuts was evaluated by means of physical, chemical, microbiological and sensory analysis, while for the second study, there were also performed headspace gas composition along the storage. Three replications of each study were carried out. The lamb meat at different storage temperatures and the three packaging systems, presented good stability or acceptable indexes in relation to most physical and chemical parameters evaluated. Samples showed good microbiological stability according to standards established by Brazilian legislation for pathogenic microorganisms throughout the storage period. In the first study, there was a significant reduction in tenderness (3 to 8 kg), nevertheless, the frozen meat continued sensory acceptable, showing texture scores around 7 (like moderately). Therefore, it is clear that the lamb meat has a shelf life of at least 12 months when stored at -18ºC. In relation to evaluation of the stability of chilled lamb loin, it was detect a high increase counts of anaerobic psychrotrophic, reaching around 107 CFU/g at 14 days storage. For thies reason, this meat was sensory evaluated only in relation to attributes color, overall appearance and flavor. Even considering the high counts of psychrotrophic, the consumers did not detect significant changes in the attributes evaluated during the 28 days of refrigerated storage. For he second work, it was verified that the gas compositions applied were more effective in reducing the proliferation of deteriorative microorganisms when compared with the traditional vacuum packaging. The system with 100% CO2 presented lower microbiological counts than that with 75% O2 and 25% CO2. Thus the packaging system containing 100% CO2 assured greater stability during 28 days storage. However, the lamb loin packed in this condition presented a lower preference sensory appearance compared to other treatments during the evaluated period.
8

EVALUATION OF VACUUM PACKAGING ON THE PHYSICAL PROPERTIES, SOLUBILITY, AND STORAGE SPACE OF DAIRY POWDERS

Eshpari, Hadi 01 July 2011 (has links)
As many of the dairy powders manufactured have to travel long distances to reach their customers, both domestically and internationally, there is considerable interest among dairy powder manufacturers to maintain the quality of their products for relatively long storage periods. Dairy powders can have a long shelf life if packaged and stored properly. Vacuum packaging can be an attractive packaging strategy to maintain the quality of dairy powders and provide added value by improving the efficiency of using the storage space; because of the inherent compactness of these products. Vacuum packaged dry dairy ingredients may also have added ease of handling for end users. However, little is known about the impact of vacuum packaging on the physical properties of dry dairy ingredients. The main objective of this study was to determine the effect of vacuum packaging over 12 months storage on particle size, particle density, bulk density, tapped density, flowability, compressibility, color, moisture content, surface morphology, and solubility of six types of dairy powders. In addition, the effect of dairy ingredients type was also assessed. Commercial samples of nonfat dry milk powder, whole milk powder, buttermilk powder, milk protein Isolate, whey protein concentrate#80, and sweet whey powder were repackaged in duplicate using multi-wall foil side gusseted bags under varying degrees of vacuum (1, 0.7, 0.4 bar) and a control with no vacuum, then stored for 3, 6, and 12 months at 25°C and 60% relative humidity. Each powder was sampled and analyzed in duplicate for all the above listed quality attributes, upon receiving the powder and after 3, 6, and 12 months of storage. Moreover, the effect of vacuum packaging on storage space was evaluated comparing three different models; Model (1) represented a 25 kg bag of atmospheric packaged non fat dry milk with the actual dimensions of a commercial 25 kg bag of non fat dry milk. Model (2), a hypothetical model, represented a 25 kg bag of vacuum packaged non fat dry milk with a length and a width equal to those of model (1). Model (3), another hypothetical model, also represented a 25 kg bag of vacuum packaged non fat dry milk with a length equal to half of a pallet width and a width equal to one third of a pallet length, in order to achieve the highest pallet efficiency possible. The pallet used for all three models was considered to be a (48 × 40) pallet. The height of models 2 and 3 was allowed to reflect the bulk reduction effect of vacuum packaging and was determined based on the weight, density and the known dimensions of the bags. It is important to note that the density of models 2 and 3 was assumed to be equal to the density of a small bag of nonfat dry milk. The saved space per bag and pallet efficiency of vacuum packaging and atmospheric packaging were compared using the three models described above. Physical properties analyses of the dairy powders revealed statistically significant effect of vacuum pressure on only color values: L-, a-, and b but none of the other powder quality attributes examined. Powders packaged under vacuum showed a significantly higher mean of L- color value (p-value = 0.003 < 0.01), but significantly lower means of (a- and b-) color values (p-values = 0.005, and 0.001, respectively). This effect was more dramatic in high fat containing powder such as whole milk powder. In fact, vacuum packaged whole milk powders were significantly whiter, less red, and less yellow. It is likely that vacuum packaging has prevented color changes due to lipid oxidation in whole milk powder. Physical properties analyses of the dairy powders also revealed statistically significant increases in the particle density, particle size, bulk density, and tapped density due to the effect of storage time (all p-values = 0.000 < 0.01), statistically significant decreases in the angle of repose and compressibility due to the effect of storage time (p = 0.000 < 0.01) and (p = 0.004 < 0.01), respectively. The physical properties analyses also revealed a statistically significant effect of the powder type on particle density, particle size, bulk density, and tapped density, angle of repose, compressibility, and color values: L-, a-, and b- (all p-values = 0.000 < 0.01). In other words, particle density, particle size, bulk density, and tapped density of the powders increased over the storage time, while angle of repose (AOR) and compressibility decreased over the storage time. The powder type had a significant effect on particle density, particle size, bulk density, tapped density, AOR, compressibility, and color values: L-, a-, and b; however, it did not have any significant effect on solubility and moisture content. In addition, observations of the surface morphology of dairy powders were made using a scanning electron microscope. This evaluation demonstrated the differences in powder particle shape and surface morphology which are believed to be partially responsible for the significant differences observed in the physical properties, due to the effect of powder type. It was shown that vacuum packaging does increase the efficiency of using the storage space by removing the interstitial air and increasing the density of the powder. As described above, the height of model (2) and the length of model (3) both were expectedly shorter compared to those of model (1). Storage space calculations for non fat dry milk were performed based on comparing the volume of the 3 models and showed 15 % saving in storage space per bag and per pallet, due to vacuum packaging. The effect of space saving on the number of bags per pallet was evaluated using CAPE PACK v2.09 software and showed an increase from 45 bags/ pallet in model (1) to 50 bags/ pallet in model (2) and 54 bags/ pallet in model (3). Overall, this study demonstrates the impact of vacuum packaging on physical properties, solubility, and storage properties of dairy powders. The data suggest that the proposed vacuum packaging method may be beneficial to maintain the quality of the powders studied and it results in space savings per unit of dairy powder compared to conventional atmospheric packaging.
9

Wafer-scale Vacuum and Liquid Packaging Concepts for an Optical Thin-film Gas Sensor

Antelius, Mikael January 2013 (has links)
This thesis treats the development of packaging and integration methods for the cost-efficient encapsulation and packaging of microelectromechanical (MEMS) devices. The packaging of MEMS devices is often more costly than the device itself, partly because the packaging can be crucial for the performance of the device. For devices which contain liquids or needs to be enclosed in a vacuum, the packaging can account for up to 80% of the total cost of the device. The first part of this thesis presents the integration scheme for an optical dye thin film NO2-gas sensor, designed using cost-efficient implementations of wafer-scale methods. This work includes design and fabrication of photonic subcomponents in addition to the main effort of integration and packaging of the dye-film. A specific proof of concept target was for NO2 monitoring in a car tunnel. The second part of this thesis deals with the wafer-scale packaging methods developed for the sensing device. The developed packaging method, based on low-temperature plastic deformation of gold sealing structures, is further demonstrated as a generic method for other hermetic liquid and vacuum packaging applications. In the developed packaging methods, the mechanically squeezed gold sealing material is both electroplated microstruc- tures and wire bonded stud bumps. The electroplated rings act like a more hermetic version of rubber sealing rings while compressed in conjunction with a cavity forming wafer bonding process. The stud bump sealing processes is on the other hand applied on completed cavities with narrow access ports, to seal either a vacuum or liquid inside the cavities at room temperature. Additionally, the resulting hermeticity of primarily the vacuum sealing methods is thoroughly investigated. Two of the sealing methods presented require permanent mechanical fixation in order to complete the packaging process. Two solutions to this problem are presented in this thesis. First, a more traditional wafer bonding method using tin-soldering is demonstrated. Second, a novel full-wafer epoxy underfill-process using a microfluidic distribution network is demonstrated using a room temperature process. / <p>QC 20130325</p>
10

Wafer Level Vacuum Packaging Of Mems Sensors And Resonators

Torunbalci, Mert Mustafa 01 February 2011 (has links) (PDF)
This thesis presents the development of wafer level vacuum packaging processes using Au-Si eutectic and glass frit bonding contributing to the improvement of packaging concepts for a variety of MEMS devices. In the first phase of this research, micromachined resonators and pirani vacuum gauges are designed for the evaluation of the vacuum package performance. These designs are verified using MATLAB and Coventorware finite element modeling tool. Designed resonators and pirani vacuum gauges and previously developed gyroscopes with lateral feedthroughs are fabricated with a newly developed Silicon-On-Glass (SOG) process. In addition to these, a process for the fabrication of similar devices with vertical feedthroughs is initiated for achieving simplified packaging process and lower parasitic capacitances. Cap wafers for both types of devices with lateral and vertical feedthroughs are designed and fabricated. The optimization of Au-Si eutectic bonding is carried out on both planar and non-planar surfaces. The bonding quality is evaluated using the deflection test, which is based on the deflection of a thinned diaphragm due to the pressure difference between inside and outside the package. A 100% yield bonding on planar surfaces is achieved at 390&ordm / C with a v holding time and bond force of 60 min and 1500 N, respectively. On the other hand, bonding on surfaces where 0.15&mu / m feedthrough lines exist can be done at 420&ordm / C with a 100% yield using same holding time and bond force. Furthermore, glass frit bonding on glass wafers with lateral feedthroughs is performed at temperatures between 435-450&ordm / C using different holding periods and bond forces. The yield is varied from %33 to %99.4 depending on the process parameters. The fabricated devices are wafer level vacuum packaged using the optimized glass frit and Au-Si eutectic bonding recipes. The performances of wafer level packages are evaluated using the integrated gyroscopes, resonators, and pirani vacuum gauges. Pressures ranging from 10 mTorr to 60 mTorr and 0.1 Torr to 0.7 Torr are observed in the glass frit packages, satisfying the requirements of various MEMS devices in the literature. It is also optically verified that Au-Si eutectic packages result in vacuum cavities, and further study is needed to quantify the vacuum level with vacuum sensors based on the resonating structures and pirani vacuum gauges.

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