Wu Yuen-Ting. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2005. / Includes bibliographical references (leaves 88-90). / Abstracts in English and Chinese. / Chapter 1. --- Introduction --- p.1 / Chapter 1.1 --- Background --- p.1 / Chapter 1.2 --- Research Objective --- p.4 / Chapter 1.3 --- Contribution --- p.5 / Chapter 1.4 --- Structure of this thesis --- p.6 / Chapter 2. --- Literature Review --- p.7 / Chapter 2.1 --- Genetic Algorithms --- p.7 / Chapter 2.1.1 --- Pre-processing step --- p.8 / Chapter 2.1.2 --- Generation of initial population --- p.10 / Chapter 2.1.3 --- Crossover --- p.11 / Chapter 2.1.4 --- Mutation --- p.12 / Chapter 2.1.5 --- Selection --- p.12 / Chapter 2.1.6 --- Results of GA on Container Loading Algorithm --- p.13 / Chapter 2.2 --- Layering Approach --- p.13 / Chapter 2.3 --- Mixed Integer Programming --- p.14 / Chapter 2.4 --- Tabu Search Algorithm --- p.15 / Chapter 2.5 --- Other approaches --- p.16 / Chapter 2.5.1 --- Block arrangement --- p.17 / Chapter 2.5.2 --- Multi-Directional Building Growing algorithm --- p.17 / Chapter 2.6 --- Comparisons of different container loading algorithms --- p.18 / Chapter 3. --- Principle of LFF Algorithm --- p.8 / Chapter 3.1 --- Definition of Flexibility --- p.8 / Chapter 3.2 --- The Less Flexibility First Principle (LFFP) --- p.23 / Chapter 3.3 --- The 2D LFF Algorithm --- p.25 / Chapter 3.3.1 --- Generation of Corner-Occupying Packing Move (COPM) --- p.26 / Chapter 3.3.2 --- Pseudo-packing and the Greedy Approach --- p.27 / Chapter 3.3.3 --- Real-packing --- p.30 / Chapter 3.4 --- Achievement of 2D LFF --- p.31 / Chapter 4. --- Error Bound Analysis on 2D LFF --- p.21 / Chapter 4.1 --- Definition of Error Bound --- p.21 / Chapter 4.2 --- Cause and Analysis on Unsatisfactory Results by LFF --- p.33 / Chapter 4.3 --- Formal Proof on Error Bound --- p.39 / Chapter 5. --- LFF for Container Loading Problem --- p.33 / Chapter 5.1 --- Problem Formulation and Term Definitions --- p.48 / Chapter 5.2 --- Possible Problems to be solved --- p.53 / Chapter 5.3 --- Implementation in Container Loading --- p.54 / Chapter 5.3.1 --- The Basic Algorithm --- p.56 / Chapter 5.4 --- A Sample Packing Scenario --- p.62 / Chapter 5.4.1 --- Generation of COPM list --- p.63 / Chapter 5.4.2 --- Pseudo-packing and the greedy approach --- p.66 / Chapter 5.4.3 --- Update of corner list --- p.69 / Chapter 5.4.4 --- Real-Packing --- p.70 / Chapter 5.5 --- Ratio Approach: A Modification to LFF --- p.70 / Chapter 5.6 --- LFF with Tightness Measure: CPU time Cut-down --- p.75 / Chapter 5.7 --- Experimental Results --- p.77 / Chapter 5.7.1 --- Comparison between LFF and LFFR --- p.77 / Chapter 5.7.2 --- "Comparison between LFFR, LFFT and other algorithms" --- p.78 / Chapter 5.7.3 --- Computational Time for different algorithms --- p.81 / Chapter 5.7.4 --- Conclusion of the experimental results --- p.83 / Chapter 6. --- Conclusion --- p.85 / Bibiography --- p.88

Submitted by MONICA DE ALBUQUERQUE MALDONADO null (monica.a.maldonado@gmail.com) on 2017-02-20T13:10:38Z No. of bitstreams: 1 Dissertação 2017_Monica Maldonado (2).pdf: 5292728 bytes, checksum: 79bbdabdb677de9e607fa930132e2f04 (MD5) / Approved for entry into archive by LUIZA DE MENEZES ROMANETTO (luizamenezes@reitoria.unesp.br) on 2017-02-22T19:30:44Z (GMT) No. of bitstreams: 1 maldonado_ma_me_bauru.pdf: 5292728 bytes, checksum: 79bbdabdb677de9e607fa930132e2f04 (MD5) / Made available in DSpace on 2017-02-22T19:30:44Z (GMT). No. of bitstreams: 1 maldonado_ma_me_bauru.pdf: 5292728 bytes, checksum: 79bbdabdb677de9e607fa930132e2f04 (MD5) Previous issue date: 2017-01-06 / O aspecto social é possivelmente o menos desenvolvido dos três pilares da sustentabilidade. Pesquisas realizadas anteriormente priorizam os assuntos ambientais e econômicos. O interesse ao desenvolvimento de embalagens tem aumentado recentemente, com vários programas e iniciativas que instigam o aprimoramento da sustentabilidade das embalagens. O desenvolvimento de embalagem sustentável deveria considerar indicadores e critérios de embalagens considerando o ciclo de vida do produto e da embalagem. Poucos trabalhos, no entanto, discutem a questão de embalagens e sustentabilidade considerando o ponto de vista da cadeia de suprimentos, mas as decisões tomadas no início do ciclo-de-vida da embalagem e do produto afetam diretamente a sustentabilidade e seu impacto sobre desempenho e custos na cadeia de suprimentos pode ser devastador. Nesse contexto, essa pesquisa busca contribuir com o entendimento dos aspectos de sustentabilidade social em embalagens. O objetivo principal deste trabalho é propor uma ferramenta para análise da sustentabilidade social em embalagens, com base na relação entre 20 critérios de embalagens e 3 princípios de sustentabilidade social (justiça, igualdade/equidade e transparência) considerados no design/desenvolvimento de embalagens. A ferramenta proposta é um questionário, que foi respondido por associados da Associação Brasileira de Embalagens, com o intuito de exemplificar a aplicação da ferramenta. Os resultados foram analisados e apresentados em gráficos do tipo radar, que permitem uma melhor visualização das questões abordadas em cada princípio. No entanto, devido à diversidade de questões e abrangência do tema, a maioria das embalagens analisadas, deve possuir, eventualmente, elementos de sustentabilidade social. Contudo, uma embalagem socialmente sustentável deve considerar, nos processos de design e desenvolvimento, uma justa distribuição dos recursos na sociedade, igualdade de diereitos estabelecidos e acesso à informação e oportunidade para participação. Além disso, como a sociedade está “inserida” no meio ambiente, a discussão de práticas de sustentabilidade ambiental é importante para a sustentabilidade social. / The social aspect is possibly the least developed of the three pillars of sustainability. Previous research prioritizes environmental and economic issues. The interest in packaging development has increased recently, with several programs and initiatives that instigate the improvement of packaging sustainability. The development of sustainable packaging should consider indicators and packaging criteria considering the product’s and packaging’s life cycle. Few papers, however, discuss packaging and sustainability from a supply chain perspective, but decisions taken early in the packaging and product life cycle affect directly sustainability and its impact on performance and costs in the supply chain can be devastating. In this context, this research seeks to contribute to the understanding of social sustainability aspects in packaging. The main objective of this work is to propose a tool for the analysis of social sustainability in packaging, based on the relationship between 20 packaging criteria and 3 principles of social sustainability (fairness, equality/equity and transparency) on packaging design / development. The proposed tool is a questionnaire, which was answered by members of the Brazilian Association of Packaging, with the purpose of exemplifying the application of the tool. The results were analyzed and presented in radar type charts, which allow a better visualization of the issues addressed in each principle. However, due to the diversity of issues and scope of the theme, most of the packages analyzed should have, possibly, elements of social sustainability. However, a socially sustainable package should consider, in design and development processes, a fair distribution of resources in society, equality of established rights and access to information and opportunity for participation. In addition, as society is "inserted" in the environment, the discussion of environmental sustainability practices is important for social sustainability.

L'innovation dans le conditionnement du vin amène les industriels à proposer de nouveaux emballages, plus pratiques et plus respectueux de l'environnement. Une bouteille éco-conçue, à base de polyéthylène terephthalate (PET), contenant du PET recyclé a été développée en vue de d'emballer du vin rosé de type Cinsault. Le vin est un aliment très sensible à l'oxygène et malgré les bonnes propriétés barrières du PET, un conditionnement sur une longue durée peut entrainer une dégradation de ses qualités aromatiques. Pour protéger le vin au mieux, un absorbeur d'oxygène a alors été rajouté au PET constituant la bouteille. Les modifications du profil aromatique du vin peuvent être dues à l'entrée d'oxygène mais aussi aux transferts des composés d'arôme au travers de la bouteille et du bouchon. Ces transferts sont potentiellement accentués par la présence de PET recyclé et d'absorbeur d'oxygène. En vue de comprendre au mieux ces phénomènes les travaux de thèse présentés ici ont porté sur :-L'étude des propriétés thermique, structurales et barrière aux gaz et aux composés organiques volatils (arômes et éthanol) des différents matériaux ainsi que sur l'impact des COV sur la modification de ces propriétés-L'étude de l'oxydation d'un composé d'arôme sensible, le méthionol et l'effet protecteur des absorbeurs d'oxygène-L'étude de l'évolution du profil aromatique du vin et de la sorption des arômes dans les bouteilles et le bouchon après 12 mois de conditionnement dans les bouteilles en PET contenant ou non du PET recyclé et un absorbeur d'oxygène. Ces travaux ont permis de montrer que de nombreux changements ont lieu au cours du stockage du vin et que les réactions d'oxydation sont favorisées lors de l'utilisation de PET. Toutefois, une conservation du rosé sur un temps court (6 mois) est possible. Le recyclage du PET modifie les propriétés thermiques et diminue légèrement les propriétés barrières aux arômes du matériau. Toutefois malgré ces différences structurales, la présence de PET recyclé dans la bouteille de PET n'influe pas de façon marquée la qualité organoleptique du vin. L'ajout d'une quantité adaptée d'absorbeur d'oxygène (3%) dans la bouteille en PET permet d'augmenter la durée de conservation du vin, jusqu'à 12 mois, avec un produit équivalent en qualité à celui trouvé pour une bouteille en verre. Les phénomènes de transferts d'arômes entrainent quant à eux des pertes négligeables en composés aromatiques. La présence d'absorbeur d'oxygène, même si elle modifie les propriétés thermiques du PET et augmente ses propriétés barrières aux composés d'arôme, ne semble pas au final impacter les transferts d'arômes lors de la conservation du vin. / Innovation in wine packaging prompts industrials to offer more convenient and environment friendly packages. An eco-designed bottle, made of partially recycled polyethyleneterephthalate (PET) (containing a part of recycled) was specifically developed to package a Cinsault rosé wine. Wine is a product very sensitive to oxygen, and despite the good barrier properties of PET, storing wine for an extended period of time, may reduce its organoleptic qualities. To protect the wine, an oxygen scavenger was embedded in the PET. Alterations of aromatic profile of the wine can be related to oxygen ingress and loss of aroma compound caused by their transfers through the bottle. Furthermore, these transfers are potentially magnified by the presence of recycled PET and oxygen scavengers. To accurately understand those phenomena, the thesis presented here covers the following subjects:-The study of thermal structural properties and barrier properties to gas and volatile organic compounds (aroma and ethanol) of the involved materials-The study of oxidation of a sensitive aroma compound (methionol) and preservation using oxygen scavengers-The study of wine aromatic profile and aroma sorption through the bottle and the stopper evolutionduring 12 months of packaging in PET bottles and relationship with the barrier properties of materialsThis work shows that during storage of wine, numerous changes in aromatic profile take place and that oxidation and ageing reactions are favoured using PET bottle. However the use of PET allows the storage of rosé wine for a short duration (6 months). Recycling of PET slightly reduces the thermal properties and the aroma barrier properties. However, despite its structural differences, the quality of the wine is not deeply affect. The addition of a suitable amount of oxygen scavenger (3%) in PET bottles provides a longer duration of storage for wine (up to 12 months) with results equivalent to a glass bottle. Whatever the packages, the aroma transfer phenomena (sorption and permeation) only account for a negligible part of aroma compounds losses. Even if the presence of oxygen scavengers slightly alters the thermal and aroma barrier properties of the PET, not consequences are evidenced on aroma transfer during the storage of wine.

No cultivo da bananeira, a proteção física dos cachos é uma das principais técnicas culturais utilizada com a finalidade de melhorar a qualidade dos frutos. O objetivo desse trabalho foi estudar a influência do uso de diferentes tipos de embalagens para proteção do cacho de banana, cultivar Nanicão, durante o seu desenvolvimento e na pós-colheita dos frutos. Foram realizados dois experimentos em um bananal irrigado, com 8 anos de idade, em clima Cwa. O primeiro experimento foi realizado em duas épocas do ano para verificar a influência dos tipos de embalagens no desenvolvimento dos frutos e na sua qualidade. Os tratamentos foram: 1) testemunha (sem uso de proteção do cacho); 2) saco de polipropileno - TNT; 3) saco de polietileno azul; 4) saco de polietileno transparente), 5) saco de polietileno tratado com inseticida); e 6) saco de polietileno branco. Avaliou-se o período de frutificação (intervalo entre a emissão da inflorescência até a colheita dos frutos), massa do cacho, massa do engaço+ráquis, número de pencas por cacho, massa da 2ª penca, número de frutos da 2ª penca, massa da casca e polpa, relação polpa/casca, densidade dos frutos, lesões causadas por tripes, defeitos ou injúrias nos frutos, coloração da casca, sólidos solúveis, firmeza da polpa, acidez titulável e pH da polpa. No segundo experimento verificou-se a conservação desses frutos após a colheita e amadurecimento em ambiente controlado dos frutos. Avaliou-se a coloração da casca, sólidos solúveis da polpa, acidez titulável da polpa, pH da polpa, firmeza da polpa, perda de massa e relação polpa/casca. O delineamento utilizado em ambos os experimentos foram o inteiramente causalizado. A análise de variância dos dados obtidos foi realizada e no caso de significâncias as médias foram comparadas pelo teste Tukey (5%). Conclui-se que o uso das embalagens para proteção do cacho reduz o período de frutificação, independentemente da época de desenvolvimento do fruto. A massa do cacho, a massa do engaço+ráquis, número de pencas, massa da 2ª penca, número de frutos da 2ª penca, densidade dos frutos e pH da polpa não são influenciados pelo uso de embalagens para proteção do cacho. O uso de embalagens no cacho protege contra o ataque de tripes da erupção. No inverno, todos os tipos de proteção física do cacho de banana tiveram desempenho semelhantes no controle dessa praga. No verão, o melhor controle foi obtido pela embalagem impregnada com inseticida. O uso de embalagens para proteção do cacho interfere nos atributos físico-químicos considerados importantes na maturação dos frutos, tais como coloração da casca, sólidos solúveis, firmeza e acidez titulável. As embalagens confeccionadas de material translúcido propiciam a produção de frutos com menor quantidade de injúrias e maior período de conservação, após o amadurecimento em ambiente controlado dos frutos. Cachos de banana que se desenvolveram no verão apresentaram maior massa e período de frutificação inferior aos frutos desenvolvidos no inverno. / In banana crop, the fruit physical protection is an important cultural technique performed in order to improve fruit quality. The aim of this work was to study the different types of bag influence for banana bunch protection, cv. Nanicão, during fruit development and post-harvest. Two experiments were developed under irrigated conditions in a banana filed with 8 years of cultive, in climate Cwa. The first experiment was conducted in two seasons aiming to verify the influence of different bags types in the fruits development and quality. The treatments were: 1) control (without bunch protection); 2) polypropylene bag - TNT; 3) Blue polythene bag; 4) Transparent polyethylene bag), 5) polyethylene bag Treated with insecticide); and 6) White polyethylene bag. Evaluated variables were: fruiting period (interval between the inflorescence emission until fruit harvest), bunch weight, mass of stems + rachis, number of hands per bunch, mass of the 2nd bunch, number of fruits of the 2nd bunch, mass of peel and pulp, pulp / peel ratio, fruit density, injuries caused by thrips, defects or injuries in fruits, peel color, soluble solids, firmness, titratable acidity and pH of the pulp. In the second experiment was evaluated the conservation of these fruits after harvest and acclimatization. Evaluated variables were: skin color, soluble solids of the pulp, titratable acidity of the pulp, pulp pH, firmness, weight loss and pulp / peel ratio. The experimental design, in both experiments, was completely randomized design. Data variance analyses were performed and in the case of significance means were compared by Tukey test (5%). The use of packaging bunch protection reduces the fruiting period, regardless of the fruit development time. The bunch weight, the mass of stems + rachis, number of hands, mass of the 2nd bunch, number of fruits of the 2nd bunch, fruit density and pH of the pulp are not influenced by the use of packaging bunch protection. The use of packaging in the bunch protects against attack by thrips eruption. During the winter conditions, all kinds of physical protection of the banana bunch had similar performance against this bug. Under summer conditions, the best control was through the use of impregnated with insecticide packaging. The use of packaging bunch protection interferes in physicalchemical attributes considered important in the maturation of the fruit, such as coloring hunting, soluble solids, firmness and titratable acidity. The packaging made by translucent material provides fruit production with less injuries and greater conservation period, after fruit acclimatization. Banana bunches developed in the summer were heavier and fruiting period was shorter than the fruit developed during the winter.

O uso do método de esterilização por radiação gama ajuda na redução da contaminação microbiológica. O polietileno linear de baixa densidade (PELBD) é um polímero de cadeias lineares e ramificações curtas. Neste trabalho o PELBD injetado foi irradiado por uma fonte de 60Co com 2000 kCi de atividade, na presença de ar, em doses de 5, 10, 20, 50 ou 100 kGy e taxas de dose de cerca de 5 kGy.h-1 em temperatura ambiente (25 ºC). Após a irradiação, foi necessário submeter as amostras a um tratamento térmico em uma estufa por 60 min a 100 ºC para a recombinação e aniquilação dos radicais residuais. Na sequência as amostras injetadas foram irradiadas e caracterizadas para identificar os efeitos de degradação térmica, cisão e reticulação em cada dose. Verificou-se uma degradação térmica da resina ao passar pelo processo de modelagem por injeção confirmada pela análise de FTIR. Os PELBD injetados irradiados nas doses de 5, 10 ou 20 kGy tiveram maior tendência a cisão do que aqueles nas doses de 50 ou 100 kGy, nos quais predominou a reticulação. Desta forma determinaram-se os efeitos da irradiação e do processo nos PELBD moldados por injeção. / The use of the method of sterilization by gamma radiation helps in reducing microbiological contamination. The linear low density polyethylene (LLDPE) is a linear polymer chain with short chain branching. In this work, the LLDPE were irradiated in 60Co gamma source with 2000 kCi of activity, in presence of air, with doses of 5, 10, 20, 50 or 100 kGy, at about 5 kGy.h-1 dose rate, at room temperature. After irradiation, the samples were heated for 60 min at 100 ºC to promote recombination and annihilation of residual radicals. In the sequence LLDPE injected samples were irradiated and characterized to identity the effects of terminal degradation, scission end crosslinking occurred in each dose. There was a thermal degradation of the resin through the process of injection molding confirmed by FTIR analysis. And LLDPE injected irradiated at doses of 5, 10 or 20 kGy has a greater tendency to scission than those at doses of 50 or 100 kGy, where predominated crosslinking consequently the effects of irradiation and injection molding were investigated in LLDPE processed.

FundaÃÃo Cearense de Apoio ao Desenvolvimento Cientifico e TecnolÃgico / O objetivo deste estudo foi verificar o efeito do Ãcido acÃtico 1% sobre a microbiota da carne ovina maturada. Foram utilizados 5 animais ovinos machos castrados do tipo Sem RaÃa Definida (SRD), com idade aproximada de 1 ano, provenientes do interior do estado do CearÃ. ApÃs o abate as carcaÃas dos animais foram refrigeradas por 12 horas a 0ÂC e em seguida foram coletadas amostras da superfÃcie dos seguintes locais: paleta, pescoÃo, peito, lombo, coxÃo e cavidade abdominal. Nessas amostras foram realizadas anÃlises microbiolÃgicas de contagem padrÃo em placas de bactÃrias mesÃfilas, pesquisa de coliformes totais e fecais. As paletas foram entÃo retiradas das carcaÃas e cortadas em fatias de peso similar, da porÃÃo proximal para a porÃÃo distal desse corte. As fatias das paletas direitas foram submetidas a tratamento de imersÃo em soluÃÃo de Ãcido acÃtico a 1% por 1 minuto e as fatias esquerdas foram imersas em Ãgua potÃvel (controle). Todas as fatias foram em seguidas embaladas individualmente à vÃcuo em filme flexivel, impermeÃvel ao oxigÃnio e armazenadas para maturaÃÃo a 1ÂC. Para as anÃlises microbiolÃgicas da carne de paleta, foram coletadas fatias nos dias 3, 13, 23, 33 e 48 de armazenamento. Em cada dia foram coletadas fatias, sendo 5 de cada tratamento de imersÃo. As anÃlises realizadas foram contagem padrÃo em placa (mesÃfilos e psicrofilos), contagem de bolores e leveduras, contagem de clostridios sulfito-redutores, pesquisa de coliformes totais e fecais e pesquisa de Salmonella. NÃo houve diferenÃas significativas (P>0,05) na contagem de bactÃrias entre os diferentes locais da carcaÃa ovina analisada. Em relaÃÃo ao estudo de armazenamento da carne, foi observada uma reduÃÃo (P<0,05) da contagem de bactÃrias mesÃfilas nas carnes tratadas com Ãcido nos dias 13 e 23 de estocagem. Com 3 e 13 dias de armazenamento houve uma reduÃÃo significativa (P<0,05) na microbiota de psicrÃfilos na carne da paleta ovina tratada com Ãcido. Entretanto nos dias 23, 33 e 48 de armazenamento esse comportamento nÃo foi observado. Em relaÃÃo a bolores e leveduras, houve uma reduÃÃo (P<0,05) da microbiota das amostras tratadas em relaÃÃo a das nÃo tratadas. Este efeito foi evidente atà o dia 13 de armazenamento. Somente no 3 dia de armazenamento, as amostras tratadas apresentaram contagens de coliformes totais significativamente (P<0,05) menores que as nÃo tratadas. Tal comportamento, porÃm, nÃo foi verificado nos dias 13, 23, 33 e 48 de estocagem. As amostras tratadas com Ãcido acÃtico 1% apresentaram valores menores (P<0,05) de coliformes fecais do que as nÃo tratadas. Observou-se ausÃncia de clostrÃdios sulfito-redutores em todas as amostras, independente do tratamento e do tempo de maturaÃÃo. A pesquisa de Salmonella, indicou presenÃa deste microrganismo em 20 e 24%, das amostras tratadas com Ãcido acÃtico 1% e nÃo tratadas, respectivamente. Os valores de pH foram significativamente menores (P<0,05) nos dias 3, 23 e 33 que nos dias 13 e 48 de armazenamento. Os resultados sugerem que o abate cuidadoso de animais ovinos nas condiÃÃes ambientais do Nordeste Brasileiro, permite obter carcaÃas com nÃveis aceitÃveis de microrganismos na superfÃcie. A imersÃo das carnes em Ãcido acÃtico 1% seguida de estocagem a vÃcuo permite manter as carnes refrigeradas (1ÂC) por 13 dias, com controle eficiente da microbiota deteriorativa, mantendo um padrÃo higiÃnico-sanitÃrio adequado, mas nÃo à suficiente para inibir o crescimento de Salmonella. / The objective of this study was to verify the effect of 1% acetic acid on the microbial condition of aged lamb meat. The experiment used five undefined breed (SRD) wethers, with 1 year of age. After slaughter the carcasses were chilled at 0ÂC and kept for 12 h. Samples for microbiological analysis were collected from the surface of shoulder, neck, breast, loin, leg and the ventral side of the flank. These surfaces were evaluated for mesophiles and total and fecal coliform microrganisms. Shoulders were then separated from the carcass and cut to standard weight slices, from the proximal to the distal region of the cut. The right side shoulder slices were dipped in 1% acetic acid solution for 1 min and the left side shoulder slices were dipped in distilled water (control). The slices were individually vacuum packaged in a film, with low permeability to oxygen and then stored at 1ÂC. On days 3, 13, 23, 33 and 48 of the aging period samples (5 trated with 1% acetic acid and 5 control) were collected, to be analyzed for total plate count, mould and yeast, sulfite-reduzing clostridia, total and fecal coliforms and Salmonella. There was no difference (P>0.05) in surface microrganism counts among different locations in the lamb carcass. Related to the aging of meat trated with acetic acid it was observed a decrease (P<0.05) in mesophiles count on trated samples with 13 and 23 days of aging. At 3 and 13 days of aging occurred a significant (P<0.05) decrease of psicrophylic organisms in meats treated with acetic acid. However at 23, 33 and 48 days of storage this effect was not observed. There were a decrease (P<0.05) in moulds and yeast counts is samples treated with acid. Mould andyeast counts were smaller (P<0.05) at day 13 than those at days 33 and 48 days of aging. Only at day 3 of aging treated samples showed lower (P<0.05) total coliform counts than samples with no acid. Meat samples treated with 1% acetic acid showed lower (P<0.05) fecal coliform counts than samples with no acid. It was observed absence of sulfite-reduzing clostridia in all samples independent of acid treatment or aging time. The presence of Salmonella detected in 20% of the treated samples and in 24% of the untreated ones. Meat pH values were lower (P<0.05) on days 3, 23 and 33 than on days 13 and 48 of aging. Results suggest that proper slaughter conditions in Northeast Brasil produce lamb carcasses with acceptable counts of microrganisms. Deeping of meat cuts in 1% acetic acid solution followed by vacuum packazing is appropriate to age meat at 1ÂC for 13 days. This treatment keeps low levels of psicrofilic counts, allows a sound higienic condition of the meat but it is not enough to inhibit the presence of Salmonella.

No description available.

No description available.

Probiotic bacteria are added to commercial yoghurts as adjunct cultures, to impart health benefits to consumers. To gain maximum therapeutic benefit, the bacteria must remain viable over the shelf life of the yoghurt. Studies have shown, however, that the viability of these bacteria decreases significantly over this period and in some products, is negligible prior to the expiry date. Some strains of probiotic bacteria are oxygen sensitive. Yoghurt has been found to contain a significant concentration of dissolved oxygen and it has been proposed that this has a negative effect on probiotic viability. In this research, several tests were conducted and observations made. Experiments were conducted with non-commercial probiotic cultures to observe the effect of low oxygen environment on probiotic viability. No significant difference existed in viability between probiotic bacteria stored in oxygen reduced yoghurt and regular yoghurt. All yoghurt stored in oxygen barrier packaging material displayed enhanced shelf-life properties, this was observed in replicated experiments. Oxygen barrier packaging combined with an oxygen scavenging material was found to be the most effective oxygen removal system, particularly when used with set type yoghurt. / Doctor of Philosophy (PhD)

The study presented here consists in an original piece of work to better understand complex food packaging interactions. The majority of investigations on food polymer interactions related to orange juice and this provided a good base to our study (Literature reviews: cf. Chapters 1a and b). Additionally a rather remarkable finding in 1994 was that limonin, a trace bitter material found in some varieties of orange juice was rapidly absorbed by highly plasticised polyvinyl chloride (PVC plastisol) (Chapter 2). Several commercial absorbants are available for debittering, relying on limonin absorption on the large surface area of the highly porous absorbant pellets. However, the absorptive properties of the smooth plastisols apparently relied on a different mechanism. Limonin is a very large (470.5 g/mol) compound, but some preliminary experiments with another much smaller orange juice constituent d- of absorbates in plastisols, methods used earlier (Moisan 1980, Holland and Santangelo 1988) to measure solubilities and diffusion constants in packaging films could be advantageously used to survey these properties in a wide range of materials, including model compounds of various types, and a number of compounds which may be found in citrus juices (Chapters 3, 4 and 5). Experimentally, the method found most suitable was to use a ‘test film’ of pure plastisol which was wrapped tightly on both sides by a similar ‘supply film’ blended with 1 Molar test material (also called ‘absorbate’), setting up a concentration gradient. The inner test film was removed at regular intervals (minutes to hours) to measure (mainly by weighing) the uptake of the test reagent with time. Rather unexpectedly, it was found in a number of cases that the test film lost weight, either from the beginning, or after a period of time. Three main types of behaviour were identified: Type A lost weight from the beginning and over a long period of time, Type B gained weight initially and then lost weight, and Type C gained weight until a steady state was reached. Often the maximum, or near maximum, mass increase occurred within around 100 minutes, indicating a very rapid, liquid-like diffusion mechanism, in harmony with the rapid uptake of d-limonene and limonin. The major parameters of interest with these compounds are their diffusion rates and their solubilities, and in the presence of aqueous media (orange juice and other foodstuffs) the partition coefficient between the plastisol and water, which is related to the hydrophobicity function LogP for the compound. The major complicating factor in these measurements is the observation that the plasticiser materials themselves also migrate, in the reverse direction, because of the lower effective concentration in the supply film. This effect tends to be small, but is one explanation for the mass loss observed above, and cannot be ignored over the long term, nor in its practical applications to contamination in foods. There are many possible applications for the techniques described above. The removal or addition of compounds in food packaging itself is one. Upgrading foods, such as orange juice, commercially, is another. In many cases ‘scalping’ off-flavours or other minor components takes place exclusively through solid or liquid contact with the packaging. The removal from the headspace measured by the current gas permeation methods is irrelevant for the vast numbers of involatile, but easily diffusable compounds. For such compounds these novel applications are simple and rapid, require little specialised equipment, and fill a niche in the armoury of food and packaging chemists. / Doctor of Philosophy (PhD)