High-pressure (HP) depresses the phase-transition point of water especially in the case of ice-I (down to -21°C at about 210 MPa). This phenomenon has several potential advantages in food processing applications, such as pressure shift freezing (PSF) and HP thawing. However, scientific knowledge available in this area is still relatively limited. The main objectives of this research were to investigate the phase-transition behavior of foods under pressure processing in the context of PSF and HP thawing techniques and to evaluate their impact on product quality. / Distilled water and fresh pork muscle were tested by a HP differential scanning calorimeter (DSC) using isothermal pressure scan (P-scan) and isobaric temperature scan (T-scan). P-scan tests showed that the phase-transition temperature (T) of pork was a function of the weighted-average pressure (P¯1--2): T = -1.17 - 0.102P¯1--2 - 0.00019 P&d1;21-2 (R2 = 0.99) that was much lower than that of pure ice. The phase-change latent heat of pork was estimated by P-scan. T-scan indicated the phase-transition point at a constant pressure, but it showed less accurate than P-scan. The ratio (Rice, %) of ice crystals formed by rapid release of pressure (P) was evaluated using the HP DSC: Rice-water = 0.115P + 0.00013P2 (R2 = 0.96) for water, and Rice-pork = 0.084P + 0.00012P2 (R2 = 0.95) for pork muscle. In the developed method, the pressure-dependent thermal properties of test materials are not required. / A preliminary study on ice-crystal formation was carried out using small gelatin gel samples frozen by conventional air freezing (CAF), liquid immersion freezing (LIF) and PSF at different pressures. The ovoid structure left from ice crystals was evaluated for area, equivalent diameter, roundness and elongation. The diameter (mean +/- S.D.) was 145 +/- 66, 84 +/- 26, 91 +/- 30, 73 +/- 29, and 44 +/- 16 mum for the treatments of CAF, LIF and PSF at 100, 150 and 200 MPa, respectively. Roundness and elongation did not show a clear trend with different freezing tests. Similar experiments using small-size Atlantic salmon (Salmo salar) resulted in the diameter of 110 +/- 41, 17 +/- 8.4, 16 +/- 8.8, 8.2.5 and 5.0 +/- 2.1 mum for CAF, LIF and PSF at 100, 150 and 200 MPa, respectively. The roundness was 0.38 +/- 0.14, 0.55 +/- 0.21, 0.57 +/- 0.18, 0.63 +/- 0.14 and 0.71 +/- 0.14 for the above treatments, respectively. (Abstract shortened by UMI.)

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Made available in DSpace on 2015-04-11T13:56:27Z (GMT). No. of bitstreams: 1 Adriana Pontes.pdf: 1647563 bytes, checksum: d9d96e4402b6a1b5ee7e660f48b9a438 (MD5) Previous issue date: 2013-05-03 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / The Amazon region population has a habit of acquiring preferably fish "in natura" and / or chilled than in seasons between harvests demand increases in retail outlets consisting of public markets, fairs and supermarkets. To prolong the life business is the development of fundamental techniques associated with maintenance, so the food to keep up their nutritional and organoleptic as well as its consumer security, so the use of Modified Atmosphere Packaging can be efficient to keep these parameters. The aim of this study was to evaluate the influence of modified atmosphere associated with refrigeration technique as prolong the storage matrinxã (Brycon amazonicus) maintained at 2 ± 1 ° C. The fish were processed and washed with sodium hypochlorite solution to 5 ppm, then with saturated sodium chloride solution at 5% for 10 minutes and analyzed for chemical composition, physical-chemical, microbiological and sensory evaluation for Product quality during the time of storage of modified atmosphere packaging (vacuum, CO2 and 100% CO2/N2 60/40%). The results showed higher microbial growth in control samples (untreated) and vacuum, which maintained good quality for about 21 days of storage, when they reached the limits set by law for Staphylococcus coagulase positive, however, showed considerable reduction in bacterial treatments EAM with CO2/N2-60/40% and 100% CO2-good quality that extended for approximately 35 days of storage. Mesophilic bacteria and psychrotrophs not reached the limits of 6.5 log CFU g-1 in all treatments and storage times. The pH shown not to be a good index for evaluating the quality of the product. No changes were detected in lipid oxidation treatments over time. The vacuum treatment was the only one where the TVB-N values reached 29.65 mg 100g-1 at 21 days of storage. The sensory analysis of fish, through the method of quality score did not indicate rejection limits during storage, however, the acceptability test of packaged samples CO2-100% not achieved good results, possibly due to high concentration of carbon dioxide in the samples. The modified atmosphere packaging when associated with chilling is a promising technique to extend the life of matrinxã longer, compared to the conventional methods (vacuum and air), thus supporting the transport over long distances and improving logistics produc. / A população da Região Amazônica tem o hábito de adquirir pescado preferencialmente in natura e/ou refrigerado tanto que nas épocas de entressafras a demanda aumenta nos pontos de venda que consistem em mercados públicos, feiras livres e supermercados. Para prolongar o tempo de vida comercial é fundamental o desenvolvimento de técnicas associadas à conservação, de modo que o alimento mantenha ao máximo suas qualidades nutritivas e organolépticas como também sua seguridade de consumo, portanto, o uso da Embalagem em Atmosfera Modificada poderá ser eficiente para manter esses parâmetros. O objetivo deste trabalho foi avaliar a influência da atmosfera modificada associada à refrigeração como técnica de prolongar o tempo de armazenamento do matrinxã (Brycon amazonicus) mantido a 2 ± 1°C. Os peixes foram processados e lavados em solução com hipoclorito de sódio a 5 ppm, em seguida, com solução de cloreto de sódio a 5% durante 10 minutos e analisados quanto a sua composição centesimal, características físico-químicas, microbiológicas e sensoriais para avaliação da qualidade do produto durante o tempo de armazenamento das embalagens com atmosfera modificada (vácuo, CO2 100% e CO2/N2 60/40%). Os resultados obtidos apresentaram maior crescimento microbiano nas amostras controle (sem tratamento) e vácuo, que mantiveram boa qualidade por acerca de 21 dias de conservação, quando atingiram os limites estipulados pela legislação para Staphylococcus coagulase positiva; no entanto, evidenciou considerável redução bacteriana nos tratamentos com EAM CO2/N2-60/40% e CO2-100% que estendeu a boa qualidade por, aproximadamente 35 dias de armazenamento. As bactérias mesófilos e psicrotrófilos não atingiram os limites estabelecidos de 6,5 log UFC.g-1 em todos os tratamentos e tempos de conservação. O pH mostrou não ser bom índice para avaliar a qualidade do produto. Não foram detectadas variações na oxidação lipídica nos tratamentos ao longo do tempo. O tratamento a vácuo foi o único onde o N-BVT atingiu valores de 29,65 mg.100g-1 aos 21 dias de conservação. A análise sensorial do pescado, através do método de índice de qualidade, não indicou limites de rejeição durante o armazenamento, entretanto, no teste de aceitabilidade das amostras embaladas com o CO2-100% não obteve bons resultados, possivelmente pela elevada concentração de dióxido de carbono nas amostras. As embalagens com atmosfera modificada quando associada à refrigeração é uma técnica promissora para estender a vida útil do matrinxã por mais tempo, comparando-se aos métodos convencionais (vácuo e ar), auxiliando desta forma, no transporte em longas distâncias e melhorando a logistíca do produto

Submitted by Rosivalda Pereira (mrs.pereira@ufma.br) on 2017-06-22T18:57:22Z No. of bitstreams: 1 MarcioSilva.pdf: 1636302 bytes, checksum: 2d6a8473ae527d2c774587fbf3fd6f4c (MD5) / Made available in DSpace on 2017-06-22T18:57:22Z (GMT). No. of bitstreams: 1 MarcioSilva.pdf: 1636302 bytes, checksum: 2d6a8473ae527d2c774587fbf3fd6f4c (MD5) Previous issue date: 2014-03-26 / Fundação de Amparo à Pesquisa e ao Desenvolvimento Científico e Tecnológico do Maranhão (FAPEMA) / This study aimed to develop a scheme based on the Quality Index Method (QIM) to tambaqui (Colossoma macropomum) raw stored in ice that determines its shelf life. It was studied 96 specimens of tambaqui captured with fishing net and slaughtered (killed) by hypothermia in ice and water , it was packed in ice boxes and kept on ice in a 1:1 (Kg fish/ice) ratio at a controlled temperature of 0 ± 1 ° C for 24 days. Fishes were evaluated at time 01 , 03 , 05 , 08 , 10 , 12 , 15 , 17 , 19 , 22 , 24 day of ice storage. After sensory, physical-chemistry and microbiological analyses the developed scheme presented 04 quality attributes with a total of 30 points. The pH showed little variation from 6.52 to 6.71, from the beginning to end of the experiment. The average content of BVT changed from 15.23 mg N.100g- 1 to 23.17 mg N.100g- 1 and it did not reach the amount considered unsafe for consumption. Mesophilic, and Psicotrophic bacteria remained with their values below log 106. The experiments with Pseudomonas and Enterobacterias showed their values below the limit recommended by the World Health Organization (WHO) that is log 107, and it was demonstrated by producer bacteria H2S a growth of values reduced throughout the experiment. Then the method proved to be efficient to assess the loss of sensory quality related to the length of time in storage and it indicated an expiration date of 22 days which determine the shelf life of tambaqui. Microbiological analyzes with specific bacterial counts of deteriorating organisms strengthen the sensory results and it suggests the tambaqui (Colossoma macropomum) raw stored in ice is fit for consumption until the 22nd day. / Este estudo teve como objetivo desenvolver um protocolo baseado no Método de Índice de Qualidade (MIQ) para o tambaqui (Colossoma macropomum) inteiro armazenado em gelo e determinar sua vida de prateleira. Foram utilizados 96 exemplares capturados com rede de despesca e abatidos por hipotermia em água com gelo, acondicionados em caixas isotérmicas mantidas em gelo na proporção de 1:1(Kg peixe/gelo), a uma temperatura controlada de 0±1 °C durante 24 dias. Os peixes foram avaliados nos tempos 01, 03, 05, 08, 10, 12, 15, 17, 19, 22, 24 dias de armazenamento em gelo. Realizadas análises sensoriais, físico-químicas e microbiológicas. O protocolo desenvolvido apresentou 04 atributos de qualidade, cuja soma totalizou 30 pontos. O pH mostrou pequena variação média de 6,52 a 6,71, do início ao final do experimento. O teor médio de BVT variou de 15,23 mg N.100g-1 a 23,17 mg N.100g-1 não atingindo o valor considerado impróprio para o consumo. As bactérias Mesófilas, Psicrófilas e Psicotróficas mantiveram-se com seus valores médios abaixo de log 106. As bactérias Pseudomonas e Enterobactérias apresentaram seus valores médios entre os experimentos próximos abaixo do limite máximo preconizado pela Organização Mundial da Saúde (OMS) que é log 107 e valores reduzidos de crescimento foram demonstrados por bactérias produtoras de H2S durante todo o experimento. Para determinação da vida de prateleira o método mostrou-se eficiente para avaliar a perda de qualidade sensorial relacionada com o tempo de armazenamento, indicando um prazo de validade de 22 dias. As análises microbiológicas, com a contagem bacteriana de organismos deterioradores específicos, reforçam os resultados sensoriais, sugerindo que o tempo de vida de prateleira para o tambaqui inteiro armazenado em gelo é de 22 dias.