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Typescript (photocopy). / Digitized by Kansas Correctional Industries

Call number: LD2668 .T4 1985 C525 / Master of Science

A net shift analysis was used to analyze growth in employment and value added from 1954 to 1982 in SIC 2037, Frozen Fruits, Fruit Juices, and Vegetables. This analysis indicated that the Pacific Northwest dominated the growth experienced in this sector over this time period. Oregon's share of total U.S. employment in SIC 2037 increased from 7.3 percent in 1954 to 16.1 percent in 1982. Value added in Oregon was 16.1 percent of the U.S. total in 1982, and growth in both employment and value added was at a greater rate than the overall U.S. rate of growth in this sector. Washington's share of employment increased from 10.3 percent to 13 percent, and the share of U.S. total value added in this sector grew from 11 percent to 14.2 percent. Value added by the freezing of fruits and vegetables in Idaho increased to 10.3 percent of the U.S. total in 1982, and employment grew to a share of 10.5 percent, from 3.5 percent in 1954. An informal survey of executives in six food processing plants in Oregon suggested that expanding international export markets was essential to continued growth for this industry in the Pacific Northwest. A model of Japan's import demand of frozen vegetable products, specifically corn and potatoes, is estimated using data from 1978 through 1986 of real own price at the export site, Japanese consumer expenditures adjusted by Japan's CPI, and Japan's domestic production of frozen corn and potatoes. Commerce Department data on exports by Customs District was used to disaggregate import demand by region; namely Oregon, Washington, the two together as Pacific Northwest, and the total U.S. It was found that the demand for frozen corn imports is more responsive to changes in real own price than the import demand for frozen potatoes. Income elasticities were positive and higher for frozen potato import demand than for frozen corn demand, except for Oregon originating exports. Production in Japan of frozen corn has a higher negative impact on exports from Oregon ports than Washington based exports. Production of frozen potatoes in Japan did not have a negative impact on import demand from any of the four export sites. / Graduation date: 1989

This item was digitized as part of the Million Books Project led by Carnegie Mellon University and supported by grants from the National Science Foundation (NSF). Cornell University coordinated the participation of land-grant and agricultural libraries in providing historical agricultural information for the digitization project; the University of Arizona Libraries, the College of Agriculture and Life Sciences, and the Office of Arid Lands Studies collaborated in the selection and provision of material for the digitization project.

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.)

Graduation date: 1953

Orientador: Vivaldo Silveira Junior / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-08T21:24:52Z (GMT). No. of bitstreams: 1 Barbin_DouglasFernandes_M.pdf: 2471115 bytes, checksum: d96f699c328a8086ec9a94c3315aab07 (MD5) Previous issue date: 2007 / Resumo: A redução do tempo de congelamento de produtos alimentícios é um objetivo almejado, devido este processo ser caro e que envolve elevado gasto energético. Os produtos alimentícios são predominantemente congelados em túneis com convecção forçada por insuflação de ar; porém, é preferível realizar a exaustão de ar, ao invés de insuflação, pelo fato da exaustão promover uma circulação de ar mais uniforme ao redor do produto. Um túnel de ar forçado por exaustão é composto por um ventilador que circula de forma a retirar o ar, produzindo uma região de baixa pressão, onde se localiza o produto, buscando uniformizar a circulação do ar frio em contato com o mesmo. Desse modo, este trabalho se propôs à montagem experimental de um túnel ¿portátil¿ de congelamento por ar forçado, onde se pode estudar a utilização de insuflação e exaustão de ar. Este túnel foi construído e alocado no interior de uma câmara de armazenagem de produtos congelados, buscando melhorar a distribuição do ar, potencializando a troca térmica entre o ar e o produto a ser congelado. A montagem foi monitorada através de termopares para determinação das curvas de congelamento e eficiência do sistema. Durante o processo de congelamento, foi avaliada a transferência de calor através da montagem, comparando os processos de exaustão e insuflação e analisados os coeficientes de transferência de calor entre o ar de resfriamento e o produto em diferentes posições e camadas do palete, bem como a distribuição do ar de resfriamento em circulação ao redor do produto. Os resultados mostraram uma redução no tempo de congelamento das amostras com a utilização do túnel ¿portátil¿ em relação ao processo sem a utilização deste aparato dentro da câmara. O processo de exaustão apresentou uma redução de até quatro horas para o congelamento em relação à insuflação. Os valores de coeficiente de convecção foram maiores para a exaustão do que para a insuflação em todas as camadas da montagem, com exceção da superior, que recebia o ar diretamente do interior da câmara na insuflação. Um coeficiente de heterogeneidade foi proposto para avaliar a diferença de temperaturas no produto durante o congelamento. Estes valores, juntamente com a análise das temperaturas obtidas no processo, mostraram que a distribuição do ar, bem como a transferência de calor, ocorre de maneira mais homogênea no interior do palete na exaustão do que na insuflação / Abstract: The conditions necessary to keep the air temperature and movement at the product surface will determine the freezing process efficiency. Since the energy level could implement on the final cost, the reduction of the freezing process time was a major goal in the whole experiment. Food products are predominantly frozen in air blast freezing tunnels. Therefore, exhausting air is preferable than blowing it through, since it minimizes air short-circuiting and results in more uniform cooling. To produce an homogeneous refrigeration, the main configuration to be determined for pallets storing plastic packages in boxes are the package distribution and air orientation. The main components of an exhausting forced-air tunnel are a fan that causes the equipment inside air evacuation creating a low pressure region. The product is arranged on this spot creating uniform distribution of the cold air inside the equipment, around the product. Therefore, the objective of this work is to build an experimental portable forced-air freezing tunnel, and work on comparative studies with air exhausting and blowing. The tunnel was built and placed inside a freezing product storage chamber, and the objective was to improve the air circulation and the thermal distribution between the product and cold air, for a sample batch left inside the chamber. The batch was monitored using thermocouples for freezing variation and system efficiency graphic determination. It was also provided the heat transfer analysis, comparing the exhausting and blowing process, and the heat transfer coefficients of the cold air and the product as well as the air distribution around the product. The results have shown reduction of the freezing time of the samples when the portable tunnel was used comparing without the tunnel tests (reference). The air evacuation process reduced up to four hours with comparison to the blowing system the freezing process. Convective coefficient results were higher for air evacuation than air blowing in every part of the batch, except for the upper layer of products were the cold air of the chamber was directly in contact with the product. These results, with the temperature analysis obtained, indicated that the air distribution occurs more uniformly around the products in the exhausting process than blowing system, as well as the heat transfer / Mestrado / Mestre em Engenharia de Alimentos

This investigation was carried out in order to determine whether or not blanching and freezing tends to reduce the incidence of bacteria, particularly those of the coliform group, and also the yeasts and molds.

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