Typescript, etc. / Digitized by Kansas Correctional Industries

Call number: LD2668 .T4 1953 M8 / Master of Science

Call number: LD2668 .T4 1986 E86 / Master of Science / Grain Science and Industry

Digitized by Kansas Correctional Industries

Call number: LD2668 .T4 1962 B39

The effect of different blanching treatments and packaging materials on the enzymatic (lipoxygenase and peroxidase) activity and fatty acid stability of two different varieties of sweet corn on the cob (Jubilee and GH 2684) was evaluated during nine months of frozen storage at -23.3°C. The initial moisture content in the kernels of the two sweet corn varieties averaged 72.5%. After nine months of frozen storage the moisture content in the kernels of corn depended greatly on the packaging material used. The ears stored in Cryovac B and E bags showed the best moisture retention (72.2% final moisture content), followed by the polyethylene bags (71.4%) while the ears stored without packaging material showed severe dehydration (70.1%). The peroxidase and lipoxygenase activities were determined using spectrophotometric assays on a crude extract obtained from liquid nitrogen powdered corn. Both unblanched varieties of sweet corn showed similar initial peroxidase specific activity and general behavior during the nine months of frozen storage. The presence of lipoxygenase isozymes with different thermal stabilities in both varieties was suggested by the higher lipoxygenase specific activity found in Jubilee after freezing and nine months of frozen storage (0.135 units/mg protein) compared with the GH 2684 variety (0.115 units/mg protein). Complete inactivation of lipoxygenase was obtained after 9 minutes steam blanching at 100°C. Peroxidase was more heat resistant showing some remaining specific activity after 9 minutes steam blanching with a complete inactivation after 15 minutes steam blanching. No regeneration of either enzyme was observed during the nine months of frozen storage suggesting a permanent disruption of the active site of both enzymes. Relative fatty acid content was determined by gas chromatographic analysis of fatty acids methyl esters. The major fatty acids present in both varieties were palmitic (14.93%), stearic (2.79%), oleic (31.54%), linoleic (46.87%) and linolenic (1.89%) acids. Good stability of the polyunsaturated fatty acids was observed during the nine months storage at -23.3°C, with autoxidation as the main mechanism responsible for the decrease in the relative percent of polyunsaturated fatty acids. Some enzymatic oxidation also occurred, decreasing the linolenic acid content. The control of the degradation of polyunsaturated fatty acids depended mostly on the frozen storage temperature (-23.3°C) and not on the oxygen permeability of the different packaging materials. The results obtained in our study suggested that blanching of the ears of sweet corn had an important effect on reducing the enzyme activity but little effect on the polyunsaturated fatty acid degradation after 9 months of storage at -23.3°C. / Graduation date: 1994

A mathematical simulation model based on the theories of transport phenomena and thermodynamics was developed to predict the storage behavior in a bed of corn. Coupled heat and mass transfer equations for a porous-capillary hygroscopic body were utilized in this study. The boundary conditions of heat and moisture were determined using the law of conservation, the law of heat and mass diffusion, and the law of convective heat and mass transfer. The system was solved using the implicit finite difference method with matrix inversion for an axisymmetric body with 36 annular elements. The bulk moisture diffusivities were determined using five mixing models(parallel, series, equivalent-resistor, modified Maxwell, and geometric mean). Five phase conversion factors(0.0, 0.25, 0.50, 0.75, and 1.0) were utilized to evaluate the five mixing models. Three laboratory storage bins, and eight grain sample columns were designed and constructed. Three experiments were conducted to enable the determinations of temperature and moisture content within the interior of the storage bin. The simulation model was verified by comparing the predicted results with the experimental values. Results indicate that the geometric mean model with a phase conversion factor of zero was the best selection. A postulated path for internal moisture flow was suggested. / Master of Science

Made available in DSpace on 2014-08-13T14:51:00Z (GMT). No. of bitstreams: 0 Previous issue date: 2014-02-27Bitstream added on 2014-08-13T17:59:40Z : No. of bitstreams: 1 000776208.pdf: 940309 bytes, checksum: 260c5fabcb4295b842183a551928ea2b (MD5) / As sementes de milho doce possuem características que contribuem para baixa qualidade fisiológica, como elevados teores de açúcares em detrimento ao amido, alta sensibilidade a danos por embebição, susceptibilidade ao ataque de fungos, que favorecem a perda da viabilidade, vigor e redução da longevidade. Neste contexto, a utilização do condicionamento osmótico pode elevar a uniformidade e a velocidade de germinação e, portanto, melhorar a qualidade fisiológica das sementes. Porém, ainda não se sabe se as sementes osmoticamente condicionadas devem ser armazenadas em condições especiais para manutenção da qualidade obtida pelo tratamento. Assim, este trabalho tem como objetivo verificar o efeito do condicionamento osmótico de sementes de milho doce durante o armazenamento. As sementes foram tratadas com soluções de Polietilenoglicol (PEG 6000), secadas através do método de estufa de circulação de ar e posteriormente armazenadas em embalagem de plástico, em ambiente de laboratório e em câmara fria. Elas foram avaliadas a cada dois meses por período de seis meses. O delineamento experimental utilizado foi inteiramente casualizado, em esquema fatorial 2 x 4 (Condicionadas e não condicionadas e 4 períodos de armazenamento), com 4 repetições. Foram avaliados, o teor de água, germinação, primeira contagem de germinação, condutividade elétrica, envelhecimento acelerado, germinação em areia, velocidade de emergência de plântulas e comprimento de plântulas, massa da matéria seca de plântulas. Os resultados foram submetidos a análise de variância (ANOVA), as médias dos tratamentos comparadas pelo teste de Tukey a 5% de probabilidade. Foi concluído que nas sementes de milho doce osmoticamente condicionadas apresentam melhor qualidade fisiológica, porém esta não se mantém durante o armazenamento / The sweet corn seeds possess characteristics that contribute to decrease the physiological quality of its seeds, such as high levels of sugar over starch, high sensitivity to damage during imbibition. In addition, the seeds have also susceptibility to fungi, which favored the loss of viability, vigor and reduced longevity during storage. In this context, the use of priming may increase the uniformity and speed of germination and therefore improve seed quality. However, it is not known whether the osmoprimed seeds could be stored under special conditions for maintaining the quality obtained by the treatment. This study aims to determine the effect of priming of sweet corn seeds during storage. The seeds were treated with solutions of polyethylene glycol (PEG 6000) and evaluated every two months over a period of six months. The experimental design was completely randomized, factorial 2 x 4 (Conditioned and unconditioned and 4 days of storage) with 4 replications. The seeds were dried and subsequently stored in plastic bags, under laboratory conditions and in cold chamber. We evaluated the water content, germination, first count of germination, electrical conductivity, accelerated aging, germination in sand, speed of seedling emergence and seedling length, seedling dry matter. The results were submitted to analysis of variance (ANOVA), and the averages were compared by the Tukey test at 5 % of probability. It was concluded that primed showed a better quality but it is lost during storage.

Orientador: Edvaldo Aparecido Amaral da Silva / Banca: Cláudio Cavariani / Banca: João Nakagawa / Resumo: As sementes de milho doce possuem características que contribuem para baixa qualidade fisiológica, como elevados teores de açúcares em detrimento ao amido, alta sensibilidade a danos por embebição, susceptibilidade ao ataque de fungos, que favorecem a perda da viabilidade, vigor e redução da longevidade. Neste contexto, a utilização do condicionamento osmótico pode elevar a uniformidade e a velocidade de germinação e, portanto, melhorar a qualidade fisiológica das sementes. Porém, ainda não se sabe se as sementes osmoticamente condicionadas devem ser armazenadas em condições especiais para manutenção da qualidade obtida pelo tratamento. Assim, este trabalho tem como objetivo verificar o efeito do condicionamento osmótico de sementes de milho doce durante o armazenamento. As sementes foram tratadas com soluções de Polietilenoglicol (PEG 6000), secadas através do método de estufa de circulação de ar e posteriormente armazenadas em embalagem de plástico, em ambiente de laboratório e em câmara fria. Elas foram avaliadas a cada dois meses por período de seis meses. O delineamento experimental utilizado foi inteiramente casualizado, em esquema fatorial 2 x 4 (Condicionadas e não condicionadas e 4 períodos de armazenamento), com 4 repetições. Foram avaliados, o teor de água, germinação, primeira contagem de germinação, condutividade elétrica, envelhecimento acelerado, germinação em areia, velocidade de emergência de plântulas e comprimento de plântulas, massa da matéria seca de plântulas. Os resultados foram submetidos a análise de variância (ANOVA), as médias dos tratamentos comparadas pelo teste de Tukey a 5% de probabilidade. Foi concluído que nas sementes de milho doce osmoticamente condicionadas apresentam melhor qualidade fisiológica, porém esta não se mantém durante o armazenamento / Abstract: The sweet corn seeds possess characteristics that contribute to decrease the physiological quality of its seeds, such as high levels of sugar over starch, high sensitivity to damage during imbibition. In addition, the seeds have also susceptibility to fungi, which favored the loss of viability, vigor and reduced longevity during storage. In this context, the use of priming may increase the uniformity and speed of germination and therefore improve seed quality. However, it is not known whether the osmoprimed seeds could be stored under special conditions for maintaining the quality obtained by the treatment. This study aims to determine the effect of priming of sweet corn seeds during storage. The seeds were treated with solutions of polyethylene glycol (PEG 6000) and evaluated every two months over a period of six months. The experimental design was completely randomized, factorial 2 x 4 (Conditioned and unconditioned and 4 days of storage) with 4 replications. The seeds were dried and subsequently stored in plastic bags, under laboratory conditions and in cold chamber. We evaluated the water content, germination, first count of germination, electrical conductivity, accelerated aging, germination in sand, speed of seedling emergence and seedling length, seedling dry matter. The results were submitted to analysis of variance (ANOVA), and the averages were compared by the Tukey test at 5 % of probability. It was concluded that primed showed a better quality but it is lost during storage. / Mestre

Orientador: Marlene Rita de Queiroz / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Agricola / Made available in DSpace on 2018-08-15T16:57:39Z (GMT). No. of bitstreams: 1 Nascimento_VaniaRosalGuimaraes_M.pdf: 3937712 bytes, checksum: 22617dfc4dd3e6254ab76e50ba704be8 (MD5) Previous issue date: 2010 / Resumo: A eficiência do processo de armazenagem de grãos não consiste apenas em "guardar" a produção agrícola, mas, sobretudo evitar a ocorrência de migração de umidade, incidência de insetos e desenvolvimento de microrganismos nos grãos durante esse processo. A técnica de aeração é atualmente empregada na redução e homogeneização da temperatura intergranular com o objetivo de minimizar esses problemas. Essa prática consiste na passagem forçada de ar ambiente através da massa de grãos. Assim, o objetivo desta pesquisa consistiu em avaliar e comparar o desempenho de três diferentes estratégias de aeração de grãos de milho, armazenados por vinte e quatro dias. As estratégias pesquisadas foram as seguintes: um sistema funcionando continuamente; outro sistema acionado durante o período da noite e um terceiro sistema que operou somente quando a umidade relativa do ar ambiente estava em equilíbrio com a umidade do ar interno aos grãos. Foram utilizados grãos de milho com dois níveis de umidade distintos, 13 e 18%. Realizou-se monitoramento contínuo da temperatura por meio de sensores instalados dentro dos silos e amostras de grãos foram retiradas durante os ensaios para determinação do teor de umidade, contagem de fungos e condutividade elétrica. Ao final dos ensaios, observou-se que todas as estratégias de aeração empregadas favoreceram redução de temperatura, em grãos secos (13%) e umidificados (18%). Porém, nenhuma estratégia manteve a temperatura no interior dos grãos homogênea durante o período de armazenamento. Ressalta-se, no entanto, que o sistema de aeração contínuo aplicado aos grãos de milho úmidos proporcionou menor heterogeneidade da temperatura ao longo da altura da massa de grãos, além de evitar o desenvolvimento de fungos. O teor de umidade dos grãos sofreu variações durante o período experimental, com tendência de secagem dos grãos ao final do processo. Verificou-se grande ocorrência de fungos nos grãos advindos do campo, principalmente Fusarium e Penicillium. A condutividade elétrica dos grãos de milho apresentou-se constante durante o período de armazenamento. A operação de aeração promoveu resfriamento dos grãos, entretanto em níveis elevados de temperatura e propícios para a incidência de insetos. Dessa forma, a aeração deve fazer parte do manejo integrado de pragas, mas não a única ferramenta / Abstract: The efficiency of grain storage doesn't consist only to "save" the agricultural production, but mainly to avoid the problem with the moisture migration, incidence of insects and development of microorganism in grains, during the process. Aeration is currently used for reducing and homogenization the intergranular temperature, aiming to minimize these problems. This practice consists of blowing ambient air through the grain mass. The objective of this research was to evaluate and compare the performance of three different strategies for aeration of corn grains, stored for twenty-four days. The strategies were: (1) a continuously system; (2) an aeration system activated only during the night and (3) an aeration system operating only when the relative humidity environment corresponds to the grains equilibrium moisture content. Corn grains at two different moisture content levels, 13 and 18% were used. Continuous monitoring of temperature was carried out through 12 sensors installed inside the bins. Grain samples were taken during the experiments for determination of moisture content, mold counts and electrical conductivity. At the end of the tests, all aeration strategies showed temperature reduction in to the bins with dried grain dry grains (11%) and wet grain (16,8%). However, any strategy maintained the homogeneous temperature inside the grain during the storage period. It is emphasized, however, that the continuous aeration system applied to the wet corn grain allowed low heterogeneity in the temperature along of the height of grain mass, and avoided the growth of mold. Grain moisture content changed during the experimental time with tendency of drying at the end of the process. There was a high occurrence of field mold in the grains, mainly Fusarium and Penicillium. Electrical conductivity of corn grains remained constant along the storage time. Aeration promoted cooling of the grains, however the temperature levels were high and appropriate conducive to the incidence of insects. Therefore, aeration should be a part of integrated pest management, but not the only tool / Mestrado / Tecnologia Pós-Colheita / Mestre em Engenharia Agrícola