Thesis (Ph. D.)--Washington State University, May 2006. / Includes bibliographical references (p. 180-185).

The effect of varying combinations of irradiation treatment, freezing procedures and duration of storage on the color of naturally and artificially pigmented egg yolk determined by two objective methods was studied. The relationship between the two methods of color evaluation was also determined. Naturally pigmented yolks were obtained from eggs laid by pullets of a single strain of Single Comb White Leghorn fed a standard diet. Artificially pigmented yolk was prepared by addition of either beta-carotene or canthaxanthin to the naturally pigmented material. Color of yolk was assessed: 1. On the basis of pigment concentration determined by absorbance of acetone extract and expressed as beta-carotene equivalent (BCE) and 2. On the basis of chromaticity coordinates (x,y), lightness (%Y), dominant wavelength (DWL) and excitation purity (EP) determined by reflectance spectrophotometry. Both irradiation dose (0, 0.5, 1.0 and 2.0 Mrad) and time of irradiation (before or after freezing) had significant effect on the chromaticity coordinates, BCE values and excitation purity of naturally and artificially pigmented yolk samples. Higher radiation doses and irradiation before freezing were associated with decreased chromaticity coordinates, BCE values and excitation purity. In artificially pigmented samples increases in irradiation dose and irradiation before freezing resulted in significant decreases in lightness. Samples frozen and stored at -10 F° had consistently higher mean chromaticity values and lower excitation purity than those at -35 F°. The temperature effect on BCE values was inconsistent among experiments. After 30 days storage mean x-values were lower and mean y-values were higher than after 10 days storage. These changes were associated with almost no change in DWL or EP. Nitrogen-packed samples had consistently lower BCE values than air-packed and this difference was significant in all but Experiment 1. No corresponding differences were found in chromaticity coordinates, lightness, DWL or EP. Correlation analyses revealed highly significant (P≤0.01) linear relationships between BCE and both chromaticity values and lightness ranging from + 0.09 to + 0.79. / Land and Food Systems, Faculty of / Graduate

Submitted by Johnny Rodrigues (johnnyrodrigues@ufcg.edu.br) on 2018-05-28T17:43:32Z No. of bitstreams: 1 TAMIRES DOS SANTOS PEREIRA - DISSERTAÇÃO PPGSA PROFISSIONAL 2015..pdf: 2702576 bytes, checksum: 45431567404c5290f49012771848f87a (MD5) / Made available in DSpace on 2018-05-28T17:43:32Z (GMT). No. of bitstreams: 1 TAMIRES DOS SANTOS PEREIRA - DISSERTAÇÃO PPGSA PROFISSIONAL 2015..pdf: 2702576 bytes, checksum: 45431567404c5290f49012771848f87a (MD5) Previous issue date: 2015-12-17 / O ovo em sua forma integral ou a clara e gema apresentam-se como ingrediente fundamental em inúmeros produtos alimentares ao agregar propriedades nutricionais e funcionais. A secagem é uma maneira bem sucedida de conservação dos ovos, considerando algumas vantagens como: ocupar menos espaço no estoque; facilidade de transporte; boa uniformidade; utilização mais fácil e ter qualidade microbiológica estável. Uma vantagem considerável na secagem em camada de espuma é a sua capacidade de manter a alta qualidade dos produtos, apresentando grandes possibilidades para a indústria alimentícia, além da baixa temperatura empregada e com tempo de desidratação reduzido devido à maior área de contato com o ar. Este trabalho tem como objetivo estudar a cinética de secagem em camada de espuma das claras dos ovos de granja e de capoeira (caipira), bem como ajustar os dados experimentais das curvas de secagem com modelos cinéticos como o de Henderson e Pabis, Midilli e Kucuk, Page e um modelo linear. Foram determinadas características da espuma, como densidade, expansão, capacidade de incorporação de ar e estabilidade da espuma. O estudo da influência das variáveis independentes sobre a secagem foi feito de acordo com um planejamento experimental fatorial completo 23 + 4 pontos centrais. As variáveis operacionais a serem estudadas (variáveis de entrada) foram: espessura da camada de espuma; tempo de agitação da espuma e temperatura de secagem. E as variáveis dependentes do processo (variáveis de saída) foram tempo de secagem e umidade final, teor de proteínas e luminosidade (cor). Foi realizada a caracterização físico-química, microscópica e de cor do pó obtido. A clara de ovo, por conter naturalmente propriedades espumantes devido ao alto teor e estrutura de suas proteínas apresentou resultados satisfatórios em relação à caracterização física da espuma. Todos os experimentos apresentaram uma boa reprodutibilidade, com curvas representadas caracteristicamente pela taxa constante e a taxa decrescente. Para o ajuste dos dados da clara de capoeira os modelos não lineares que melhor representaram os dados experimentais foram o de Midilli e Kucuk e o modelo de Page seguidos do modelo linear que foi utilizado para o ajuste dos dados até os 150 minutos de secagem. O modelo de Midilli e Kucuk apesar de apresentar o melhor coeficiente de determinação (R2) não foi estatisticamente significativo. Para a clara de granja o modelo linear apresentou o melhor ajuste considerando o tempo máximo de 130 minutos de secagem, seguido pelos modelos não lineares de Midilli e Kucuk e o de Page respectivamente. O processo de secagem da clara de ovo pelo método de camada de espuma mostrou-se satisfatório quanto aos parâmetros avaliados, sendo que as condições testadas não influenciaram de forma significativa em características tecnológicas importantes do produto final, como o teor de proteínas. / The egg in their entirety form or the white and the yolk present as essential ingredient in many food products by adding nutritional and functional properties. Drying is a successful way of conservation of eggs, whereas some advantages as to occupy less space ease of transport, good uniformity, easier to use and be stable microbiological quality. A considerable advantage in the foam-mat drying is its ability to maintain high product quality, presenting great opportunities for the food industry, besides the low temperature employed and reduced dehydration of time due to the larger area of contact with air. This work aims to study the drying kinetics in foam-mat drying the white of the farm eggs and capoeira (caipira) and to adjust the experimental data of the curves of dryness with the kinetic model obtained as Henderson and Pabis, Midilli and Kucuk , Page and a linear model. The study of the influence of the independent variables about dryness was made according to an experimental factorial plan complete 23 + 4 central points. The operational variables to be studied (input variables) were: thickness of the foam layer; shaking time of foam and drying temperature. And the dependent variables of the process (output variables) were drying time and final moisture content, protein content and brightness (color). It was made physicochemical characterization, and microscopic color of the powder obtained was performed. Egg whites to contain naturally foaming properties due to the high content and structure of its proteins showed satisfactory results regarding the physical characteristics of the foam. All experiments showed good reproducibility with curves represented by the characteristically constant rate and decreasing rate. For the adjustment of the data of the capoeira white data nonlinear models that best represent the experimental data were of Midilli and Kucuk and followed by Page linear model was used to fit the data until 150 minutes drying. The model of Midilli and Kucuk despite having the best coefficient of determination (R2) was not statistically significant. For the white of the farm linear model showed the best fit considering the maximum time of 130 minutes drying, followed by non-linear models and Midilli and Kucuk and the Page respectively. The process of drying the egg white froth layer method was satisfactory for the evaluated parameters, and the conditions tested did not influence significantly on important technological characteristics of the final product as the protein.