Teses em Tecnologia de Alimentos (Doutorado) - PPGTA/UNICAMP
URI Permanente para esta coleçãohttp://10.7.2.76:4000/handle/2011/9599
Navegar
Submissões Recentes
Item Acesso aberto (Open Access) Estudo do equilibrio de fases para sistemas óleo vegetal/dióxido de carbono empregando a equação de Peng-Robinson(Universidade Estadual de Campinas, 1997-06-06) ARAÚJO, Marilena Emmi; MEIRELES, Maria Angela de Almeida; http://lattes.cnpq.br/7459851068586682This work is concerned with the prediction of the vapor-liquid equilibria using the Peng-Robinson EOS for systems: fat and oils related compounds/supercritical CO2. The van der Waals mixing rules were employed with two binary interaction parameters. The combining rules proposed by Kwak & Mansoori and Park, Kwak & Mansoori that involve three binary interaction parameters were also used. It has also been studied the extraction of Amazon seed oils with carbon dioxide (pressures of 150-300 bar; temperatures of 50°C-60°C). The effects of the operational conditions on the fatty acids and triglycerides composition of the oils were investigated. A software was developed using Delphi 1.0 for Windows to obtain the binary interaction parameters and for the vapor-liquid equilibria P-T flash calculation. The published pure components' data (Tb, Tc, Pc and vapor pressure) of fatty acids and fatty acid esters were employed to evaluate the methods available for predictions of Tb, Tc and Pc. The Constantinou & Gani and the Somayajulu methods, using experimental values of Tb, were selected for the prediction of Tc and Pc, respectively. The Constantinou & Gani method was selected for the prediction of Tb, Tc and Pc, and the Tu method was selected for the prediction of the acentric factor of fatty acids. The Joback & Reid method was selected for the prediction of Tb and Tc, and the Constantinou & Gani for the prediction of Pc of fatty acid esters. The Vetere correlation was selected for the calculation of the acentric factor for low molecular weight fatty acid esters, and the Tu method for the fatty acid methyl esters' family. The results show that the Peng-Robinson EOS with the van der Waals mixing rules with three combining rules were able to describe qualitatively the vapor-liquid equilibria of the systems studied. There were no significant differences among the three combining rules. The composition in fatty acids and triglycerides of the oils of Cupuacu, Bacuri, Palm Kernel and Passion fruit, extracted with CO2 showed a slight variation for the pressure and temperature ranges studied.Item Acesso aberto (Open Access) Efeito dos diferentes tratamentos e embalagens nas características da polpa de acerola e na determinação dos teores de ácido ascórbico e das antocianinas durante o armazenamento(Universidade Estadual de Campinas, 1999-12-21) SILVA, Maria de Fatima Vilhena da; MENEZES, Hilary Castle de; http://lattes.cnpq.br/6478475854489070West Indian cherry is a rich source of ascorbic acid and a relative source of anthocyanins. The fruit and its products have been objects of great demand to serve individually as a nutritional source, or as a supplementary source of this vitamin for other foods. Ascorbic acid and the anthocyanins present antioxidant and preventative properties of various diseases which affect man, such as cancer, cardiovascular problems and others. One of the problems in the industrialization of this fruit and its products is related to the losses of ascorbic acid and the color of the product. Thus, this research was conducted with the objective of investigating the degradation of ascorbic acid and of the anthocyanins in West Indian cherry pulps submitted to different treatments: pulp without heat treatment, thermal inactivation or blanching, pasteurization (HTST) with and without aeration. The pulps were tested in glass and tin packages, and stored for six months for a better evaluation of their vitamin potential and lhe level of color maintenance of the products. All the experiments were developed at the pilot plant level. The second chapter considers the tests conducted with different methods for the determination of ascorbic acid in West Indian cherry pulp for the selection of those which offered good results as compared to CLAE, and which are fast, precise and economic. The method which fitted these characteristics, was that of titration with 2,6-dichloroindophenol. However, due to the intense color of the pulp, it was necessary to study a way to facilitate the titration and make the results more precise. The modifications made to this method to reach these objectives are presented in the second chapter. The new modifications showed result in excellent performance and the data were statistically similar to those obtained by CLAE. In the third chapter, an investigation of the physicochemical characteristics of the West Indian cherry pulps was made, emphasizing the effect of processing and types of package at zero time and during the storage period of six months. In this chapter, the individual results, the correlation amongst the analyses for ascorbic acid, total anthocyanins, pH, total titrable acidity expressed as malic acid and as citric acid, total solids and °Brix were shown. The results showed high correlation between ascorbic acid and anthocyanins. In the fourth chapter, a detailed study of the color of the pulps was made using the L a b system, that is, a study of the "hue", difference in color and saturation of color during storage. It was possible to verify from the results, that the product color was directly related to the type of processing and storage conditions. In the fifth and last chapter, the anthocyanins in the pulp without heat treatment were identified, and also the effects of processing on these pigments. The anthocyanin encountered in highest amounts was cyanidine, malvidine and pelargonidine also being present. The latter was shown to be more sensitive to heat treatments. Deaeration of the pasteurized pulp, and type of package showed no significant difference.