Influência da temperatura e do teor de gordura nos parâmetros reológicos do leite condensado e creme de leite
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Data
2007-06-25
Autores
Flauzino, Rodrigo Dias [UNESP]
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
Neste trabalho estudou-se a influência da temperatura (275,4 a 359,8 K) e teor de gordura (10,2% a 30,6%) nos parâmetros reológicos do creme de leite, como também a influência da temperatura (278 a 343 K) nos parâmetros reológicos do leite condensado. A caracterização reológica foi realizada com o auxílio de um reômetro rotacional do tipo cone e placa, localizado no DEA/FZEA/USP, e de um reômetro rotacional do tipo cone e placa, localizado no DETA/UNESP. Os dados experimentais foram ajustados aos modelos de Ostwald-De Waele, Bingham e Herschel-Bulkley, para determinação dos parâmetros reológicos. Observou-se para o leite condensado, em toda faixa de temperatura de estudo (278 a 343 K), comportamento pseudoplástico, sem tensão inicial de escoamento, e neste caso os parâmetros reológicos foram ajustados de acordo com o modelo de Otswald-De-Waele. Para o creme de leite, observou-se comportamento viscoplástico (Binghamiano), na faixa de temperatura entre 275,4 e 306,4 K nas concentrações de 20,3 a 30,6%, sendo, neste caso, os parâmetros reológicos ajustados de acordo com o modelo de Bingham. Para a faixa de temperatura entre 275,4 e 359,8 K nas concentrações de 10,2 a 20,3%, observou-se comportamento Newtoniano, sendo, neste caso, os parâmetros reológicos ajustados de acordo com o modelo de Newton. Além disso, para temperaturas acima de 313K, em todas as concentrações, foi observado comportamento Newtoniano. Para os dois produtos, a influência da temperatura foi representada por uma função exponencial. Correlações simples foram utilizadas para analisar o efeito combinado da temperatura e da fração de gordura nos parâmetros reológicos do creme de leite.
The rheological behavior of milk cream with different fat contents (10,2% to 30,6%) was studied at a wide range of temperatures (275,4 to 359,8 K), as also the rheological behavior of sweetened condensed milk at a wide range of temperatures (278 to 343K). The rheological characterization was made using a cone and plate rotational rheometer, located at DEA/FZEA/USP, and a rheometer of the type cone and plate, located in DETA/UNESP. The experimental data have been adjusted to the Ostwald-De Waele, Bingham and Herschel-Bulkley models, to determine the rheological parameters. It was observed for sweetened condensed milk, in all the temperature bands, pseudoplastic behavior, without yield stress, and the rheological parameters have been adjusted the Otswald-De-Waele model. For milk cream, it was observed viscoplastic behavior (Binghamian), in the temperature bands between 275,4 and 306,4 K at fat contents of 20,3% to 30,6%. The rheological parameters have been adjusted to the Bingham model. For the temperature bands between 275,4 and 359,8 K at fat contents of 10,2% to 20,3%, it was observed Newtonian behavior, and therefore the rheological parameters have been adjusted to the Newton model. Besides, for temperatures above 313K, in all concentrations, it was observed Newtonian behavior. For the two products, the influence of the temperature was represented by an exponential function. Simple correlations were used to analyze the effect of the temperature and the fat fraction in the rheological parameters of the milk cream.
The rheological behavior of milk cream with different fat contents (10,2% to 30,6%) was studied at a wide range of temperatures (275,4 to 359,8 K), as also the rheological behavior of sweetened condensed milk at a wide range of temperatures (278 to 343K). The rheological characterization was made using a cone and plate rotational rheometer, located at DEA/FZEA/USP, and a rheometer of the type cone and plate, located in DETA/UNESP. The experimental data have been adjusted to the Ostwald-De Waele, Bingham and Herschel-Bulkley models, to determine the rheological parameters. It was observed for sweetened condensed milk, in all the temperature bands, pseudoplastic behavior, without yield stress, and the rheological parameters have been adjusted the Otswald-De-Waele model. For milk cream, it was observed viscoplastic behavior (Binghamian), in the temperature bands between 275,4 and 306,4 K at fat contents of 20,3% to 30,6%. The rheological parameters have been adjusted to the Bingham model. For the temperature bands between 275,4 and 359,8 K at fat contents of 10,2% to 20,3%, it was observed Newtonian behavior, and therefore the rheological parameters have been adjusted to the Newton model. Besides, for temperatures above 313K, in all concentrations, it was observed Newtonian behavior. For the two products, the influence of the temperature was represented by an exponential function. Simple correlations were used to analyze the effect of the temperature and the fat fraction in the rheological parameters of the milk cream.
Descrição
Palavras-chave
Leite condensado, Reologia, Creme de leite, Produtos lácteos - Propriedades reológicas, Milk cream, Sweet condensed milk, Rheology
Como citar
FLAUZINO, Rodrigo Dias. Influência da temperatura e do teor de gordura nos parâmetros reológicos do leite condensado e creme de leite. 2007. 99 f. Dissertação (mestrado) - Universidade Estadual Paulista, Instituto de Biociências, Letras e Ciências Exatas, 2007.