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Advisor(s)
Abstract(s)
A transformação do leite em outros alimentos, como é o caso do queijo, permite diversificar e melhorar a qualidade nutricional da nossa alimentação diária. A sua importância deve-se ao facto de ser um alimento altamente nutritivo, isto porque, apresenta na sua composição proteínas, gordura, sais minerais e vitaminas. O fabrico do queijo é um processo complexo, visto que envolve várias etapas e várias modificações bioquímicas. Os principais processos de fabrico são a coagulação, o dessoramento, a salga e a cura. Consoante os parâmetros tecnológicos atuando ao nível destas quatro fases, pode obter-se uma grande variedade de queijos. A composição (teores de água, de proteínas, de matéria gorda, de minerais), o pH da coalhada, bem como as condições em que decorre a cura estão intimamente relacionados com a textura o sabor e o aroma do produto. Das mais de 2000 variedades de queijos existentes, as suas características reológicas e de textura são de muita importância para a padronização da qualidade. Este trabalho teve como objetivo estudar as caraterísticas físico-químicas dos queijos “Prato Gordo” e “Barra Light” durante o processo de cura (0, 8, 15 e 21 dias) e do queijo “Fresco Meio Gordo” apenas no final do seu processo de fabrico, uma vez que este queijo não sofre cura. De cada lote determinou-se o teor de humidade e o pH (parâmetros químicos) e realizou-se um ensaio reológico e a análise da textura (parâmetros físicos). Os resultados obtidos demostraram que, os queijos apesar de partirem da mesma matéria prima, o leite, são queijos que diferem entre si, pois resultam de diferentes modos de produção, originando queijos com caraterísticas bastantes distintas tanto a nível das propriedades químicas como físicas. Ao nível químico, todos os queijos apresentaram teores de humidade e pH que estavam de acordo com os valores de referência da empresa – Laticínios do Paiva. Ao nível físico, conclui-se que no queijo “Prato Gordo” no final do processo de cura, os valores obtidos nos parâmetros da textura são maiores, à exceção dos parâmetros de dureza, coesividade e resiliência em relação ao queijo “Barra Light”. Quanto ao queijo “Fresco Meio Gordo” registou-se uma grande variedade entre lotes. De entre os três lotes estudados, apenas um lote apresentou valores de desvio padrão inferiores, garantindo neste caso uma maior homogeneidade, comparativamente com os restantes lotes.IV Verificou-se também que o tempo de cura estava fortemente correlacionado com a maioria dos parâmetros de textura dos queijos “Prato Gordo” e “Barra Light”. Evidenciou-se ainda que tanto nos queijos maturados como nos queijos frescos a componente elástica foi superior à componente viscosa (G' G") o que está correlacionado com uma estrutura sólida relativamente forte.
Transformation of milk into another foods, for example in cheese, allows to diversify and improve the nutritional quality of our everyday food habits. Its importance it’s due to the fact that milk is a highly nutritional aliment, that’s because on its composition it has proteins, fat, mineral salts and vitamins. Cheese production it’s a very complex process, due to the various phases and biochemical changes that occurs throughout the process. The main production processes are, coagulation, desorption, salting and curing. According to the technological parameters acting at the level of these four phases we can a large variety of different cheeses. The composition (water, protein, fat and minerals percentages), pH of the curd, as well as the conditions that the curing occurs are deeply related with the texture, flavor and aroma of the product. Of the more than two thousand varieties of cheeses, their rheological and texture properties are extremely important to the quality standardization. The objective of this work was to study the chemical and physical characteristics of the "Prato Gordo" and "Barra Light" cheeses during the ripening process (0, 8, 15 and 21 days) and of "Fresco Meio Gordo" cheese only at the end of its manufacturing process, only because these cheese are not ripened. Cheeses from each batch were monitored for their moisture content and pH (chemical parameters) and rheological and texture analyses (physical parameters) were performed. The results showed that the cheeses, despite starting from the same raw material - milk, differed from each other, since they resulted from different modes of production, giving rise to cheeses with quite different characteristics as far as chemical and physical properties are concerned. At the chemical level, all cheeses presented moisture contents and pH values that were in agreement with the reference values of the company – Laticínios do Paiva. At the physical level, it was concluded that in the "Prato Gordo" cheese at the end of the maturation process, the values obtained in the texture parameters are higher, except for the parameters of hardness, cohesiveness and resilience about of "Barra Light" cheese, the opposite has already been verified, that is, at the end of the maturation process, the lower the values obtained in these parameters.
Transformation of milk into another foods, for example in cheese, allows to diversify and improve the nutritional quality of our everyday food habits. Its importance it’s due to the fact that milk is a highly nutritional aliment, that’s because on its composition it has proteins, fat, mineral salts and vitamins. Cheese production it’s a very complex process, due to the various phases and biochemical changes that occurs throughout the process. The main production processes are, coagulation, desorption, salting and curing. According to the technological parameters acting at the level of these four phases we can a large variety of different cheeses. The composition (water, protein, fat and minerals percentages), pH of the curd, as well as the conditions that the curing occurs are deeply related with the texture, flavor and aroma of the product. Of the more than two thousand varieties of cheeses, their rheological and texture properties are extremely important to the quality standardization. The objective of this work was to study the chemical and physical characteristics of the "Prato Gordo" and "Barra Light" cheeses during the ripening process (0, 8, 15 and 21 days) and of "Fresco Meio Gordo" cheese only at the end of its manufacturing process, only because these cheese are not ripened. Cheeses from each batch were monitored for their moisture content and pH (chemical parameters) and rheological and texture analyses (physical parameters) were performed. The results showed that the cheeses, despite starting from the same raw material - milk, differed from each other, since they resulted from different modes of production, giving rise to cheeses with quite different characteristics as far as chemical and physical properties are concerned. At the chemical level, all cheeses presented moisture contents and pH values that were in agreement with the reference values of the company – Laticínios do Paiva. At the physical level, it was concluded that in the "Prato Gordo" cheese at the end of the maturation process, the values obtained in the texture parameters are higher, except for the parameters of hardness, cohesiveness and resilience about of "Barra Light" cheese, the opposite has already been verified, that is, at the end of the maturation process, the lower the values obtained in these parameters.
Description
Keywords
Queijos Caraterísticas químicas Reologia Textura Cura Cheeses Chemical characteristics Rheology Texture Maturation