Relação entre a adição de sacarose e pectina, comportamentos reológicos e dinâmicas do congelamento e descongelamento de polpas de morango e abacaxi

• Ano de defesa: 2008
• Autor(a) principal: Fernandes, Tatiana Nunes
• Orientador(a): Resende, Jaime Vilela de
• Banca de defesa: Prado, Mônica Elisabeth Torres, Corrêa, Jefferson Luiz Gomes, Peres, Alexandre de Paula
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: UNIVERSIDADE FEDERAL DE LAVRAS
• Programa de Pós-Graduação: DCA - Programa de Pós-graduação
• País: BRASIL
• Palavras-chave em Português: Polpa de frutas - Refrigeração; Polpa de frutas - Descongelamento; Reologia; Pulp fruits - Freezing; Pulp fruits - Thawing; Rheology
• Área do conhecimento CNPq: CNPQ_NÃO_INFORMADO
• Link de acesso: https://repositorio.ufla.br/handle/1/3399

Physical-chemical and rheological properties of the strawberry (Fragaria ananassa) and pineapple (Ananás comosus) pulps with sucrose and pectin addition were characterized. Relation among the rheology, freezing and thawing dynamics and ice crystals microstructure of the pulps were established. The characterizations (rheologic and physical-chemical) were done before and after the process of freezing/thawing. Samples were frozen in a water-bath at -20°C, in a stainless steel recipient with a thermal isolated bottom to establish the front freezing direction in an infinite cylinder. During the freezing process the temperatures were registered, with an interval of 2 minutes until complete 3 hours of the process, with two thermocouples located on the geometric center and on the lateral of the recipient. Ice fractions were calculated with mathematical equations. Samples were taken off from the cylinder during the freezing process at each 60 minutes. Thawing process was assessed by the relation among time and surface area growing with the thawing process at 19°C. The addiction of sucrose and pectin increased the soluble solids and decreased the water content, and the freezing process did not influence in these responses for the both pulps. Strawberry pulp was a pseudoplastic fluid and the pineapple pulp dilatant fluid. Both pulps showed a synergic effect of the sucrose and pectin in acid enviroment and this fact confirmed the increase in the viscosity. The thawing processes of the strawberry and pineapple pulps were faster on the most concentrated samples. Strawberry pulp ice fraction did not have influence with the addiction of sucrose and pectin, proving the absence of polarized concentration during the freezing process. The presence of sucrose and pectin decreased the pineapple pulp ice fraction. The microstructure of strawberry and pineapple pulps were influenced by the factors studied decreasing the freezing front velocity on the most concentrated samples.