High-Solid Systems of Partially Hydrolysed Waxy Maize Starch: Rheological and Structural Characterisations
نویسندگان
چکیده
O comportamento reológico de dispersões com alto teor de sólidos, de misturas de amido de milho ceroso hidrolisado (HWS), em presença do concentrado de proteínas do soro do leite (WPC) e uréia, foi estudado por medidas oscilatórias de pequena amplitude no regime linear, sob aquecimento a 80 oC e resfriamento a 25 oC, a pH 7,5. A amostra de HWS não-gelificante foi obtida por sonicação de amido de milho ceroso previamente gelatinizado. O fluxo sob cisalhamento contínuo e a microestrutura foram investigados após o resfriamento a 25 oC. As dispersões foram preparadas na razão 1:1 (m/m) WPC/uréia, com concentrações crescentes de HWS. Comportamentos reológicos típicos de sólidos e de líquidos foram observados após resfriar as misturas a baixa temperatura, em função da razão HWS/WPC. Na menor razão HWS/WPC, uma estrutura tixotrópica foi caracterizada sob fluxo contínuo, e visualizada por microscopia óptica sob baixa ampliação como uma rede contínua. Com o aumento da razão HWS/WPC dentro de uma certa faixa, misturas gelificantes e não-gelificantes resultaram em estruturas com separação de fases, as quais não fluíram. Com a razão HWS/WPC mais alta, uma dispersão pseudoplástica foi formada, consistente com o comportamento reológico típico de líquidos sob regime linear, e homogênea, quando visualizada sob microscopia óptica.
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