Rheological properties suspensions of tribomehanically treated and untreated whey proteins and starch at pH=3

Na reološka svojstva hrane utječu temperatura, procesni parametri, kemijski sastav, pH vrijednost te posebno udio i vrsta suhe tvari. Svrha ovog rada bila je ispitati utjecaj međudjelovanja tribomehanički tretiranih i netretiranih proteina sirutke sa škrobom na reološka svojstva modelnih sustava pripremljenih s proteinima sirutke te dodatkom škroba. Utjecaj temperature i pH na suspenzije proteina sirutke i škroba ispitan je na 10%-tnim modelnim suspenzijama proteina sa dodatkom škroba pri pH=3. Određivanje viskoznosti ispitivanih modelnih sustava provedena su na rotacionom reometru Rheometric Scientific RM-180 u temperaturnom rasponu od 10-70°C. Reološka svojstva ispitivanih suspenzija proteina izražena su reološkim parametrima pomoću Ostwald de Waele-ovog zakona. Znatno viša vrijednost viskoznosti zabilježena je u modelnim sustavima tretiranog izolata proteina sirutke sa dodatkom škroba nego u modelnoj otopini sa netretiranim IPS. Utjecaj temperature na viskoznost modelnih suspenzija ispitan je primjenom Arrheniusovog modela. Povišenjem temperature dolazi do kontinuiranog smanjenja viskoznosti u svih ispitivanih sustava.Temperature, process parameters, chemical composition, pH value especially the content and the type of a solid matter have a significant influence on the rheological properties of food. The purpose of this work was to investigate the influence of temperature on the viscosity of model systems prepared with tribomehanically treated as well as untreated whey proteins and starch. The influence of temperature change on rheological parameters was tested on 10 % whey protein-starch model suspensions at pH=3. All rheological properties of our suspensions were determinated using a rotational viscosimeter, Rheometric Scientific RM-180, in temperature range 10-70 °C. Rheological parameters were described by Ostwald de Waele power- law model. Significantly higher value of viscosity was determined in tribomechanically treated whey protein model systems. The influence of temperature was determined by Arrhenius equation. The growth of temperature causes a continuous decrease of viscosity in every suspension we used