Determination of Rheological Properties of Liquid Food through Pilot Plant Testing

3 INTRODUCTION This MSc thesis work has been conducted at SIK, the Swedish Institute of Food and Biotechnology in Gothenburg (Sweden). It also part of the Ingegneria Meccanica per l’Industria Alimentare MSc program at Università degli Studi di Parma. 1.1 Background Rheology is by definition, a science dealing with the deformation and flow of matter (Marriane- Webster, 1929). All materials have rheological proprieties, for this rheology is relevant in many field of study, like food, polymer technology, mining, oil recovery, medicine and geology. Looking specifically in the food industry, the ability to gather data on material’s behaviour gives manufacturer an important “product dimension”. Knowledge of a material's rheological characteristics is valuable in predicting pumpability and pourability, performance in a dipping or coating operation, or the ease with which it may be handled, processed, or used. The interrelation between rheology and other product dimensions often makes the measurement of viscosity the most sensitive or convenient way of detecting changes in colour, density, stability, solids content, and molecular weight. (F. Bueche, 1960) Ascertained that rheological data are irreplaceable for some industry, companies had to face the problem to gather these data quickly trying, if it’s possible, to avoid the time needed by the internal laboratories to supply this data to the floor shop. This problem is more marked in the food industry where the demands of automated and real-time monitoring techniques coupled with high standard sanitary requirements have grown significantly over the past decade (J. CULLEN P., 2001). The classical way to obtain both shear and extensional viscosities’ data are no more considered enough quick and even the so-called in line rheometers have demonstrated to have some problem especially regarding the hygienic conditions, and the reproducibility of the measurement. (Dealy, 1990).