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Keywords:

  • capillary rheometer;
  • microwave;
  • rheology;
  • sucrose solution;
  • thermal process

Abstract

Thermal process design, optimization, and deviation require the knowledge of engineering properties of food, such as rheological behavior, which is highly dependent on temperature. If a process is calculated based on the parameters obtained by extrapolation, it might lead to over- or underprocessing. The long time required for the product to reach the desired temperature, which is usual in many rheometers, may induce unexpected changes on the product. Model solutions are often used in engineering projects in order to simulate characteristics of real products. Thus, the objective of this study was to obtain rheological data of sucrose model solution at the actual high UHT (ultra-high temperature) process temperatures using a pressurized capillary rheometer, heated by a microwave system. The results provide the rheological behavior of the sucrose solutions and show that there is no deviation of the linearity of the Arrhenius plot above 100 °C for this product. This work was useful to illustrate the use of the applied methodology and to validate the newly built microwave-heated capillary rheometer. The data obtained confirm the stability of nonsaturated sucrose solution when treated above 100 °C and presents an important contribution to the literature database, since sucrose solutions are used as models for many table syrups, such as maple and sorghum syrups.

Practical Application

The paper deals with the practical use of a pressurized capillary rheometer, rapidly heated by a microwave system, which was built and patented. The data on high temperature rheology obtained with this equipment can be used to accurately design thermal treatments of fluid food, in order to optimize the time and temperature conditions, thus not having the risk to happen an under- or overprocessing of the fluid, due to unexpected alterations that might occur at high temperatures, which are not accounted for when calculating the rheological properties through extrapolation or by measuring samples which were overheated.