An investigation on the effects of concentration and temperature on the time-independent rheological behavior of peach syrup

Abstract

Understanding the rheological properties of fluid foods, especially their viscosities, plays an important role in determining the quality control and design of equipment for food industry plants. Hence, in this research, the time-independent rheological behavior of peach syrup was determined using a Brookfield viscometer, and the effects of concentrations at 35, 40, 45, and 50 °Brix, and temperatures at 15, 25, 35, 45, 55, and 65 °C were investigated in a range of 1.4-49.78 s−1 shear rate. To investigate the rheological effect of these parameters, the shear stress and apparent viscosity parameters were plotted at different shear rates. To describe the time-independent behavior of peach syrups, Power law, Bingham, Casson, and Herschel–Bulkley models were used; among these models, the Power law model with an R2 of 0.9980, the root mean square error (RMSE) of 3.2717, and the Chi square (χ2) of 20.2782 was determined as the best one for the description of shear stress-shear rate diagrams. Furthermore, the dependence of consistency coefficient obtained from the Power law model on temperature parameter was investigated using the Arrhenius model, and the dependence of consistency coefficient on concentration parameter was determined using the Power and exponential models. Overall, the results showed that peach syrup had a non-Newtonian pseudo-plastic behavior. The investigations also showed that an increase in the concentration of peach syrup led to enhancing the apparent viscosity of the samples, while an increase in the temperature and shear rate reduced the apparent viscosity.