نوع مقاله : مقاله پژوهشی
1 استادیار، دانشگاه ملی بناب
2 کارشناسی ارشد، دانشگاه آزاد اسلامی واحد مراغه
3 استادیار، دانشگاه آزاد اسلامی واحد مراغه
عنوان مقاله [English]
Among the juice, peach juice has high popularity and in terms of nutrition also has been highly regarded. Iranian peach puree is one of the main sources of peach juice production in Iran. In this research, steady shear flow behavior of peach concentrate produced from this puree were investigated at the concentration of 5, 10, 15, 20 and 25 °Bx. and temperature of 5, 25, 45 and 65 °C. The shear stress-shear rate data obtained for the concentrates were fitted by different rheological models including Newtonian, Power law, Bingham and Herschel-Bulkley. In addition, the concentration dependency was investigated by power law and exponential models and the temperature dependency was evaluated by the Arrhenius-Eyring model. All the samples showed pseudoplastic behavior. Power law model (Ostwald-de Waele’s model) with high determination coefficient (R2 = 0.934-0.999) and low root mean square errors (RMSE = 0.027-0.327) had the best fit to the experimental data. It was observed that increase in the temperature leads to an increase in the flow behavior index (n) and a decrease in the consistency coefficient (k). On the other hands, increasing the concentration decreased n and increased k values. Power-law model also predicted the concentration dependency of apparent viscosity (η50) with a high precision. The concentration dependency of apparent viscosity (η50) increased with the temperature increment. The combined Power-Arrhenius model had a high coincidence in order to show the influence of concentration-temperature on η50 (R2 = 0.997, RMSE = 0.040). It can be concluded that the rheological properties of Iranian peach concentrates are remarkably influenced by the temperature and concentration.