No abstract

No abstract

Summary The effects of temperature and pretreatment on drying kinetics and thermal degradation of phytonutrients present in pomegranate arils were investigated. The arils were divided into two groups, and half of the samples were pretreated by dipping into 80 °C hot water for 2 min. The drying process was conducted in the vacuum drier at the temperatures of 55, 65 and 75 °C. The fastest drying was completed at 75 °C after pretreatment of the samples. The highest anthocyanin–phenolic compound contents and antioxidant capacity were detected in the arils dried at 55 °C. Seven thin‐layer drying models were used to predict drying curves, and Arrhenius and Eyring–Polanyi models were employed to predict phytonutrient degradation kinetics. Activation energy for drying was 24.26 kJ mol−1 for pretreated samples and 31.54 kJ mol−1 for untreated samples. Effective moisture diffusivities were ranged from 1.43 × 10−9 to 6.03 × 10−9 m2 s−1.

No abstract

Rheological properties of sour cherry juice were determined by a Controlled Stress Rheometer. Sour cherry juice with different solid contents (40, 45, 50, 55, 60, 65, 68.5 and 70 Brix) was prepared using a rotary evaporator after squeezing and filtration of sour cherries. The rheological behavior of these concentrates was studied in the temperature range of 5, 10, 20, 30, 40, and 50°C. Sour cherry juice was found to exhibit Newtonian behavior. The effect of temperature on viscosity can be described by means of an Arrhenius equation. Activation energies appeared in the range of 22.44-73.49 kJ/mol with increasing concentration. To study effect of concentration on the viscosity, power-law and exponential equations were used. Finally, two equation describing the combined effect of temperature and soluble solids content on the viscosity of concentrated sour cherry juice were obtained.