Effect of hydrocolloids addition on rheological properties ：亲水胶体对流变性能的影响精品.pdfVIP

Effect of hydrocolloids addition on rheological properties, and sensory quality of tomato ketchup during storage EL-Desouky, A.I. Food Sci. Dept., Fac. of Agric., Moshtohor, Benha Univ., Egypt. ABSTRACT The effect of two different hydrocolloids on rheological properties and sensory quality of tomato ketchup during storage was studied. The starch was add to tomato ketchup at level of 0 ,1 ,2 and 3% while pectin was add at level 0.5 and 1%. Tomato ketchup was stored at room temperature for six months. The rheological behavior of tomato ketchup samples contained different ratios of hydrocolloids were measured in shear rate range 0.0 to 100 s-1 and studied at a wide range of temperatures (5 - 75 °C) using a Brookfield Digital Viscometer. The results indicated that these tomato ketchups behave as non- Newtonian fluids (pseudoplastic) and have a definite yield stress. Higher significant correlation was found between the viscosity and temperature. The viscosity decreased with increasing in the temperature. All hydrocolloids increased consistency of tomato ketchup. With increasing storage period, viscosity of tomato ketchup decreased. The water separation as important sensory attribute decreased with the addition level of hydrocolloid and increased with increasing storage duration. The effect of temperature on their viscosity can be described by means of an Arrhenius-type equation. The activation energy for viscous flow depends on the chemical composition; the activation energy decreased with increasing hydrocolloids addition. Sensory tests for tomato ketchups were done during storage and