Effect of reducing pulp-particles on the physical properties of carrot juice

Abstract

Sedimentation is a main problem in carrot juice. Several studies reported that cloud stability could be improved by using polysaccharide stabilizer and reducing pulp content, however these might affect texture attributes of the product. This study evaluated physical properties of carrot juices that were prepared by using different machines i.e. (i) hydraulic pressing, (ii) hammer mill, and (iii) high pressure homogenizer, which reduced sizes of the carrot pulps to 332, 283, and 82μm diameter, respectively. No significant changes (p < 0.05) in the pulps diameter during storage at 4oC for 2 weeks were seen. Apparent consistency of the products was not significantly different (2.08 - 2.16), however a significant difference was found in serum viscosity (1.23, 1.31, and 1.41, respectively) that indicated that the smaller pulp size had higher relative viscosity. After 14 days, both viscosities of all samples tended to slightly decrease. Values of pH and total soluble solids (oBrix) of all samples were 3.39 - 3.42 and 11.0 -11.2, respectively, while colors were 86.3 lightness (L), 40.4 redness (a), and 75.8 yellowness (b). These characteristics remained constant during storage. The homogenization process provided the product with a higher viscosity due to smaller pulp sizes, which did not have any effects on the quality factors such as the color, pH and oBrix of the carrot beverages.