The Effect of Salep and Carboxy Methyl Cellulose on the Quality of Ketchup

Ketchup is a heterogeneous suspension that is used as a condiment to improve the flavor and color of the food. During storage it changes color, losing consistency with the occurrence of syneresis. In this study the stabilising effect of salep and carboxy methyl cellulose (CMC) on the acidity, pH, color, syneresis, rheological characteristics, microstructure and sensory properties of the ketchup have been examined. In this research salep at the level of 0.18, 0.36, 0.45, 0.54, 0.72 and 0.9% with CMC were used in the formulation of ketchup. Color parameters, syneresis, the rheological characteristics, microstructure and sensory properties of the samples were evaluated after one day and thirty days of production. The samples containing 0.45% CMC and 0.45 to 0.22% salep after one day, and samples containing 0.45% CMC after thirty days of production had the least brightness. The samples with 0.9% salep had the maximum red intensity for both periods and samples containing 0.72% and 0.9% salep had the best color score after one day and thirty days of production, respectively. Syneresis in the samples were decreased by the addition of salep in both periods. CMC have a greater impact on the psuedoplastic behavior of ketchup and the highest viscosity was related to the samples containing 0.72% salep. By fitting the power law equation, sample containing 0.45% CMC showed stronger gel structure as compared to other samples containing salep. Microscopic images showed the sample containing 0.72% of salep had more compact and better texture than others. The scores given to the sensory properties were in acceptable range and there were no significant differences between the samples. Salep had a positive effect on the color of ketchup, reduced the syneresis and improved the viscosity. Although CMC had a greater impact on psuedoplastic behavior of ketchup, but microscopic images of the samples confirmed better and more compact structure for samples containing 0.72% salep.