The use of potato starch/xanthan gum combinations as a thickening agent in the formulation of tomato ketchup

Tomato ketchup was prepared using potato starch (PS)/xanthan gum (XG) combinations as a thickening agent, and its sensory textural properties, viscosity stability, low-field nuclear magnetic resonance (LF-NMR) imaging and rheological properties were evaluated. Results showed that PS/XG as a thickener enjoyed the highest score (4.6) with good sensory evaluation. Due to the electrostatic and steric repulsive forces between PS and XG, the tomato ketchup prepared by 2.5% w/w PS/XG (PS:XG was 80:1) had better acid resistance, superior hardness, adhesion adhesiveness and cohesiveness than potato starch (PS), modified starch (MS), and no thickener (Control). Particularly, PS/XG enhanced the viscosity of ketchup for its electrostatic repulsion which delays starch retrogradation. LF-NMR imaging demonstrated that the moisture distribution in ketchup prepared by PS/XG was the most uniform. With a thixotropic behavior, PS/XG had a similar flow curve as MS. Therefore, PS/XG exhibited a compelling potential as a thickener in the formulation of ketchup.