Study Of The Mechanism Of Modified Starch In Ketchup

Ketchup is a system of two-phase products.During the long-term storage,the main problem associated with quality of ketchup is the tendency of the separation between solid and liquid phases.This phase separation results in inferior sensory and poor flow property,and then reduces the quality of ketchup.Modified starch has a stabilizing effect,so the addition of modified starch can improve the stability of tomato paste.The main purpose of this paper is to study the effect of different kinds of modified starch on the stability of ketchup.In this paper,we used the following starch to add into tomato paste samples: cassava starch(NS),phosphate starch(PS),starch(SAES)and starch(OSES).In order to achieve this goal,the physical and chemical properties,microstructure and rheological properties of ketchup were determined.First,the physical and chemical properties of pH,soluble solid content and water content were measured.After adding modified starch,the water retention property was obviously enhanced.Through the determination of the rheological properties of the samples,,the flow characteristics of the shear thinning of tomato paste are presented.Ketchup is a pseudo plastic fluid with yield stress.The G '>G'',we can know that the elastic modulus is always greater than the viscosity modulus,which indicates that the ketchup is a flexible system.The determination of microstructure is mainly characterized by the observation of particle size and Zeta,scanning electron microscope(SEM),optical microscope and atomic force microscope(AFM).Particle size analysis of ketchup mainly recorded the average particle size and the uniformity of particle size distribution(PDI).It was found that the average particle size of ketchup without starch was the largest.The larger the PDI value,the moreuneven distribution.After adding the native starch,the particle size was smaller,and the PDI value was relatively small.The addition of modified starch made the system had smaller the average particle size and more uniform size distribution.The determination of Zeta electric potential of the ketchup showed that after adding the starch,the electrostatic force between the sample system is enhanced.So the system is more stable.After the observation of ketchup by optical microscope,SEM and AFM showed that which was without starch showed the color of ketchup itself and did not appear in the grid structure,and the surface is very rough,and the samples of the original starch appeared less grid structure.The addition of modified starch samples appeared to have more mesh structure,more intensive.In conclusion,the addition of modified starch can enhance the stability of tomato sauce.It can reduce the separation between solid and liquid phases.