Modifying starch have an important role in food production. This article refers to the study of process modification impomoea batatas (sweet potato) starch by NaCIO. The process was studied with the factors affecting the rate of NaCIO, time and temperature modifications. The aim of the modifications is to increase the viscosity and solubility of Impomoea batatas starch. By the method of experimental planning, the survey identified domain, set up a model and conduct experiments. From the experimental results using the optimization model of type 2 and convolution algorithms targeting "function expected". The results were worked out by statistical software Design-Expert 7.1. The author have found a optimize project for the modifications of Impomoea batatas starch as follows: NaCIO rate: 0.26 percent, time 3 h 50 minutes, temperature 31°C. For this method starch durable gel, viscosity and solubility are higher native starch, and have the values: viscosity: 2.5E
solubility: 67.2 percent and endurance gel: 530 g. Impomoea batatas starch have high amylose pectin content (79.5 percent), after modifying increase in solubility, viscosity particularly strong. This is different from some previously oxidized starch. With the features high viscosity, modificated starch have been studied as an additive to make create viscidity of viscous fish sauce products. Result in concentrations of 4 percent using additional starch viscouce fish sauce have good viscidity, 4 months after storage, when diluted to concentrations in use the sensory quality equivalent to the original sauce.