Study on extracting parameters of starch from waste residue of purple sweet potato anthocyanins

In order to make full use of purple sweet potato and improve comprehensive utilization rate of the raw material,starch was extracted from purple sweet potato anthocyanins waste residue. Experiments were done using water and 1.25% citric acid as solvent respectively under the conditions of different solid–liquid ratio,pH value of slurry,soaking time and soaking temperature. The optimum extracting conditions of starch obtained by single factor experiment and orthogonal experiment were as follow,ratio of sample weight(g) to solvent volume(ml) was 1︰4,pH value was 5.0,soaking time was 2.0 h and soaking temperature was 30 ℃. Under these conditions,extraction rate could reach 57.49%,and starch purity was 85.37%.