Chemical and functional properties of starch nanoparticle from purple sweet potato var. ayamurasaki

Abstract

The native purple sweet potato (PSP) starch of the Ayamurasaki variety has drawbacks that limit its application in food. This study aims to produce starch nanoparticles from PSP by hydrolysis using 3 types of acids, such as citric acid, acetic acid, and lactic acid. The hydrolysis process was carried out by incubating PSP starch suspension using an acid solution with a concentration of 7.5% and the ratio of starch and acid was 1:5 (w/w). The resulting PSP starch nanoparticles were analyzed for their chemical and functional characteristics. The study design used a Completely Randomized Non-Factorial Design with four repetitions. The results showed that the hydrolysis process produced starch with amylose content, total sugar content, reducing sugar content, and swelling power which were significantly different (p<0.05) from the native PSP starch. However, the dextrose equivalent value (DE), degree of polymerization (DP), and solubility of the PSP starch nanoparticles were not significantly different (p>0.05) from the native PSP starch. The type of acid had a significantly different effect on the amylose content, total sugar and reducing sugar content, but had no significant effect on the DE, DP, swelling power and solubility values of the PSP starch nanoparticles. Significantly (p<0.05) hydrolysis of starch with acetic acid resulted in the highest yield of starch nanoparticles. Starch hydrolysis with acetic acid significantly (p<0.05) produced the highest yield of PSP starch nanoparticles.