EFFECT OF CHEMICAL MODIFICATIONS ON THE FUNCTIONAL AND RHEOLOGICAL PROPERTIES OF POTATO (SOLANUM TUBEROSUM) STARCHES - K. H. Khan; T. M. Ali; A. Hasnain (Journal of Animal and Plant Sciences, 2014)
The present study investigated the effect of single and dual chemical modifications on functional and rheological properties of starch isolated from Pakistani potato cultivar. The isolated starch was chemically modified to produce acid-thinned, acetylated, oxidized and acetylated-oxidized starch. The objective of chemical modification was to tailor and improve the native properties of potato starch so that it could be used in wide variety of food products. The chemicals used for acid-thinning, acetylation and oxidation were hydrochloric acid, acetic anhydride and sodium hypochlorite, respectively. The scanning electron micrographs revealed the presence of small, medium and large sized granules ranging from 7-111 µm. Except acid-thinning, all other chemical modifications increased swelling power of potato starch. Each of the modifications reduced time to reach viscosity while pasting temperature of acetylated and dual modified acetylated-oxidized potato starch was also significantly reduced. Acid-thinning reduced peak viscosity of potato starch suggesting its use as a bulking agent in confectionery products. Shear stability also declined due to acetyl-oxidation of potato starch, owing to substitution of hydroxyl groups by acetyl, carboxyl and carbonyl groups. Oxidized and acid-thinned starch formed gels with higher firmness and rupture strength compared to native starch. However, increase in rupture strength with cold storage of starch gels declined significantly due to chemical modifications.
Keywords: journal article; potato starch; modification; functional; rheological