Effect of Different Modification Methods on Physicochemical Properties of Potato Starch and Its Uses in Salad Dressing

摘要

This work was carried out to study the effect of pregelatinization, acid-thinning and dextrinization methods on physicochemical and rheological properties of potato starch. The obtained modified potato starches were used at 5% to replace fat in salad dressing processing. No significant difference was noticed in moisture content between native and pregelatinized potato starches. The nitrogen free extract (99.20 - 99.91%) suggests that pure potato starch was obtained by the applied isolation method. A gradual decrease in water binding capacity was recorded for dextrinized and acid-thinned potato starches compared to native potato starch. A similar observation was recorded for oil binding capacity for acid-thinned and pregelatinized potato starches compared to native potato starch. Data also, indicated that higher solubility and lower swelling power at 90 ℃ were recorded for dextrinized potato starch. Dextrinization method increased syneresis to high extent during storage up to 120 hr as compared to other treatments; it means that it was unstable in refrigeration. The large granules probably had slightly lower pasting temperature and higher peak viscosity at 95 ℃ for acid-thinned and native potato starch as compared to that from the pregelatinized potato starch which recorded slightly lower peak viscosity. Emulsion stability was higher for control salad dressing, followed by samples containing pregelatinized and acid-thinned potato starches. It could be concluded that salad dressing with 5% of native, pregelatinized and acid-thinned potato starches had acceptable sensory attributes.