Effects of potassium alum addition on physicochemical, pasting, thermal and gel texture properties of potato starch

Abstract

Summary The study investigated the effects of the addition of different concentrations of potassium alum (PA, 0, 0.1, 0.3, 0.5, and 0.7 g 100 g −1 ; w/w, on a starch weight basis) on the pasting, thermal, gel texture and other physicochemical properties of potato starch. The addition of PA resulted in a significant increase in solubility and a decrease in swelling power and light transmittance of stored pastes. Differential scanning calorimeter analysis demonstrated an increase in gelatinisation temperatures and gelatinisation enthalpy and a decrease in phase transition temperature range (Δ T r ) with increasing PA concentration. Results of rapid visco‐analysis indicated that addition of PA decreased the peak, trough, breakdown, final and setback viscosities, but increased in peak time. Textural tests showed that the addition of PA retarded gel strength development during refrigerated storage. The high ionic strength and water‐binding capacities of Al 3+ , K + and SO 4 2− point to being the key factors for these observed changes.