Optimization of Synthesis of Cassava Starch Phosphates by Response Surface Methodology and Characterization of the Modified Starches

Abstract Cassava starch has not been widely exploited in modified starch sector, despite its beneficial and peculiar properties including bland taste and flavor, easy extractability, and good paste clarity. In this study, cassava starch is phosphorylated using sodium tripolyphosphate (STPP) and sodium trimetaphosphate (STMP) at different pH levels according to a central composite design and optimized reaction conditions for maximum phosphorus content. The granule morphology, crystalline pattern, pasting properties, physicochemical properties, and in vitro starch digestibility of the modified starches are determined. The reaction conditions have significant effects on the P content. The highest P content (0.160%) is obtained for the sample synthesized using 8% of STMP and 4% of STPP (based on starch dry weight) at a pH of 9.0. X‐ray diffraction analysis revealed no noticeable change in crystalline properties of the modified starches in comparison to native starch. Samples with lower %P have similar granule morphology as the native starch, whereas at higher levels of P, granule rupture and agglomeration are noticed. Wide differences in the pasting and swelling properties are observed among the modified starches. Crosslinked starches formed at higher levels of pH show highly reduced paste viscosity and restricted in vitro starch digestibility.