Structural and physicochemical properties of corn starch modified by phosphorylase b, hexokinase and alkaline phosphatase

To improve the functional properties of corn starch, phosphorylase b (PB), hexokinase (HK), and alkaline phosphatase (AP) were used to produce enzyme-modified starches (PBMS, HKMS, and APMS). The results showed that enzyme-modified starches had different phosphorus contents and degrees of substitution. The presence of P--O bonds and P-O-C bonds further demonstrated that phosphate groups were grafted into starch. The proportions of monostarch phosphate in PBMS, HKMS, and APMS were 77.05 %, 79.33 % and 85.88 %, respectively. The introduction of phosphate groups affected the functional properties of starch. The swelling powers of PBMS, HKMS and APMS increased from 0.99 % to 12.86 %, 10.83 % and 5.95 %, respectively. Compared to native starch (1820 mPa & sdot;s), the peak viscosities of PBMS, HKMS and APMS increased to 2655, 2838, and 2021 mPa & sdot;s, respectively. Meanwhile, the introduction of phosphate groups endowed phosphorylated starch with better freeze-thaw stability, larger paste transparency, higher solubility, and slower retrogradation rate.