Preparation and Properties of Hydroxypropyl Pea Starch

Hydroxypropyl pea starch was made with propylene oxide as an etherization reagent and sodium hydroxide as a catalyst,and its properties were studied.The effects of some factors,such as amount of propylene oxide,pH,reaction temperature and reaction time on substitution degree of hydroxypropyl starch were investigated.The factors were optimized using response surface methodology.The optimum conditions for preparing hydroxypropyl pea starch were 12% propylene oxide dosage,pH 11.3,temperature 40 ℃ and reaction time 18 h.The results obtained showed that the pasting temperature of hydroxypropylated pea starches with different substitution degrees decreased by 11–18 ℃,whereas peak viscosity increased by 74%–109%,compared to the native starch.At 34–90 ℃,progressive increases in swelling capacity were observed as the MS(molar substitution) increased among hydroxypropylated starches.At the same time,in vitro digestibility of hydroxypropyl pea starch was lower than that of the native starch.