Elucidating the impact of dual modification with hydroxypropylation andenzymatic hydrolysis on physicochemical properties of corn and sago starch

Enzymatic hydrolysis is one of the most commonly used techniques in starch modification. However, the performance of enzymatic hydrolysis has been restricted by the inherent properties of native starch. In this study, hydroxypropylation with two different concentration levels of propylene oxide (10% and 20%) was carried out on corn and sago starches. The effect of hydroxypropylation on the physico-chemical properties of the enzyme-hydrolyzed starch was investigated. The results showed that the starches treated with 20% propylene oxide had higher molar substitution and dextrose equivalent with greater effects. Scanning electron microscope (SEM) revealed that hydoxypropylation had developed pores and pits on the granular surfaces and subsequently enhanced enzyme penetration. Hydroxypropylation showed no changes in the crystalline pattern, yet a decrease in the amylose content of both corn and sago starches, respectively. Other than that, hydroxypropylation decreased the pasting properties and retrogradation tendency but increased the swelling power of enzymehydrolyzed starch significantly. Overall, this work suggested that hydoxypropylation pretreatment could improve the efficiency of subsequent enzyme hydrolysis and produce modified starch with great potential in food processing applications.