Effect of chemically modified starch on retrogradation and quality characteristics of semi-dry rice noodles

Retrogradation of semi-dry rice noodles severely reduced their eating quality during storage. Three commonly used modified starches (oxidized starch, acetylated starch, and hydroxypropyl starch) were applied to investigate the anti-retrogradation effects of semi-dry rice noodles during cold storage. Loss of water content, migration of water, and increase in relative crystallinity, retrogradation enthalpy, and hardness could be retarded by adding chemically modified starches, especially hydroxypropyl starches. The effect of hydroxypropyl starch addition levels (2%, 4%, 6%, 8%, and 10%) on the properties of rice flour and the edible quality of semi-dry rice noodles was further evaluated. The water solubility index of rice flour decreased with the addition of hydroxypropyl starch, while the swelling power showed the opposite trend. The quality of semi-dry rice noodles were improved with the addition of hydroxypropyl starch. Compared to the control, semi-dried rice noodles with 8% hydroxypropyl starch possessed superior properties, i.e. lower cooking loss (decreasing from 12.89% to 6.62%), lower adhesiveness (decreasing from 5.40 to 4.31 g·s), and higher hardness (rising from 10.89 to 13.81 N). These findings demonstrated that the incorporation of hydroxypropyl starch is a promising strategy for the preparation of semi-dry rice noodles with satisfactory cooking and edible qualities as well as a long shelf life.