High-amylose rice: Starch molecular structural features controlling cooked rice texture and preference

Area of Science:

• Food Science
• Plant Biology
• Nutritional Science

Background:

• Cooked high-amylose rice exhibits slower starch digestibility, offering nutritional advantages.
• However, high-amylose rice often presents inferior eating qualities, primarily characterized by increased hardness.

Purpose of the Study:

• To elucidate the molecular structural mechanisms underlying the inferior eating quality of cooked high-amylose rice.
• To identify specific starch structural features that correlate with palatability and sensory attributes.

Main Methods:

• Structural analysis of parent starch and leached starch using size-exclusion chromatography.
• Sensory evaluation of cooked rice attributes by a trained human panel, focusing on palatability and hardness.

Main Results:

• Rice hardness was the primary factor negatively correlated with panelist preference.
• Starch hardness was determined by the quantities of medium and long amylopectin chains and amylose in the parent starch.
• Amylose content and longer amylopectin chains in the leached starch also influenced hardness.

Conclusions:

• Cooked rice palatability is influenced not only by amylose content but also by other molecular starch structures, including amylopectin chain lengths.
• Understanding these molecular determinants can aid rice breeders in developing high-amylose rice varieties with improved texture and health benefits.