New insights into how the structure of starch synergistically affects the digestibility, texture, and cooking properties of instant rice noodles incorporated with starch-lipid complexes

The influences of different cooking methods on the starch structures and functionalities of instant rice noodles (IN) incorporated with starch-lipid complexes were investigated. The reassembled ordered structures were improved; helical and crystalline structures, short-range-ordered, and ordered aggregate structures were observed in all processed samples. The scanning electron microscopy (SEM) results revealed that the microstructure of microwaved IN was the most compact, followed by the boiled and steamed IN, whereas stir-fried IN displayed a more irregular morphology. Steaming and boiling treatments resulted in decreased rapidly digestible starch (RDS) and resistant starch (RS) contents, but increased fractions of slowly digestible starch, stir-frying decreased RDS content but increased RS fractions of IN through forming into more amylose-lipid complexes. Both stir-frying and microwaving presented good potential in improving the nutritional properties of IN via delaying the elevated blood sugar levels. All examined cooking methods improved the textural properties (hardness, chewiness, and gumminess) of IN. Structure-functionality relationships revealed that the crystalline structures, short-range-ordered structures, and aggregate structures synergistically affected the cooking, texture, and digestibility of IN. By altering such key structures, the texture, cooking, and digestion characteristics of IN can be considerably improved.