Basic principles in starch multi-scale structuration to mitigate digestibility: A review

Background: In the human diet, starch makes a significant contribution to the maintenance of human nutrition and health due to its controlled digestibility. Starch digestion is controlled by its microstructure. Increasing developments in the modification of starch multi-scale structures that modulate digestibility have taken place due to increasing attention to health-promoting starchy foods. The process of starch structuration is a challenging concern in food science since the basic principles for designing starch structures with a specific digestibility are unknown. Scope and approach: Starch multi-scale structures significantly affect digestibility. However, starch digestibility cannot be precisely modulated without a solid theory of starch structuration to inform the tailoring of the digestibility of starchy foods. In this review, the effects of starch multi-scale structures (fine structures of amylose and amylopectin; short-range ordered structures; helical, crystalline, lamellar, aggregate structures; and structures formed after food processing) on the digestibility and the molecular mechanisms of the regulation of starch digestion are comprehensively discussed. The key structures that can be manipulated for target-modulation of starch digestibility are summarized. Key findings and conclusions: Basic principles for mitigating starch digestibility, such as increasing the thickness of semi-crystalline lamellae and crystalline lamellae, nanoscale aggregates, V-, A-, or B-type crystals, double helices, long amylopectin helices, short-range ordered structures, the content of amylose fractions and high-branched amylopectin are established. Ordered starch structures, including short-range and long-range ordered structures, play critical roles in mitigating starch digestibility while faulty- and perfectly arranged helical, crystalline, lamellar structures, and nano aggregates are proposed to be slowly digestible and resistant starches, respectively.