Modulation of the digestibility and multi-scale structure of cassava starch by controlling the cassava growth period

Starch digestibility is the dominant factor affecting the nutrition of starchy food. Starch with different digestibility can be obtained through tailoring the starch multi-scale structures by controlling the crop growth period. Here, the multi-scale structure and digestibility of cassava starch obtained from different cassava growth periods were investigated, and the structure-digestibility relationships were revealed. The results indicated that the cassava starch synthesized during different growth periods showed differences in digestibility. The combined total content of slowly digestible starch (SDS) and resistant starch (RS) was highest at the growth period of 7 months, and the individual content of SDS and RS was highest at the growth periods of 10 and 11 months, respectively. The multi-scale structure changes during different growth periods demonstrated that smaller weight-average molecular molar mass, larger molecular density, more ordered short-range structure, and thinner amorphous lamellae decreased starch digestion, while higher amylose content and B2 chain ratio, longer average chain length, thicker crystalline lamellae, and repeated semicrystalline lamellae contributed the formation of RS fractions. Hence, specific starch structures can be tailored by simply controlling the growth period for obtaining slow and resistant digestible cassava starch to improve its nutritional value.