The influence of electron beam irradiation on the multi-scale structure and digestibility of high amylose maize starch

High-amylose maize starch (HAMS) has garnered significant interest owing to its unique functional properties, such as the capacity to increase resistant starch content in food, and its associated health benefits. In this study, two varieties of SBEIIb -mutated HAMS were used to investigate the effects of electron beam irradiation (EBI) treatment at varying doses (5, 10, 15, and 20 kGy) on the multi-scale structure and digestibility of NAFU50 and NAFU60. The results indicated that EBI treatment significantly reduced the amylose content of both starches (NAFU50 = 12.56 %; NAFU60 = 16.88 %), while concurrently increasing the long-chain amylose content (NAFU50 = 15.09 %; NAFU60 = 14.63 %). After EBI treatment, the relative crystallinity and long-chain components of starch showed a significant downward trend. However, the crystal structure type of starch did not change due to irradiation. Notably, a higher dose(10 kGy) was found to increase the content of resistant starch (RS) and modified its viscosity and expansion capacity, indicating a threshold effect at this dose. Principal component analysis and Pearson correlation analysis further revealed that when the dose exceeded 10 kGy, the changes in the multi-scale structure and functional properties of starch tended to stabilize. Overall, this study provides necessary information for the modification of starch and offers a theoretical basis for its application in the food industry. • The key to increasing resistant starch content was a 10 kGy EBI dose, which optimally balanced degradation and recombination processes. • Multi-scale structural modifications induced by EBI, including depolymerization of long chains and increased short-chain fragments, enhanced the ordered structure and reduced rapidly digestible starch. • EBI improved starch digestibility (increased SDS and RS) and functionality (increased solubility, decreased swelling power), confirming its effectiveness in tailoring nutritional properties.