Variation in HMW-GSs at Glu-D1 locus causes differences in protein behaviors and starch structures during noodle cooking and retrogradation

To study the effect of gluten strength on starch structure and digestibility during noodle processing, two gluten samples containing HMW-GSs N/17 + 18/5 + 10 and N/17 + 18/2 + 12, respectively, were separated from wheat near-isogenic lines and combined with identical wheat starch to prepare two recombinant noodles. The structural changes in protein, starch, and their interactions during noodle cooking and retrogradation were investigated. The results indicated that the noodles with 5 + 10 subunits exhibited better cooking and textural characteristics compared to 2 + 12. Cooking and retrogradation led to protein aggregation, with the 5 + 10 noodles displaying higher levels of SDS-unextractable polymeric proteins characterized by increased disulfide bonds, hydrophobic interactions, and β-sheets. Meanwhile, the double helices within starch were disrupted, producing more single helices rich in inclusion complexes. The dense and extensive gluten matrix in 5 + 10 noodles inhibited the destruction of starch granules during cooking, and promoted starch recrystallization and the formation of starch-protein complexes, which contributed to a higher RS content (29.13 %). In contrast, the 2 + 12 noodle exhibited greater release of short-chain starches and monomeric proteins during cooking, leading to a disordered structure that impeded starch recrystallization and improved starch digestibility. The findings support improving noodle quality and starch digestion resistance through the incorporation of suitable HMW-GSs.