Bibliografisk note

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Yu Tian gratefully acknowledges the support of the China Scholarship Council ( CSC ) funding for her PhD studies at the University of Copenhagen (UCPH), Denmark. Xingxun Liu acknowledges grants from the National Natural Science Foundation of China ( 32372476 ).

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Lamellar structure. The thickness of the crystalline and amorphous lamellae was both positively correlated with AC parameters (especially for the ACL of long and medium AM chains), ACLs of fb2 chains, ACLs of AM chains (ACLde-AM), and single helix content, and negatively correlated with ACLs of fa chains (ACLfa), the content of fb1 chains (RCfb1), molecular size of AP molecules (Rhde-AP), βam2, βam3, and crystallinity. The correlation data confirms that AM is an important contributor for the lamellar structure of HASs as reported (Koroteeva, Kiseleva, Krivandin, et al., 2007; Koroteeva, Kiseleva, Sriroth, et al., 2007; Zhong, Tai, et al., 2022). We can now further elaborate that higher AC (especially more long AM chains) and longer AM chains (especially longer medium and long AM chains) result in HASs with thicker crystalline and amorphous lamellae. It has been suggested that long AM chains mainly orients within the amorphous lamellae (Koroteeva, Kiseleva, Krivandin, et al., 2007; Yuryev et al., 2004; Zhong, Liu, Qu, Blennow, et al., 2020) and branched AM molecules, so-called ‘AM-like material’, which are AM molecules suggested to be generated by SBE-suppressed mutants (Zhong, Qu et al., 2022), displace the function of AP molecules in which AM backbone chains stacked in the amorphous lamellae and their branches forms helical structures in the crystalline lamellae. This is well-supported by the existence of lamellar structure in the AM-only starch, AOBS, although AM resulted in a weak and disordered lamellae structure (Table 3). Based on this assumption, it is reasonable that long AM chains affects both amorphous and crystalline lamellae. Furthermore, the correlation analysis indicates that longer AP fb2 chains contributed to thicker crystalline lamellae and amorphous lamellae, perhaps due to that these chains can possibly be double helix connector chains (Zhong et al., 2020; Zhong, Li et al., 2021) and located in both amorphous lamellae (as backbone chains) and crystalline lamellae (forming helical structures) (Bertoft, 2017). Thus longer chains resulted in thicker lamellar structures. A few studies reporting relationships between AC and lamellar structural parameters by using starches with a lower, but wider, range of AC (i.e., 0%–50%) has revealed no effects of AC on lamellar structure (Cardoso & Westfahl, 2010; Koroteeva, Kiseleva, Krivandin, et al., 2007; Koroteeva, Kiseleva, Sriroth, et al., 2007; Yuryev et al., 2004), which at first glance is inconsistent with our conclusion. However, data from starch systems with higher AM contents derived also from different genotypes with similar AC contents is here demonstrated to reveal clear effects on the lamellar structures. The data show that the thickness of both the crystalline and the amorphous lamellae were positively correlated with the single helix content and negatively correlated with crystallinity suggesting that HASs with thicker crystalline lamellae and amorphous lamellae had less ordered crystalline structures. The FWHM, an indicator of lamellar structure ordering, where a lower value signifies higher lamellar ordering (Blazek et al., 2011; Xu et al., 2020), generally exhibited a positive correlation with the thicknesses of both crystalline and amorphous lamellar parameters, specifically da and dc. This suggests that HASs with thicker crystalline and amorphous lamellae tend to have a less ordered lamellar structure. In addition, the FWHM was also positively correlated with the content of single helices, and negatively correlated with the length of the fa chains, βam1, βam2, βam3, degree of branching, and the content of double helices, mainly suggesting that (I) double helices stabilize the lamellar structure and single helices has a disordering effect on the lamellar structure, which is in agreement with the effect of AC on lamellar structure, and (II) longer AM chains resulted in more disordered lamellar structure, which is consistent with the negative correlation found between the single helix content and βam1, βam2, βam3.Crystalline structure. Total crystallinity (the sum of the B-, and V-type crystal contents) of HASs and the crystallinity of the B-type crystals were both positively correlated ACLs of the fa and fb3 chains, and the content of fb1 chains, and negatively correlated with the content of fa chains, the relative amounts of medium AM chains, and the content of single helices. This mainly demonstrates that (I) the B-type crystal polymorph is the main crystal type in HASs (Table 3), (II) the short branches, fa and fb1 chains are important for crystalline structure ordering, again supporting that short fa chains form crystal defects, long fa chains and fb3 chains build more perfect crystals, and long fb1 chains function as connector chains as reported (Bertoft, 2017), and (III) the effect of medium AM chains, which are mainly located in the crystalline lamellae (Zhong, Liu, Qu, Blennow, et al., 2020), are mainly to disrupt crystalline structures likely by forming crystalline defects such as single helices in a double helical matrix. The content of the V-type crystalline polymorph showed an opposite correlation with structural parameters such as total crystallinity and B-type crystallinity, due to that AM is a main contributor to V-type crystals (H. Li et al., 2019; Obiro et al., 2012).Yu Tian gratefully acknowledges the support of the China Scholarship Council (CSC) funding for her PhD studies at the University of Copenhagen (UCPH), Denmark. Xingxun Liu acknowledges grants from the National Natural Science Foundation of China (32372476).

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