Konjac glucomannan molecular weight: A critical factor in shaping the physicochemical and digestive properties of sweet potato starch matrices.

The molecular weight (Mw) of non-starch polysaccharides exerts a significant impact on the interaction mechanisms between non-starch polysaccharides and starch, as well as on the resultant modification effects of starch. This study primarily focused on examining how konjac glucomannan (KGM) with varying Mw affects the physicochemical and digestive characteristics of sweet potato starch (SPS), additionally exploring the intermolecular interactions between KGM and SPS. The findings indicated that a higher Mw of KGM produced an enhancement in the viscosity peak of SPS and inhibited the pasting process to a greater extent. Moreover, the viscoelasticity of the composite gel improved with increasing Mw, resulting in a denser and stabler structure. Additionally, the content of resistant starch increased following the addition of KGM, compared to pure starch (19.81 % ± 0.58), which partially suppressed the digestibility of SPS; Notably, this inhibitory effect intensified with higher Mw. Regarding relative crystallinity, it exhibited an inverse relationship with the Mw of KGM, with pure starch displaying the highest relative crystallinity at 12.2 %. In summary, the physicochemical and digestive properties of starch can be altered by the addition of KGM, irrespective of its Mw. These findings contribute to a deeper comprehension of how non-starch polysaccharides interact with starch.