Pectin molecular weight as a key determinant for designing functional yogurt textures: toward personalized nutrition

The texture of soft materials, such as yogurt, emerges from the complex interplay of their constituent molecules. While polysaccharides are widely used to modulate texture, achieving predictable outcomes is hindered by their structural heterogeneity. Here, we demonstrate that pectin molecular weight (Mw) acts as a master regulator for designing customizable yogurt textures through precise control of casein network assembly. By fractionating lemon pectin into discrete MW fractions, we achieved distinct viscoelastic landscapes in yogurt systems: intermediate Mw (20.01 kDa) induced weak, flowable gels by disrupting optimal pectin-protein interactions (electrostatic and hydrophobic interactions), whereas high and lower Mw (40.09 and 7.77 kDa) reinforced the network through enhanced protein-protein binding (disulfide bonding). This reveals a non-monotonic (U-shaped) dependence of gel strength on pectin chain length. Our findings provide a mechanistic framework for Mw-directed texture engineering, offering practical guidelines for developing texture-tunable foods tailored for vulnerable populations, such as the elderly and individuals with dysphagia. This work thereby advances the intersection of food science and human wellness.