Fabrication of Charged Self-Assembling Patchy Particles Templated with Partially Gelatinized Starch

Starch, as a staple carbohydrate, is frequently used as a thickener to enhance food texture. As such, there is an increasing interest in studying starch modification to improve its thickening ability. Instead of the conventional mechanism of swelling-based thickening, the present work presents an alternative using starch-based patchy particles as a texturizer prepared through a bottom-up method by physically grafting small amaranth starch granules (∼1 μm) onto corn starch granules (>10 μm). After thermal treatment in aqueous ethanol, starches were partially gelatinized, and the particle stiffness was reduced. The corn starch and amaranth starch were modified to carry a negative charge and a positive charge, respectively. The hydrated swollen starch granules were centrifuged and dehydrated, which stitched particles together, forming a corona-shaped patchy structure with a negatively charged core and positively charged patches. The electrostatic interaction allowed particles to associate, and the pockets created in the flocs were able to trap more water. The enhanced water-holding capacity consequently contributed to a significantly higher storage modulus, loss modulus, and viscosity compared to the native starch and the mixed charged starch with the same blending ratio between amaranth and corn starch. The enhanced viscoelasticity was not affected by cooking and mechanical stress, which could be used as a shear-reversible thickener to modify texture with less raw ingredients, thus helping to reduce the amount of energy-dense starch in diets. This is the first time that the concept of patchy particles has been extended to food-grade ingredients with a facile and scalable method.