An agar structured fluid prepared by pipe wall shear as a dysphagia diet

The risk of dysphagia in the elderly has gradually become a social problem. An important strategy is to modify the food texture to reduce aspiration risk. Microgel, a structured fluid usually prepared by Couette flow and jacketed stirring, has attracted much attention due to its unique rheological properties and complex microstructure. This study proposed a continuous production process of agar structured fluid through pipe wall laminar shear. The rheological properties and particle size distribution of the agar microgel were characterized. The morphology of microgel and its interaction with water molecules were examined through scanning electron microscopy (SEM) and low-field nuclear magnetic resonance (LF-NMR), and some positive feedback examples were obtained through the videofluorographic swallowing study (VFSS). A molecular model was proposed in which agar microgel is a supramolecular structure with a multidomain weak interaction, whose “hairy” structure is the site of domain-domain interaction. Agar microgel as a structured fluid can achieve higher yield stress and elastic modulus at the same concentration compared to xanthan gum solution, which is expected to be the next cost-effective and age-appropriate pre-thickened diet for older adults with dysphagia.