Investigation of 3D-printable chickpea-mealworm protein mixtures and their bolus rheology: A soft-textured and safe-swallowing food for the elderly

Abstract

Eating and swallowing food are major challenges for the elderly with dysphagia. Three-dimensional (3D) food printing allows the creation of elderly food with nutrition, attractive shapes, and soft texture customizations. This study aimed to investigate the printability of soft-textured food (the mixture of chickpea protein isolate (CPI) with mealworm protein isolate (MPI) gel) by using single-nozzle printing (SNP) and coaxial printing (CoP) techniques. Artificial food boluses were prepared and their rheological properties were determined to understand safe swallowing. In the CoP system, extrusion pressure delivered alginate hydrogel (AH) as an outer fluid to support the structure of fragile food ink, resulting in printability and structural stability. Foods produced using the SNP technique exhibited printing failure. All printed foods exhibited a lower hardness value of ≤5 × 103 N/m2, corresponding to stage 4 of the universal design food (UDF) guideline. After oral food process simulation, the artificial CoP bolus showed significantly higher values of viscoelasticity, yield stress, and viscosity than the SNP and control boluses. This suggests a favorable cohesive bolus form that can prevent pulmonary aspiration during food swallowing. The CoP bolus displayed a denser microstructure due to the binding effect of the alginate molecules with positive electrolytes in the artificial saliva, which agreed with its higher rheological properties. This study successfully transformed unprintable soft food to be printable with an attractive 3D printing food shape using CoP technique as personalized food for the elderly. Additionally, this study provided insight into the relationship between bolus rheology and safe swallowing management.