Rheological enhancement of dysphagic emulsions using biopolymer mixture of rose cactus (Pereskia bleo) mucilage–pea protein isolate coacervate and locust bean gum

Rose cactus mucilage (RCM), extracted from Pereskia bleo leaves, has the potential to form complex coacervates with pea protein isolate (PPI) via electrostatic interactions. Such complexes may enhance emulsion systems through improved protein functionality and rheological behaviour. While texture-modified foods are widely used in dysphagia care, few studies have systematically examined how rheological properties are influenced by ingredient interactions during formulation. This study aimed to evaluate the effects of RCM–PPI coacervates and locust bean gum (LBG) on the rheological properties of dysphagia-oriented beverage emulsions, focusing on viscosity at 50 s⁻¹ shear rate (η₅₀), flow index, yield stress, and viscoelastic moduli, using response surface methodology (RSM). RCM–PPI coacervates were prepared at a mixing ratio of 8:2 (RCM:PPI), optimized at pH 3.6 to achieve maximum electrostatic interaction. Scanning electron microscopy confirmed coacervate formation, revealing spherical protein globules bound to the wrinkled RCM surface, indicating strong biopolymer interaction. The emulsions were formulated using a two-factor face-centered central composite design (14 runs) with RCM–PPI (10–16% w/w) and LBG (0.4–0.8% w/w) as independent variables. RSM optimization identified 11.4–13.2% RCM–PPI and 0.4–0.6% LBG as optimal for achieving the desired rheological profile. The results demonstrate the synergistic role of RCM–PPI coacervates and LBG in tailoring rheological properties suitable for honey-thick dysphagia beverages. This study provides new insights into mucilage–protein interactions and supports the application of plant-based biopolymers for designing rheology-modified foods with clinical relevance.