Effects of gel texture and oral processing on structural breakdown and bolus properties of fibrous whey protein-wheat starch composite emulsion gels.

Texture-oral processing interactions are crucial for bolus formation and nutrient release. This study examined oral processing of fibrous whey protein-starch emulsion gels with different hardness levels. Using an in vitro oral model, the effects of saliva volume, cutting level, and compression on bolus properties, starch digestion, and emulsion breakdown were evaluated. Oral processing promoted gel fragmentation, generating small particles (<30 mm2) and markedly reducing hardness (10-30-fold) and viscoelasticity. Initial gel hardness mainly governed bolus particle size and oil droplet release, while oral processing parameters, especially salivary volume and compression, mainly influenced bolus rheology. Saliva volume was also the dominant factor governing starch hydrolysis, while cutting level had limited impact. Notably, softer gels showed lower sensitivity to oral processing variations, indicating better swallowing suitability. Overall, these results demonstrate the synergistic roles of gel structure and oral dynamics in regulating bolus properties, offering insights for designing safer, nutritionally optimized dysphagia-friendly foods.