From first bite to swallow initiation : an evidence-informed assessment framework for transitional foods in Dysphagia management : a thesis presented as fulfilment of the requirements for the degree Master of Speech and Language Therapy at Massey University, Albany, New Zealand

Abstract

Transitional foods, foods that undergo textural transformation from one texture to another through moisture or temperature changes during consumption, represent a promising dysphagia management approach, yet systematic evaluation frameworks specifically addressing transformation mechanisms are lacking. Current texture-modified food assessment practices focus predominantly on initial texture properties and pharyngeal safety outcomes, with limited attention to oral-stage transformation processes that define transitional food effectiveness. This study developed an evidence-informed evaluation framework for transitional foods through rapid systematic review and thematic synthesis of texture-modified food assessment literature. Systematic searches across four databases (PubMed, CINAHL, Cochrane Library, Scopus) identified 28 studies examining oral processing assessment approaches in texture-modified foods for adult populations. Data extraction systematically captured assessment components, methods, population characteristics, and quality indicators. Methodological quality was appraised using the Critical Appraisal Skills Programme tool and a purpose-developed assessment schedule, with thematic synthesis conducted using NVivo to identify patterns characterizing current assessment practices and gaps requiring framework specification. Systematic extraction identified 121 distinct parameters across nine conceptual domains. Assessment concentrated in rheological properties (43%), oral biomechanics (43%), and pharyngeal efficiency (43%), while transformation dynamics (29%) and saliva interaction (21%), the primary mechanisms distinguishing transitional foods from static texture-modified foods, remained substantially underrepresented. Quality appraisal revealed strong measurement practices (76% average measurement quality score) but design transparency gaps, with 82% of studies conducting reliability procedures yet only 18% reporting statistical reliability metrics. Only three studies specifically examined transitional foods as defined by IDDSI, necessitating framework development from broader texture-modified food literature. Thematic synthesis revealed six overarching patterns: safety-focused assessment highlighting underdeveloped oral transformation measurement; rheological testing dominance with static measurement bias; balanced method distribution masking functional imbalance across assessment stages; high-quality studies demonstrating methodological strengths alongside reporting gaps; multi method triangulation concentrated in established domains with limited integration of transformation mechanisms; and IDDSI framework adoption primarily for texture classification (46% of studies) with limited application as a measurement tool for transformation assessment (14%). These synthesis findings directly informed development of an eight-domain Evidence-Informed Transitional Food Assessment Framework addressing identified gaps through accessible, evidence-based methods. The framework mandates pre/post texture comparison to validate transformation occurrence, incorporates gravimetric saliva interaction assessment using precision scales, operationalises IDDSI testing as transformation measurement applicable to expectorated bolus, and integrates patient centred sensory evaluation alongside safety validation. The framework provides clinicians, researchers, and food industry stakeholders with evidence-based methods for systematic transitional food evaluation using globally accessible approaches, supporting evidence-informed food selection, prescription, and product development in dysphagia management.