Effect of Carrot-to-Water Ratio and Xanthan Gum Concentration on the Textural Properties of Carrot Purée

Carrot purées were prepared at carrot-to-water ratios of 1:0.25, 1:0.50 and 1:0.75 (w/w), with 0, 1.5, 2.0 or 2.5% (w/w) xanthan gum (XG), to examine how formulation affected International Dysphagia Diet Standardisation Initiative (IDDSI) Level 4 performance and instrumental texture. Twelve formulations were assessed using the IDDSI Fork Drip and Spoon Tilt Tests, texture profile analysis for hardness, adhesiveness and cohesiveness, and laser-diffraction particle-size measurement. All three formulations without XG failed the Fork Drip Test, whereas all nine XG-containing formulations passed. However, only C50/2.5, prepared at a carrot-to-water ratio of 1:0.50 with 2.5% XG, also passed the Spoon Tilt Test; therefore, only 1 of 12 formulations (8.3%) met both IDDSI Level 4 criteria. Across the formulation set, plotted mean hardness ranged from approximately 950 to 3,180 N/m², adhesiveness from approximately 640 to 1,810 J/m³, cohesiveness from approximately 0.25 to 0.85, and volume-weighted mean particle diameter, D[4,3], from 266 to 416 μm. Although 9 of 12 formulations passed the Fork Drip Test, only one formulation passed both IDDSI tests. This shows that passing one IDDSI test did not mean that a formulation met the full Level 4 requirements. The results showed that successful Level 4 performance depended on the combined effect of carrot-to-water ratio and hydrocolloid concentration. The instrumental results also showed clear differences in texture and particle size between the formulations. As only one formulation met both IDDSI criteria, C50/2.5 was selected as a provisional reference formulation for further optimisation.