Influence of fat on the perceived texture of set acid milk gels: a sensory perspective

Correlation of sensory perception of texture with instrumental parameters is key to understanding how specific structure formation can influence the consumer acceptability of a food product. Experimental acid milk gels with different solids-non-fat content (10–20%, w/v), with and without added fat (0–4% fat, w/v), were manufactured and characterised using quantitative descriptive analysis, confocal microscopy and small/large deformation rheology. Confocal micrographs of the gels showed that the gel structures were in agreement with the perceived sensory textural differences, in that the addition of fat, up to 4% (w/v), caused major changes in the microstructure of the network and in the overall perception of texture. This was observed mainly at low total solids levels (10–14%); no significant changes in microstructure or sensory perception of texture were detected at high total solids levels (above 18%), regardless of fat addition. The main effects of increasing fat content in the gels were a decrease in the mean pore size and an increase in the average cluster size. Added fat also caused the gels to become firmer, more resistant to penetration, more cohesive and sticky, creamier and less compressible before fracture (less ‘give’). Both instrumental and quantitative microstructural image analysis results correlated with perceived texture, and, when used in combination, these data sets generated an estimated model with satisfactory predictive ability for textural parameters as assessed by a trained panel (pred r2=96.3%).