Relationships Among Acid Milk Gel Sensory, Rheological, and Tribological Behaviors

Abstract

Sensory evaluation is a useful technique to optimize the textural properties of semisolid foods. However, this method may not be time- and cost effective for all food products, particularly those needing rapid, low-cost development or troubleshooting. Rheometry can determine food mechanical behaviors that have been correlated to sensory attributes. Tribometry is a complementary measurement for rheometry since some textural attributes, e.g. smoothness and astringency, may be related to friction behaviors rather than viscosity or viscoelastic behaviors. Accordingly, the objective of this study was to determine the relationships among acid milk gel rheological, tribological, and sensory behaviors, as well as how addition of human whole saliva (HWS) during instrumental testing impacted these relationships. Textural attributes of 24 formulations of acid milk gels were evaluated using descriptive sensory analysis. Rheological and tribological behaviors of the acid milk gels were evaluated with and without the addition of HWS. Overall, several sensory attributes showed correlations with rheological and tribological behaviors, including critical strain, tanδ, complex modulus, zero shear viscosity, and flow behavior index, and friction coefficients at different sliding speeds. Viscosity parameters were correlated with mouthcoat, mouth viscosity, low-melting, smoothness, firmness, astringency, grittiness in mouth, and graininess. Friction coefficient at a sliding speed of 30 mm s−1 provided the best correlation to sensory attributes. However, chalkiness, graininess, and grittiness in mouth were correlated with friction coefficients at sliding speeds of 10–30 mm s−1. Changes in rheological and tribological behavior due to addition of HWS during instrumental testing impacted correlation strength and what parameters were correlated. The results of this study provide a better understanding of the relationships among acid milk gel rheological, tribological, and sensory relationships. This understanding can be helpful to develop textures of reduced- or non-fat semisolid foods that are similar to their full-fat counterparts.