Evaluation of the Functional and Rheological Properties of Grape Pomace Flour with Different Particle Sizes

Grape pomace, a by-product of the winemaking industry, contains nutritionally relevant compounds, including proteins, lipids, carbohydrates, phenolic compounds, vitamins, and dietary fibers. Given its functional and technological potential, this by-product has been valorized as a flour for use in food formulations. The particle size of the flour directly influences its physicochemical and rheological properties, affecting its performance in food matrices. This study evaluated the functionality of grape pomace flour with different particle sizes. Samples were subjected to drying, milling, and sieving, followed by the analysis of water absorption capacity (WAC; g water/g flour), oil absorption capacity (OAC; g oil/g flour), milk absorption capacity (MAC; g milk/g flour), water solubility (%), moisture retention capacity (g/g), and rheological properties (M.A.R.S iQ Air Rheometer, Thermo Scientific), including viscosity (Pa·s), elasticity, and flow behavior (Pa).

The results showed that the flour exhibited a high absorption capacity for all the tested solvents (water, oil, and milk), with values exceeding 1.5 g solvent/g flour, indicating strong potential for retention and interaction with both polar and non-polar components. These properties are particularly relevant for applications in food products requiring emulsifying stability. The gelling capacity was more pronounced at ratios of 1:1.5 and 1:2 (flour-to-water), with a significant increase in viscosity, suggesting the formation of a cohesive three-dimensional structure. Rheological analyses revealed a viscoelastic behavior suitable for structured food systems such as gels, emulsions, and moldable doughs. Moreover, samples with finer particle sizes showed improved functional performance, indicating greater technological potential for incorporation into value-added food formulations with specific texture and stability requirements.