Optimization of the Rheological Properties of Fat Replacers Based on Inulin at Different Degrees of Polymerization and Their Application in Beef Burgers

: Fats play a key role in the rheological and textural properties of meat products. However, growing awareness of the link between diet and disease has stimulated research on fat replacers that can replicate these functional properties. Inulin, a β-D-fructose polymer available in various degrees of polymerization (DP), is promising as a fat replacer due to its gel-forming ability in aqueous systems and its neutral sensory profile. This study focused on optimizing the formulation of inulin gel-based fat replacers for producing reduced-fat beef burgers. A D-optimal mixture-process design was employed, considering inulin with high-DP (HDP) and low-DP (LDP). The aim was to determine the optimal amount of inulin, water, and guar gum to achieve gels with rheological properties (η, shear viscosity; K, consistency index) similar to beef fat. The optimal formulations consisted of 51.52% inulin, 48.48% water, 1.50% guar gum for LDP gel, and 39.12% inulin, 60.88% water, 1.50% guar gum for HDP gel. These gels demonstrated shear viscosity and consistency indices comparable to beef fat. While rheological behavior at constant temperatures was similar, inulin gels showed increasing viscoelastic moduli (G' and G″) with temperature, in contrast to the melting behavior of animal fat. When used in beef burger formulations, the optimized gels resulted in improved cooking yields, reduced shrinkage, and better dimensional stability compared to conventional controls. These benefits are attributed to the hydrophilic and stabilizing properties of inulin. The findings support the use of inulin-based gels as effective fat replacers, offering a promising strategy to reduce fat content in meat products without compromising functional quality.