Effect of inulin gel with different degree of polymerization and cooking methods on low-fat beef burger quality and safety

The present study investigated the incorporation of inulin-based gels with different degree of polymerization as partial fat replacer in low-fat beef burgers, assessing their effects on physicochemical, nutritional, and sensory properties in comparison with traditional full-fat burgers used as control (12 g/100g beef back fat in the recipe). Then, the influence of different cooking methods (gas-griddle, infrared broiling, combi-oven, and sous-vide) on the formation of hazardous heterocyclic aromatic amines (HAAs) was also evaluated. Multivariate analyses (PCA and PLS-DA) revealed a clear separation between conventional and low-fat formulations, identifying fiber, carbohydrate and lipid content, chewiness, and sensory parameter of colour intensity as the key variables contributing to sample differentiation (VIP ≥ 1). Incorporation of inulin-based gels significantly increased dietary fiber (mean 3.20 g/100g and 3.72 g/100g for HDP and LDP, respectively), meeting the "source of fiber" claim (Regulation (EC) No 1924/2006), while reducing lipid content from 16.37 g/100g (control) to 11.67-11.32 g/100g in reformulated samples. Textural analysis reported a marked decrease in chewiness (from 35.67 N in control to 22.83-22.69 N in inulin burgers), indicating a more tender structure. From a food safety perspective, both the formulation and cooking method significantly affected heterocyclic aromatic amine levels, with the latter exerting the strongest effect (p < 0.05). Total HAAs content was highest in infrared broiling (35.5 ng/g) and gas-griddle (22.1 ng/g), whereas no HAAs were detected in sous-vide samples.