Abstract
This study investigated the complete replacement of pork backfat in frankfurters with inulin-based emulsion gels made from linseed, walnut or algal oil and structured in two ratios (1:2:0.5 and 1:2:1, oil-water-inulin). Proximate composition, water holding capacity, emulsion stability and colour were assessed after production, while texture profile analysis (TPA) was monitored during 45 days of vacuum storage. The reformulated sausages showed a significant reduction in fat content (from 21.91% to 3.81%, p < 0.001) and increased water and carbohydrate levels (p < 0.001). These shifts in composition resulted in a slightly lower pH, higher cooking and purge losses and lower emulsion stability (p < 0.001), particularly when treated with algal oil. Colour measurements revealed lighter (higher L*, p = 0.008) and more yellowish sausages (p < 0.001), with walnut oil at a 1:2:0.5 emulsion ratio showing the least deviation from the control (ΔE = 7.45). The TPA showed that oil type was the dominant factor. Walnut formulations, especially in the 1:2:1 ratio, had hardness and chewiness values closest to those of the control, while algal sausages were softer and less cohesive (p < 0.05). PCA and heatmap analyses confirmed clustering by oil type and storage time, underlining the technological suitability of the walnut gels. Overall, inulin-oil gels enable nutritional reformulation but pose a technological challenge, with walnut oil proving to be the most promising substitute and algal oil requiring additional stabilisation.