This article reports an infrared spectroscopic study, using attenuated total reflectance (ATR-FTIR), on the structural characteristics of lipids in frankfurters as affected by different strategies to replace animal fat with chia flour and olive oil. Three incorporation strategies were considered: direct addition (FCO) and addition in a conventional emulsion (non-gelled) (FCE) or an emulsion gel using alginate as a gelling agent (FCEG). Reduced-fat (all-pork-fat) frankfurters (FP) were used as reference. Proximate composition and specific technological properties (pH, processing loss, texture) were also evaluated. FCE and FCEG frankfurters showed a shift to higher frequencies and the highest (p<0.05) half-bandwidth in the νasCH2 and νsCH2 bands. These spectroscopic results could be related to the fact that the lipid chain was more disorderly in these samples, presumably because there were more lipid interactions than in the reference frankfurter. These features of lipid structure correlated significantly with processing loss and textural behaviour.