Annatto seed oil (ASO) and cupuassu seed fat (CSF) were combined at the ratios: 30:70, 50:50, and 70:30 (% w/w). Their fatty acid profile, nutritional quality, FTIR (Fourier Transform Infrared) spectra, and rheological behavior were evaluated. ASO increased the content of polyunsaturated fatty acids in the blends; whereas CSF conferred higher contents of monounsaturated fatty acids. The blends exhibited low atherogenicity and thrombogenicity indices, suggesting nutritional advantages. The Newtonian fluid behavior and FTIR results suggested that mixing ASO and CSF at different proportions did not affect the functional groups. ASO showed an activation energy value which indicated that this fat viscosity was more sensitive to temperature changes. The Newtonian model proved to be suitable to describe the behavior of samples, according to statistical fit parameters R2, χ2, and RSS. The resulting blends presented improved physicochemical properties and nutritional attributes, indicating their feasibility for the development of new products.

Enzyme-assisted extraction is considered an environmentally friendly technique. Cellulase, pectinase and protease were tested for cupuassu seeds fat extraction. The best fat efficiency (81.66%) was obtained for the solute:solvent 1:5 (m:w), orbital shaker at 120 rpm, 60 °C, for 8 hours and enzyme concentrations (cellulase, pectinase and protease) of 1.0%. The fat was characterized for physicochemical properties, fatty acid profile, phenolic compounds, antioxidant activities and oxidative stability. The fat showed good thermal stability (14.26 h) and high contents of monounsaturated (42.42%) and saturated (43.47%) fatty acids with higher concentrations of oleic and stearic acids, respectively, and a high content of phenolic compounds (141.84 µg EAG·g-1) in the fat, and in the aqueous extract (926.47 µg EAG·g-1). The results indicated that the cupuassu seed fat obtained by enzymatic extraction showed superior properties to cupuassu fat obtained by cold pressing, in addition to generating an aqueous fraction which is rich in bioactive compounds that can be used as ingredients in the food and pharmaceutical sectors.