Butia is a wild native fruit (Butiá odorata) typical of the palm groves of Rocha (Uruguay), whose consumption and commercialization are growing. The shell and pulp are used to make many types of food (jams, sauces, chocolate fillings, etc.), but the seed is a processing waste. However, inside there are almonds with a high lipid content (45 %), which justifies its mechanical extraction. This results in a virgin oil that could be attractive for different applications (food, cosmetics and pharmaceuticals).
The present work evaluated the rheological behavior of the oil extracted from Butia seeds. Flow and viscoelastic behavior tests were carried out in an Anton Parr MCR92 rheometer using a parallel plate geometry (d=50 mm; gap=1 mm), with the objective of characterizing the oil and evaluating possible uses. For the selection of temperatures, a melting thermogram of the oil was used, which showed a single endothermic peak (Tp = 12 °C) that melting completely at 20 °C. The oil presented a non-Newtonian behavior at 8 °C (pseudoplastic), changing to Newtonian with increasing temperature (15, 25 and 37 °C). The viscosity decreased with increasing temperature reaching at 37 °C a value of 26 mPa.s. Oscillatory stress sweep test were performed at different temperatures (8, 10 and 12 degrees) which revealed in all cases a predominantly elastic behavior (G’ > G”), typical of fluids with high internal structure (high solid content at those temperatures). The linear viscoelastic region (LVR) was bounded with values of up to 0.01 % in deformation. The flow point (when the material became almost liquid-like behavior) was low in the three conditions analyzed (< 1,5 % in deformation), but a slight increase was observed with increasing temperature (weaker crystal lattice). Moreover, the temperature sweep test showed that the change from elastic to viscous behavior occurred at a temperature close to 17 °C. These results indicate that the oil exhibits rheological properties that are strongly dependent on temperature, from to a structured and elastic behavior at low temperatures (between 8-15 °C) to a more fluid and Newtonian profile at higher temperatures (> 15 °C). These characteristics suggest the potential of this oil for applications where texture and temperature are critical, especially for food (such as spreads, fillings and emulsions) and cosmetic formulations.