**3.2 Obtaining crude oil**

Three important steps should be considered for obtaining the crude oil, which directly affects the oil quality and product yield, including the storage of the raw material, preparation, and extraction of the crude oil. The variation in moisture content and temperature during fruit storage can trigger enzymatic and oxidation reactions, leading to a reduction in the quality of the oil extracted due to the increase in free fatty acids and other degradation compounds, known as peroxides [20].

The proximate composition of the macauba fruit consists of 47.76% and 32.05% lipids in the kernel and pulp, respectively; thus, continuous pressing is the most suitable method for oil extraction due to the high lipid contents [36, 59].

The screw-type press, also known as screw expeller, is a continuous press in which the fruit pulp or kernel is fed into a thick-walled cylinder containing a rotating, polished screw with gradually decreasing size. The oil from the plant cell is in the form of globules covered by a cell membrane. A typical characteristic of plant cells is the presence of thick cell walls; thus, the cell wall should be broken down to get the oil globules out. For that, the pulp or kernel cluster is fed continuously into the press and compressed at high pressure (4–35 MPa). In turn, while the oil is extracted, the compressed fruit cake is discarded at the end of the stretch. The high-energy consumption generated during shearing can considerably increase the temperature of both the oil and cake [20].
