Olive pomace is the main residue of the olive oil extraction process. It is a thick sludge – the remaining pulpy material after most of the oil is removed from the olive paste. To extract the remaining oil it contains, the olive pomace is treated with solvents. After refining and mixing this with edible virgin olive oil for flavor, aroma, and color, olive pomace oil is obtained. Olive pomace oil is used in cooking for its milder flavor and stability at high temperatures [1], as well as being nutritionally relevant due to its high oleic acid content (C18:1) [2]. Olive pomace fat analysis is necessary to check the efficiency of the oil removal process. The official method to determine this requires a time-consuming drying step followed by solvent extraction. Near-infrared spectroscopy (NIRS) is a fast, chemical-free method for olive pomace testing without any sample preparation.

The obtained NIR spectra of olive pomace samples (Figure 1) were used to create a prediction model for quantification of fat content. The quality of the prediction model was evaluated using a correlation diagram (Figure 2) which displays a high correlation between the NIR prediction and the reference values measured with Soxhlet extraction. The respective figures of merit (FOM) display the expected precision of a prediction during routine analysis.