## 3 Results and Discussion
### Chemical Composition of Olive Cakes
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{\
\begin{tabular}{c} **Chemical** \\ **Composition** \\ **(\% DM)** \\ \end{tabular} } & \multicolumn{4}{c}{**Olive Cakes**} \\ \cline{2-7}  & **EOC 1** & **EOC 2** & **TPOC (Pittted)** &
\begin{tabular}{c} **TPOC** \\ **(Dehydrated)** \\ \end{tabular} & **COC 1** & **COC 2** \\ \hline DM & 90.16 \(\pm\) 0.03 b  & 89.79 \(\pm\) 0.03 b  & 35.41 \(\pm\) 0.74 e  & 96.76 \(\pm\) 0.54 a  & 69.62 \(\pm\) 0.30 c  & 65.53 \(\pm\) 0.47 d  \\ OM & 94.15 \(\pm\) 0.01 d  & 93.54 \(\pm\) 0.01 e  & 91.20 \(\pm\) 0.00 f  & 97.61 \(\pm\) 0.00 b  & 96.91 \(\pm\) 0.10 c  & 98.42 \(\pm\) 0.02 a  \\ NDF & 67.97 \(\pm\) 0.16 b  & 65.09 \(\pm\) 0.92 c  & 57.43 \(\pm\) 0.02 d  & 75.72 \(\pm\) 0.98 a  & 67.68 \(\pm\) 0.27 b  & 77.98 \(\pm\) 0.25 a  \\ ADF & 36.77 \(\pm\) 1.26 c  & 52.36 \(\pm\) 0.51 b  & 51.18 \(\pm\) 0.3 b  & 54.31 \(\pm\) 1.57 b  & 52.27 \(\pm\) 0.27 b  & 57.68 \(\pm\) 0.14 a  \\ ADL & 24.19 \(\pm\) 0.01 bc  & 25.63 \(\pm\) 0.23 ab  & 23.32 \(\pm\) 0.97 c  & 25.87 \(\pm\) 0.16 a  & 26.16 \(\pm\) 0.09 a  & 26.53 \(\pm\) 0.04 a  \\ CEL & 25.67 \(\pm\) 0.17 b  & 26.74 \(\pm\) 0.28 b  & 27.87 \(\pm\) 0.67 b  & 28.45 \(\pm\) 1.72 ab  & 26.11 \(\pm\) 0.18 b  & 31.15 \(\pm\) 0.17 a  \\
**CP** & 6.84 \(\pm\) 0.72 a  & 7.26 \(\pm\) 0.36 a  & 6.75 \(\pm\) 0.11 a  & 6.75 \(\pm\) 0.11 a  & 6.33 \(\pm\) 0.08 ab  & 5.38 \(\pm\) 0.02 b  & 6.50 \(\pm\) 0.13 ab  \\
**CF** & 1.51 \(\pm\) 0.05 d  & 1.45 \(\pm\) 0.04 d  & 10.03 \(\pm\) 0.06 b  & 9.14 \(\pm\) 0.08 bc  & 14.5 \(\pm\) 0.59 a  & 8.43 \(\pm\) 0.43 c  \\ \hline \hline \end{tabular}  
* EOC: Exhausted olive cake; TPOC: two-phase olive cake; COC: crude olive cake. DM: dry matter; OM: organic matter; NDF: neutral detergent fibre; ADF: acid detergent fibre; ADL: acid detergent lignin; CEL: cellulose; CP: crude protein; CF: crude fat. Mean \(\pm\) standard deviation of determinations (\(n\) = 2). Different letters in the same column correspond to significant differences between species (\(p\) < 0.05). ANOVA followed by a post hoc Tukey test.  
\end{table} 
Table 2: Chemical composition of the olive cakes (g/100 g). mately 25% moisture content, while two-phase mills tend to produce cakes with higher water content due to the inclusion of the entire aqueous phase from the olive [41]. Comparing olive cake composition across studies proves challenging due to diverse influencing factors. These include olive origin, fruit ripeness, agronomic practices, soil and climate conditions during cultivation, extraction processes and oil storage conditions. Despite these challenges, comprehending an olive cake's variable composition is crucial for optimising its utilisation across various industries [43; 44; 45; 46]. As expected, the CF content was significantly lower in the EOCs (\(p<0.001\)). This is due to the fact that, in mills, this olive cake is commonly subjected to a final extraction process with a solvent (hexane) to remove the oil from the cake [47; 48]. COC had the highest CF content (mean of 14.40 \(\pm\) 0.51). This olive cake is obtained by pressing in traditional mills and stands out for having an intermediate dry matter content, low levels of crude protein and a high fat content [49; 50; 51]. The CF content in the COC (8.43-14.5 g/100 g) is in line with the literature for this extraction system, demonstrating consistency with the literature, where other authors have found values ranging from 3.3 to 16.2 g/100 g of CF for cakes from the same extraction system [52; 53; 54]. On the other hand, the results obtained for olive cakes from the two-phase extraction system (TPOCs) showed values ranging from 9.0 to 10.0%, in contrast to the findings of other authors, who reported content of 13% for olive cakes from the same extraction system [48]. Distinguishing between the three-phase and two-phase extraction systems is fundamental.