Chemical composition of olive cakes resulting from various mills in Lebanon.

Olive cakes are a by-product of the olive oil industry. Their possible valorization in animal feeds requires the knowledge of their chemical composition. Whatever the mode of extraction of the olive oil, whether traditional, or with three phases or with two phases, the olive cakes present a variable chemical composition which is different from that of other oleaginous sources. The analysis of olive cake samples from different types of mills and collected in different areas of Lebanon shows that they present relatively high amounts of crude fiber (44-58%) and fat content (7-17%) and low amount of proteins (3-5%) and ash (2%). The polyphenols do not exceed 0.5% of the dry matter. More advanced analysis on the parietal fraction, by the method of Van Soest, made it possible to deduce the amounts of cellulose (32-37%), hemicelluloses (20-23%) and lignin (19-24%). The parameter most significantly varying as a function of the mill type is fat content. This result is confirmed by a Principal Components Analysis (PCA) based on the compositional variables. The olive cakes resulting from traditional mills are richer in fat contents than those resulting from mills with two or three phases. Lastly, the composition of the parietal components presents a slight, not very significant, variation for the different samples analyzed. This can lead to the conclusion that it is the same variety of olive which is treated with different extraction processes.