The main biochemical characteristics of the three types of OPs are
reported in Table 2. Olive cake C had the highest total polyphenol
concentration, followed by OPB, whereas OPA had almost half the
quantity of OPC. The most abundant phenols were 3,4-DHPEA-EDA
and verbascoside. OPs B and C were also very rich in p-HPEA-EDA.
A reverse order was observed for the peroxide number and free
acidity (OPA>OPB>OPC). As a consequence, the concentration
ratio between peroxide number and ortho-diphenols was higher in
OPC than in the other two OPs, suggesting a higher oxidative stability.
Gas-chromatography analysis of OP lipids revealed that oleic acid
was the predominant FA in all of the OPs, with the highest concentration
found in OPC, followed by OPB. As a result, OPC had a 2-fold
lower saturated/unsaturated ratio compared to OPA and OPB. Of all
the OPs, the proportion of the PUFA n−6 series was higher than in
the PUFA n−3 series