The harvest period is one of the most important
factors influencing olive oil quality. This period is extended
for several months and the late-extracted olive oils are
characterized by quality loss and reduced resistance to
oxidation. The aim of this work was to verify the effect of
olive leaves addition during the oil extraction process in the
olive oils quality and composition. In two consecutive years
(2009 and 2010), different olive leaves amounts (1%, 2.5%,
5% and 10% w/w) were added during the extraction process
of cv. Cobrançosa olive fruits, collected in the late season.
Standard quality parameters, oxidative stability, fatty acids
profile, tocopherols, chlorophylls, and carotenoids contents
were evaluated. Olive leaves addition induces a slight
increase in acidity, peroxide value, K232, and K270 without
compromising olive oils classification, but the resistance to
oxidation was significantly improved. Vitamin E increased
nearly 30% with 10% of leaves added mainly due to the
considerable increase in α-tocopherol. A similar effect was
observed in the contents of chlorophylls (chlorophyll a and
pheophytin a) and carotenoids (lutein and β-carotene), that
attributed a more intense greener pigmentation and enhanced
nutritional attributes. Significant correlations were
observed for several parameters with the amounts of leaves
added. Moreover, leaves addition modified the characteristics
and composition of the olive oils in a way that was
possible to discriminate and to classify each group.
