Olives and Olive Oil - Tropical and Subtropical Fruits: Postharvest Physiology, Processing and Packaging - page 502

of liquids is performed using natural decantation (oldest
method), centrifugation, or a combination of both. The ver-
tical centrifuge enables continuous liquid-liquid separation
by adding specific amounts of water.

it has a calorific value of around 4200 kcal/kg dry weight
(Civantos, 2008c).
As discussed earlier, the residual vegetable water from
the three-phase centrifugation system is highly pollutant
(COD 64500 mg/liter), which makes it necessary to re-
move the alpechin. One method for extracting this is the
use of alpechin evaporation ponds, which allows for the
subsequent use of the dried residue as organic fertilizer due
to its high potassium and phosphorus content. The major
drawbacks of this process are environmental since it tends
to incur odors, concentrations of insects, leaks, and so on.
Therefore another alternative is the application of alpechin
as irrigation fertilizer due to its high content of organic
material, absence of heavy metals and pathogens. Owing
to its properties, it is more recommended for use in base
soils rich in carbonates, and it is advisable to limit irrigation
doses. Finally, there are also alpechin treatment facilities
that use a variety of treatment systems. To date, however,
there has not been a wide implementation of these facilities
(Civantos, 2008c).

Storage and postharvest losses
Because olive oil extraction is concentrated into a few
months a year, it must be stored taking into account the
characteristics of the product and the possibility of alter-
ation. Storage must be done in easy-to-clean vats that are
made of impermeable and inert materials to avoid reactions
between the oil and the surfaces of the vat. These vats must
be kept at a temperature of around 15 ◦ -18 ◦ C, and sudden
temperature changes must be avoided that can cause alter-
ations in the vats. Traditional underground vats are best at
meeting these requirements because the coating (usually
vitrified refractory tiles) minimizes change, keeps it at a
constant temperature, and isolates it from light and air.
However, olive oil can also be stored in aboveground vats.
It is recommended that these vats be covered (protected
from atmospheric changes), coated in an inert material,
and have a conical bottom fitted with a drain valve (Alba,
2008).
Among the main causes for deterioration of olive oil
during its storage is prolonged contact with improper con-
tainer materials, such as metal containers. In addition, small
amounts of water (0.5%) (containing sugars, proteins, and
enzymes) remaining in the olive oil can cause fermentation
under certain temperature conditions and produce com-
pounds (such as short-chain fatty acids) that cause defects
in the oil. Lastly, note the oxidation of fatty acids, whose
action may be delayed by appropriate methods such as
avoiding head spaces, exposure to light, exposure to high
temperatures, and even exposure to high levels of metal
such as copper and iron (Di Giovacchino, 2003).
In general, olive oil is a product that has no expiration
date but does have a “best before,” date as established by
IOC standards (IOC, 2009).

Olive oil quality
In the United States, the US Department of Agriculture
regulations (USDA, 1948) were used to classify olive oil
into four categories: grade A or Fancy, grade B or Choice,
grade C or Standard, and grade D or Substandard. This
classification was made based on free fatty acid content
(calculated as a percentage of oleic acid), odor, flavor,
and absence of defects. The California Olive Oil Coun-
cil, a trade association of olive oil producers, petitioned
the USDA to revise the current US grade standards to con-
form to current industry standards commonly accepted in
the United States and abroad. In April 2010, the USDA
published the new United States Standards in the Federal
Register for olive oil grades, which become effective in
October 2010 (USDA, 2010) (Table 26.7). These stan-
dards are based on the physicochemical parameters used
in both the EU and the IOC standards, and consequently
in the olive oil world. The current standards of the EU on
the characteristics of olive oil and olive pomace oil are
reflected in the Official Journal of the European Union
(EU, 2003) (Table 26.7). IOC is the only international in-
tergovernmental organization in the field of olive oil and
table olives. Specifically, 94.7% of oils produced world-
wide are covered by the IOC. One of the objectives of the
IOC is to study and implement measures that harmonize
national legislation concerning the marketing of olive oil
and table olives, with a view to promote international trade
and to detect different types of fraud and adulteration that
could discredit the product and alter the balance of the

By-product utilization
Orujo, or solid olive pomace, is formed by dry material
in the olive, water and an oily residue. This material may
undergo a subsequent oil extraction in the extraction indus-
tries, or orujeras, obtaining olive pomace oil.
Similarly, the two-phase olive pomace, or alpeorujos,
is used to extract these second centrifuge oils (redo or
remilled), recovering between 35% and 50% of the oil
contained in the mass. In turn, the solid olive pomace ob-
tained after a second centrifuge can be used as fuel since