Note: Descriptions are shown in the official language in which they were submitted.
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A METHOD FOR TREATING OLIVES TO BE UTILIZED FOR OLIVE
OIL PRODUCTION
BACKGROUND OF THE INVENTION
FIELD OF THE INVENTION
The present invention generally relates to olive oil production and more
specifically to olive oil production at a prolonged time after olive
harvesting.
DISCUSSION OF THE RELATED ART
Olive oil is produced by grinding fresh olives into a paste and extracting the
oil from the paste by mechanical or chemical means. The amount of oil
contained
in the olive depends on the particular cultivar and the degree of ripeness.
Typically
1 Kg of olives yields about 150 - 200ml of oil. The oil is accumulated in the
mesocarp cells, mostly in the vacuoles and to a smaller extent in the
cytoplasm.
Grinding or crushing of the olives breaks the olive stones and flesh, creating
a
paste. Typically, grinding is followed by malaxation of the paste to
facilitate
breaking of the mesocarp cells, assisted by the sharp stone segments, thus
releasing the oil contained in the vacuoles and resulting in coalescence of
the oil
droplets and separation of the liquids from the solids. The liquid, which
contains
both oil and vegetation water, is extracted from the paste by applying
pressure or
centrifugation and is then separated into oil and water. Depending on the
specific
method and equipment, the separation of the paste into liquid and solid and
the
separation of the liquid into oil and water may be performed sequentially or
concurrently. There exist various modifications of these basic steps. For
example,
the method known as "Sinolea" is based on the different surface tension of the
vegetable water and the oil. According to this method, rows of metal discs or
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plates are dipped into the paste. The oil adheres to the metal disks and is
removed
with scrapers in a continuous process while the solid and water phases stay
behind.
The quality of olive oil depends on the extraction method, the olive
cultivar, the maturity (ripeness) index of the olives and also, to a great
extent, on
the time delay between olive harvest and oil extraction. Because olive oil is
extracted from the fruit flesh, the time elapsing from harvesting to oil
extraction is
very crucial. In the period between harvesting and oil extraction, the fruits'
enzymes are very active. The oxidation and enzymatic reactions, which begin in
the fruit immediately upon harvesting, increasingly degrade the quality of the
oil.
Therefore, olive oil needs to be extracted from the fresh harvested olives as
soon
as possible, preferably within no more than 24 hours. Oil obtained after a
longer
wait is of lower quality presenting higher acidity levels. Thus, unlike seed
oils (e.
g., sunflower oil, sesame oil, soybeans oil, etc.) which are extracted from
seeds or
nuts that can be stored for prolonged time and processed all year round, the
olive
oil industry is a seasonal industry which depends on availability of fresh
olives.
Harvesting time varies in each country and with the season and the cultivar.
Generally, fresh olives are available for about four months during opposing
seasons in the Northern and Southern hemispheres (October to January in the
Northern Hemisphere and April to July in the Southern hemisphere). Another
important factor that influences the oil quality is the freshness of the olive
oil
itself, namely the storage period and the storage conditions until
consumption.
Olive oil, even when stored under optimal conditions, deteriorates over time.
It is
therefore recommended to consume olive oil close to its production time.
The quality of olive oil can be characterized by various analytic and
organoleptic parameters, the most common being the free fatty acid (FFA)
expressed as percent of oleic acid. Other characteristics include peroxide
value
and various positive and negative organoleptic attributes. Most countries use
the
International Olive Council (IOC) standards for defining oil quality and oil
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category. The IOC, which has a United Nations charter to develop criteria for
olive oil quality and purity, consolidates standards for olive oils categories
as well
as guidelines for analyzing and tasting the oils. For example, olive oils that
can be
qualified under the category of virgin olive oils are oils that are obtained
from the
olives by using only mechanical or other physical means which do not involve
any
chemical processes such as use of solvents or re-esterification. Additionally,
they
should meet the specific standards set by the IOC with regard to the
concentration
of specific ingredients and organoleptic tests. Within the Virgin Olive Oil
category, the oils fit for consumption are classified as Extra Virgin Olive
Oil,
Virgin Olive Oil and Ordinary Virgin Olive Oil according to their FFA level (<
0.8%, < 2% and < 3.3, respectively).
Olive oil production is a traditional industry originating in the
Mediterranean and known since as early as 3,000 B.C. Today, olives are
cultivated
in many regions of the world and olive oil is used throughout the world.
However,
olive oil production and consumption is still the highest in the
Mediterranean. The
oil is considered to be a prime component of the so called 'Mediterranean
diet'.
In recent years, the olive oil market has been growing dramatically. The
increasing interest in olive oil stems from both its unique rich taste and its
health
benefits and coincides with the growing public awareness to health food, as
well
as with the general increasing interest in gourmet food. The health benefits
associated with olive oil consumption include controlling LDL level while
raising
HDL level and reducing risk of coronary heart diseases. These health benefits
are
attributed to the high level of monounsaturated fatty acids, mainly oleic
acid, and
to the relatively high content of minor nutrients, in particular anti-oxidants
such as
polyphenols. Studies also suggest beneficial effects of olive oil consumption
on
blood sugar level and on the gastrointestinal tract, including reducing the
risk of
ulcers, gastritis and colon cancer. Indeed, olive oil is considered by many to
be
superior to other vegetable oils. However, side by side with the prosperity in
the
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olive oil market, the olive oil fraud industry flourishes as well. Olive oil
is one of
the most adulterated agricultural products. Customers are therefore becoming
increasingly aware of the possibility that oil distributed as high quality
olive oil is
actually adulterated oil mixed with, or even consists almost entirely of,
inferior
oils of lower cost.
The awareness to health food products, as well as to their freshness and
authenticity, has brought with it a new trend of small scale production of
basic
food products (e.g. bread) for self consumption at home or in small food
establishments such as restaurants, delicatessen and specialized boutiques.
This
way control over freshness and ingredients is ensured. In accordance with this
trend, small scale appliances, sized to be placed on a kitchen counter, such
as
bread machine, home-use coffee roasting device, etc., are now gaining
popularity.
With respect to olive oil, recent years show an increasing number of olive oil
boutiques which specialize in production of high quality oil by careful
selection of
olives and close control over production. A household countertop cold press
machine for producing small quantities of olive oil designed by the inventors
of
the present invention is described in international publication W02010/007610.
However, although olive oil can be consumed as is when freshly pressed from
the
fruit, the need to extract olive oil within a very short time from harvesting
does not
enable producing olive oil out of season or in countries distant from olive
growing
regions.
It is therefore the general object of the present invention to provide olives
suitable for oil extraction all year round and/or at locations remote from
olive
growing regions.
In particular, it is an object of the invention to provide olives which retain
their oil qualities for a prolonged storage period without adding chemical
food
preservatives.
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It is a further object of the invention to provide methods for treating
freshly
harvested olives to substantially retain their oil quality for a prolonged
time after
being treated so as to enable extraction of high quality oil from the olives
at a
prolonged time after they have been harvested.
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SUMMARY OF THE PRESENT INVENTION
One aspect of the invention is a method for treating freshly harvested olives
to substantially retain the quality of oil contained therewithin for enabling
production of high quality olive oil from said treated olives at a prolonged
time
after harvest. The method comprises: washing the freshly harvested olives in a
washing liquid; heating the olives to a temperature sufficient to achieve
enzymatic
inactivation; rapidly cooling the heated olives to a temperature in the range
of 0 to
-10 C; vacuum packaging a predetermined quantity of olives; and storing the
packed olives at a refrigerating temperature. The specific conditions in each
step
of the method are preselected in accordance with the cultivar and maturity
index
of the treated olives. The washing liquid may be water or ethanol or a mixture
thereof. The heating may be performed by subjecting the olives to microwave
radiation or by immersing the olives in a liquid bath of said predetermined
temperature. In accordance with some embodiments of the invention, a salt or a
mineral powder is added to the treated olives before packaging. The salt or
mineral
powder may be NaCl, KCI, NAHCO3, talcum powder and lime powder, or a
combination thereof.
Another aspect of the invention is treated freshly harvested olives with
retained oil qualities characterized in that the oil extracted from the
treated olives
at a prolonged storage time after being treated is characterized by having a
Free
Fatty Acid (FFA) level of no more than 2%. According to some embodiments of
the invention, the treated freshly harvested olives with retained oil
qualities are
obtainable by the method described above and are characterized in that the oil
extracted from the treated olives at a prolonged storage time after being
treated is
characterized by having a Free Fatty Acid (FFA) level of no more than 2%.
According to some embodiments, the Free Fatty Acid level may be of less than
or
equal to 0.8 %. The prolonged storage time is of at least one month. The
prolonged
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storage time is of at least one month. For some embodiments, the prolong
storage
time may be of at least three months or of at least six months. Preferably,
the oil
extracted from the treated olives after a storage time of at least 2 months
has a
Free Fatty Acid (FFA) level which does not exceed the FFA level in the oil
extracted at the time immediately after treatment by more than 1%. Preferably,
the
freshly harvested olives are treated within 24 hours from being harvested and
are
vacuum packaged and kept at refrigerating temperatures until use. Extraction
of oil
from the treated olives of the invention for the purpose of measuring FFA
level or
other parameters is preferably performed by using an Abencor system.
According to some embodiments of the invention the oil extracted from the
treated olives after the prolonged storage time is further characterized by
having a
peroxide value that meets the standard of the International Olive Council
(IOC) for
peroxide value in Virgin Olive Oils and/or organoleptic characteristics that
meet
the standards of the International Olive Council (IOC) for organoleptic
characteristics of Virgin Olive Oils.
Yet a further aspect of the invention is a vacuum package comprising
treated olives of the invention, optionally further comprising a salt or
mineral
powder selected from one or more of the following: NaCl, KCI, NaHCO3, talcum
powder and lime powder.
BRIEF DESCRIPTION OF THE DRAWINGS
The present invention will be better understood and appreciated from
the following detailed description taken in conjunction with the drawings in
which:
Fig. 1 is an overall flow chart illustrating the method of treating freshly
harvested olives in accordance with an embodiment of the present invention.
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DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The present invention is generally directed at enabling off-seasonal
olive oil production and/or at areas remote from olive growing regions. In
accordance with the invention, freshly harvested olives are treated to
substantially
retain their oil qualities for a prolonged time after treatment such that when
stored
under appropriate conditions they can be used as a "raw material" for olive
oil
production at a prolonged time after being harvested. The treated olives can
be
stored for at least one month and up to at least ten months or even for longer
periods, providing the capability to produce fresh olive oil all year round.
Preferably, the treated olives are packaged into relatively small quantities
of 0.5 to
Kg that can be shipped and distributed to retailers and consumers. Preferably,
the treated olives maintain the appearance and texture of fresh olives.
The oil extracted from the stored treated olives of the invention is
characterized by having Free Fatty Acidity (FFA) of no more than 2% and other
characteristics, such as peroxide value and organoleptic characteristics that
meet
the standards of the International Olive Council (IOC) for the category of
Virgin
Olive Oils. In this respect, it should be emphasized that in the context of
the
invention, extraction of oil mainly refers to purely mechanical or other
physical
extraction methods that do not involve chemical processing. Thus, the
expression
"oil extracted from the treated olives" should be understood as oil extracted
by
purely mechanical or other physical means. More specifically, since even when
the oil is extracted by purely mechanical means, its composition may vary with
specific method and specific conditions, extraction of oil from the treated
olives of
the invention for the purpose of assessment is preferably performed using an
Abencor system.
The invention further provides methods for treating freshly harvested
olives to substantially retain their oil qualities for a prolonged storage
time under
refrigerating temperatures without adding any chemical food preservative.
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The olives selected to undergo the treatment process of the invention
should be freshly harvested, high quality olives carefully selected. Any
bruised,
defected or otherwise poor quality olives and any twigs, stems and leaves
should
be carefully removed before treatment. The selected olives may be of any
maturity
index, preferably in the range of 2-6, and of any olive cultivar, or a mixture
of
different cultivars. In accordance with some embodiments of the invention, the
olives are organically grown olives.
Fig. 1 is a flow chart of the process of treating freshly harvested olives,
in accordance with an embodiment of the invention. The process may be
performed in a batch manner or may be a continuous process with any degree of
automation. In order to obtain high quality oil from the end product of the
process,
the treatment is preferably performed within 24 hours from harvesting. The
exact
conditions in each step (e.g. temperatures, duration of step, etc.) vary with
the
specific cultivar and maturity index of the treated olives and are pre-
selected for
each cultivar/maturity-index combination to optimize results.
Referring to Fig. 1, the first step (10) in the process is washing the
olives to remove pesticides, dust, and any dirt left on the surface of the
fruit.
Preferably, this step is performed by immersing the olives in a liquid bath at
room
temperature for about 0.5 to 10 minutes. The washing liquid may be water or
ethanol or a mixture thereof. Use of ethanol in the washing step provides the
benefits of disinfection in addition to general cleaning. It also facilitates
evaporation of the washing liquid from the olives' surface upon drying.
In the next step (20) the olives are heated to a predetermined
temperature in the range of about from 40 to 80 C for deactivating the enzymes
present in the fruit so as to stop any enzymatic reactions. In accordance with
one
embodiment, step 20 is performed by immersing the olives in a liquid bath at
the
selected temperature for about 2 to 10 minutes. The liquid may be water or
ethanol
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or a mixture thereof. Alternatively, heating may be performed by subjecting
the
olives to microwave radiation.
In the next step (30), the heated olives are rapidly cooled to a
temperature in the range of 0 to -10 C to prevent over-heating and possible
oxidation or any other reactions. Step 30 may be performed by immersing the
olives in an ice-water, by cold air blowers or by any other method known in
the
art.
In the next step (40) the olives are dried, if necessary, by blowing dry
air to remove any water left on their skins and in the following step (60)
predetermined quantities of olives are packaged in sealed vacuum packages in
air
impervious flexible film, using standard equipment typical in the art. The
packaged olives are then stored at regular refrigeration temperatures of 0 - 4
C
(step 70). Once the treated olives are sealed in packages, the packages can be
handled in an integral manner from the packaging area to storage and through
distribution channels to the final consumption site using regular
refrigeration
equipment.
Optionally, different salts and/or mineral powders may be added to the
olives (step 50) before packaging for inhibiting mold growth and for
maintaining
the fruit texture by lowering the water activity of the olives. The added
salts and
mineral powders also facilitate phase separation between the oil and vegetable
water during the oil extraction process. Optional added minerals are selected
from
sodium chloride, potassium chloride, sodium bicarbonate, micronized talc and
lime powder. The amount of added salts and/or minerals is preferably 50g or
more
per IKg of packed olives.
Example 1
Fresh olives from three different harvests in winter 2007-2008 were treated
according to a first treatment procedure (treatment procedure 1) of the
invention as
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in the following: After cleaning and washing, the freshly harvested olives
were
subjected to microwave radiation of 600 Watt for 1 minute, followed by
immediate cooling in ice water. The olives were dried, vacuum packed into
packages of 700g (using a LEVAC C30 M8 vacuum packaging machine,
manufactured by Lerica, Italy) and stored at 4 C. At one, three and five
months
after treatment, oil was extracted from one or more packages of the olives
using an
Abencor system (MC2 Ingenieria y Sistemas, Barcelona, Spain). Organoleptic
characteristics assessment and analysis of the extracted oil for Free acidity
(FFA),
peroxide level and polyphenols concentration were carried out according to the
IOC guidelines. The results are summarized in Table 1.
Analysis methods: Determination of free acidity and peroxide value were
carried out following the analytical methods recommended by Commission
Regulation EEC n 2568/91 of July 11, 1991. Free acidity given as a percentage
of
oleic acid, was determined by titration of a solution of oil in ethanol-ether
(1:1)
with ethanolic potash. Peroxide value, expressed in milliequivalents of active
oxygen per kilogram of oil (meq/kg) was determined as follows: a mixture of
oil
and isooctane-acetic acid 3:2 was left to react in darkness with a potassium
iodide
solution; the free iodine was then titrated with a sodium thiosulfate
solution.
Extraction and Analysis of Phenolics.: Phenolic fraction was isolated from a
solution of oil in hexane by triple extraction with water-methanol (60:40
v/v).
Total phenols, expressed as catechin equivalents (ppm), were determined with a
UV-visible spectrophotometer (Beckman Coulter, Inc. Fullerton, California, US)
at 735nm using the Folin-Ciocalteu reagent. Phenolic compounds were separated
by a HPLC system consisting of a TSP P4000 pump coupled to a UV 6000LP
Diode Array detector and with Chromquest software. Analytical separation was
achieved on an Ultrasphere RP-C18, 5 m column (250x4.6 mm i.d.) (Beckman,
USA). Phenolic compounds were monitored at 280 nm, and identified on the basis
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of their absorbance spectrum and retention times compared to those of standard
compounds following the IOC official method (COI/T.20/Doc No. 29).
Tablel: Assessment of oil extracted from three harvests (treatment procedure #
1)
Variety, Storage FFA1 Peroxide Polyphenols Organoleptic assessment
orchard & period (%) Value2 content in
Date (months) [mg/kg Oil]
1 0.23 3.28 210.0 Bitterness level 1,
Picual, pungency level 0
Kish 3 0.30 2.03 141.0
14.12.2007
0.64 8.76 142.0
Fruity and grassy oil
0 0.10 2.20 175.0 (level 4-5), Bitterness
level 0, pungency level 3
Picual,
Revivim, 1 0.64 3.17 125
27.12.2007
3 1.57 3.55 108.0
5 1.45 6.80 130.0
Strong "apple smell" and
0 0.06 5.50 168.0 aroma, Bitterness level 1,
pungency level 2-3
Picholine, Fine "apple smell",
Gshur 1 0.24 2.48 136.0 Bitterness level 1,
03.01.2008 pungency level 2
3 0.27 3.35 100.0
5 0.35 4.08 111.0
1 FFA is expressed as % free oleic acid (grams of oleic acid per 100 grams
oil);
2 Peroxide level measured in millieq. of oxygen / kg Oil
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The results clearly demonstrate that the free acid level remains below 2%
for all samples, including those extracted after 5-months storage period. The
peroxide value remains well below the standard of the IOC for Virgin Olive Oil
(< 20 millieq. Peroxide oxygen per Kg/oil)
EXAMPLE 2
Picual olives from the same harvest (Revivim, 18.12.2008) were treated by
four different procedures as in the following:
Treatment procedure # 2: 1min in 70% EtOH / Ice water cooling / Vacuum
packaging / 4 C storage
Treatment procedure # 3: 1min in 70% EtOH / Ice water cooling / 100 gr
KC1 per 700 gr olives/ Vacuum packaging / 4 C storage
Treatment procedure # 4: 4min at 60 / Ice water cooling / Vacuum
packaging / 4 C storage
Treatment procedure # 5: 4min at 60 / Ice water cooling / 100 gr KCl per
700 gr olives / Vacuum packaging / 4 C storage
Oil was extracted from treated olives immediately after treatment (t=0) and
after 2.5 month storage period. Oil assessment and analysis was performed as
in
Example 1. The results are summarized in Table 2.
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Table 2: Assessment of oil extracted from olives of the same harvest treated
according to different procedures
Treatment Storage FFA1 (%) Peroxide Polyphenols Organoleptic
procedure period Value2 content in assessment
number (months) [mg/kg Oil]
Strong fruitness,
0 0.17 6.34 103.84 "orange smell",
2 Bitterness level 2-3,
pungency level 0
2.5 0.37 5.89 65.09
0 0.13 5.89 281.30
3
2.5 0.20 5.43 189.86
0 0.24 11.10 87.18 Delicate oil, fruity
4 aroma
2.5 0.35 4.98 33.71 Good oil, neutral
Good oil, balanced
0 0.21 7.93 91.05 (slightly strong), low
bitterness, pungency
level 2
2.5 0.22 8.15 54.24 Good oil
EXAMPLE 3
The procedure 5 in Example 2 was repeated with Koroneiki olives. Oil was
extracted from treated olives immediately after treatment (t=0) and after 2.5
month
storage period. Oil assessment and analysis was performed as in Example 1. The
results are summarized in Table 3.
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Table 3: Assessment of oil extracted from Koroneiki olives treated according
to
treatment procedure # 5
Treatment Storage FFAI (%) Peroxide Polyphenols Organoleptic
number period Value2 content in assessment
(months) [mg/kg Oil]
Good oil,
bitterness
0 0.24 4.53 413.42 level 5,
pungency
level 2, fruity
and grassy
Fruity-grassy
2.5 0.35 5.89 370.80 oil (balanced),
high bitterness
As can be clearly seen, the oils extracted in both Examples 2 and 3 meet the
criteria of the IOC for Extra Virgin Olive Oil with respect to free acidity
and
peroxide level (< 0.8%, < 20 millieq. Peroxide oxygen per Kg oil,
respectively).
It will be appreciated by persons skilled in the art that the present
invention
is not limited to what has been particularly shown and described hereinabove.
Rather the scope of the present invention is defined only by the claims which
follow.
