Note: Descriptions are shown in the official language in which they were submitted.
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A method of preparing an edible oil product having an increased shelf life and
the edible oil
product thereby obtained
The invention relates to a method of preparing an edible oil, in particular
extra-virgin olive
oil, which benefits of an increased shelf life, as well as the edible oil
obtainable by the
method of the invention.
The European Regulation EU 432/2012 provides that polyphenols in extra-virgin
olive oil
contribute to the protection of blood lipids from oxidative stress.
In addition, the EFSA (European Food Safety Authority) has recognized that the
olive oil
polyphenols can prevent oxidative stress, have antioxidant effects, improve
fat metabolism,
protect the LDL fraction from oxidative damage.
The method of the invention and the product thereof are therefore the result
of a study
conducted by the inventors, in order to identify new strategies to improve the
bio-nutritional
and health quality of olive oil over time, with particular reference to the
special phenolic
compounds of olive oil.
The above-mentioned object is achieved by a method of preparing an edible oil,
in particular
olive oil, more in particular extra-virgin olive oil, which comprises the
following steps:
- providing a given volume of edible oil, particularly extra virgin olive
oil;
- inserting a predetermined number of whole olives into the above-mentioned
volume of
edible oil, the whole olives having a polyphenolic content ranging from 1 to 5
% of
polyphenols on the total weight of the olives, characterized in that the whole
olives, before
being introduced into the edible oil, are subjected to irradiation with
ionizing radiations at
an absorbed dose comprised within the range of from 2.5 to 15 kgray, even more
preferably
comprised within the range of from 2.5 to 5 kgray or lower. A particularly
preferred absorbed
dose is about 4.5 kgray.
The European patent EP 2416664 B (Costa d'Oro S.p.A.) discloses a method of
preparing
an edible oil in which the whole olives, before being introduced into the
edible oil, are
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subjected to a treatment with an anti-mould agent, after which they are
subjected to a
dehydration treatment such as to achieve the elimination of a quantity of
water of between
7% and 15%.
The international patent application WO 99/52377 A (UNILEVER NV (NL); UNILEVER
PLC (GB)) 21 October 1999 (10.21.1999) discloses a method of increasing the
polyphenol
content in olive oil by immersing whole olives into olive oil. WO 99/52377 A
also discloses
that such a transfer of the ingredients of the olive fruit from the fruit to
oil can be further
increased by means of a dehydration treatment which can increase the transport
of the olive
fruit ingredients from the fruit to the oil.
EFSTATHIOS Z. PANAGOU: "Greek dry-salted olives: Monitoring the dry-salting
process
and subsequent physico-chemical and microbiological profile during storage
under different
packing conditions at 4 and 20 C", LWT ¨ FOOD SCIENCE AND TECHNOLOGY,
discloses a method comprising the dehydration of olives up to the elimination
of 21% water,
followed by a treatment with potassium sorbate that increased the shelf life
of the olives.
The method according to the present invention advantageously allows increasing
the final
polyphenol content in the oil. The polyphenols contained in the olives are
released over time
within the volume of oil, playing the role of natural antioxidants.
Compared to the prior art methods, the irradiation with ionizing radiations is
an extremely
effective technology. Ionizing radiations are in fact able to destroy any bud,
parasite,
bacterium, virus or microorganism present in the olives which will
subsequently be
introduced into the edible oil. It has also been demonstrated that the
irradiation with ionizing
radiations does not cause the formation of toxic substances in processed
foods.
Consequently, the irradiation with ionizing radiations allows avoiding all the
conventional
treatments currently required for sterilization and microbiological safety.
The irradiation with ionizing radiations is also an extremely simple
technology: the olives to
be irradiated are arranged on a conveyor belt and passed under a beam of
radiation emitted
by cobalt 60 or by an electron generator. In the latter case, these are
radiations of very short
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wavelength (70nm) that break the DNA strands of organisms and microorganisms,
whose
replication is thus prevented.
As will be apparent from the examples that follow, the edible oil obtained
with the method
of the invention is also characterized by a higher polyphenol content compared
to the same
oil treated with the method disclosed in European patent EP 2416664 B of the
prior art. An
improvement in the state of preservation is also noted, measurable with the
conventional
parameters used for this purpose, i.e. the number of peroxides and the U.V.
K232 and K270
spectrophotometric indices.
The organoleptic characteristics of the edible oil remain substantially stable
over time or
with a sensory score perceptibly better when examined by a Panel.
The invention also relates to the edible oil, in particular the extra-virgin
olive oil, obtainable
with the method of the invention, whose features are illustrated in detail in
the example
section.
In a preferred embodiment of the method of the invention, green olives before
the onset of
ripening are used, namely olives which have not yet reached the stage of
complete ripening
.. of the fruits, in which the epicarp color changes from a deep green color
typical of olives not
yet ripe, to a final color which can vary, depending on the cultivar, from red
purple to black.
The use of olives before the onset of ripening is preferable as they contain a
higher amount
of polyphenols compared to ripe olives and are therefore able to perform the
best antioxidant
function, in addition to providing a final product characterized by an
improved visual
appearance.
In another preferred embodiment of the method of the invention, the olives
inserted into the
edible oil belong to the Coratina cultivar, which among Italian cultivars is
the richest in
polyphenols.
In yet a further preferred embodiment, the method involves the use of a number
of olives of
from 1 to 4 per 1 litre of oil.
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Even more preferably, the olives used in the method of the invention have a
caliber of 20-
22, expressed as the number of olives per 100 grams. Such a caliber has proved
particularly
suitable for use in technological automation processes for the insertion of
the olives into the
oil container, such as a bottle for oil having a neck diameter of about 35 mm.
The following examples are provided merely for non-limiting illustration of
the scope of the
invention as defined by the appended claims.
Example 1: microbiological analyses
Samples of Coratina olives were subjected to a treatment according to the
prior art (referred to
as "treatment 1") and to the treatment according to the present invention
(referred to as "treatment
2").
Treatment 1: the olives were subjected to partial dehydration in a stove at
120 C to remove
10% of water from the fruits.
Treatment 2: the olives were subjected to irradiation with ionizing radiations
at an absorbed
dose of 4.5 kgray.
Table lA below (where t = time) shows the values of the microbiological
parameters
measured in the olives subjected to treatment 1 and in the preserving oil
thereof, at time zero,
after 6 months and after 1 year from the insertion of the olives into the oil.
Table 1 B below (where t = time) shows the values of the microbiological
parameters
measured in the olives subjected to treatment 2 and in the preserving oil
thereof, at time zero,
after 6 months and after 1 year from the insertion of the olives into the oil.
Table 1 A:
Treatment 1 Preserving oil
t. t. t. t. t. t.
zero 6 12 months zero 6
months 12 months
months
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pH (4.4 max) 4.25 4.28 4.36 - - -
Water activity 0.80 0.81 0.81 - - -
aw (0.85 max)
Moulds <1 <1 <1 <1 <1 <1
Yeasts <1 <1 <1 <1 <1 <1
Total microbial < 1 < 1 < 1 < 1 < 1 <
1
load
(300,000 CFU/g
max)
Clostridium sulfite < 1 < 1 < 1 < 1 < 1 < 1
reducers
Total coliforms < 1 < 1 < 1 < 1 < 1 < 1
Spores of <1 <1 <1 <1 <1 <1
clostridia
Table 1B:
Treatment 2 Preserving oil
t. t. t. t. t. t.
zero 6 12 zero 6 12
months months months months
pH (4.4 max) 4.23 4.23 4.28 - - -
Water activity 0.80 0.80 0.81 - - -
aw (0.85 max)
Moulds <1 <1 <1 <1 <1 <1
Yeasts <1 <1 <1 <1 <1 <1
Total microbial load < 1 < 1 < 1 < 1 < 1 < 1
(300,000 CFU/g
max)
Clostridium sulfite < 1 < 1 < 1 < 1 < 1 < 1
reducers
Total coliforms < 1 < 1 < 1 < 1 < 1 < 1
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Spores of clostridia < 1 < 1 < 1 < 1 < 1 < 1
From the microbiological analysis shown in Table 1, it is clear that both
treatments carried
out on the olives are effective and able to maintain a proper microbiological
stabilization of
the fruit in oil, and that there is no risk of contamination of the preserving
oil.
Example 2: analysis of the release of antioxidants and evaluation of the shelf
life effect and
of the organoleptic characteristics of the oil
On the basis of microbiological results obtained in example 1, control tests
of the main
physical-chemical parameters of the same extra-virgin olive oil were carried
out, with the
addition of whole olives treated with the method of the present invention
("treatment 2") or
with the prior art method referred to as "treatment 1".
The extra-virgin olive oil as such (AS), without addition of whole olives, was
used as a
control.
The results are shown in the following Table 2.
Table 2:
TIME ZERO
OIL A.S. Oil + 1 olive Oil + 1 olive
Coratina Coratina
Treatment 1 Treatment 2
Acidity 0.25 0.25 0.25
N. peroxides 6.0 6.0 6.0
K232 1.65 1.65 1.65
K270 0.10 0.10 0.10
DELTA K 0.00 0.00 0.00
Panel Test Fruity Fruity Fruity
Total polyphenols 230 230 230
(PPm)
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AFTER 2 MONTHS
OIL A.S. Oil + 1 olive Oil + 1 olive
Coratina Coratina
Treatment 1 Treatment 2
Acidity 0.25 0.25 0.25
N. peroxides 7.2 6.5 6.3
K232 1.70 1.67 1.65
K270 0.12 0.10 0.10
DELTA K 0.00 0.00 0.00
Panel Test Fruity Fruity Fruity
Total 230 241 262
polyphenols
(PPm)
AFTER 4 MONTHS
OIL A.S. Oil + 1 olive Oil + 1 olive
Coratina Coratina
Treatment 1 Treatment 2
Acidity 0.25 0.25 0.25
N. peroxides 8 6.8 6.7
K232 1.77 1.69 1.67
K270 0.12 0.10 0.10
DELTA K 0.00 0.00 0.00
Panel Test Fruity Fruity Fruity
Total 230 251 272
polyphenols
(PPm)
AFTER 6 MONTHS
OIL A.S. Oil + 1 olive Oil + 1 olive
Coratina Coratina
Treatment 1 Treatment 2
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Acidity 0.25 0.25 0.25
N. peroxides 8.8 7.2 6.9
K232 1.80 1.72 1.70
K270 0.13 0.10 0.10
DELTA K 0.00 0.00 0.00
Panel Test Fruity Fruity Fruity
Total 230 264 283
polyphenols
(PPm)
AFTER 8 MONTHS
OIL A.S. Oil + 1 olive Oil + 1 olive
Coratina Coratina
Treatment 1 Treatment 2
Acidity 0.25 0.25 0.25
N. peroxides 9.2 7.7 7.0
K232 1.84 1.75 1.72
K270 0.13 0.10 0.10
DELTA K 0.00 0.00 0.00
Panel Test Fruity Fruity Fruity
Total 230 272 298
polyphenols
(PPm)
AFTER 10 MONTHS
OIL A.S. Oil + 1 olive Oil + 1 olive
Coratina Coratina
Treatment 1 Treatment 2
Acidity 0.25 0.25 0.25
N. peroxides 9.2 8.0 7.3
K232 1.87 1.78 1.74
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K270 0.14 0.11 0.11
DELTA K 0.00 0.00 0.00
Panel Test Fruity Fruity Fruity
Total 230 288 312
polyphenols
(PPm)
AFTER 12 MONTHS
OIL A.S. Oil + 1 Coratina Oil + 1 Coratina olive
olive Treatment 2 - ionizing
Treatment 1 - in
stove
Acidity 0.25 0.26 0.26
N. peroxides 10.5 9.0 7.9
K232 1.87 1.82 1.76
K270 0.14 0.12 0.11
DELTA K 0.00 0.00 0.00
Panel Test Fruity Fruity Fruity
Total 230 309 322
polyphenols
(PPm)
The results show that:
(i) The olive subjected to treatment 1 is able to improve the oil storage
conditions to
which it is added, compared to oil as such. This is determined by the partial
release of the
polyphenols contained in olive oil into the oil. Polyphenols are in fact
strong antioxidants.
(ii) The olive subjected to treatment 2 is able to improve the oil storage
conditions to
which it is added, both as compared to oil as such and as compared to the oil
samples
containing the olive subjected to treatment 1. This is determined by the fact
that the olive is
able to release into the oil a greater amount of polyphenols compared to the
olive subjected
to treatment 1.
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Therefore, the olive treated with ionizing radiations according to the present
invention has an
even more effective and ameliorative effect on the oil shelf life, compared to
the olive treated by
partial dehydration according to the prior art.
5 Example 3:
The European Regulation EU 432/2012 states that the indication of the
beneficial health
effect of polyphenols can be put on the label only if the product contains at
least 250 mg/kg
of hydroxytyrosol and derivatives thereof (e.g. oleuropein and tyrosol;
lignans should be
10 excluded from total biophenols). The indication must be accompanied by
the information to
the consumer that "the beneficial effect is obtained with a daily intake of 20
g of olive oil".
For this reason, on the samples subjected to the tests of Table 2, further
investigation was
carried out with regard to the analysis of polyphenols alone. These
investigations consisted
in performing the analysis of polyphenols with the HPLC technique. The HPLC
technique
in fact allows eluting the polyphenols and separating them into individual
classes. This
allows verifying whether in the total polyphenols released by the olive into
the oil, the classes
of compounds for which it is possible to claim the health benefit, i.e.
hydroxytyrosol, tyrosol
and derivatives thereof, as listed from 1 to 7 in Table 3 below, are actually
present.
Table 3:
TIME ZERO
OIL A.S. Oil
+ 1 Coratina olive
Total polyphenols 230 230
1 - Tyrosol (p, HPEA) 5 5
2 - Hydroxytyrosol (3,4 DHPEA) 6 6
3 - Decarboxy oleuropein aglycone (3,4
45 45
DHPEH-EDA)
4 - Decarboxy ligstroside aglycone (p,
67 67
HPEA-EDA)
5 - Oleuropein aglycone (3,4 DHPEA-
75 75
EA)
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6 - Ligstroside aglycone (p, HPEA-EA) 22 22
7 - Lignans 10 10
Total polyphenols (1+2+3+4+5+6+7) 220 220
AFTER 2 MONTHS
OIL A.S. Oil + 1 olive
Coratina
Total polyphenols 230 262
1 - Tyrosol (p, HPEA) 5 8
2 - Hydroxytyrosol (3,4 DHPEA) 6 10
3 - Decarboxy oleuropein aglycone
45 45
(3,4 DHPEH-EDA)
4 - Decarboxy ligstroside aglycone (p,
67 67
HPEA-EDA)
- Oleuropein aglycone (3,4 DHPEA-
75 88
EA)
6 - Ligstroside aglycone (p, HPEA-EA) 22 34
7 - Lignans 10 10
Total polyphenols (1+2+3+4+5+6+7) 220 252
AFTER 4 MONTHS
OIL A.S. Oil + 1 olive
Coratina
Total polyphenols 230 272
1 - Tyrosol (p, HPEA) 5 10
2 - Hydroxytyrosol (3,4 DHPEA) 6 14
3 - Decarboxy oleuropein aglycone
45 43
(3,4 DHPEH-EDA)
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4 - Decarboxy ligstroside aglycone (p,
67 70
HPEA-EDA)
- Oleuropein aglycone (3,4 DHPEA-
75 90
EA)
6 - Ligstroside aglycone (p, HPEA-EA) 22 35
7 - Lignans 10 10
Total polyphenols (1+2+3+4+5+6+7) 220 262
AFTER 6 MONTHS
OIL A.S. Oil + 1 olive
Coratina
Total polyphenols 230 283
1 - Tyrosol (p, HPEA) 5 11
2 - Hydroxytyrosol (3,4 DHPEA) 6 15
3 - Decarboxy oleuropein aglycone
45 48
(3,4 DHPEH-EDA)
4 - Decarboxy ligstroside aglycone (p,
67 68
HPEA-EDA)
5 - Oleuropein aglycone (3,4 DHPEA-
75 95
EA)
6 - Ligstroside aglycone (p, HPEA-EA) 22 36
7 - Lignans 10 9
Total polyphenols (1+2+3+4+5+6+7) 220 273
AFTER 8 MONTHS
OIL A.S. Oil + 1 olive
Coratina
Total polyphenols 230 298
1 - Tyrosol (p, HPEA) 5 12
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2 - Hydroxytyrosol (3,4 DHPEA) 6 16
3 - Decarboxy oleuropein aglycone
45 56
(3,4 DHPEH-EDA)
4 - Decarboxy ligstroside aglycone (p,
67 68
HPEA-EDA)
- Oleuropein aglycone (3,4 DHPEA-
75 96
EA)
6 - Ligstroside aglycone (p, HPEA-EA) 22 38
7 - Lignans 10 12
Total polyphenols (1+2+3+4+5+6+7) 220 286
AFTER 10 MONTHS
OIL A.S. Oil + 1 olive
Coratina
Total polyphenols 230 312
1 - Tyrosol (p, HPEA) 5 13
2 - Hydroxytyrosol (3,4 DHPEA) 6 16
3 - Decarboxy oleuropein aglycone
45 60
(3,4 DHPEH-EDA)
4 - Decarboxy ligstroside aglycone (p,
67 67
HPEA-EDA)
5 - Oleuropein aglycone (3,4 DHPEA-
75 100
EA)
6 - Ligstroside aglycone (p, HPEA-EA) 22 44
7 - Lignans 10 12
Total polyphenols (1+2+3+4+5+6+7) 220 310
AFTER 12 MONTHS
OIL A.S. Oil + 1 olive
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Coratina
Total polyphenols 230 322
1 - Tyrosol (p, HPEA) 5 15
2 - Hydroxytyrosol (3,4 DHPEA) 6 18
3 - Decarboxy oleuropein aglycone
45 59
(3,4 DHPEH-EDA)
4 - Decarboxy ligstroside aglycone (p,
67 68
HPEA-EDA)
- Oleuropein aglycone (3,4 DHPEA-
75 107
EA)
6 - Ligstroside aglycone (p, HPEA-EA) 22 43
7 - Lignans 10 12
Total polyphenols (1+2+3+4+5+6+7) 220 310
The analytical data presented in the experimental section of the present
patent application
show the following:
(i) The addition to the extra-virgin oil of an olive previously treated and
stabilized
5 with ionizing radiations does not alter the organoleptic characteristics
compared to the same
extra-virgin olive oil as such (AS), on the contrary, the peculiarities of the
product are
significantly strengthened.
(ii) After 1 year, the addition of olives treated according to the present
invention
contributes to a better preservation of the oil (better analytical and
organoleptic
characteristics) compared to the oil as such and compared to an oil treated
according to the
prior art.
(iii) The analysis of polyphenols shows that the olive treated with the method
of the
present invention and added to the bottled extra-virgin olive oil causes a
significant increase
in the polyphenol content compared to the control sample.
(iv) The HPLC analysis shows that there is a significant release of phenols
whereby
the health benefit can be claimed.
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The results also show that, by using as starting material an oil characterized
by a polyphenol
content lower than that is necessary to claim the health benefit, 2 months
after the addition
of an olive rich in polyphenols and treated with the process of the present
invention, there is
an increase in the polyphenol content in the oil that is sufficient for the
recognition of the
5 .. health benefit.
We can therefore conclude that the process according to the present invention
provides
extremely advantageous characteristics to the edible oil, in particular olive
oil, more in
particular extra-virgin olive oil, mainly a higher content in polyphenols
which increase the
10 beneficial bio-nutritional and health effects thereof.
