Note: Descriptions are shown in the official language in which they were submitted.
2~ 7~8
The present invention relates to a method of keeping
the freshness of fruit and vegetables. More particularly,
it relates to a method of keeping the freshness of fruit
and vegetables by suppressing generation of ethylene and
also removing generated ethylene as far as possible so
that the fruit and vegetables can be prevented from coming
into contact with ethylene. The present invention
provides a novel freshness-keeping material, which can be
widely utilized throughout the storage and distribution of
fruit and vegetables.
These days, with so many kinds that we may have no
sense of the season at all, fruit and vegetables arè
widely on the market and delight our eyes and taste.
.
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Pursuant to such circumstances, many attempts have been
made on methods of keeping the freshness of fruit and
vegetables. For example, the methods include the low-
temperature preservation method, the CA (gas controlled
atmosphere)storage method (or environmental gas control),
the plastic-film packing, and a method that employs an
ethylene adsorbent e.g. activated carbon or molecular
sieves, or an ethylene inactivator e.g. potassium
permanganate or a bromine compound.
As is seen in the above, the methods of keeping the
freshness of fruit and vegetables are roughly grouped into
the following two types:
1. A method in which the physiological functions of the
whole fruit and vegetables are lowered to retard their
ripening or aging, as in the low-temperature preservation
method and the CA storage method.
2. A method in which the ethylene the fruit and
vegetables produce is removed so that their ripening or
aging can be prevented from being promoted.
In the low-temperature preservation method, however,
there is the disadvantage that the lowering of the
physiological functions of fruit and vegetables brings
about a number of fruit and vegetables having adversely
undergone low-temperature trouble. The CA storage method
can not achieve satisfactory prevention of after-ripening
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or aging, and moreover requires high cost. The plastic-
film packing has been defenseless against the propagation
of microorganisms in the insides of packs. The method
that employs the ethylene-removing agent has been intended
for a countermeasure taken only on account of the
generated ethylene, so that no satisfactory effect has
been gained.
- The present inventors had an idea that the
generation itself of ethylene is suppressed to prevent
after-ripening or aging of fruit and vegetables, and made
studies on various compounds. As a result, they have
found that the after-ripening or aging of fruit and
vegetables can be very remarkably prevented when fruit and
vegetables are placed in the presence of hinokitiol
(naturally occurring CloH1202,
isopropyltropolone) compounds (hereinafter "hinokitiols")
e.g. hinokitiol, hinokitiol alkali metal salts,
hinokitiol-cyclodextrin clathrate compound (hereinafter
"H-CD") together with a conventional ethylene-removing
agent. The present invention has been thus accomplished.
The present invention provides a method of
preventing after-ripening or aging of fruit and
vegetables, comprising placing fruit and vegetables in the
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presence of a hinokitiol and an ethylene-removing agent,
and an after-ripening or aging preventive composition that
can give the stated effect.
The hinokitiols used in the present invention
include hinokitiol per se, H-CD (~ - or r-cyclodextrin
clathrate compound), and various metal salts, in
particular, alkali metal salts ( e.g. sodium salt and
potassium salt) of hinokitiol.
The ethylene-removing agent used in the present
invention includes the agents used in removing generated
ethylene through a physical, chemical or biochemical
means, including adsorbents capable of adsorbing ethylene,
as exemplified by activated carbon, rock powder, and
molecular sieves, and reagents capable of inactivating
ethylene by chemical reaction, as exemplified by potassium
permanganate.
In the present invention, there are no particular
limitations on the method of placing fruit and vegetables
in the presence of the hinokitiols and ethylene-removing
agent. The following methods, however, may preferably be
used. For example, simple and preferable methods are as
follows: In a packaging container kept in an airtight or
nearly airtight state; i) both the hinokitiols and
ethylene-removing agent are put in separate packaging
containers or the same packaging container, made of an air-
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permeable material, as exemplified by a bag or box made ofpaper, cloth or nonwoven fabric, and the resulting
packaging containers or container is/are put together with
fruit and vegetables, or ii) both the hinokitiols and
ethylene-removing agent are supported on separate
carriers, respectively, or on the same carrier, as
exemplified by paper, cloth, nonwoven fabric or plastic
film, by adhesion, adsorption or absorption, and the
resulting material (herein called "freshness-keeping
material") comprising the carrier and the stated chemicals
supported thereon is put together with fruit and
vegetables. The freshness-keeping material can be
prepared by a method in which an adhesive is coated on the
surface of the carrier and the chemicals are sprayed
thereon, a method in which a solution of the chemicals is
sprayed on the carrier followed by drying, or a method in
which the carrier is dipped in a solution of the chemicals
followed by drying. There is also included a method in
which fruit and vegetables are put in a packaging
container comprising the freshness-keeping material.
EXAMPLES
The present invention will be described below in
greater detail~
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Example 1 (Test 1 using apples)
Apples "Star-King"/M26 Rank cultivated in Morioka
Branch of Fruit Tree Experiment Station and harvested on
October 26, 1987 were transported to Tokyo. On the day
after their arrival in Tokyo, each apple was weighed and
then put in a gas bag of 18 cm x 24 cm laminated films
comprised of 0.015 mm thick KOP and 0.070 mm thick PE
(polyethylene). After deaeration, 300 mQ of the air was
introduced into the bag, which was then left to stand at
Z0C for 3 hours. A given amount (2 mQ) of gas is
collected from this gas bag, and the quantity of ethylene
generated from the apple was measured by gas
chromatography (measuring apparatus: GC-6AM PrTF,
manufactured by Shimadzu Corporation). In order to lessen
the scattering in the generation quantity of ethylene,
test groups of 1st to 7th groups were prepared in each of
which 10 apples were contained, and treated in the
following way.
The 1st group is a control, in which 10 apples were
put in a corrugated paper box.
In the 2nd group, 10 apples each covered with a
freshness-keeping material SR-60 [rayon paper impregnated
with 60 mg/m of H-CD (~-CD: see Japanese Unexamined
Patent Publication No. 193941/1985), followed by drying]
were put in a corrugated paper box.
4 8
In the 3rd group, 10 apples each covered with a
freshness-keeping material SRH-150 (rayon paper
impregnated with 150 mg/m of hinokitiol dissolved in
alcohol, followed by drying) were put in a corrugated
paper box.
In the 4th group, 10 apples and 5 bags of
-commercially available ethylene adsorbents (products of
Sekisui Jushi Co., Ltd.; Neopack B0 5g) were enclosed in a
bag (60 cm x 80 cm) made of polyethylene film of 0.03 mm
thick (hereinafter "PE bag"). The most part of the air in
the bag was removed away, and the bag was tied on its
mouth with a rubber band and then put in a corrugated
paper box.
In the 5th group, apples treated in the same way as
in the 2nd group were put in a PE bag, in which 5 bags of
commercially available ethylene adsorbents (the same as
those described above) were enclosed together. These were
put in a corrugated paper box in the same way as the 4th
group.
In the 6th group, apples treated in the same way as
in the 2nd group and 5 bags of ethylene adsorbents (the
same as those described above) were put in a PE bag, and
these were put in a corrugated paper box in the same way
as the 4th group.
In the 7th group, 10 apples were put in a PE bag,
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the most part of the air in the bag was removed away, and
the bag was tied on its mouth with a rubber band and then
put in a corrugated paper box.
On the 5th, 10th and 17th days after they were put
in the corrugated paper boxes, the quantity of ethylene
generated per apple in each group was measured by the same
gas chromatography as previously described. Results of
measurement are shown in Table 1 and Fig. 1.
In the 2nd and 3rd groups, ethylene was produced in
a smaller quantity in the 3rd group in which the
hinokitiol was contained in a larger amount, and was
produced in a decreased quantity at the 10th to 17th days.
In the 4th, 5th and 6th groups in which the ethylene-
removing agents were enclosed, the ethylene was produced
in a smaller quantity in the 4th group than in the
control, but resulted in no difference from the control at
the 17th day. On the other hand, in the 5th and 6th
groups in which the freshness-keeping materials were
enclosed together, the ethylene was produced in a smaller
quantity until the 10th day. Moreover the ethylene was
produced in the 6th group in a quantity only about 1/4 of
that in the 4th group, and at the same time was produced
in a more decreased quantity with lapse of days than that
at the initial stage of the measurement.
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Table 1 Influence of hinokitiol on the
formation of ethylene of Star-King
Group 0 day 5th day 10th day17th day
1 *26.6 88.8 86.3 83.4
2 26.4 91.1 78.4 86.8
3 26.6 66.8 57.4 55.9
4 26.4 44.4 45.9 82.1
24.1 36.9 29.6 45.3
6 26.3 21.5 18.0 19.7
7 31.3 50.1 90.0 114.0
* unit: ~Q/kg/3hrs
For reference, the concentrations of carbon dioxide
gas, oxygen and ethylene in polyethylene bags in which
apples were enclosed were measured. Two apples of the
same kind as in the above experiments were put in each of
4 sheets of bags (28 cm x 40 cm) made of polyethylene film
of 0.03 mm thick. The most part of the air in the bags
were removed away, and the bags were tied on its mouth
with a rubber band. This was designated as a 1st group.
Two apples and an ethylene adsorbent (the same as
that described above) were put in each of 4 sheets of the
same polyethylene bags as the above, which were similarly
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handled to give a 2nd group.
The 1st and 2nd groups were left to stand at 20C,
and the gas quantities in the bags were measured by gas
chromatography on the 1st day, 4th day, 5th day and 6th
day. Results are shown in Table 2. The concentrations of
the carbon dioxide gas, oxygen and ethylene were not so
much influenced by the presence of the ethylene-removing
agent.
Table 2 Gas concentration in
polyethylene bag
First group
1st day 4th day 5th day 6th day
C2 (%) *3 9 4.1 6.1 6.1
2 (%): 8.4 5.5 5.1 4.5
C2H6 (ppm): 19.8 29.1 31.9 31.0
Second group
1st day4th day 5th day6th day
C2 (%): 3.2 3.8 5.4 5.8
2 (%) 9.5 10.6 8.3 8.1
C2H6 (ppm): 0.8 0.9 1.6 5.0
* unit: ~Q/kg/3hrs
4 8
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Example 2 (Test 2 using apples)
An aqueous suspension containing 0.5 % of H-CD and
20 % of activated carbon were put in a water tank equipped
with a stirrer, followed by stirring. A sheet of rayon
paper (100 cm X 100 cm) was passed through the resulting
solution, and then dried using a drum dryer (apparatus:
-C-SR-60, manufactured by ).
The resulting rayon paper was confirmed to contain 60
mg/m of hinokitiol. Ten apples were wrapped with this
rayon paper, and the wrap was put in a polyethylene bag of
0.03 mm thick. Another rayon paper was also passed
through an aqueous suspension comprising 20 % of activated
carbon only, and then dried. Ten apples were similarly
wrapped with the resulting paper, and the wrap was put in
another polyethylene bag. As a control, 10 apples were
wrapped with non-treated rayon paper, and the wrap was put
in still another polyethylene bag. The above three
packages obtained were stored at 20C, and the quantity of
ethylene in each package was measured in the same manner
as in Example 1. Results are shown in Table 3. The
presence of the hinokitiol-cyclodextrin clathrate compound
brought about remarkable suppression of the formation of
ethylene.
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Table 3
0 day 5th day 10th day17th day
Control:*26.6 88.8 86.3 83.4
C-SR-60: 25.3 38.11 30.8 30.5
Activated
carbon: 26.2 45.2 50.9 79.3
* unit: ~Q/kg/3hrs
Example 3 (Test 3 using apples)
A mixture of 25 of potassium permanganate and 2 g of
H-CD was put in a bag made of nonwoven fabric (20 cm x 20
cm), and the bag was then sealed by heat sealing. Four
apples of the same kind as used in the previous Examples
were put in a bag made of polyethylene film of 0.03 mm
thick, and the nonwoven fabric bag containing the above
chemicals was enclosed together in the polyethylene bag.
The polyethylene bag was tied on its mouth with a rubber
band. Separately from this, a bag in which 25 g of
potassium permanganate only was used as the chemical, and
a bag in which 2 g of H-CD only was used were each
enclosed together with apples in the same way as the
above. The above three were tested in the same way as in
Example 2 to measure the ethylene quantities in the bags.
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Results are shown in Table 4. In the test group in which
both the potassium permanganate and H-CD were used, the
formation of ethylene was remarkably suppressed, compared
with the cases in which they were respectively used alone.
Table 4
0 day 5th day 10th day17th day
Control:*26.6 88.8 86.3 83.4
KMnO4 + H-CD:26.1 25.3 24.6 30.5
H-CD: 26.5 70.2 67.5 71.8
KMnO4: 25.3 43.7 48.1 70.3
* unit: ,uQ/kg/3hrs
Example 4 (Test 4 using apples)
A mixture of activated carbon and H-CD in weight
ratio of 20:1 was coated by gravure printing on one side
of a polyethylene sheet of 0.03 mm thick, using starch
glue as an adhesive. The resulting sheet comprises 60
mg/m2 of hinokitiol adhered thereon. This sheet was
formed into a bag, and 10 apples of the same kind as used
in the previous Examples were put therein. The quantities
of ethylene in the bag were measured in the same manner as
in Example 1. Separately from this, polyethylene sheets
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respectively comprising activated carbon and H-CD alone
adhered thereon were also prepared to measure the
quantities of ethylene. Results obtained are shown in
Table 5. The polyethylene sheet to which both were
applied brought about remarkable suppression of the
formation of ethylene.
Table 5
0 day 5th day 10th day17th day
Control:*26.6 88.8 86.3 83.4
C + H-CD:26.2 35.3 40.6 71.0
H-CD: 26.5 68.2 70.5 72.9
Activated
carbon:25.0 44.7 55.1 71.0
* unit: ,uQ/kg/3hrs
As having been described in the above, placing fruit
and vegetables in the presence of at least one selected
from hinokitiol, a hinokitiol-cyclodextrin clathrate
compound and an alkali metal salt of hinokitiol has
suppressed or removed the formation of or formed ethylene
to prevent the after-ripening or aging of fruit and
vegetables, and thus enabled maintenance of satisfactory
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f reshness .
