Note: Descriptions are shown in the official language in which they were submitted.
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WO 93/02130 PCT/AU92/00383
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FLEXIBI.E~ FILMS FOR MODIF E~D A~MOSPHER13 PAC~GING
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Thi~ in~ention relates to f}exible ~olymeric 4ilm~ u~eful
S in the modlfied atmo~here ~ackaging of ~resh ~roduce ~uch
as fresh fruit~, vegetable~ and flower~. ~he inve~tion :~:
include~ polymeric film~ in the fo~m of a ~uitable packa~e
that can control the atmo~phere surrounding fresh produce
in ~uch a way that~the po t-har~est life of the ~roduce is
extended. The film~ of the invention contain a
glycerolate. ~ -
Back~rouna of th~ Inv~ntion
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Deterior~tion of ~roduce a~ter harve~ting invol~e~ many
complex factors, among which oxygen, cabon dioxide, water
a~d ethylene ha~e;~been identified a~ playing importa~t and~;~
:interrelated roles:in ~he ripening and decomposition
rocess. When ~roduce i~ enclo~ed in:pla~tic ~ilm,
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20: re~piration continue~, con~uming oxygen~and producing
carbon dioxide. ~ ~
In general, produce is adver ely affected by low
. concentratio~s of oxygen. The relative concentration of
oxygen and carbon~dioxide i~ alco impor~ant. The
concentra~ion of ~he~e ga~es will vary accordlng to the
~ leati~e permeab~ ty of~the ~olymer film. -
: For each ~roduce tXpe there i~ an op~imum range of
concentra~ions of CO2 and 2 which retard the re~piratory
~rate aaa impro~e the quality to the greatest extent under
~ra~e condltio~, Althou~h high concentration~ of CO~
ar~ ~ometim~ beneficial ( 8 . g . ~trawberries and ~u~hrooms)
low ~ conc~ntration~ have deleteriou~ effect~ on the
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WO93/02130 PCT/AU92/0038~
d U 2
~uality of the ~roduce. The relati~e flow of the two ga~e~
throu~h the ilm under storage condition~ and the ty~e o
produc~ determine the final com~osition of the atmo~here. :~
~thylene i~ al~o known to advance the onset of an
irr~Yersible ri~e in re~iration a~d ri~enin~.
~ ~he action o~ low le~els o~ ga~eou~ ethylene a~ maturation
hormone i~ well es~abli~hed. In particular, addition of
low level~ (ca l-lO ~pm) of ethyle~e to ~roduce, ~tored
under controlled atmo~here co~di~ion~ i~ an e~tabli3hed
~rocess to induce the onset o~ ri~ening. ~The re~er.e
: procedure, that of removal o~ ethyle~e from ~tored ~roduce,
: ha lso been commo~ly ~rac~iced over man~ year~. Methods
or remo~al of ethyle~e hare generally centred around
~: 15 ~orubbing processe~, in which the ga~ was xeactively ~;~
: ~crubbed~out o4~a:~re~irculating atmo3~here, for ex ~ le by
bubbling through ~ota~sium permanganate solution.
Howevér; it~will be a~preclated that the concentration of
ethylene within a~ackage may al30 :be effecti~ely reduc~d -~
0 :~: ~by u~ing a ~ckaging-material o~:a~pro~riate permeability.
A~ the~concentration~o~ ethylene i~ the atmosphere out~ide
the package~i~ practically nil, diffusion of ethylene
through the packaging~material will esBentially be a one-
way: proc~ hat:permanently removes ethylene from the
atmo~here with~n the package.
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On thie ~ther ~anid, ~if~u~ion oflcarbon dioxide andioxygen
hxou~h packagi~g film~ i~ a complex two-way ~roce~ that :~
s only imper~ec~ly unde ietood.
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!~ 93/0~}30 2 11 ~ O ~ 3 PCT/AU92/00383 ~:
PRIOR RR~AT~D _PPLICATION ~:~
In our earlier Au~t~alian ~ate~t a~plication 81642/91, the
e~t~re di~clo~ure i~ which i~ by this reference
incorporat~d in~o the ~re3ent ~ecification, we have
de~crihed and claimed a ~lexible ga3-~ermeable ~olymeric -~
~ilm u~e~ul in the modified atmo~ph0re ~a~kaging o~ ~resh ;-
~roduce, c~aracterl~ed in that the film incor~orate~ a~
ethylene reacti~e agent, a ~referred agent being ~odium
~ermanganate.
S~MMARY OF HF I~V~o~l~Y ~.
We have ~ow found that the relati~e flow of carbon dioxide
15 and o~ygen through ~ackagi~g film~ can~be affected in a ~-
mann~ be~eficial to the ~torage life o~ ~re~h ~roduce
packaged therein b~ the incorporation of cert~in materials ~-
into the ~id film~. The materials are con~eniently added
to the initial polymer before extrusion.
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In accordan~e with the in~2ntion, the additives used are
o~e or ~ore me~al glycerolate , preferably zinc
: ~lycerolate~ T~e ~ilm may be any ~uitable flexible
~olyme~ic ~ilm, ~or exam~le polyethylene, ~olypro~ylene,
:~ 25 ~oly~inyl chloride and other well-Xnown film~ suitable for
~ackaging~ and preferably contain ~iller~, for example
~ilica, alumina,~ magne~ium oxide and/or,~umice.
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The glycerolate may be preRent in the film in an amount
~xom 0.025 to 0.4% by weight. In a pre~erred embodiment of
, ~ ~he inve~ion, the glycerolate i~ incor~orated into filmg
which al~o contain one or more of the agent~ di~clo~ed in
¦ our abo~e mentioned Au~tralian a~plication 81642/91.
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WO93/02130 211 4 0 ~ D 4 PCT/A~92/00~
Although we do not wi~h to be limited by a~y ~ypothetical
or ~os~ulated mechani~m for the ob~Prved be~e~icial
effect~, it i~ belie~ed that the metal glycerolate in
co~bina~i~n with ~he ~illing material~ ha~ an ef~ect o~ .~ :~
~oiding and ~oxe formatio~ of the micro~orous polymer film. ;~
xamp~~1
A masterba~ch was pre~ared with low density ~olyethylene in
10 which ~umice and zinc glycerolate were added so that the :
loadin~ were 20% a~d 1% res~ectively. Before extrusion
the maRtexbatch wa~ then combined with linear low den~ity
~olyethylene o that ~he final com~o~ition of the~ blown
film~ao~tained about 4% pumice and .2% zinc ~lycerolate.
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~xample~ 2 and 3
In a similar manner to ~xam~le l,~ilm~ were ~re~ared ~-
containin~
2~
. - Example 2 Example_3
Polyeth~lene ~ 99% 99%
Finely ~round ~ilica 0.025% : ~ 0.025%
: Sodium perma~:ganate 0.02% 0.04%
25~ Zinc glycerolate 0.05% ` 0.05% .. :
Exam~
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In a ~imilar ma~ner to ~xam~le l, a film wa~ pre~ared
:30 co~taininy O.Z% ~odium permanganate, 0.1% glycerolate and .:
2~o ~umlce.
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2 ~ J 3 ~ PCl'/AU92/003B3
,~0 93/02130
PROD~C}3 TRIAl S
Txials with fre~h produce have ~hown that the film~ of the
in~ention arld par~icularly thoae de~cribed in the ~oregoing
5 exampl~3 are ~atis:~ac~co:cy f or the storage of broccs1i and
other ~roduce wi~h imllar respiratory rate~. In
partiGular, ~re~hne~3 o~ broccoli and callliflower wral?~ed
i~ the~e f iIm~3 wa3 main~ained under ~torage condition~ of
about 4C for periods :of u~? to 50 day~
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