CA2186746A1

CA2186746A1 - Method and device for controlling handling conditions

Info

Publication number: CA2186746A1
Application number: CA002186746A
Authority: CA
Inventors: Kjell Blixt; Stig Jonsson
Original assignee: Individual
Current assignee: Visual Indicator Tag Systems AB
Priority date: 1994-04-29
Filing date: 1995-04-05
Publication date: 1995-11-09
Also published as: SE9403859L; US5857776A; AU2457895A; WO1995030136A1; SE9403859D0; JPH09512633A; EP0757787A1

Abstract

A method and a device for controlling the handling conditions of at least one objet are disclosed.
The method comprises checking the temperature or the temperature as a function of time of at least one ob-ject, such as an individual package or a stack of such packages, the ob-ject being intended to be handled under certain predetermined condi-tions to enable it to retain as much as possible of its original quality.
To this end, a device is inserted into the object, or between two objects in a stack of objects, the device consisting of a substantially flat, elongate casing (1), having a slot-shaped space (2) between two opposed walls (3, 4) of the casing (1), and an elongate slide-shaped body (5) which is movable into and out of the slot-shaped space (2) and which is provided at one end with a means (6) which indicates by colour change the exceeding and the falling-short of the predetermined conditions. The colour of the means (6) is thereafter observed visually by withdrawing the slide-shaped body (5) inserted in the slot-shaped space (2) of the casing (1) from the space (2). During the visual observation, the colour of the means (6) is suitably compared with a colour scale on the slide-shaped body (5) Preferably, the casing (1) of the device is perforated (at 7) at one end. Furthermore, at least the portion of the inside of the casing contacting the means (6) when inserted in the casing is suitably provided with ridges (8) extending in the longitudinal direction of the casing.

Description

-Wo 95/30136 r~, METHOD AND DEVICE FOR CONTROLLING HANDLING

CONDITIONS

The present invention relates to a method and a devlce for time and/or L ,~ ~Lule: control, and more spe-I~;f1rplly to a method for controlling the h~nfll;n~ condi-tions of at least one ob3ect, such as an individual pack-5 age or a stack of such packages containing refrigeratedor frozen products, the object being intended to be handled under certain ~L~:de~ , ;n~fl conditions, and to a device for carrying out the method, The term "h~nfll 1n~" as used in the present context 10 relates to storage, transport and similar treatment of an ob3ect, and the expressions "h~nfll in~ conditions" and " conditions " as used in the present context relate to either the temperature prevailing during the h~nfll i n~ Of the ob~ect, or the time and the i - ~ILule, i.e. the 15 total or i-lle:yL~L~d influence of time and L.~ LCILUL~ on the ob3ect during the h~nfll ln~ thereof .

There are a great many ob 3 ects and products, such as foodstuffs, ~c1n~q, vaccines, blood products, photo-graphical film etc, that are temperature-sensitive and 20 should be stored or handled at a certain , - Cl Lul~ in order to prevent quality degradation. Typical ~ , 3 ,~c: of such products are foodstuffs, such as refrigerated foods, e.g. milk, vegetables etc, or frozen foods, e.g. meat, fish, ice-cream etc. For example, in order that a deep-25 frozen product should have a satisfactory quality whenreaching the shop, it should not be sub3ected to a tem-p~laLule ~x~ fl~n~ e.g. about -15C to -18C, after d~:pal LUL~: from the producer and until the time of arrival in the shop. For refrigerated foods, the corr~p~nfl~n~

30 temperature is about +4-8C. On its way from the producer to the l;UI~ I , a frozen food passes through a large number of h~n~ n~l steps, such as storage with the pro-ducer, LLCIII~L~UL Lc.Llon from the producer to the whole-saler, storage with the wholesaler, LL~I~UL LcLlon ~rom Wo 95/30136 r~ t z the whr~l r q~l r~r to the retailer, and storage with the retailer. :~n all these partial steps, the deep-frozen food must be handled correctly, i . e . at a temperature which does not exceed about -15C to -18C, in order to prevent its quality from degrading. To this end, the tem-p~ Lul~ of the product is checked at regular intervals in each partial step, i.e. during transport and storage.
One way of p :lroL~lng such r-hPr-k~nrJ is to insert a needle-equipped electronic thr-- Lt!1 into a stack of p~rk~gr~ containing deep-frozen L,ludu~_Ls, and to read the L_.~eLaLul~ on the th, LC~L. However, this involves several disadvrlllL~ ~s. First, the electronic th~ ter is expensive to manufacture and purchase, and requires f or its operation batteries which must be replaced at regular intervals. Moreover, the l' L~L must be calibrated for correct indication, and the 1' ter needle must Qn each measuring rr~r~1rn be ~eld inserted in the stack of p~r k~r-c with frozen products for several minutes to enable the 1' L~::l to adiust itself and display the correct I ,, rlLul~. As deep-frozen ~l~)du~;LY, r cr~r~ ly foods, are normally stacked on pallets and at least one check must be made on the IJ1OI1U~ on each pallet, it is understood that the total time for r-hPrk;nrJ
e. g . the load on a long-distance truck or in a store-room is quite rr~nQ~rlr~rable and thus involves ~ub:,Ldl~Lial costs .
There is thus a need to make the control quicker and less expensive, and preferably also to make po~ hl e sub-seguent control of the h;lnfll i n~ of the product to ensure that this h;~n(~l ;n~ falls within the limits applying to the product /~ I r~rl, in respect of its r-nn~ -h~ 1 ~ ty .
This is also 1, La.lt in view of the strict products liability currently in~ ' L upon manufacturers in most countries .
The present invention aims to achieve this and obviate the shul I i nrJc inherent in the prior-art tech-nique, by means of a device which is easy and inexpensive Wo 95/30136 2 1 8 6 7 4 6 r~
to manufacture and which constantly is at the t~ ,- ClLUl of the product c~n~-~rnP~9, to enable a quick t, ~LU~
control without any delay for L ,~ c~ re adjustment of the device.
If one wishes to perform a more complete control of the h~lntll ing condltlons of a product, and thus of lts quality, lt is further possible according to the lnven-tlon, instead of only mhPmkln~ the L , cLLuLe~ also to check both temperature and time, more specifically by making an integration of the; , ~LU1~ conditions to which the product is subjected over the time during which the hAn~ll in~ of the product takes place.
According to the invention, there is provided a method for controlling the hFln(11 in3 conditions of at least one ob~ect, such as an individual package or a stack of such park~Pc~ the object being intended to be handled under certain predetPrm;n~-l conditlons, the method being characte~ised by inserting into the object a device consisting of a substantially flat, elongate casing having a slot-shaped space between two opposed walls of the casing, and an elongate sllde-shaped body, which is movable into and out of the slot-shaped space and which is provided at one end with a means contalning at least one composltion selected from temperature-sen-sltlve composltlons and time-t ,~laLul~-sensitive com-posltions and lndicating by colour change the ~ Prlln!T
and the falling-short of the predet-~rmlnP-l conditions, and by removing for control L,Ul~VS~s the slide-shaped body inserted in the slot-shaped space of the casing, from said slot-shaped space for visual observation of the colour of said means.
According to the invention, there is also provided a device for controlling the hf`nfll ln~ condltions of at least one ob~ect, such as an lndivldual package or a stack of such packages, the object belng lntended to be handled under certain predetPrmln~rl conditions, char-acterised in that it consists of a substantially flat, Wo 95/30136 r~

elongate caslng having a slot-shaped space between two opposed walls of the casing, and an elongate slide-shaped body, which is movable into and out of the slot-shaped space and which is provided at one end with a means con-5 taining at least one composition selected from tempera-ture-sensitive compositions and time- ~ ulè-senSi-tive compositions and indicating by colour change the r~e~tl1ns and the falling-short of the predet~rm;nf~ con-ditions .
Other features of the invention will appear from the following description and the claims.
To facilitate the understanding of the invention, it will be ~ r; hPrl hereina~ter with reference to a prefer-red ~-1; L thereof which is illustrated in the accom-panying drawings.
In the drawings, Fig. 1 is a top plan view of the casing and the slide-shaped body of the device according to the invention; Fig. 2 is a cross-sectional view of the casing taken along line II-II in Fig. l; Fig. 3 is a plan view o~ the device ln Fig. 1 with the parts ~! 1PCI;
Fig. 4 is a longitudinal sectional view of the device taken along line IV- IV in Fig . 3; and Fig . 5 is a per-spective view of a loading pallet carrying a stack of packages and the devlce according to the invention in-2 5 serted in the stack .
As appe~rs from Fig. 1, and as previously mentioned, the device according to the invention consists of a sub-stantially flat, elongate casing 1 having a slot-shaped space 2 between two opposed walls 3, 4 of the casing, and an elongate, slide-shaped body 5 which is movable into and out of the slot-shaped space 2 and which is provided at one end with a means 6 which indicates by colour change the ~ 1; n~ and the falling-short of the prede-t~rm; no(l conditions to be checked.
As also illustrated in Figs 1-4, the casing 1 is p~LL~JLaLed ~at 7) at one end, on a level wlth the means 6 when the slide-shaped body 5 is inserted in the casing 1.
.

Wo9S/30136 P~ll~r ~

The openlngs 7 formed by the p~lrulc,Llon of the casing are intended to provide as quick a temperature equalisa-tion as po~;hll~ between the ob~ect whose L ,--~Lul~ is to be checked, and the means 6. In the Figures of the 5 drawing, the pdirul~Llon is shown as three p~rulcLL~d op~n1n~q, but it is un,lel:iL~od that it may have any suit-able design ensuring the desired, quick temperature equa-lisation between the ob~ect and the means 6.
According to one embodlment, the means 6 includes a 10 reversibly temperature-sensitive composition, preferably in accordance with British Patent l, 557, 742, which is hereby i~l~ulL~uL~Ldd by re$erence. This t, c,LuLe-sensi-tive composition is a water-based composition with con-trolled colour change and pH shift upon freezing or at a 15 selected ~ ILULC~ below freezing point, the composi-tion having a first, L 1 nrl ~ n~ an a~ueous solu-tion which contains a buffer and which upon a change of its t_..~eL~Lul~: between a first t , aLul~ above its freezing point and a second t ,~rc,Lul~: at or below lts 20 freezing point exhibits a pH shift, and the composition containing as additional , L- a regulator entailing a change of the proton conductivity of the frozen aqueous solution so as to affect the pH shift upon freezing, and at least one pH indicator exhibiting colour change upon 25 pH shift. The regulator may be an alcohol, a carboxylic acid or a precursor thereof . Particular ~ , l~c of alco-hols are methanol, ethanol, glycols and glycerol. Parti-cular ~ of carboxylic acids are formic acid, ace-tic acid, succinic acid, citric acid and glutamic acid.
30 F , ~ of precursors of Alrrhrl ~ or carboxylic acids are enzyme-substrate mixtures which by enzymatic reaction produce, respectively, alcohol and carboxylic acid, e.g.
l ipas e- esterase- glyceryl tri ~ l UCI L-3 .
According to another embodiment, the means 6 com-3!~; prises an irreversibly time-temperature-sensitive compo-sition for controlling the hzln~ n~ conditions in respect of the h~ntll ;ng temperature as a function of the hi~nr~l ;ns WO 9S/30136 l ~~

time. Such time-temperature-sensitive compositions are previously known and preferahly ~ q1 gnP~q as ~lPqrr~ hPd in US Patents 4,043,871 and 4,284,719, which are hereby incorporated by reference. As stated in the latter 5 patent, the means 6 may include such a time-L ~ ~LUL~:
sensitive composition distributed in two small, closed plastic ampoules s~l,aL~lL~:d by a common, rupturable par-tition. One plastic ampoule r.rm~nq an aqueous solution of enzyme and pEI indicator, while the other plastic 10 ampoule cont ins a ~ub~L~ e sllqFpnll~d in an aqueous medium. When the time-~ _ ~LUL~ indication is to com-mence, the rupturable partition is broken by the exertion of a compressive force on one of the plastic; , 1 Pq. In this way, the ~:ul!Lt:-lL~ of the plastic I, lPq will com-15 municate with each other so that the CUl~L~ L~ of theampoules are mixed and an enzymatic re ction is started.
This enzymatic reaction proceeds with the production of a reaction product, such as caproic acid ii the substrate is tricaproin and the enzyme is a lipase, tl~rPnrl1n~ on 20 L~ e~CILU~ ~nd time. The pll indicator present is intend-ed, by co1rllr~n~, to indicate the excess of a certain amount of reaction product, such as acid.
The use of the L~e~ d, I ~-LaLuL~-sensitive composition according to G3 1,557,742 or the preferred 25 time-temperature-sensitive composition according to US

4,284,219 as the means 6 entails when rhPrl ~n~, e.g.
deep-frozen products, that the means freezes and its volume increases. In order that the means 6, upon such an increase of volume, should not get stuck in the slot-30 shaped space 2 between the walls 3 and 4, these walls arepreferahly provided, at least in the portion of the cas-ing inside th2t is contacting the means 6 when this is inserted in the casing 1, with ridges 8 ( see Fig . 2 ) extending in the longitudinal direction of the casing.
35 This results in a small contact surface between the means and the inside of the casing ( limited to ~the crests o~

WO9S/30136 T~~ S

the ridges ), such that the slide-shaped body 5 can easily be inserted into and removed from the casing 1.
The casing and the slide-shaped body of the device according to the invention can be manufactured from seve-5 ral different materiaLs, but for the device to functionproperly, it is preferred that certain special materials are selected. Thus, the device should be able, when inserted in a stack of objects, such as a stack of pack-ages holding deep-frozen products, to withstand the com-10 pressive force exerted on the casing 1 by the stack, forwhich reason the casing should consist of a ~ ni17-ly-stable material. Furth, ~, the casing should con-sist of a material having low thermal conductivity in order that heat should not l~nn~ qq~rily be conducted 15 from the surro~n~l1n~q to the location of the L ~ LuL~-sensitive means 6. For these reasons, the casing mate-rial, and suitably also the material for the slide-shaped body 5, is selected from the group consisting of plas-tics, paper, papell,oal~ and starch. Because of its high 20 thermal conductivity, metal is however a less preferred material, desplte it belng ~ q~r~n~lly stable. The pre-ferred materials paper, p~r ~rhoRrd and starch also have the adv~.L~y~ of being envil~ Lc-lly-friendly.
When inserting the device according to the invention 25 into a stack of ob~ects, as shown in Fig. 5, it is impor-tant that the device be not inserted so far that the slide-shaped body 5, for subsequent ~h~ k;n3 of the h~n~l in~ conditions, cannot be withdrawn from the slotted casing 1. For this reason, the casing is provided at one 30 end ( the outer end ) with an abutment 9, which is down-wardly bent from the longitudinal axis of the casing at right angles or almost right angles. The abutment 9 serves as a stop preventing the casing 1 from being inserted into a stack farther than the abutment 9. Simi-35 larly, it may be convenient also to design the outer endof the slide-shaped body 5 as a downwardly-bent abutment, as shown in Fig. 4, although this is not compulsory.

WO g5/30136 r~

~ he device according to the invention is also usable for the contrDl of separate ob~ects, such as a big pack (master package) of refrigerated or deep-frozen food.
Instead of inserting the device between two ob; ects, as 5 done when -hP-~kin~ a stack of ob~ects, the device is now inserted into the object itself. The object should then suitably have been prepared in view of such an insertion of the device, e. ~ . by providing a centrally-positioned depreæsion or opening in the obj ect .
As previously mentioned, the ~ PPAin~ or the fall-ing-short of the predetPrm;np~l hAnfll in!T conditions is indicated by a colour change of the i ~lc-Lul~-sensitive means 6. If only a control of the L ~ Lul~ prevailing at a certain point of time is to be made, the means 6 15 consists of a reversibly ~ ~Lul.d-sensitive composi-tion, preferably in ~-co~A~n(-P with the tpAr~h~n~s of GB
1,557,742. If, on the other hand, the L.~ Lul~ is to be checked as a function of time, l.e. by an illte~lc.Llon of L , lLult: over time, the means 6 consists of an 20 irreversibly time-L ,_laLul~-sensitive composition, preferably in accordance with the tP~rhin~F: of US
4,284,719. In order to arrange the composition on the slide-shaped body 5, the composition is placed in a con-tainer, such as capsule or ampoule, of a suitable mate-25 rial, such as plastics, which is attached to the body 5.
It is also r~ hlP to attach two or more containersto the slide-shaped body 5. I'hese containers may hold different compositions of the above-mentioned type, i.e.
different t~ Lul~-sensitive compositions and/or di~-30 ferent time-temperature-sensitive compositions. Thus, the containers may hold mutually different time-t ,~ ~Lule:-sensitive compositions, which indicate by colour change when different amounts of the prede~PrminPtl hAn~ nSJ con-ditions, i.e. the estimated keeping-quality time, have 35 been ~ 1. Suitably, use is made of two or more, pre-ferably three mutually different compositions in separate containers. For example, it is possible to arrange three _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 6 1 ~~
21 867~6 dif ferent time-temperature-sensitive enzymatic composi-tions in ~ aldLe ampoules, the composltions being so prepared as to change colour when the product to be con-trolled is subjected to such time-temperature conditions 5 that its keeping quality has been Cu~ l to a dif ferent degree . Thus, the composition in a f irst ampoule may be so pLep~l~d as to change colour when the product is sub-jected to such a combination of time and ~ clLUL~d that 10-30%, preferably about 25~6, of its estimated keeping 10 quality has been ~r~n~ ~~1, while the composition in a second ampoule may be so ~ al~:d as to change colour when 30-60%, preferably about 50%, of its keeping quali-ty has been ~:u.~ ~, and finally the composition in a third ampoule may be 80 L,l~pa-d as to change colour when 60-10096, preferably about 75%, of its keeping guality has been ~:UII~ . A device in which the means 6 thus com-prises several different time-temperature-sensitive com-positions can be ~1PY; ~n~rl in the manner shown in Fig. 1, with the exception that the means 6 consists, not of a 20 single capsule or ampoule, but of several such rArslll P~:
or ampoules, lPrPnfl~n~ on how many different compositions are used. In this context, lt should be added that lt is not only poc~1hle to use several different tlme-tempera-ture-sensltive compositions, but that the means 6 may 25 similarly consist of several different L ,- atuL,;:-sensi-tive compositions r~h~n~n~ colour at different tempera-tures, or that the means 6 may consist of a combinatlon of t , clLul~:-sensitive compositions and tlme-tempera-ture-sensitlve, -9~t~r~n~. An ~crPc1~l ly preferred com-30 bination consists of three different time-t~ elc:Lul-sensitive compositions, as described above, comblned with one t , clLul~-sensltive composltion. Thus, practically full information can be obtained about the h~n~l 1n~ con-ditions of a product, and a warning system can be provid-35 ed which makes it possible, in the case of perishableproducts, to take measures before the products have been destroyed. Since such a system provides immediate infor-Wo 95/30136 r~ r~ ~~
21 867~6 ~

mation about the hAn-ll in!J conditions of a product, it can be used for supplying products on the basis of the handl-ing conditions to which they have been subjected, as opposed to the present systems, according to which the 5 products first manufactured are first supplied ( first in, first out), whether the ylu~u~_L~i have been subjected to different hAn~l ;n~ conditions or not.
When the predetPrminptl conditions should be control-led, this is done by visual observation of the colour of lO the means 6. As previously mentioned, the means 6 indi-cates by colour change if the predetPrm~nP-l L _._iatUL~
has been PYreP~Prl or fallen short of, or if the predeter-mined time-temperature conditions have been PYrPp~1erl or not. For example, the means 6 may have an orange colour 15 at the pl~:de~ ;nPfl t ,~LaLUL~ (e.g. about -18C), while the colour is bright yellow at lower ~ ,- aLuLdS, and violet at higher L~.c)eL~LuLus. To make it possible during the visual obs~L va Lion to ~Euickly decide whether the conditions have been PY~-PPtlPA or not, it is suitable 20 to compare the colour of the means with a colour gauge, i . e . a colQur scale showing which colour corresponds to the predetPrm~nP-l L~.~eL~Lul~ or L ,~ aLuL~:~ above or below this ~, aLule, or alternatively showing which colour ~ulLd~ullds to acceptable or u-la~ Ldble time-25 temperature conditions. It is ~ eLLe:d to arrnnge such acolour 8cale 10 on the slide-shaped body 5, as indicated in Fig. 1.
By the device according to the invention being of a simple deslgn, as described above, and made of inexpen-30 sive materials, it can be manufactured at relatively lowcosts. Such low costs and the envii Ldlly-friendly material from which the device is made entail that the device can be of ~11 SpQCAhl P type, which means that it is not nPrPCcAry to recycle the device oe the temperature 35 control of a certain stack of objects is completed.
Although the invention has been ~1PC~ hP~l above with reference to a preferred embodiment, it is understood Wo 95/30136 r that it is not restricted this particular embodiment, but may be 'if;P~l within the scope of the ~rp~n~lecl claims.
Thus, for example, the temperature-sensitive body need not be a circular ampoule 6, as intimated in the draw-5 ings, but may consist of an elongate column, arranged inthe longitudinal direction of the slide-shaped body 5, of the L ~ l ult:-sensitive composition described above.
The L .._ldLul~-sensitive means 6 may also consist of some other temperature-sensitive material, such as a tem-10 p~aL~tul~-sensitive dye or any other t , ~tul~-sensitive material rh;~ng~n5J colour upon a change of L ~ clLUL~:.

Claims

1. A method for controlling the handling conditions of at least one object, such as an individual package or a stack of such packages, the object being intended to be handled under certain predetermined conditions, c h a r a c t e r i s e d by inserting into the object a device consisting of a substantially flat, elongate casing (1) having a slot-shaped space (2) between two opposed walls (3, 4) of the casing (1), and an elongate slide-shaped body (5), which is movable into and out of the slot-shaped space (2) and which is provided at one end with a means (6) indicating by colour change the exceeding and the falling-short of said predetermined conditions, and containing at least three compositions selected from (a) temperature-sensitive compositions with control-led colour change and pH shift upon freezing or at a selected temperature below freezing point, the composi-tions having a first component including an aqueous solu-tion which contains a buffer and which upon a change of its temperature between a first temperature above its freezing point and a second temperature at or below its freezing point exhibits a pH shift, and the compositions containing as additional, components a regulator entailing a change of the proton conductivity of the frozen aqueous solution so as to affect the pH shift upon freezing, and at least one pH indicator exhibiting colour change upon pH shift; and (b) time-temperature-sensitive enzymatic composi-tions containing an enzyme, an enzymatic substrate and a pH indicator, the enzymatic composition having the abi-lity, to integrate the function of time and temperature, to bring about a colour change;

said at least three compositions including:
a first time-temperature-sensitive enzymatic compo-sition changing colour when 10-30% of the predetermined conditions have been consumed;
a second time-temperature-sensitive enzymatic compo-sition changing colour when 30-60% of the predetermined conditions have been consumed;
a third time-temperature-sensitive enzymatic compo-sition changing colour when 60-100% of the predetermined conditions have been consumed, and removing for control purposes the slide-shaped body (5) inserted in the slot-shaped space (2) of the casing (1), from said slot-shaped space (2) for visual observation of the colour of said means (6).

2. A method as claimed in claim 1, c h a r a c -t e r i s e d in that the colour of the means (6) is compared with a colour scale (10) on the slide-shaped body (5) during the visual observation.

3. A device for controlling the handling conditions of at least one object, such as an individual package or a stack of such packages, the object being intended to be handled under certain predetermined conditions, c h a r a c t e r i s e d in that it consists of a sub-stantially flat, elongate casing (1) having a slot-shaped space (2) between two opposed walls (3, 4) of the casing (1), and an elongate slide-shaped body (5), which is mov-able into and out of the slot-shaped space (2) and which is provided at one end with a means (6) indicating by colour change the exceeding and the falling-short of said predetermined conditions and containing at least three compositions selected from (a) temperature-sensitive compositions with control-led colour change and pH shift upon freezing or at a selected temperature below freezing point, the composi-tions having a first component including an aqueous solu-tion which contains a buffer and which upon a change of its temperature between a first temperature above its freezing point and a second temperature at or below its freezing point exhibits a pH shift, and the compositions containing as additional components a regulator entailing a change of the proton conductivity of the frozen aqueous solution so as to affect the pH shift upon freezing, and at least one pH indicator exhibiting colour change upon pH shift; and (b) time-temperature-sensitive enzymatic composi-tions an enzyme, an enzymatic substrate and a pH indica-tor, the enzymatic composition having the ability, to integrate the function of time and temperature, to bring about a colour change, said at least three compositions including:
a first time-temperature-sensitive enzymatic compo-sition changing colour when 10-30% of the predetermined conditions have been consumed;
a second time-temperature-sensitive enzymatic compo-sition changing colour when 30-60% of the predetermined conditions have been consumed;
a third time-temperature-sensitive enzymatic compo-sition changing colour when 60-100% of the predetermined conditions have been consumed.

4. A device as claimed in claims 4 and 6, c h a r -a c t e r i s e d in that the means (6) also comprises one temperature-sensitive composition.

5. A device as claimed in any one of claims 3 and 4, c h a r a c t e r i s e d in that the casing (1) is per-forated (at 7) at one end, on a level with temperature-sensitive means (6) when the slide-shaped body (5) is inserted in the casing (1).

6. A device as claimed in any one of claims 3-5, c h a r a c t e r i s e d in that at least the portion of the inside of the casing that is contacting the tempera-ture-sensitive means (6) when inserted in the casing (1), is provided with ridges (8) extending in the longitudinal direction of the casing.

7. A device as claimed in any one of claims 3-6, c h a r a c t e r i s e d in that the casing (1) consists of a dimensionally-stable material having low thermal conductivity.