A DEVICE SERVING AS INDICATOR OF THERMAL HISTORY ESPECIALLY FOR FROZEN PRODUCTS AND THE LIKE

Abstract: A device serving as an indicator of thermal history, namely for frozen products and the like, consisting of a container (10) of non-opaque material containing a fluid (12) with controlled viscosity as a function of temperature; a mobile portion (13) having a controlled geometry capable of moving in such a fluid as a result of a force applied by an elastic member (14); holding means (17) which can be released, designed to retain such a mobile member in an initial position at room temperature and when the device is frozen; the arrangement being such that after freezing and the release of such holding means the mobile portion is displaced in another position as a result of the force applied by said elastic member, in a time which is a function of the viscosity of the fluid; thus the device shows the thermal history of the frozen product and the like as a function of temperature elevations it has undergone, and the time elapsed since the holding means have been released.

Description: A DEVICE SERVING AS INDICATOR OF THERMAL HISTORY ESPECIALLY FOR FROZEN PRODUCTS AND THE LIKE SPECIFICATION Technical field The invention concerns a device useful as an indicator of thermal history, particularly for frozen products and the like. It is common knowledge that frozen foodstuffs should be kept at a predetermined low temperature, such as -18°C, for instance, within a comparatively narrow range, and should not in any case be thawed and frozen again. At present no means is available to check the actual thermal history of frozen products, namely frozen foodstuffs and the like. The consumer therefore must choose the goods from the frozen food section in food stores and cannot check the thermal history of the goods. Purchasers can only rely on notions of "confidence" totally deprived of any sσientfic relevance. The same problem applies to a number of other items such as pharmaceutical products which must be kept at a temperature much lower than room temperature to retain their effectiveness. As far as these products are concerned there are no known means of telling first hand whether the pharmaceutical product has been exposed to temperature rises which might i pare its properties. ' Industrial applicability The purpose of the present invention is to provide an indicator of thermal history especially designed for frozen products and the like, which shows whether the product has gone through a rise in temperature in excess of the standards specified by the manufacturer, and might provide information concerning the time and the exposure to temperature variations in excess of the temperature recommended for a proper preservation. It is well known that the above products can be exposed to temperature rises without ever exceeding 0°C and retain, at least . seemingly, their frozen state; however if at -18"C undesired biological processes are practically stopped, at -3 or -4°C such biological processes can take place, their occurrence being also a function of the time of exposure to a temperature higher than the recommended one, which as pointed out earlier is of about -18 β C. Disclosure of the invention The aim of the present invention is therefore to provide a device which displays the thermal history of frozen products, and that gives an indication of the time of exposure to a temperature higher than the recommended temperature. According to the present invention, there is provided a device based on the cooperation between an elastic element pre-loaded when the device is triggered and a fluid material with a controlled viscosity, which is a function of temperature; so that the indicator combined with the elastic member immediately shows consumers whether the frozen product on sale has gone through "thermal mishandling" which makes it unfit for consumption. The present invention shall now be described with reference to a preferred embodiment thereof, shown by way of example which should not in any way limit other possible embodiments; and according to the attached drawings, wherein: Brief description of the drawings figure 1 shows a longitudinal section of a first embodiment of the device according to the above invention; figure 2 shows a section along plane II-II of figure 1; figure 3 shows a longitudinal " section of a second embodiment of the device in question; figure 4 shows a section along plane IV-IV of figure 3; figure 5 shows a partial section view of a triggering tool for devices according to the invention; and figure 6 shows a temperature/viscosity diagram of a component designed for use in the devices according to the invention. Mode for carrying out the invention With reference to the drawings and in particular to figures 1 and 2, the above device includes a case made of transparent material shown in 10 with a lid 11. Within the case there is a mixture with a predetermined viscosity as a function of the temperature, as we shall explain more in detail. Inside the case 10 there is provided an indicator 13 with a neutral buoyancy, subject to pull force in the direction of the F arrow by means of a tension spring 14, anchored in 15 to the indicator 13 and in 16 to the left end of the case 10. As shown in figs. 1 and 2, the member 13 is held in a position which is at the right of the case 10, by means of a metal "pin" 17, which goes through the wall of the case 10 and a hole 18 of indicator 13. The purpose of the pin will be explained later on. An elastic gasket can be positioned in the area which is to be crossed by the pin 17, and will serve as a self-healing sealing element to prevent leakage of fluid after removal of the pin 17, after thawing. The gasket, not shown in the figures for the sake of simplicity, will consist of an elastomer which preserves the self-healing sealing properties after exposure to low temperature. A suitable material could be a silicone-type elastomer. The above also applies to the embodiments given in figures 3 and 4 which will be discussed later. Figures 3 and 4 show a second embodiment of the device in question. The parts corresponding to those in figures 1 and 2 will be marked with the same reference numbers . In the embodiment shown in figures 3 and 4, the spiral spring 14 of fig.l is replaced by a leaf spring, 18 which carries at the end an indicator 19. At the initial stage of the assembly, the cases 10 and 10' are rotated by 90" when compared with figures 1 and 3 and are filled with the fluid 12 and 12' of the kind specified below, up to a level of 20, 20', respectively. The lid, 11, 11' is then fastened by means of thermal welding or similar techniques. At this stage the indicator 18, 19 will be in the position shown in the figure. For its practical use the case 10, 10' is firmly fastened to the frozen foodstuff package or to the package to be frozen: standard freezing temperature - 18/-20 β C. Prior to shipping the frozen products provided with the device according to the invention, it should be "turned on". This can be achieved as shown in figure 5, i.e. by means of a tong-like device, to hold the pin head 17 pulling it in the direction of the arrow T, removing it and releasing the restraint on the indicator 13 (or 19 in fig. 3) . According to the practical construction of the device, the removal of the "pin" 17 (17') is possible by simple mechanical force, or the pin 17 (17') could be made with copper or aluminum or other material with a high thermal conductivity, and the element 30 could be preheated to facilitate the removal of the pin 17 (17'). At this stage the device is turned on. As a result of the viscosity of the fluid or material 12 (12') , which is a function of temperature, with the elapsing of time, because of the pressure of spring 14 or 18, the indicator 13 or 19 will arrive at the position 13A, 19A respectively. The viscosity of medium 12 will be selected in such a way that if the thermal history of the frozen product and the indicator is according to the specified standard, the indicator 13, 19 will take the position 13A , 19A, at the end of the expected lifespan of the frozen product for which the proper cold chain has been maintained. In this case the time is equal to 6n. absolute viscosity . ( radius of friction surface)/ the elastic constant of the spring. In case of non compliance with the cold chain, the indicator will take the position 13A or 19A more or less rapidly according to the level of thermal mishandling the product has gone through, alerting the consumer as to the product's eligibility for consumption. Among the various mixtures of medium 12, 12' conceivable according to this invention, is recommended a mixture of glycerine and water 65% (0.5 Stokes at - 20°C) , which is especially convenient on account of its lack of toxicity and a response which is substantially in keeping with the biological processes as qualitatively depicted in fig. 6. Those who are experienced in this field will of course understand that a number of modifications could be envisaged in the practical implementation of the technical principle underlying this invention: elasticity constants of the springs, variations in space of "viscous action", addition of modifications of the mechanical set up to penalize differently deviations from the standard in the cold chain, and there could be alternative ways of turning on the device. Moreover, the devices based on the technical principle underlying the invention could be applicable to fields other than frozen foodstuffs, such as pharmaceutical products. Even though we have shown applications related to given temperature ranges, it could apply to cryogenic temperatures or temperatures close to room temperature by selecting material whose viscosity is a function the temperature.

Claims: CLAIMS 1. A device useful as an indicator of thermal history, namely for frozen products and the like, which consists of a container of non opaque material to accomodate a fluid having a controlled viscosity, as a function of temperature; a mobile portion having a controlled geometry which can move about in the fluid as a result of a return force of an elastic component; holding means which can be released, arranged to retain such mobile portion in an initial position at room temperature and when freezing takes place; the set up being such that after freezing and the release of the restraining elements, the mobile component is displaced and takes on a different position, as a result of the force applied by the elastic element, in a time which is function of the fluid viscosity, providing information on the history of the frozen product and the like, according to the temperature rises it has undergone and the time elapsed since the restraining elements have been released. 2. An indicator according to claim 1 characterized in that the mobile component operates as an indicator which can be seen outside the container. 3. An indicator according to claim 2, characterized in that said elastic element consists of a spring. 4. An indicator according to claim 3, characterized in that the mobile element is of a definite size, fastened to said spring, consisting of a spiral spring, said mobile element being made of a material with neutral buoyancy in such a fluid. 5. An indicator according to claim 3, characterized in that the mobile element has a definite size and is fastened to the spring which is a leaf spring. 6. An indicator according to one or more of the abo claims, characterised in that it consists of a pin to be removed after freezing, positioned in such a way that the above elastic element is mechanichally stressed. 7. An indicator according to claim 6, characterized in that self-sealing gaskets are provided in the area of the container which is to be crossed by the pin. 8. An indicator according to claim 7, characterized in that said pin is removed by applying concurrently a pulling force and localized heat. 9. An indicator of thermal history especially designed for frozen products and the like basically according to the above claims and as described with reference to the relevant figures and drawings.

Inventors: BIANCHINI MARCO, BIANCHINI, MARCO
Applicants: BIANCHINI MARCO, CONSIGLIO NAZIONALE RICERCHE, CONSIGLIO NAZIONALE DELLE RICERCHE
Application year: 1993
Main classification: G01K3
IPC codes: G01K3, G01K11