US 2782749 A
Description (OCR text may contain errors)
Feb. 26, 1957 J. 5. BECKETT ET AL 2,782,749
DETERIORATION TEL L .TALE
Filed July 25, 1955 /2 S POI L ED M JOHN S. BECKETT,
WILLIAM J. MARENUS,
BY f 4 ATTORNEY 2,782,749 DETERIORATIUN TELLTALE John S. Beckett, Glendale, andWilliam J. Marenus, Burbank, Calif assignors to Aseptic Thermo Indicator Company, North Hollywood, Calif, a corporation of California Application July 25, 1955, Serial No. 523,960 4 Claims. (Cl. 116114) This invention relates to a telltale indicator for food packages and the like and in particular for a visual telltale device which shows that a package of food has been subjected to a temperature higher than normally safe temperature for a time sufiicient to cause deterioration of the contents. More particularly, it relates to a visual indicator which may accompany a package of food, for example, a box of chocolate candy, which will show whether or not the contents of the package have been warmed to a temperature and for a sufiicient length of time to cause deterioration to an undesirable or dangerous point of spoilage, or to cause the production of unfavorable odor, taste, or appearance. It is a requirement that such an indicator accompany the package from the time it is packaged until it reaches the ultimate consumer, and the device must be of such a nature that any recooling will not destroy any indication of a prior overexposure of the package.
It is the object of the present invention to provide a warning or telltale device for the outside of packaged foods and the like, which indicates that the package has been subjected to a temperature above normal temperature for a sufiiciently long time to cause deterioration. Another object is to provide a warning or telltale device to accompany food packages which is cumulative in its indication of time-temperature efiects over the entire history of the package. A further object is to provide a warning or telltale device of the character described which is inexpensive to make and to install in or on the packages and which does not depend for its telltale activity on the specific nature of the food or contents of the package, or whether or not it is frozen, refrigerated, or merely not overheated. Another object is to provide a telltale device which will perform its function irrespective of its orientation or environment, and which is of such form that it is not easily displaced from the package or rendered ineffective in the normal handling of the package in the trade.
These and other objects are attained by our invention, which will be understood from the following description, reference being made to the accompanying drawings, in which:
Fig. l is a perspective view of a simple form of the telltale device of this invention;
Fig. 2 is a plan view of another form of the telltale device;
Fig. 3 is a cross-sectional view taken on the line 3-3 of Fig. 2;
Fig. 4 is a bottom plan view of the device shown in Fig. 2 after deterioration has been indicated;
Fig. 5 is a side elevational view of another form of the telltale device; and
Fig. 6 is a cross-sectional view of the form shown in Fig. 5 taken on the line 6-6 of Fig. 5.
Referring to the drawings, the device in its simplest form consists of an absorbent base 11 which is preferably thick blotter stock paper or similar absorbent material, having a front (visible) face 12 and a reverse face 13, which makes surface contact with a layer of an indicator material 14 which is of the general nature of a wax or fat (but not limited thereto) which has the further prop- Patented Feb. 26, 1957 Z erty of not having a sharp melting point but softening and becoming less viscous with temperature rise above the temperature of a substantially solid or non-diffusing state and of then diffusing through the base 11, to become visible from the front face 12. The indicator material upon diffusing through the absorbent base becomes visible at the front face by the changed surface appearance, for example, by appearing as a grease spot by rendering the base semi-transparent or translucent. The indicator material may be colored differently from the base and, therefore, become plainly visible when it has diffused through the paper.
The diffusion of the indicator material 14 through the base 11 may also be made visually evident by providing, as in Figs. 2, 3, and 4, insignia 15 on the reverse face 13 of the base 11, for example, as by printing with a contrasting colored ink so that the insignia 15, at the beginning invisible from'the front face 12, becomes visible when the indicator material 14 has softened and diffused through the base 11, making the base 11 translucent. In another variation, the insignia 15 may be formed or printed, using a colored substance which is dissolved in the diffused indicator material 14 when it is in liquified state, and then this colored indicator material diffuses through the base to become visible.
The base, which usually'consists of some variety of paper blotter stock or cardboard, must be sufiiciently opaque so that it will hide the coating or the insignia and the coating on the reverse face, but which is of such a nature that the coating material in its diffused form, when diffused through the base, becomes visible on the front face. The thickness, porosity and nature of the paper provides means for controlling the time rate of diffusion of the coating substance to the point of visibility.
One use of our invention is in providing an indicator to show deterioration of chocolate candy. Chocolate candy, as generally manufactured, when at temperatures below about maintains a glossy surface appearance for long periods of time, but this glossy surface quickly becomes grey when the candy has been exposed to temperatures in the neighborhood of to for a short time, or for slightly lower temperatures for somewhat longer periods. Candy which shows this bloom is not readily saleable and such visual appearance is usually accompanied by deterioration in flavor and taste. We have found that the coating agent 14 for this particular indicator may satisfactorily consist of cocoa butter alone. When commercially pure cocoa butter is used as a coating on the reverse face of a paper or cardboard upon which has been printed a contrasting insignia 15, also on the reverse face, the insignia when viewed from the top face is invisible, but when the telltale device is subjected to temperatures of around 80 or higher, the cocoa butter coating softens, diffuses through the paper base, and causes the paper to become translucent so that the printed indicia become visible from the front face. This temperature time indicator coincides with the appearance of bloom on the candy itself.
Candy compositions vary, and it is necessary to select the indicator composition for a particular product. For example, the time-temperature relations for spoilage (bloom) of a certain kind of chocolate candy are shown in Table 1.
Table 1 Temperature, F. Spoilage Time of Candy 48 hours (2.0 days).
672 hours (28.0 days). 12,480 hours (520 days).
2.5 hours (0.1042 day).
This rate of spoilage may be represented by Equation A (A) loget=8l8 53/ T-151.16905 Table 2 Temperature, F. Creep Time for .75
2 hours, 20 minutes. 8 hours.
This rate of creep for a given distance may be represented by Equation B (B) 1oget=8l853/T151.26519 where t represents the time in days and T is the temperature in degrees Fahrenheit absolute (degrees Rankine). By comparison, it will be noted that equation A is substantially the same as Equation B, so that the rate of spoilage of this particular candy maybe indicated by the rate of creep of the methyl cinnamate and cocoa butter mixture.
The proportion of the above illustrative example for the diffusing material may be altered to include, for example, more cocoa butter, which accelerates the rate of creep through a given length or thicknessof'paper, or less cocoa butter which will retard the rate of creep. If the temperature varies, the spoilage time is the time-temperature integrals of the above equation.
Referring again to the drawings, particularly Figs. and 6, there is shown another alternative form of the telltale device of this invention. An elongated strip 17 of blotting paper, preferably having an enlarged end 18 to serve as a reservoir for the waxy indicator material, is saturated at its enlarged head only, and the surfaces coated with additional indicator'material 19. The elongated strip 17 is provided with insignia 20 printed thereon to show the distance of creep of the indicator along the strip 17. When the device has been subjected to term peratures and times sufficient to show a mark at a selected indicia 20 printed thereon, the candy in the container will be known to have deteriorated and formed a bloom, without opening the package.
The coating material may consist of any material which has a softening point and diffusibility within the desired range in which the indicator is expected to operate. The sharpness of the melting point may be varied with the product under control since wider or shortendiffusing ranges may be necessary depending upon whether the substance under control deteriorates or is entirely spoiled upon exposure to a critical temperature, or whether there is a time temperature relationship with more or less spoilage occurring over a wide range of temperatures and times.
The coating substance may be selected from a wide range of chemical compounds and natural products having suitable ranges of temperature at which they become sufficiently fluid to diffuse into the base. Materials with sharp melting points may not be used. synthetic waxes,'fat and grease mixtures, or mixtures. of these with one or'more sharp melting materials giving compositions which when heated, soften and diffuse'into a porous base of the general nature of paper may be used.
Natural and Examples of these materials are natural waxes, carbowax mixtures, commercial cocoa butter, tallow mixtures, and mixtures thereof, with or without compatible sharp melting point materials such as cyclohexacaproic acid, ethyl stearate, methyl cinnamate, and n-octadecylacetate.
The coating substance may also be used as a carrier for an acid substance, which when the coating is melted, is released and diffuses through the base which had been impregnated with an acid-indicating dye, thus indicating diffusion by the changing of the color of the dye incorporated in the base. I
As pointed out above, the insignia may be printed with contrasting colored ink, or they may be marked with an ink-linesubstance which itself dissolves in the liquified diffusible substance as it diffuses into or through the base, the insignia becoming visible on the front face. by the diffusion of the dye itself, or by the making of the base more translucent becauseof the diffusedsubstance he method of forming the coating substance layer on the reverse side of the base usually involves the making of a coating on anotherrelatively non-absorbent sheet .or strip, and then pressing the coating surface :into tight contact with the reverse-face of the base (Figs. 1 to 4) to avoid the diffusion into the base which would result from directly applying the melted coating substance to the reverse face of the base. Other methods such as spreading or impact spraying may be employed, including refrigeration prior to attachment of the telltale to the package.
.The advantages of our telltale indicator will be apparent from the above description. The indicators are simple and inexpensive to manufacture; they may bepre- (but deteriorating) temperature exposure of such materials as chocolate candy,- whole blood, enzyme products, bacteriological cultures and specimens and the like.
1. A telltale device for indicating deterioration of the contents of aclosed package of food or the like comprising an absorbent base having a visible surface portion; and a diffusion material in contact with a portion of said base, said diffusing material being wax-like and having a softening range from a substantially solid non-diffusing state to a limpid rapidly diffusing liquid state, said range coinciding with a selected range of temperatures, said diffusing material being adapted to soften and diffuse into said base when the temperature becomes elevated above a selected non-deterioration temperature, for a distance. dependent upon. the time, said visible surface of said base being altered in appearance by said diffused material.
2. A telltale device for indicating deterioration of the contents of a closed package of food or the like comprising an absorbent base having a visible surface portion; and a diffusion material in contact with aportion of said base, said diffusing material being wax-like and having a softening range from a substantially solid nondiffusing state to a limpid rapidly diffusing liquid state, said range coinciding with a selected range of temperatures, said diffusing material being adapted to soften and diffuse into said base when the temperature becomes elevated above a selected non-deteriorationtemperature, the time, temperature and distance diffused into, said base being related by the equation loget=K/ TK where .?t is the time in days, T vis the temperature in degrees Fahrenheit absolute (degrees Rankine), K is a constant determined by the particular base and theparticular diffusion material, and K is a constant for the particular rate of deterioration'of the contents. 7 V V 3: A telltale device-for; indicating deterioration of the contents of a closed package of food or the like comprising an-absorbent paper base having an opaque front surface; and a-coating of diffusion material on the reverse face of said base; said material being a mixture of wax-like substances having a softening range from a substantially solid non-diffusing state to a limpid rapidly difiusing liquid state, extending over a range of temperatures; said diffusion material being adapted to soften and diifuse into said base when the temperature becomes elevated above a selected non-deterioration temperature for a distance dependent upon the time, at least a portion of said front surface being altered in appearance when said diffused material has diffused through said base.
4. A telltale device for indicating deterioration of the contents of a closed package of food or the like comprising an absorbent base having a visible surface portion; and a diffusion material in contact with a portion of said base, said diflusing material consisting of a mixture of 15 2,379,459
a wax-like substance having a range of softening temperatures, and a compatible chemical compound having 10 base.
References Cited in the file of this patent UNITED STATES PATENTS 1,535,536 MacDonald Apr. 28, 1925 Schreiber July 3, 1945 2,490,933 Tornquist Dec. 13, 1949