WO2005080964A1

WO2005080964A1 - Food product condition indicator label

Info

Publication number: WO2005080964A1
Application number: PCT/US2005/004445
Authority: WO
Inventors: Daniel F. Peters; James G. Mcgory; Ricky Helton; Blake Mcgory; Mark Mcgory
Original assignee: Peters Daniel F; Mcgory James G; Ricky Helton; Blake Mcgory; Mark Mcgory
Priority date: 2004-02-13
Filing date: 2005-02-14
Publication date: 2005-09-01

Abstract

A label containing a food condition indicator is provided wherein a label has a pull-tab along an edge. The pull-tab separates an overlaminate layer of the label structure and the printed portion of the label from the package to expose an indicator strip that is positioned between the printed portion of the label and the overlaminate layer. The indicator strip contains an indicator compound that is adapted to change color when the indicator strip is placed in contact with the juices of a packaged meat product in order to detect whether bacterial action has rendered the meat product undesirable for consumption.

Description

FOOD PRODUCT CONDITION INDICATOR LABEL

Technical Field The present invention relates to a label that includes a product condition indicator for assessing the freshness and suitability for human consumption of packaged food products. More particularly, the present invention relates to a food product condition indicator carried on and forming part of a product label that is applied to a packaged food product, and to a method for producing such labels.

Background Art Fresh food products sold in supermarkets and other retail outlets, particularly meat products, are generally packaged utilizing a pulpboard or Styrofoam tray. The tray is overwrapped with a transparent, see-through film to enable a purchaser to visually view and inspect the product before purchase. Meat products are intended to be constantly refrigerated in order to prevent spoilage or rancidity. In that regard, proper storage of meat products at appropriately low temperatures is important. Refrigerated storage of meat products during the various stages between slaughter of the animals or the catching of seafood is necessary to maintain freshness and suitability for human consumption. Temperature control is needed during the processing of the food product before packaging, while the processed product is being packaged, while the processed product is being transported from the processor to the distributor, while the processed product is being stored by the distributor, while the product is being transported to the retailer, while the product is being stored by the retailer before sale, while the product is on display by the retailer for sale, and also after the product is purchased by a consumer. Maintaining the proper temperature levels of meat products during each of the periods of processing, transporting, and storage of the product prolongs the period during which the product can be safely consumed by the ultimate purchaser. Conversely, failure to maintain the necessary temperatures during any portion of those periods could shorten the time period before which spoilage occurs and the product is no longer suitable for safe consumption. Spoilage is the result of bacterial action that is takes place when a meat product is exposed to higher than desirable temperatures. Such exposure can occur during any of the previously- mentioned time periods during which the food is being processed, stored, or transported before consumption is intended to take place. As a rough guide for the consumer, meat products generally have a "sell by" date printed on the package, such as on a label. However, the "sell by" date might not be the best indicator of suitability of the product for consumption, because the product might have been removed from refrigeration for too long a time after the "sell by" date has been determined and placed on the package, or the refrigeration period may have been temporarily interrupted for some reason. Consequently, the bacterially-induced spoilage process may have accelerated at a time before the "sell by" date, and that acceleration condition may not be known to the retailer or to the consumer. Thus even though the meat product is purchased before and is intended to be consumed before the "sell-by" date indicated on the package, the purchasing consumer has no assurance that the purchased product is still in edible condition when purchased, or, if stored for later use, that it will be in edible condition at the time of intended use. Thus, there is a problem in that both before and after purchase, neither the retailer nor the purchaser can quickly and adequately determine whether the product is suitable for safe consumption. The present invention is directed to a solution to those problems.

Disclosure of Invention The present invention is directed to an indicator carried by a label that is applied to a package containing a fresh food product that is subject to spoilage. The indicator enables the condition of the food product to be visually determined to allow an assessment to be made of the suitability for consumption of the food within the package. A prime example of a category of food products with which the present invention can be used is meat products. As used herein, the term "meat product" is intended to encompass packaged products that include uncooked or pre-cooked, pre-packaged beef, pork, poultry, seafood, and the like types of food items. The indicator can also be used on other food products subject to spoilage by bacterial action. In accordance with one aspect of the present invention an indicator strip is provided for indicating the suitability for human consumption of a food product. The indicator strip includes a base sheet of material having a first surface and a second surface that is opposite from the first surface. An indicator compound is carried on the first surface of the indicator strip for exposure to a food product for assessing suitability for human consumption of the food product. The indicator compound changes color upon contact with a food product that has deteriorated to a point where suitability for human consumption is questionable. A release coating is carried on the second surface of the indicator strip to prevent permanent adhesion of the indicator strip to a carrier member. In accordance with another aspect of the present invention a product label is provided. The label includes a carrier sheet and a printable surface layer that is removably applied to the carrier sheet. An indicator strip is positioned in overlying relationship with the printable surface layer and an overlaminate film overlies the printable surface layer and the indicator strip. In accordance with a further aspect of the present invention a method of producing a product label that includes an indicator strip that carries an indicator material for indicating the condition of a food product is provided. The method includes the steps of joining a body layer material with a carrier sheet, and printing product-related information on an upwardly-facing surface of the body layer material. An indicator strip is applied over the body layer material and a pull-tab component is provided on the upwardly-facing surface of the body layer spaced from the indicator strip. The upwardly-facing surface of the body layer and the indicator strip and the pull tab are overlaminated with a clear overlaminate film. The overlaminate film and the body layer are die cut in an area outward of the indicator strip and along an edge of the pull tab component to provide a product label that is removable from the carrier sheet, whereby when the label is applied to a package surface the pull tab can be grasped by a user to expose and allow removal of the indicator strip.

Brief Description of Drawings The structure, operation, and advantages of the present invention will become further apparent upon consideration of the following description, taken in conjunction with the accompanying drawings in which: Figure 1 is a perspective view of an embodiment of a label that includes a food product condition indicator strip. Figure 2 is a cross-sectional view taken along the line 2-2 of Figure 1. Figure 3 is a diagrammatic, perspective view of one method by which the label shown in Figures 1 and 2 can be produced. Figure 4 is a cross-sectional view similar to that of Figure 2 of another embodiment of the label shown in Figure 1.

Best Mode for Carrying Out the Invention Referring now to the drawings, and particularly to Figures 1 and 2 thereof, there is shown a label 10 that has a top face 12 and a bottom face 14. Label 10 as shown is of generally rectangular form, although other geometric shapes of labels can also be provided if desired. Printed matter is visible when viewing top face 12 of label 10. Examples of possible printed matter include information to identify a particular product or source with which the label is utilized, use instructions, product characteristics, or other relevant product- related information that either might be of interest to a consumer or that might be required to be present by law or by an administrative agency regulation. When utilized as a food product label, for example for meat, poultry, fish, or dairy products, the printed matter can identify the nature of the product within the package, the weight, the price, etc. Bottom face 14 of label 10 includes an adhesive coating to enable the label to be applied to a desired wrapper or package. The label adhesive can be a permanent, pressure-sensitive adhesive for secure attachment to the wrapper or package. A peelable release liner can be applied over the adhesive coating on the bottom face 14 of label 10 if the adhesive is of a pressure- sensitive type. As best seen in Figure 2, positioned below top face 12 and above bottom face 14 is a food product condition indicator strip 16 that can be utilized to test a food product for spoilage, to enable a determination of suitability of the food product for consumption. Indicator strip 16 can carry a compound that is adapted to change color upon contact with the product juices that are present within the package. Access to indicator strip 16 is obtained by providing a pull tab 18, which can be an integral part of label 10 and which can be provided along an edge of the label, to allow a user to grip pull tab 18 and peel an outer layer from label 10 in order to expose indicator strip 16 and render it accessible to the user. The user can then remove the indicator strip from the label merely by lifting it from the label, so that the strip can be used to check the condition of the food product within the package that carries the label. Indicator strip 16 can be a generally rectangular sheet, as shown in Figure 1 , that carries an indicator material that can change color when it is placed in contact with the juices of a food product that may have spoiled and that may not be acceptable for human consumption. Indicator strip 16 is of a smaller size than the label itself so it can be completely contained and encased between layers of the label structure materials, and in a substantially sealed condition, so that it is not contaminated before it is intended to be used to test a product. Unless it is protected as herein described, contamination of indicator strip 16 can occur as a result of contact of the indicator strip either with external materials into which the label can come into contact between application by the food processor and purchase by a consumer, or from contact of the indicator strip with product juices that might migrate through the packaging material before the package reaches the consumer, if the packaging material does not provide a moisture barrier. Indicator strip 16 can be a paper sheet that can absorb and carry an indicator solution, or it can be a plastic sheet that carries at least a surface coating of an indicator solution. Suitable paper sheets include supercalendered kraft (SCK) liner, which is a natural or bleached paper. The paper can be coated with either silicone or another release agent on one or both sides to provide controlled release of the indicator strip from the label. Advantageously, the paper can have a high internal strength and such other properties that will enable it to withstand without damage conventional processing including line scoring, butt cutting, die cutting, and automatic dispensing. The basis weight, caliper, tensile strength, shear strength, and moisture range of a suitable liner material can vary with the choice of liner thickness. For example, for a 42 lb. SCK liner the basis weight is about 41.5 lb/ream (24 x

36 - 500), with a variance of ± 10%. The caliper of such a liner can be about

2.5 mils with a variance of ± 0.3 mils. The tensile strength in the machine

direction (MD) can be about 30 lb/inch of width with a minimum of about 19 lb/inch. The tensile strength in the cross-machine direction can be about 16.5 lb/inch of width with a minimum of about 10 lb/inch. The tear strength in the machine direction can be about 29 grams, with a minimum of about 18 grams, and the tear strength in the cross-machine direction can be 34 grams, with a minimum of about 22 grams. The moisture range of the 42 lb SCK liner can be from about 4% to about 7%. Additionally, the liner material should have a pH of about 6.0 or lower. Such liner materials can be obtained form American Coated Products, of Zionsville, Indiana. Suitable plastics materials for use as an indicator strip should have the ability to retain the indicator solution on an outer surface, or within the film itself if the product juices can penetrate through the outer surface of the plastic material. If the plastics material does not permit the indicator solution to penetrate through the outer surface, the solution should be capable of retention on the outer surface, so that the outer surface of the indicator strip can undergo a color change when the strip is dipped into product juices. Before application to label 10, indicator strip 16 is impregnated or coated with an indicator material. The indicator material is retained within the interstices of the paper fibers, or it remains on the fibers themselves upon evaporation of the solvent carrier for the indicator material. When a plastic indicator strip is used, the indicator material is carried on the surface of the strip. The impregnation or coating of the indicator material can be effected either by passing the strip through a solution containing the indicator material, or by applying to the strip material a surface coating of a solution containing the indicator material. One side of the indicator strip can carry a suitable release coating so it can be more readily removed from the label after peeling open pull tab 18. The indicator strip can be provided as a indicator strip that is part of the product label that is applied to the package, generally on the outer surface of the overwrap or other package material. Before the food product is intended to be used, the purchaser can check the condition of the product by removing the indicator strip from the label, applying the strip to product juices, and observing whether the indicator strip color after exposure of the strip to the product juices is indicative of a product that has not spoiled and that is suitable for consumption. The indicator strip can be coated with a solution containing an indicator compound. The coating can be a surface coating on one or both major outer surfaces if the strip is made from paper or a plastic material, or the indicator strip can be impregnated with the indicator compound if the strip is made from paper. In either event, the indicator strip is intended to provide the user with a quick, visual indication whether spoilage of the packaged product has occurred as a result of microbial action. The test for product suitability for consumption can be pH-based by providing a pH-sensitive coating or impregnation to the indicator strip, to allow a determination of the acidity level at the surface of the product. The acidity level can be the result of bacterial action. Alternatively, the test can be based upon whether a particular chemical compound or a particular chemical constituent that is indicative of a spoiled product is present on the surface of the product. In either event, the user can quickly determine whether the product should be used or should be discarded. One possible indicator compound that can be utilized is a phenylanaline or a propylanaline compound that will change color when exposed to a particular acidity or pH level. Other possible color-changing compounds that are sensitive to the surface chemistry of the product, or that are sensitive to the presence of particular microorganisms, can also be utilized, such as those listed in Table I. Another suitable indicator material is a bromocresol purple solution (C₂ιHι₅Br₂θ₅SNa). An example of such a solution is an aqueous solution containing about 2% bromocresol purple, or an ethanol solution containing about 8% bromocresol purple. Bromocresol purple is suitable as an indicator material because it is capable of detecting a pH level of 6.8, which is the pH level at which bacteria commonly replicate in meat, poultry, fish, and dairy products. Table II shows the growth criteria for various bacteria that can be found in meat products. As is apparent from Table II, pH values greater than about 6.8 provide an environment in which such bacteria can readily grow. Upon contact of indicator strip 16 with product juices, such as meat juices, the indicator strip will change color when the product juices have a pH level indicative of the fact that the product is of questionable freshness and may have spoiled or deteriorated by virtue of sufficient bacterial action. Such a color change normally occurs when the juices have a pH of greater than about 6.8. The structure of label 10 is shown in cross section in Figure 2. The main body portion of the label is a base sheet 20, which can be a paper or plastic sheet having the desired degree of label body and stiffness for ease of handling and ease of application to a product package. For a paper base sheet the basis weight can range from about 15 lb/3000 ft² to about 250 lb/3000 ft². A paper base sheet having a basis weight of about 50 lb/3000 ft² has been found satisfactory from the standpoint of handling of a label material web in a flexographic printing press, as well as in related equipment, such as laminating stations. Although paper has been referred to as a base sheet material, other materials can also serve that purpose, such as polymeric sheets having a sufficient stiffness level to allow them to be handled in processing equipment. A carrier sheet 22, on which one or more labels can be carried during label production and for label shipment, includes a release coating 24, or a release liner, on its upper surface that faces base sheet 20. A suitable release coating can be a silicone compound, or other coating materials that allow the peeling from the coating surface of a pressure sensitive adhesive. One suitable silicone compound is a silicone-based release agent identified as Syloff-23, which is available from Dow Corning Corporation, of Midland, Michigan. That compound can be coated onto the carrier sheet at a thickness sufficient to completely cover the surface of the carrier sheet to allow the peeling referred to above. Alternatively, suitable carrier sheets that include the desired release characteristics on a surface can be obtained from American Coated Products, of Zionsville, Indiana. Positioned above release coating 24 of carrier sheet 22 is a permanent, pressure-sensitive adhesive layer 26 that is provided to permanently attach label 10 to the surface of a package or a wrapper. Suitable adhesives include the following systems: hot melt, emulsion, solvent, and ultraviolet and electron beam cured adhesives, among others, and can be obtained from American Coated Products, of Zionsville, Indiana. When a polymeric sheet is used to provide base sheet 20 of label 10, it can be a polyethylene or a polypropylene film, and can have a thickness ranging from about 0.25 mils to about 10 mils. A polypropylene sheet obtained from Exxon-Mobil Chemical Company, of Rochester, New York, and sold under the trade name Labelyte has been found to be suitable. Of course, other materials, such as paper and other polymeric films, can also be utilized as the base sheet of the label. Base sheet 20 can advantageously be a pigmented polymeric sheet, which provides the background color for the label, similar to a paper sheet, and can thereby reduce the number of printing steps. The uppermost surface of base sheet 20 is printed with the desired label information in one or more colors that lie on the uppermost surface of the base sheet as one or more ink layers 28. The printed matter can include the name of the seller of the product contained within the package, as well as sufficient product identifying information to allow a consumer to determine whether the product is what the consumer wants to purchase. If base sheet 20 is a paper sheet, it can be of the desired background label color and is ordinarily printable directly, without any additional surface treatment. Base sheet 20 can have a size that extends outwardly beyond the structure shown in Figure 2, on the side opposite from pull tab 18, for example, to allow printing by the packager of the product to identify a particular product, its weight, the price per pound, and the like. Typical printing methods utilized by food packagers include thermal imaging. If base sheet 20 is a polymeric material it may require that some type of surface treatment be performed on the uppermost surface that is to be printed, in order to allow that surface to receive and accept printing inks. One possible type of surface treatment to promote adhesion of printing inks to polymeric materials is a corona discharge treatment, with which those skilled in the art are familiar, although other types of surface treatments, such as a solvent treatment, can also be utilized, if desired. The treatment type should be of such a nature as to provide to the polymeric material a surface to which inks will permanently adhere without peeling or flaking off from the surface of the polymeric base sheet. An overlaminate layer 29 of polymeric material, which can be a clear film, overlies ink layer 28. Indicator strip 16 and also a tab strip 30 are located at spaced positions above overlaminate layer 29. Neither of strips 16 or 30 is adhered to or otherwise secured to overlaminate layer 29 of base sheet 20, because each strip is intended to be readily separable from that surface. Tab strip 30 can be a narrow paper strip that can be positioned along an edge of label 10, to form pull tab 18 as shown in Figure 2. The basis weight of the tab strip material can be of the order of from about 10 lb/3000 ft² to about 200 lb/3000 ft². Because tab strip 30 is not adhered to overlaminate layer 29 of base sheet 20 it can readily be lifted from the surface of the base sheet. Tab strip 30 can have a width that is sufficient to allow a user to conveniently grip and lift pull tab 18 away from base sheet 20, for example a width of from about 0.125 in to about 0.75 in. Indicator strip 16 can have the properties discussed earlier herein. Placed in overlying relationship to base sheet 20, indicator strip 16, and tab strip 30 is a clear outer polymeric film layer 32 that provides an outer protective layer to base sheet 20. The outer layer can have a shiny appearance or a non-shiny, matte appearance, whichever is preferred. Outer layer 32 also prevents scuffing or marring of the printed matter on base sheet 20. The outer layer can be a polypropylene film having a thickness of from about 0.25 mils to about 15 mils, for example. A suitable film is designated as product number ACP 218, available from American Coated Products, of Zionsville, Indiana, although other types of films can also be utilized to provide the desired appearance and protective features. The film can be adhesively laminated to the upper surface of base sheet 20 by a permanent adhesive layer 34, such as adhesive ACP 218, available from American Coated Products, of Zionsville, Indiana. Other lamination techniques that are suitable include heat sealing, and ultraviolet and electron beam curing processes. In addition to providing an attractive appearance to the label and protecting the printed matter on base sheet 20, outer film layer 32 also provides an overlying layer to protect indicator strip 16. Thus, dirt, contaminants, and other foreign materials are prevented from contacting indicator strip 16 before it is intended to be used to test a product. And in order to allow indicator strip 16 to be removed from label 10 for test purposes the indicator strip should not adhere to outer film layer 32. One way to prevent such adhesion is to apply to the upwardly-facing surface of indicator strip 16 a thin release agent layer 36, such as a release agent known as Syloff-23, which is available from Dow Corning Corporation, of Midland, Michigan. A similar release agent layer 36 can be applied to the downwardly-facing surface of tab strip 30 when it is a material strip that is separate from and applied adjacent to an edge of base sheet 20. The label structure described above can be manufactured in different ways. One suitable way is by the method and apparatus shown in Figure 3, which enables continuous, in-line production of labels in which the several operations necessary to produce label 10 are performed sequentially. The method and apparatus shown provide a label structure that when in finished form is carried on a carrier sheet that is provided in roll form with the labels removable from the carrier sheet. The roll of labels can later be installed on a labeling machine forming part of a packaging line for continuous packaging of the associated products. Referring to Figure 3, there is shown one method, along with one possible arrangement of equipment, in which several functional equipment stages are positioned in-line, for a continuous label-making production line 40 for manufacturing labels having the structure described above. Line 40 includes an unwind stand 42 from which a web 43 that includes carrier sheet 22 and overlying base sheet 20 is unrolled and is conveyed to a printing station 44. The desired label copy 46 is printed on the upwardly-facing surface of web 43. Printing station 44 can include one or more print rolls 48 (only one of which is shown), each of which carries on its outer surface a printing plate that contains label copy of a particular color. The print rolls have associated therewith respective backup rolls to press web 43 against the print rolls at the proper pressure to obtain the desired image. Printing station 44 can be a flexographic printing press, as was noted above in connection with the label structure description, or it can be a different type of printing press, such as a gravure press, for example. After the desired label copy has been printed on the upwardly-facing surface of web 43, the web passes to a first overlamination station 50, at which a first clear film 52 is laminated to the upwardly-facing surface of press web 43 by a laminating roll 53. After first overlamination station 50 web 43 passes to an indicator strip application station 54. A roll of indicator strip material is unwound and an indicator strip web 56 is laid on the upwardly-facing surface of first clear film 52 by passing indicator strip web 56 between a pair of pressing rolls, only one of which, roll 58, is shown. Indicator strip material 56, which includes the appropriate indicator material, is not adhered to the label web but merely lies on the surface thereof to allow its later removal. Immediately downstream of indicator strip application station 54 the web passes to a die cutting station 60, between a die cutting roll 62 having suitably-shaped surface- mounted cutting knives and a backup roll (not shown). The cutting knives cut a series of spaced, individual indicator strips 16 to the desired size and shape, so that only individual indicator strips 16 remain on the label web and in the desired position relative to the final, completed label. Waste indicator strip material 64 remaining after cutting individual indicator strips 16 from indicator strip web 56 is taken up on waste roll 66. After indicator strips 16 have been applied to the label web the web passes to a pull-tab application station 68 downstream of indicator strip die cutting station 60. A supply roll 70 of pull-tab material is unwound and a pull- tab material web 72 is passed between a guide roll 74 and a backup roll (not shown), so that a strip of pull-tab material lies on the upwardly-facing surface of the label web. The pull-tab material is in strip form, having a relatively narrow width, and it is spaced outwardly of indicator strips 16. Additionally, the pull-tab material strip is positioned on the label web at a point that corresponds with an edge of the completed label, so that it lies along that edge of the label when the label is completely formed. As was the case with the indicator strip material, the pull-tab material is not adhered to the label web but merely lies on the upwardly-facing surface thereof, so it can be readily lifted and separated from that surface. Advantageously, a static charge can be applied to indicator strip material 56 to hold indicator strips 16 in the desired position on clear film layer 52. A second film overlaminate station 76 is positioned downstream of pull tab application station 68. In that regard, a roll of clear, second overlaminate film having a peelable adhesive layer that faces the label web is brought into contact with the label web. That combination is effected by passing the web of second overlaminate film 78 and the label web between a pressing roll 80 and a backup roll (not shown). The web of second overlaminate film 78 has a width sufficient to cover the desired area of the completed label, including indicator strips 16 and pull tab web 72. Although second overlaminate film 78 is adhered to the uppermost surface of pull-tab web 72, film 78 is not permanently adhered to the upwardly-facing surface of indicator strips 16 because of the release coating carried on that indicator strip surface. As shown in Figure 3, the width of the web of second overlaminate film 78 can be smaller than the width of the overall label web. As a result, there can remain a portion of the label web that is not covered by second overlaminate film 78, to allow printing on the completed label by a food processor. Such printed matter as the specific type of food product, the product weight, the cost, the cost per pound, and the like, can then be applied by the food processor to provide additional information desired by the consumer. The printing that is performed at printing station 44 can be confined to the product manufacturer's logo and other identifying information. Following the overlamination of the second overlamination film to its upwardly-facing surface, the label web passes to a label die cutting station 82. A die cutting roll 84 having surface-mounted cutting knives cooperates with a backup roll (not shown) to provide in the label web successive cuts that extend through the second overlaminate film and through the respective web layers, but not through the underlying, lowermost carrier web material. The cutting knives on die cutting roll 84 define on the moving web a plurality of individual labels that are either adjacent to or spaced from each other in the machine direction of the carrier web. The cut labels are of the desired size, so that only completed labels remain on the carrier web. The overlaminate and other cut layers of material form waste web 88. After the die cutting of labels 86 that remain on the label web, waste web 88 is collected on takeup roll 90, while the carrier web bearing the completed labels is wound into a roll at a suitable downstream take-up roll station (not shown). Although shown in Figures 1 and 2 as a separate strip of paper or other suitable material, tab strip 30 can instead be formed by die-cutting a strip from and along an edge of base sheet 20. In an alternative label structure a die cut is made in base sheet 20 along and inwardly and adjacent to an edge of base sheet 20 to define the tab strip. When that alternative structure is produced an additional, separate strip of tab material, such as is shown in Figure 3 as roll 70, is not needed. Although not shown in Figure 3, those skilled in the art will appreciate that each of the printing rolls, the laminating rolls, and the die cutting rolls has associated with it a respective backup roll. Instead, a die-cutting station is utilized to provide a die cut in base sheet 20 to form a strip that corresponds with tab strip 30. In that arrangement a release agent layer is applied to the underside of base sheet 20 in the region in which the tab strip is to be cut, to allow the so-formed tab strip to be readily separable form adhesive layer 26. A cross-sectional view of such an alternative structure is shown in Figure 4, in which the same reference numerals are utilized for the same components as are shown in Figure 2. Tab strip 30a is separated from label base sheet 20 by a die cut 39. To facilitate lifting of the tab strip from pressure-sensitive adhesive layer 26 when desiring to access indicator strip 16, a layer 38 of a suitable release agent is applied to the underside of tab strip 30a to prevent adhesion of tab strip 30a to adhesive layer 26. In addition to providing an indicator strip that is removably carried by an outer label, the indicator strip can also be packaged within an outer package or wrapper and in contact with product juices. When so arranged, the seller of the product can visually determine when a product has spoiled and should be removed from the product display and discarded. For example, the indicator strip can be placed under a clear portion of overwrap film, to be constantly in contact with product juices and to be visible from the outside of the package. Further, the indicator compound can be coated on or printed on a particular part of the inner surface of an overwrap film, to also be in constant contact with the product juices. When so applied, it can be in a position to be visible to an observer, whether a store employee or a prospective purchaser. In that regard, the overwrap material should be a plastic film that is substantially transparent in the area above the indicator strip, to allow a quick visual determination of color change without the need to unwrap the product. The product is tested for suitability for consumption by pulling on the tear tab to expose the indicator strip, which is then dipped into the product juices strip after the package has been opened, to allow observation and determination whether the strip has changed color to indicate that a sufficient degree of spoilage has occurred. As will be apparent, the present invention allows a determination of a meat, poultry, fish, dairy, or citrus product's acidity level in order to allow visual determination whether the product has or has not reached an acidity level that indicates significant bacterial presence to suggest unsuitability for consumption. Different bacteria replicate at different acidity levels and at different rates. The indicator strip is intended to show whether the acidity level of the product juices is indicative of excessive bacterial activity. The present invention also involves encapsulation of the indicator strip to assure that the strip is not exposed to environmental contaminants, such as the product itself, moisture, dirt, and handling by the packager, the distributor, the retail outlet, or the consumer. Thus, the strip is maintained in a clean condition until the time the consumer is ready to test the product for suitability for consumption. Although particular embodiments of the present invention have been illustrated and described, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit of the present invention. It is therefore intended to encompass within the appended claims all such changes and modifications that fall within the scope of the present invention.

Industrial Applicability The invention is applicable to the packaging of food products and provides a visual indicator of the suitability of the packaged product for consumption by exhibiting a color change to indicate to an observer whether the product is fit for consumption.

Table 1 pH Indicators Indicator ranqe color chanqes

3 Methyl Orange - Xylene Cyanol

Alizarin Red S 4.6-6.0 y-pnk

Brilliant Green

Bromocresol Green 3.8-5.4 y-blue

Bromocresol Green - Methyl Red Indicator

Bromocresol Purple 5.2-6.8 y-pur

Bromocresol Purple, Sodium Salt

Bromophenol Blue 3.0-4.6 y-blue

Calcein, Indicator

Calmagite Indicator

Chlorophenol Red 5.2-6.8 y-red

Congo Red 3.0-5.0 blu-red

Coomassie Brilliant Blue

Cresol Red 7.2-8.8 y-red

Cyanide Indicator

D-B2 Bromocresol Green

Dalawa Starch Indicator

Diphenylcarbazone - Bromophenol Blue Indicator Solution

Dimethyaminobenzalrhodanine

DPD Indicator Solution

E.D.T.A.

Eosin Y 0.0-3.0 y-fluor grn

Eriochrome Black T

Ethyl Red

Ferroin Indicator

Ferric Alum

Gentian Violet

Indigo Carmine 11.6-14.0

Ionic 5.5 m-Cresol Purple m-Cresol Red

Methyl Orange 3.2-4.4 r-y

Methyl Orange-Xylene Cyanole 2.9-4.4 lav-grn

Methyl Purple

Methyl Red 4.2-6.2 pnk-y

Methyl Violet meta-Cresol Purple 7.4-9.0 y-p

Murexide Indicator

Naphtholphthalein

N,N-Diethyl-p-Phenylenediamine o-Cresol Red Table I pH Indicators

P N.

Phenol Red 6.8-8.4 y-r

Phenol Red, Sodium Salt

Phenolphthalein

Special 4.8-5.8 p-grn

Potassium Chromate

Starch Indicator

Sulfo Orange 11-12.6 y-org

Bromo Thymol Blue 6.0-7.6 y-blue

Bromo Thymol Blue, Sodium Salt

Thymol Blue 1.2-2.8 r-y

Thymol Blue 8.0-9.2 y-b

Thymol Blue, Sodium Salt

Thymolphthalein

Universal pH Indicator 1 thru 10

Table II Growth Criteria for Pathogenic and Potentially Pathogenic Bacteria in Meat and Meat Products^*

when heated in "wet" environments when heated in "dry" environment such as chocolate ' compiled from Dooley & Roberts, 2000 & ICMSF, 1996 (for spores)

Claims

Claims 1. An indicator strip for indicating the suitability for human consumption of a food product, characterized in that the strip includes a base sheet of material having a first surface and a second surface that is opposite from the first surface; an indicator compound carried on the first surface for contact with a food product for assessing suitability for human consumption of the food product, wherein the indicator compound changes color upon contact with a food product that has deteriorated to a point where suitability for human consumption is questionable; and a release coating applied to the second surface of the indicator strip to prevent permanent adhesion of the indicator strip to a carrier member.

2. An indicator strip in accordance with claim 1 , characterized in that the strip changes color in response to contact with food product juices having a predetermined pH level.

3. An indicator strip in accordance with claim 2, characterized in that the predetermined pH level is at least 6.8.

4. An indicator strip in accordance with claim 1 , characterized in that the indicator strip is a paper strip.

5. An indicator strip in accordance with claim 4, characterized in that the strip is impregnated with a pH-sensitive material.

6. An indicator strip in accordance with claim 4, characterized in that the indicator strip is coated with a pH-sensitive material.

7. An indicator strip in accordance with claim 1 , characterized in that the indicator strip is a polymeric material.

8. An indicator strip in accordance with claim 8, characterized in that the polymeric material is coated with a pH-sensitive material.

9. An indicator strip in accordance with claim 1 , characterized in that the indicator compound is bromocresol purple that changes color when contacted with a material having a predetermined pH.

10. An indicator strip in accordance with claim 1 , characterized in that the indicator compound is a phenylanaline material that changes color when contacted with a material having a predetermined pH.

11. An indicator strip in accordance with claim 1 , characterized in that the indicator compound is a propylaniline compound that changes color when contacted with a material having a predetermined pH.

12. A product label including a carrier sheet having a printable base sheet that is releaseably carried by the carrier sheet and that includes an outwardly-facing printable surface, characterized in that an indicator strip is positioned in overlying and in releasable contacting relationship with the printable surface; an overlaminate film overlies the printable surface and the indicator strip, wherein the indicator strip is readily separable from the base sheet; and a pull tab positioned along an edge of the label to allow lifting of the pull tab and peeling of the overlaminate film from the printable surface to expose the indicator strip and allow its removal from the label.

13. A product label in accordance with claim 12, characterized in that the indicator strip includes a release coating on at least one major surface thereof.

14. A product label in accordance with claim 13, characterized in that the release coating faces the printable surface.

15. A product label in accordance with claim 12, characterized in that the pull tab is defined by a strip of material that is interposed between the overlaminate film and the base sheet.

16. A product label in accordance with claim 12, characterized in that the pull tab is defined by an edge region of the printable base sheet and is cut therefrom.

17. A method of producing a product label that includes an indicator strip that carries an indicator material for indicating the condition of a food product, including releaseably joining a printable body layer material with a carrier sheet and printing product-related information on an upwardly-facing printable surface of the body layer material, characterized in that an indicator strip is applied on an outwardly-facing surface of the printable body layer material; a pull tab component is provided in overlying relationship with the carrier sheet on an upwardly-facing surface of the carrier sheet and spaced from the indicator strip; overlaminating with an overlaminate layer at least a portion of the upwardly-facing surface of the body layer and the complete indicator strip and pull tab; and die cutting through the overlaminate film and the body layer in an area outward of the indicator strip and along an edge of the pull tab component to provide a product label that is removable from the carrier sheet, whereby the pull tab can be grasped by a user to expose and allow removal of the indicator strip.

18. A method in accordance with claim 17, characterized in that the pull tab component is a separate layer of strip material that overlies a portion of the upwardly-facing surface of the body layer material and underlies the overlaminate layer.

19. A method in accordance with claim 17, characterized in that the pull tab component is formed by die cutting the body layer adjacent to an edge thereof.