GB2419868A

GB2419868A - Food date indicator

Info

Publication number: GB2419868A
Application number: GB0424316A
Authority: GB
Inventors: David Leslie Mcneight
Original assignee: Advanced Analysis and Integration Ltd
Current assignee: Advanced Analysis and Integration Ltd
Priority date: 2004-11-03
Filing date: 2004-11-03
Publication date: 2006-05-10
Also published as: GB0424316D0

Abstract

An indicator for food packages of which the contents have a limited life after opening, comprising a label associated with the package actuatable on opening the package indicating passage of time after actuation. The label 11 may comprise a portion 11a to be torn off by opening of the package. The removal of the end portion 11a may initiate a colour-changing oxidation reaction by exposing a chemical composition 12 to the atmosphere. A colour change may gradually extend along the length of the label. The label may be constructed to re-seal the package when the "use-by" time of food therein has expired. The label may comprise an RFID tag having a shunt across two contacts that is broken to actuate the indicator.

Description

Food Date Indicator This invention relates to food date indicators, food',

in the present context, including beverages, milk, indeed anything found in the refrigerator or larder.

Food packaging is conventionally marked with a sell by' or use by' date, or, often, both.

A problem arises when the packed food has a limited life after opening, inasmuch as the food may not all be used at time of opening, yet there is a use by' date on the package which is substantially into the future, way beyond the safe date. It is usually indicated on the package that the food should be consumed within three or four days of opening, but, unless the package is marked, as by a pen, with the opened' date, there is nothing to say whether is it within the safe period.

The present invention provides solutions to that problem.

The invention comprises an indicator for food packages of which the contents have a limited life after opening, comprising a label associated with the package actuatable on opening the package indicating passage of time after actuation.

The label may be actuated by the act of opening the package The label may indicate elapsed time since actuation, or it may indicate a time left before a use-by' time.

After a use-by' time has elapsed, the label may display a warning that such time has expired. The label may also re-seal the package after such time has expired.

The label may comprise an indicator which, on actuation, which may involve tearing off a part of the label, progressively changes its appearance to indicate the passage of time.

The indicator may comprise a composition which changes as a chemical reaction proceeds. The chemical reaction may comprise an oxidation reaction initiated by an end of the strip being exposed to atmosphere on actuation. The indicator may, for example, gradually turn from a safe' colour such as green to a danger' colour such as red.

The indicator may be in the form of a panel, which has an overall colour which changes with time, or it may be in the form of a strip, a colour change proceeding along the strip with the passage of time, so that, for example, after two days, half the strip is green, the other half red, and, after four days, the entire strip is red. Instead of red and green, a colour change may be used which is discernible even by colour-blind people, or a line of chevrons or other indicia could appear and lengthen with the passage of time. A texture change, as by a chemical reaction increasing the volume of a compound, so that a strip becomes raised somewhat as the reaction proceeds along it, would enable blind persons to detect the change.

The reaction may be influenced by temperature, so that the use-by' time is reached more quickly if the package is left outside the refrigerator, and more quickly still if the ambient temperature is higher.

Increasingly, RFID tags are being applied to products such as food packages. They are useful to supermarkets for stock control and marketing purposes, but have capacity to be useful in other ways. One such way would be to carry information identifying the package concerned and about a sell-by or use-by date, and a modification to register elapsed time after opening. The tag could be designed to have a breakable portion that, for example, included a shunt across two contacts on the chip. The breakable portion would be broken on opening the package, resulting in the shunt going open circuit.

Placing the package within range of a reader, as by putting it into a larder or refrigerator, would alert the reader to the opening date, and this could then flag up a new use-by date against the package identification on a monitor in the larder or on the refrigerator.

Embodiments of indicators for food packages according to the invention will now be described with reference to the accompanying drawings, in which: Figure IA is a face-on view of a label embodiment; Figure lB is a side elevation, exaggerated depth-wise, of the label of Figure 1; Figure 2 is a view like Figure IA of the label after actuation; Figure 3 is a view like Figure IA of a second label embodiment; Figure 4A is a view like Figure IA of a third label embodiment; Figure 4B is an elevation like Figure lB of the embodiment of Figure 4A; and Figure 5 is a face-on view of an RFID tag embodiment.

The drawings illustrate indicators for food packages of which the contents have a limited life after opening, comprising a label I I associated with the package actuatable on opening the package indicating passage of time after actuation.

Figures I A and I B show a label 11 in the form of a strip, one end, 11 a, of which is torn off to actuate the indicator. Tearing may be comprised in the act of opening the package, the strip being placed over a closure for the package. The strip comprises a sandwich of a chemical composition 12 which changes colour on exposure to atmospheric oxygen between layers 13, 14 of plastics material. Such a composition may comprise a dye, such as a vat dye, which may be dispersed in a liquid gel or in a polymer, which may act as, or which may contain, an oxidation inhibitor to control the rate at which the strip changes colour. Gradual colour change along the strip may be due to the rate at which oxygen diffuses through the composition, or the whole of the strip may be exposed to the atmosphere on tearing, and the gradual colour change controlled by an inhibitor gradient, or the strip may be divided into sections representing days, each section having a different inhibitor concentration. In another method, different thicknesses of a permeable polymer film may cover the composition, the composition covered by the thicker film taking longer to change colour than those covered by thinner layers.

Figure 2 shows how the strip would appear two days after actuation.

Alternatively, the composition, which need not then be in the form of a strip, could change colour gradually, all at the same time, so that on actuation it is green, then changes through amber, say, to red, much as a leaf changes in autumn, to indicate the passage of time.

The colours chosen may, however, be such as can be perceived even by colour blind persons, and it may be preferable, from this point of view, to have a light/dark change of whatever colourway is chosen. Figure 3 illustrates a strip which shows a lengthening line of chevrons 31 to mark the passage of time.

For blind people, who cannot see the colour change, a system is illustrated in Figures 4A and 4B in which the chemical reaction causes a volume change in the composition 12 50 that it raises the level of the covering layer 14. Days of elapsed time can be indicated by raised markers 41 along the strip.

Any of these embodiments may be arranged to be sensitive to temperature. Chemical reactions usually, in any event, proceed faster at higher temperatures. A product that has a useful life after opening of four days if kept refrigerated may have only a life of two days if kept in a warm kitchen. The temperature sensitivity of the reaction may be selected to reflect that.

Figure 5 illustrates an RFID tag of the kind used to label products in retail outlets. While the primary use of such tags is for stock control and marketing purposes, such tags can be adapted to monitor time-afteropening by having a tear-off section 51 which contains a printed circuit shunt 52 between two contacts of the chip 53 at the heart of the tag. This embodiment requires that the tag be read when the package is introduced into the larder or refrigerator. When the package is replaced after opening, the fact that the shunt has gone open circuit will be detected and this will set a clock running in a monitor that will identify the product and display the use-by date. The chip 53 will of course, contain in one of its registers information about the life-after- opening.

Claims

Claims: I An indicator for food packages of which the contents have a

limited life after opening, comprising a label associated with the package actuatable on opening the package indicating passage of time after actuation.
2 An indicator according to claim I, in which the label is actuated by the act of opening the package.
3 An indicator according to claim I or claim 2, in which the label indicates elapsed time since actuation.
4 An indicator according to any one of claims I to 3, in which the label indicates a time left before a use-by' time.
An indicator according to any one of claims I to 4, in which, after a useby' time has elapsed, the label displays a warning that such time has expired.
6 An indicator according to any one of claims I to 5, in which the label re-seals the package after such time has expired.
7 An indicator according to any one of claims 1 to 6, comprising an indicator which, on actuation, progressively changes its appearance to indicate the passage of time.
8 An indicator according to any one of claims I to 7, in which actuation involves tearing off a part of the label,
9 An indicator according to any one of claims I to 8, comprising a composition which changes as a chemical reaction proceeds.
An indicator according to claim 9, in which the chemical reaction comprises an oxidation reaction initiated by an end of the strip being exposed to atmosphere on actuation.
11 An indicator according to claim 10, in which the indicator gradually turns from a safe' colour such as green to a danger' colour such as red.
12 An indicator according to any one of claims I to II, in the form of a panel, which has an overall colour which changes with time.
13 An indicator according to any one of claims 1 to 12, in the form of a strip, a colour change proceeding along the strip with the passage of time, so that, for example, after two days, half the strip is green, the other half red, and, after four days, the entire strip is red.
14 An indicator according to any one of claims 1 to 13, in which a colour change may be used which is discernible even by colour-blind people.
An indicator according to any one of claims ito 14, in which a line of chevrons or other indicia appears and lengthens with the passage of time.
16 An indicator according to any one of claims I to 15, in which a texture change is produced, as by a chemical reaction increasing the volume of a compound, so that a strip becomes raised somewhat as the reaction proceeds along it.
17 An indicator according to any one of claims I to 16, in which a chemical reaction is influenced by temperature, so that the use-by' time is reached more quickly if the package is left outside the refrigerator, and more quickly still if the ambient temperature is higher.
18 An indicator according to any one of claims 1 to 17, comprising an RFID tag.
19 An indicator according to claim 18, in which the RFID tag is modified by the inclusion of a shunt across two contacts of its chip that is broken so as to go open circuit on actuation.