GB2293879A

GB2293879A - Defrost warning indicator

Info

Publication number: GB2293879A
Application number: GB9420048A
Authority: GB
Inventors: Solomon Unsdorfer
Original assignee: Individual
Current assignee: Individual
Priority date: 1994-10-05
Filing date: 1994-10-05
Publication date: 1996-04-10
Also published as: GB9420048D0

Abstract

A defrost warning indicator for use with food etc. comprises a protective transparent plastic capsule containing a first chamber filled with water, and an air-filled second chamber separated from the first chamber by a membrane adapted to rupture on freezing of the water, said second chamber containing a dye pellet coated with a material which delays the dissolving action of water on the pellet if the temperature subsequently rises. <IMAGE>

Description

IRREVERSIBLE DEFROST WARNING INDICATOR This invention relates to an irreversible defrost warning indicator.

Frozen products (such as foodstuffs, prepared meals, biological/ chemical / medical samples or even transplant organs) are required to be held in their frozen state continuously from the point of origin or processing until they are in the hands of the end user for consumption or use.

However, many such products pass through various stages of transportation, handling, distribution and storage before reaching the end user who has no clear and easy way of determining whether, at any stage, the item or product has been allowed to thaw for a period or to a degree which would involve spoilage or bacterial contamination prior to being re-frozen and "appearing" untainted.

This invention makes it possible to show that a product has been allowed to defrost or thaw at any stage after the initial freezing process and allows such indication to persist regardless of any re-freezing.

The present invention provides a small container or capsule of transparent material comprising two chambers; one air-filled and one water-filled. The air-filled chamber contains a red (or other coloured) dye pellet coated with a dissolve-retardant substance (similar to the type used in delayed-action medication tablets).

Between the two chambers is a weak barrier membrane (or hour-glass constriction) which is capable of being ruptured or broken by water expansion during the initial freezing process.

A specific embodiment of the invention will now be described by way of example with reference to the accompanying drawing, in which: FIGURE A : Shows the indicator at room temperature (the state in which it is delivered, perhaps in mass quantities, to frozen food manufacturers for example) prior to its being first frozen.

FIGURE B: Shows the "safe" indication (perhaps at the point of purchase or end-delivery) where clear water has frozen and expanded into the air-filled chamber but has frozen too quickly to dissolve the coated dye pellet.

FIGURE C: Shows the "defrosted' indication, whereby the indicator is filled with red (or some other coloured) water as a result of the ice having melted within the indicator capsule and the water having dissolved the coated dye pellet.

FIGURE D: Shows the "unsafe" indication whereby - unable to be reversed - the telltale red (or other coloured) water has turned to ice indicating that the indicator - and, thus, whatever product it was attached to - has been allowed to thaw or defrost for a given period prior to being re-frozen.

Referring to the accompanying drawings, the action of freezing infigure B causes the neck of the hourglass chamber to expand, rupturing the constriction separating the water filled and air -filled chambers. As ice in the frozen condition, the water will not immediately flow into the air-filled chamber to affect the dye pellet. But, as the temperature falls, melted ice will flow into the air-filled chamber dissolving the dye pellet and colouring the water in the whole chamber of the indicator to the tint of the pellet; see figure C.

Impossible to reverse, even the re-freezing of the food or material to which the indicator is attached will not hide the evidence that it has allowed to thaw or defrost at some stage since its original freezing.

The specification of the dye pellet's coating is infinitely variable to suit the tolerance of the product being monitored (to which the indicator is to be attached) to any duration of thawed state. Similarly the dye colours can be varied (perhaps as an industry standard) to relate to such differing tolerances.

In the initial frozen state (figure B) the dye pellet is still intact and will only dissolve when the temperature has risen sufficiently above 0 degrees centigrade and the water has had its predetermined exposure to the coating of the dye pellet to dissolve it and thus fill the indicator capsule with red (or other coloured) water.

Even when re-frozen (figure D), perhaps by the retailer or freight carrier, the "unsafe" warning will persist as the capsule will contain dyed ice rather than clear ice with intact dye pellet which was the "safe" indication in figure C.

Claims

1. An irreversible defrost warning indicator container or capsule of transparent material containing two chambers; one water-filled and one air-filled the latter containing a dye pellet coated with dissolve-retardant material or substance (perhaps of the type used in delayed-action tablets) the two chambers separated by a thin membrane, barrier or constriction able to be ruptured in the act of freezing.