Frozen Food Thaw Detector

This invention relates to a thaw indicator for frozen products such as foods or biological which will indicate whether items enclosed/attached have undergone thawing subsequent to their initial frozen condition.

A variety of food items and biologicals are process in such a manner that they are intended to remain in a frozen condition until ready for use. Thawing, whether during transportation, storage or display, may affect the flavor, nutritional value, appearance, texture and possibly the healthful condition of food items. The viability of some biologicals can be at stake when continuous frozen conditions are not maintained. Through use of this invention, those involved in the distribution and/or final use of frozen products will have the ability to realize whether thawing has occurred.

This invention indicates whether the attached/enclosed item was continuously frozen since initial preparation. It is significantly different from other indicators since it accomplishes its intended purpose solely by the change of physical conditions within the device as opposed to designs which contain chemical reactants. This design can accomplish its intended objective without the use of ruptureable parts; inter-acting chemicals, solutions or dyes; such as those described in the following U.S. Pat. Nos.: 2,261,473; 3,177,843; 3,233,459; 3,243303; 3,695,903; 3,786,777; 3,942,467; 4,163,427; 4,327,117. This invention will not return to its initial condition if refrozen, thus providing a significant difference from present-condition indicators such as the indicator described in U.S. Pat. No. 2,261,473. There is no need for vapor communication between the indicator and the frozen item, thus providing a significant difference from indicators requiring this type of contact such as the indicator referred to in U.S. Pat. No. 3,844,718. This indicator can be designed to thaw at temperature levels other than 32.degree. F./0.degree. C. by utilizing additives will vary the freezing point of the frozen plug. Some additives, such as sodium chloride, common table salt, will depress the freezing point, while introducing other such as gelatin, will raise it.

FIG. 1: Is an outside view of the presently preferred form of the invention.

FIG. 2: Is a cross-sectional view of the presently preferred form of the invention.

FIG. 3: Is a side-view of the presently preferred form of the invention.

The indicator, in its initial condition, will resemble the illustration represented in FIG. 1. The outside face of the indicator will have a transparent viewing area 2 through which, you can view the pointing device 3. The pointing device 3, will be tension-loaded and restrained from moving, by means of a frozen plug 4, visible in FIG. 2. When thawing takes place, the frozen plug 4 will melt, thus allowing the tension-loaded pointer 3 to alter its position from one side of the internal cavity 5 to the other side. The outside face 1 of the indicator, can identify the frozen condition on one side and the thawed condition on the other. The pointing device 3 will designate which condition is consistant to the exposure of the indicator. The outside face 1 of the indicator can also be marked in a manner to identify the temperature above which the plug 4 will begin to melt. An external flange area 6, FIG. 3, may facilitate affixing the indicator to containers such as frozen food boxes, although alternative methods to affix the indicator would in no way adversely affect performance, nor would the elimination of said flange 6. The detector as defined above can be incorporated in a wall of an individual package of frozen food or a shipping carton containing multiple units of frozen items or a container intended to transport temperature-sensitive biological materials. The detector can also be attached to individually frozen items. Although the plug can consist of pure=water=ice, the plug can consist of either a frozen water and salt solution in a concentrate necessary to achieve a thaw temperature lower than 32.degree. F./0.degree. C. or a frozen water and gelatin solution in a concentration necessary to achieve a thaw temperature greater than 32.degree. F./0.degree.C. Also, the plug can contain additives affecting color such that the visual characteristics of the plug change upon thawing.