Title: "Cooking Indicator"

THIS INVENTION relates to the. cooking of foodstuffs by boiling, and it is one object of the invention to provide a means of easy recognition of the point at which a food item has been cooked to a desired degree by boiling. The invention is particularly, but not exclusively, applicable to the cooking of eggs in their shells.

According to one aspect of the invention, there is provided a method of treating a food item, or a package containing a food item, whereby the subsequent cooking of the food item will be facilitated, comprising applying, to the surface of the food item or to a package in which the food item is to be cooked, visual indicator means adapted to undergo a perceptible visual change upon being exposed to boiling water for a predetermined period, whereby a cook can ascertain, by visual inspection of the food item being boiled, or of the package in which the item is being boiled, whether or not the food item has been cooked to a desired degree.

Thus, in a particular method, embodying the invention, and applicable to eggs to be boiled in their shells, there is provided a method of treating eggs whereby the subsequent cooking of the egg, by boiling in its shell, will be facilitated, comprising applying, to the surface of the egg, visual indicator means adapted to undergo a perceptible visual change upon being exposed to boiling water for a predetermined period whereby a cook can ^• ascertain, by visual inspection of the egg being boiled, whether or not the egg has been cooked to a desired degree.

According to another aspect of the invention, there is provided a method of cooking a food item having visual indicator means applied thereto or to a package in which the item is to be cooked, in accordance with the first-noted method of the invention, boiling the food item whilst observing

the same and removing the item from the boiling water when the visual indicator means has undergone the appropriate visual change.

According to a yet further aspect of the invention, there is provided a means for providing a visual indication of the degree to which a food item has been cooked by boiling in water, comprising applying to a substrate provided by the food item or by a package therefor, a layer of a sparingly water-soluble substance, having a marked increase in solubility with temperature, and which is of a perceptibly different colour from said substrate, the composition and/or thickness of said coating being selected so that the substrate is disclosed, by dissolving away of the coating material, after the item and coating have been immersed in boiling water for a period of time corresponding to the required cooking time.

According to a yet further aspect of the invention there is provided a food item, such as an egg, having on an exterior surface thereof a substrate and a coating, on such substrate, of a substance which is sparingly soluble in water and has a marked increase in solubility with temperature, and which is of a perceptibly different colour from said substrate, the composition and/or thickness of said coating being selected so that the substrate will be disclosed, by dissolving away of the coating material, after the item and coating have been immersed in boiling water for a period of time corres¬ ponding to the required cooking time.

According to a still further aspect there is provided an indicator means for use in cooking a food item by boiling, said indicator means comprising a body adapted to be boiled with a food item, and adapted to undergo a perceptible visual change when it has been exposed to boiling water for a predetermined time.

Embodiments of the invent on are described in more detail below.

In one embodiment of the invention, the shells of eggs have applied thereto a substance which will .,-ndergo a marked visual change, for example a marked change from one colour to another, relatively abruptly, when the eggs have been immersed in boiling water for a predetermined period of time, for example three minutes. The substance, which may be in the form

of a dye, may be applied directly to the shells of the eggs in liquid form and allowed to dry or cure to form a water-resistant indicator area on the egg shell. Such application may be by any convenient means such as by painting, printing, spraying or the like. Alternatively, the indicator substance may be applied, in advance, to appropriately contrived labels which are then stuck to the shells of the eggs, or may be incorporated in the material of such labels, the material used for the labels and the adhesive used to stick the same to the eggs being, of course, resistant to boiling water.

The indicator material may be arranged to undergo a succession of colour changes, for example, after exposure to boiling water for different periods of time, so that, for example, after t o minutes in boiling water the indicator material may turn green, after three minutes, red, and after four minutes, blue. Alternatively, different treated areas on the surface of the egg may be arranged to undergo their respective perceptible colour change after different periods of cooking so that, for example, the ends of the egg may change colour after two minutes in boiling water, a central band after three minutes and intermediate regions after four minutes. In a further variant, the different treated areas marked may be formed as numerals corresponding to the number of minutes cooking at which they change colour. Thus, for example, a numeral "2" might change colour vividly after two minutes, a numeral "3" after three minutes, a numeral "4" after four' minutes and so on.

When applied directly to the egg shell, the indicator material may be initially transparent, the appropriate colour only appearing after boiling for the appropriate time. If desired, each egg may be coated in its entirety.

Where the indicator applied directly to the egg shell is initially trans- parent, it may be arranged to have a matt appearance, when dry, before boiling, so as to be substantially invisible on the shell of the uncooked egg. Not only will this serve to avoid discouraging those potential purchasers who might not find attractive an egg of unusual colouring, but the use of an initially transparent indicator material allows the implementation of various possible schemes for promoting the sales of eggs. For example, eggs may thus be invisibly marked with numbers, letters, symbols or the like pertain¬ ing to a competition or game, such as a game similar to a lottery, in which a

person who had purchased an egg which, on boiling, revealed a particular number, letter or symbol would be entitled to a prize or other reward, on producing at least the shell of the "winning" egg.

It will be appreciated that the same effect as obtained by using a transparent indicator material may be obtained by using an indicator material which, when dry, is of the same colour and shade as the egg shell to which it is applied, and references herein to an initially transparent marking are intended to include marking with indicator material of this character.

A simple and inexpensive means whereby such an indication by colour change may be given, in relation to the cooking of eggs by boiling, is described below.

An egg to be cooked by boiling has an area of its shell, such as a band encircling the egg, dyed with a non-toxic dye and this area is then covered with a sparingly soluble non-toxic material in a contrasting colour, for example a layer of caramelised sugar. The thickness of the layer is selected so that when the egg is placed in boiling water, after a predetermined cooking time, for example 4 minutes, has passed, the layer of masking material will just have dissolved entirely. If desired, of course, the eggshell may be provided with different areas dyed different colours and coated with respective different thickness of masking material so that, for example, after boiling for four minutes a first colour will be revealed, after cooking for five minutes an additional colour will also be revealed and so on.

It will be appreciated that any suitable masking material may be used, provided that it is non-toxic and has, or can be arranged to have by incorporating an appropriate dye therein, a colour sufficiently dense in an appropriate layer thickness to mask effectively the substrate layer.

In a variant, a plurality of superimposed layers of sparingly soluble, non-toxic material, of mutually contrasting colours, and capable of dissolv¬ ing away slowly in boiling water, is applied to the egg surface, so that during boiling of the egg over a period, successive layers are dissolved away in successive periods of time, again allowing the cook to determine from the colour disclosed, how long the egg has been boiling.

The invention is not, of course, confined to the boiling of eggs, but may be applied, for example, to "boil-in-bag" foodstuffs, in which case the substrate and masking layer are provided on the exterior of the plastics bag containing the foodstuff which is intended to be inserted into boiling water.

One alternative to boiled sugar or carmelised sugar for the masking layer is gelatine incorporating a non-toxic dye.

It will be appreciated that the substrate need not be -dyed but may retain its natural colouring, provided, of course, that the masking layer is of a contrasting colouring, as the appearance of the natural colouring of the substrate may equally be used as an indication that the foodstuff item has been adequately boiled.

It is also preferable that the solubility of the masking material in water should increase substantially with increasing temperature through the range from average ambient kitchen temperature to the boiling point of water, so that comparatively little of the masking layer will be dissolved away before the water in which the egg is immersed reaches boiling point, should the egg be immersed in water for cooking before the water has come to the boil, whereby, even in the latter event, serious undercooking will not result from relying upon the colour change provided in accordance with the ' invention.

In another variant of the invention, instead of the visual indicator being applied to the food item or to a package containing the same, the visual indicator is applied to or incorporated in a separate body, for example in the form of a ball or pellet, herein referred to as an indicator pellet, which is placed in the boiling water with the food item to be cooked and which undergoes a clearly perceptible visual change when it has been in the boiling water for a predetermined time. By way of example, the tablet may have a substrate surface thereof, of one colour, covered with a layer of a sparingly soluble non-toxic material in a contrasting colour, in the same way as described above in relation to the visual indicator applied directly to eggs, so that, after the pellet has been boiled for a predetermined time, for example for four minutes in the case of a pellet to be boiled with eggs, the contrasting colour, sparingly-soluble layer will have dissolved entirely away

exposing the substrate of the contrasting colour. Indeed, the pellet may be covered by a plurality of superimposed layers of sparingly soluble non-toxic material capable of dissolving away slowly in boiling water, each layer being of a colour contrasting with the layer above and below, so that after boiling for a first predetermined period the outermost layer will be dissolved away disclosing the contrasting colour of the next layer, after boiling for a further predetermined period, the next layer will be dissolved away reveal¬ ing the contrasting colour of the next adjacent layer immediately below, and so on. In this way, the cook may decide for how long he or she wishes to cook the respective food item or items by boiling and may, for example by reference to an appropriate colour chart or the like sold with the indicator pellet, ascertain the corresponding colour to be disclosed and may then simply wait until that colour shows on the pellet before removing the food item or items from the boiling water.