FIELD

This invention relates to frozen food products, especially food products which are comminuted and frozen. The examples relate to the preparation of frozen cheese granules or shreds. It has particular application to the preparation of frozen grated mozzarella cheese for use in cooking of food products such as pizzas. The invention also has application to a method of producing pizzas using cheese processed in this way.

BACKGROUND

Pizzas have been traditionally made with fresh grated mozzarella cheese. Such cheese usually has a high moisture content.

Attempts have been made to grate and freeze mozzarella cheese, but this has not proved to be satisfactory, when the cheese is used in the cooking of pizzas. The freezing process may cause the cheese to dry out, resulting in an imperfect product, and one which is prone to blistering, burning, and may result in a loss of colour if the resulting pizza is kept warm for a period of time between cooking and delivery to the customer.

One of the problems in grating cheese, especially a curd cheese such as mozzarella cheese, is that the moisture content of cheese produced in the dairy factory may vary considerably, with a high moisture content being more suitable for some cooking processes, but on the other hand the higher the moisture content the softer the cheese and the more difficult it is to grate or shred. An additional problem is that some food products require cheese to have a particular moisture content for certain cooking

processes, and this is difficult to achieve in the dairy factory as the moisture level may vary by 5% from the desired product specification.

OBJECT

It is an object of this invention to provide an improved process for producing or using frozen food products, especially frozen cheese, or one which will at least provide the public with a useful choice.

STATEMENT OF INVENTION

In one aspect, the invention provides a method of preparing a paniculate frozen food product, in which moisture is added to the paniculate food product prior to, or at the time of freezing, or following freezing, so that some or all of the food particles have a coating of ice on their exterior.

In another aspect, the invention provides a method of preparing frozen cheese particles, wherein moisture is added to the cheese particles prior to, or at the time of freezing of the cheese, or following freezing of the cheese, so that the product has a layer of ice associated with a majority of the cheese particles.

Preferably the cheese is comminuted prior to freezing to produce cheese granules or shreds.

In the most preferred form of the invention, the cheese is comminuted to produce small generally spherical granules.

In another aspect, the invention provides a method of producing a cheese product in which the cheese is grated or shredded, and is then rapidly frozen, wherein the grated or shredded cheese is supplied to a tumbler and moisture is sprayed onto the cheese granules or shreds during the freezing process.

Preferably the freezing of the cheese granules or shreds takes place in the tumbler, by use of a cold fluid such as a liquified air/gas or blast of cold air or gas applied to the

interior of the tumbler.

Preferably the moisture is applied by means of a spray nozzle spraying moisture onto the cheese in conjunction with the application of a liquified gas, so that the moisture droplets are caused to substantially freeze, before they contact the cheese.

Preferably the liquified gas is liquid nitrogen or liquid carbon dioxide.

Preferably the cheese is a curd cheese such as mozzarella cheese.

Preferably the initial water content of the cheese is chosen during manufacture to make the cheese amenable to comminution.

Preferably the tumbler is in the form of a hollow cylindrical or a prismatic shape optionally having a series of flats or flights on the inside thereof, capable of causing the cheese granules or shreds to be tumbled and separated during the passage through the tumbler. Preferably the tumbler is in the form of a tunnel, on a slight incline, so that the passage through the tumbler will be controlled by the rate of rotation of the tumbler, and the incline of the tumbler.

In another aspect, the invention finds a method of controlling the moisture content of a food product, in which the food product is stored as a frozen product together with additional moisture, so that when the product is thawed the additional moisture is absorbed into the food to increase its moisture content prior to cooking.

In another aspect, the invention provides a method of preparing food using a paniculate frozen food product, in which s'ome or all of the food particles have a coating of ice on their exterior, and the frozen food particles are defrosted in a container or receptacle over a sufficient period of time that the ice melts and some or all of the resulting moisture is absorbed by the food particles.

Preferably the frozen food product consists of granule of cheese coated with a layer or layers of ice. More preferably the cheese is a mozzarella cheese and granules and the total ice content is between 1 % and 5% of the total weight of cheese prior to freezing.

In the preferred form of the invention substantially all of the particles each has an ice layer of between 1.5% and 2% of the weight of its respective granule prior to freezing.

In another aspect, the invention provides a method of preparing a cooked cheese product such as a pizza, in which frozen cheese granules having a coating of ice on their exterior are defrosted in a container or receptacle over a sufficient period of time that the ice melts and some or all of the resulting moisture is absorbed by the cheese particles, and the cheese particles are applied to the food which is then cooked.

DRAWINGS

These and other aspects of this invention, which will be considered in all its novel aspects, will become apparent from the following description, which is given by way of example only, with reference to the accompanying drawings, in which:

Fig 1: is an illustration of a tumbler of the present invention in side view.

Fig 2: is an illustration of the mixing and freezing section of the present invention, in side view.

Fig 3: is an illustration of the mixing and freezing section of the present invention, in end view and within the tumbler.

Fig 4: is an illustration of the delivery end of the tumbler of the present invention.

PREFERRED EMBODIMENT

Example 1

The overall principle of the production of the frozen food product of this invention is one of rapidly freezing the cheese in grated or other paniculate form along with a metered quantity of water and forming a type of coated granule in which the core is mozzarella cheese and the coating is ice, in a substantially even mixture.

Referring to Figures 1 to 4, the freshly comminuted; i.e. diced, grated, shredded or otherwise broken down cheese is placed in a hopper 101 and caused to drop at an even rate onto a conveyer belt 102, 204, 305 which carries it into a freezing apparatus. Preferably the hopper is inside a temperature-controlled room as well as the remainder of the apparatus, and preferably the room is held at below zero degrees C.

A preferred feed rate for a working embodiment is 36 Kg per minute of grated mozzarella cheese.

The supply of cheese 203, 306 falls off the end of the conveyer belt inside a slowly rotating, slightly sloping (at about 3 degrees) tumbler 107, 301 which may have a cylindrical exterior for the purpose of rolling it on roller bearings against 105, 106 but which preferably has an octagonal interior outline as shown in Fig 3. This aids in the mixing process, and two boards 302, 307 help to ensure that the tumbling product is mixed.

Prefened dimensions of an example tumbler are 1.5 metres diameter, 6 metres length, and a rotation speed of 28-30 revolutions per minute,

As the cheese falls off the conveyer it falls into a freezing apparatus, past an array of nozzles 205, 309 squirting a coolant such as liquid nitrogen at a substantially controlled rate in a substantially downwards direction. Thus the cheese (at 207) is exposed to an effective chilling medium delivered in either a liquid or in a vaporised form. The dimensions of the tumbler are such that only the outermost skin of the cheese is likely to become frozen before its fall is arrested by contacting the internal wall of the tumbler 208. However freezing continues for some time. In addition to a spray of liquid nitrogen, the freezing apparatus within the tumbler is provided with means 206, 310 to provide a spray of water, substantially transversely across the spray of liquid nitrogen. Both the water and the coolant are introduced by means of pipes 103 & 104, 201 & 202, 303 & 304.

A preferred feed rate for the prototype embodiment is 0.5 to 5 litres per minute of water at tap temperature, and 1.5 litres per minute of liquid nitrogen, at -178 degrees C.

The water is rapidly converted into a shower of ice particles and it is desirable that it is substantially frozen prior to making contact with the wall of the tumbler, because otherwise ice builds up on the interior surface if the water freezes after contact. At least some of the water forms a coating of ice on the cheese, for all three of the water, the coolant, and the cheese particles are falling though the cooling zone within the tumbler at the same time.

The remainder of the now-frozen water and the initially coated cheese particles 209, 308 are tumbled together within the tumbler as they gradually make their way under the influence of gravity towards the outlet end of the tumbler. The cheese particles pick up a further coating of ice as they travel, so that on emergence substantially all of the ice is collected around cheese particles which are now in the form of ice-coated granules of cheese.

Ultimately the coated cheese granules emerge from the tumbler through orifices 402, 403 at the lower end of the tumbler and fall onto another conveyer belt 109 in heaps 108 and are subsequently packed and distributed; all such operations preferably occurring in sub-zero temperatures.

Prior to use, the frozen granular mozzarella cheese is preferably allowed to defrost for about 24 hours. During that period much of the melted water is absorbed by the cheese, thus raising its water content to a level suitable for use in applications such as the preparation of ready-to-eat pizzas.

Process control aspects include:

Preferably, measurement of the water content of the cheese fed into the tumbler is carried out so that the proportion of added water may be adjusted to compensate for variability on the part of the cheese factory. (Constancy of water content to better than 8-9% is difficult to realise.)

Preferably, the proportion of liquid nitrogen or other coolant may be varied (as a result of varying the feed rate of the cheese and/or the supply rate of water) so that the coating effect wherein ice is applied over the cheese granules is retained. Too little coolant may delay freezing until after the water has contacted the tumbler sides, and too much coolant may render the ice too "dry" so that it has little or no cohesion during tumbling.

Alternatives to the above preferred embodiment, which is given by way of example, include:

Variations to the size of the tumbler, to its internal geometry, its slope, and to its rotation rate

Other foods that may be frozen in this way include other cheeses, other dairy products, or small fruits and the like,

Alternative coolants apart from liquid nitrogen include liquid air, liquid oxygen, gaseous, liquid, or solid carbon dioxide, or a flow of cold air at some pressure.

Other Food Products

The method and apparatus of Example 1 has been tested with other food products and without limiting the generality of the method of preparing a paniculate frozen food product, it has been found to be suitable for products chosen from the group comprising Cheddar Cheese, Colby Cheese, Egmont Cheese, Edam Cheese, Gouda Cheese, diced vegetables, shredded vegetables, diced butter, and shredded butter.

Example 2

Preparation of a pizza using the frozen cheese product of this invention.

In general a pizza comprises a substrate or base of dough, covered with a topping including materials selected from the range of tomatoes, peppers, cheese, onions, meats, fish, shellfish, crustaceans, and the like. There is a great variety of recipes. A cheese is preferred in the majority of recipes, and mozzarella cheese is well known to be particularly suitable for the purpose because both its physical properties (it melts and acts as a matrix for other components) and for its gastronomic attributes.

The frozen cheese product of this invention allows the preparation of an improved pizza, especially at sites where fresh mozzarella cheese is not available. The frozen mozzarella preparation of this invention may be stored for an extended period, and optionally transported, in its frozen state.

Accordingly, the preparation of a pizza which includes the mozzarella (or other curd cheese) of this invention comprises an additional step superimposed on the usual steps involved in the cooking of a pizza.

Prior to blending with other ingredients used in the topping of a pizza, the frozen cheese of this invention is preferably allowed to defrost for about 24 hours. (This is not a limiting figure). One guide as to when the process is complete is to assess the amount of free water remaining in the container. The frozen granular mozzarella cheese may be placed in a covered or an uncovered container, but for food hygiene reasons the container is preferably closed. During the defrosting period much of the melted water surrounding each granule or particle of cheese is absorbed by the cheese, thus raising its water content to a preferred level suitable for use in applications such as the preparation of ready-to-eat pizzas.

It should be noted that the preferred water content for grating mozzarella cheese is lower than the preferred water content for cooking within pizza toppings, and therefore the invention has the advantage of providing an improved water content at both the comminution stage and also the cooking stage of the process of preparing cheese for eventual use in the preparation of a pizza.

Finally, it will be appreciated that various alterations and modifications may be made to the foregoing without departing from the scope of this invention as set forth.