AU685906B2

AU685906B2 - Frozen food product with a coating of ice on the exterior and process

Info

Publication number: AU685906B2
Application number: AU15472/95A
Authority: AU
Inventors: Malyon Mccrea Smith
Original assignee: Grated Cheese Co Ltd
Current assignee: New Zealand Dairy Board
Priority date: 1994-01-26
Filing date: 1995-01-20
Publication date: 1998-01-29
Anticipated expiration: 2015-01-20
Also published as: GB2300105A; AU1547295A; GB9613557D0; JP3218042B2; WO1995020324A1; BR9506584A; AU685906C; HK1008414A1; JPH09508278A; GB2300105B

Description

WO 95/20324 PCT/NZ95/00007 FROZEN FOOD PRODUCT WITH A COATING OF ICE ON THE EXTERIOR AND PROCESS

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 SUBSTITUTE SHEET (RULE 26) 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 particulate frozen food product comprising a plurality of food particles, in which moisture is added to the food particles so that some or all of the food particles have a coating of ice on their exterior, wherein the food particles are supplied to a freezing chamber and moisture is sprayed into the freezing chamber so that it is frozen into a shower of ice particles some or all of which contacts the food particles to form a coating of ice on their exterior.

Preferably, the freezing chamber comprises a generally cylindrical rotatable tumbler.

Preferably the tumbler is in the form of a hollow cylindrical or prismatic shape having •a series of flats or flights on the inside thereof, capable of causing the food particles to be tumbled and separated during the passage through the tumbler.

Most preferably, the tumbler is in the form of a tunnel, on a slight incline, so that the passage through the tumbler can be controlled by the rate of rotation of the tumbler, and the incline of the tumbler.

;1Preferably, the food particles and the moisture are frozen by means of a cold fluid such as a liquified air/gas or blast of cold air or gas supplied to the interior of the tumbler.

Preferably, the food particles are supplied to the interior of the tumbler and allowed to fall through the cold fluid before contacting the inside of the tumbler.

Preferably, the food particles consist of cheese particles, and most preferably, mozzarella cheese in the form of granules or shreds.

Preferably, the toral ice content of the mozzarella cheese is between 1% and 5% of the total weight of the mozzarella cheese prior to freezing. Most preferably, substantially all of the particles have an ice layer of betve,,n 1.5% and 2% of the weight of its respective cheese particle prior to freezing.

In a second aspect, the invention resides in an apparatus for preparing a particulate frozen food product comprising a plurality of food particles, in which moisture is added to the food particles so that some or all of the food particles have a coating of ice on their exterior, the apparatus comprising a freezing chamber having means for chilling the interior thereof, means for supplying food particles to the interior of the freezing chamber, means for spraying water into the interior of the freezing chamber, so that in use the water is frozen into a shower of ice particles some or all of which contacts the food particles to form a coating of ice on their exterior.

Preferably, the means for chilling the interior of the freezing chamber comprises a 20 supply of liquified air/gas connected to one or more nozzles situated in the interior of the freezing chamber, so that in use the nozzles can supply a cold fluid to the interior of the freezing chamber.

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

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

RA 35 Fi. 3: is an illustration of the mixing and freezing section of the present invention, in

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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 particulate form alone 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.

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555555 S* S sis WO 95/20324 PCT/NZ95/00007 Referring to Figures 1 to 4, the freshly comminuted; i.e. diced, grated, shredded or otherwise broker 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 tewrperature-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.

Preferred 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 apparatrs 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.

WO 95120324 WCT/NZ95/00007 -6- 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 underthe 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.

Al ives to the 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 particulate 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.

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Claims

1. A method of preparing a particulate frozen food product comprising a plurality of food particles, in which moisture is added to the food particles so that some or all of the food particles have a coating of ice on their exterior, wherein the food particles are supplied to a freezing chamber and moisture is sprayed into the freezing chamber so that it is frozen into a shower of ice particles some or all of which contacts the food particles to form a coating of ice on their exterior.

2. A method of preparing a particulate frozen food product as claimed in Claim 1, wherein the freezing chamber comprises a generally cylindrical rotatable tumbler.

3. A method of preparing a particulate frozen food product as claimed in Claim 2, wherein the food particles and the moisture are frozen by means of a cold fluid such as a liquified air/gas or blast of cold air or gas supplied to the interior of the tumbler.

4. A method of preparing a particulate frozen food product as claimed in I 20 Claim 3, wherein the liquified gas is liquid air or liquid nitrogen or liquid carbon dioxide.

5. A method of preparing a particulate frozen food product as claimed in Claim 4, wherein the tumbler is in the form of a hollow cylindrical or a prismatic shape having a series of flats or flights on the inside thereof, capable of causing the food particles to be tumbled and separated during the passage through the tumbler.

6. A method of preparing a particulate frozen food product as claimed in :I Claim 5, wherein the tumbler is in the form of a tunnel, on a slight incline, so that the 0: 30 passage through the tumbler can be controlled by the rate of rotation of the tumbler, and the incline of the tumbler.

7. A method of preparing a particulate frozen food product as claimed in any one of Claims 3 to 6, wherein the food particles are supplied to the interior of the S 35 tumbler and allowed to fall through the cold fluid before contacting the inside of the I l tumbler.

8. A method of preparing a particulate frozen food product as claimed in Claim 7, wherein the food particles consist of cheese particles.

9. A method of preparing a particulate frozen food product as claimed in Claim 8, wherein the cheese consists of mozzarella cheese in the form of cheese granules or cheese shreds.

10. A method of preparing a particulate frozen food product as claimed in Claim 9, wherein the total ice content of the particulate frozen food product is between 1% and 5% of the total weight of the mozzarella cheese prior to freezing.

11. A method of preparing a particulate frozen food product as claimed in Claim 10, wherein substantially all of the particles have an ice layer of between and 2% of the weight of its respective cheese particle prior to freezing.

12. Apparatus for preparing a particulate frozen food product comprising a plurality of food particles, in which moisture is added to the food particles so that o: 20 some or all of the food particles have a coating of ice on their exterior, the apparatus comprising a freezing chamber having means for chilling- the interior thereof, means •for supplying food particles to the interior of the freezing chamber, means for spraying "water into the interior of the freezing chamber, so that in use the water is frozen into sd a shower of ice particles some or all of which contacts the food particles to form a coating of ice on their exterior.

V S13. Apparatus for preparing a particulate frozen food product as claimed in Claim 12, wherein the freezing chamber comprises a generally cylindrical rotatable S0tumbler. 0

14. Apparatus for preparing a particulate frozen food product as claimed in Claim 13, wherein the means for chilling the interior of the freezing chamber comprises a supply of a liquified air/gas connected to one or more nozzles situated in the interior of the freezing chamber, so that in use the nozzles can supply a cold fluid to the interior of the freezing chamber. i I jo -4-1 Apparatus for preparing a particulate frozen food product as claimed in Claim 14, wherein the tumbler is in the form of a hollow cylindrical or prismatic shape having a series of flats or flights on the inside thereof, on a slight incline. a a *a a. a a.. a a. a a a a a a fly a ha. a C C a CRC CQ 0 C a a a a a