Dairy Products

This invention relates to dairy products, and particularly to the production of cheese.

Cheese is made by a wide variety of processes from milk, which may be cows' milk, goats' milk, ewes' milk or milk from other animals. Cheese may be hard, such as Parmesan, or soft, such as Brie and mozzarella, or crumbly or semi-liquid, such as cottage cheese, with a wide variety of intermediate textures. Cheese may be strong in flavour, such as mature Cheddar, or relatively bland, such as Caerphilly, and additional flavour effects can be brought about by introducing microorganisms or enzymes to produce blue cheeses such as Stilton and Gorgonzola. So-called 'processed cheese' is a cheese product that includes melted cheese.

Cheeses can have a range of fat contents, from zero up to 50% or more. A high fat content is sometimes regarded as undesirable from a dietary point of view. A low fat cheese is, officially, one containing no more than 3% fat. Low fat cheeses are often noted for their bland flavour, hard brittle texture and slightly bitter aftertaste.

Cheese is essentially casein - a protein - holding fat and water.

The present invention provides novel cheese and cheese products, including novel processed cheese, that can display a wide variety of tastes and textures, with a wide range of fat contents, right down to the 3% or less that qualify as low-fat cheese, and novel processes for making cheese and cheese products that incorporate functional or flavour additives prior to the blended process, as well as novel cheese making apparatus.

The invention comprises a method for making a cheese product comprising:

predetermining a fat content for the finished cheese product;

blending a first cheese having a first fat content higher than the predetermined fat content for the finished cheese with a second cheese having a second fat content lower than the said predetermined fat content;

selecting the relative amounts of the first and second cheeses so that the fat content of the finished cheese product is said predetermined fat content;

blending said cheeses under homogenizing conditions.

The blended cheeses may be heated to a temperature less than the melting temperature of at least one of them, and may be heated to a temperature less than the melting point of either of them.

The blending may be effected under low shear conditions or no-shear conditions, and may be effected by a screw feeding arrangement. The screw feeding arrangement may be heated, as by heat exchange with heated water.

The screw feeding arrangement may be heated by a water jacket or oi] jacket and a screw of the screw feeding arrangement may be heated, which may also be by heat exchange with heated water or heated oil.

A low fat cheese may be produced according to the invention by blending a major proportion of a low fat cheese with a minor proportion of a higher fat cheese, and the method may be adapted to produce a cheese with less than 3% fat.

The method may also be adapted, according to the invention, to produce a cheese with a mature cheese flavour by blending a major proportion of a fresh-produced cheese with a minor proportion of a matured cheese.

Two or more cheeses may be used.

The invention aiso comprises apparatus for making a cheese product, comprising:

a blender for combining at least two cheeses under homogenizing conditions;

supply means for supplying a mixture of said cheeses to said blender in desired proportions; and

cheese forming means adapted to receive a blended cheese product from said blender.

The blender may be temperature controlled.

The blender may comprise a screw feeding arrangement.

The blender may comprise a heat exchange arrangement, which may comprise a water jacket or oil jacket. The blender may be a screw feed arrangement of which a feed screw is heated, and the screw is heated by heat exchange with heated water or heated oil by having water or oil passages for the circulation of heated water or heated oil.

The cheese forming means may be adapted to form cheeses of a size and shape which can cool from a blending temperature within 24 hours.

The invention also comprises a cheese product having a predetermined fat content comprised of a homogeneous blend of at least two cheeses with different fat contents. The fat content may be less than 3%, containing a major proportion of a cheese with less than 3% fat content and a minor proportion of a cheese having a higher fat content. The invention also comprises a cheese product comprising a blended cheese containing a major proportion of a fresh-produced cheese with a minor proportion of a matured cheese.

The cheese may comprise further additives such as spring onions, pickles, health products, cholesterol reducing agents, etc.

Cheese products and methods and apparatus for making them according to the invention will now be described with reference to the accompanying drawings, in which:

Figure 1 is a block diagram of one production process;

Figure 2 is a picture diagram of a first part of the production process of Figure 1 ;

Figure 3 is a picture diagram of further parts of the production process of Figure 1 ;

Figure 4 is a part sectional side elevation of a screw feeding arrangement which blends cheese according to the invention;

Figure 5 is a part sectional plan view of the arrangement of Figure 4; and

Figure 6 is a section on the line Vl-Vl of Figure 5.

The drawings illustrate a method for producing a cheese product 11 , comprising:

predetermining a fat content for the finished cheese product;

blending a first cheese 12 having a first fat content higher than the predetermined fat content for the finished cheese 11 with a second cheese 13 having a second fat content lower than the said predetermined fat content;

selecting the relative amounts of the first and second cheeses 12, 13 so that the fat content of the finished cheese product 11 is said predetermined fat content;

blending said cheeses 12 and 13 under homogenizing conditions.

The fat content may be predetermined in accordance with market or dietary requirements. Various definitions of low fat cheese may be found. One such definition specifies 3% or less fat content by weight. Another, American, definition is less than 3 grams of fat per serving. "Less fat" and "reduced fat" cheeses are supposed, by an American definition, to have 25% less fat than comparable "full fat" products. In any event, it is clear that there is a demand for cheese with predetermined fat content. On the other hand, the fat content makes a major contribution to the taste of the cheese.

Some types of cheese require to mature before developing a satisfactory flavour. Over a period of time, physical and chemical changes in the maturing cheese develop characteristic flavours, strengthening and enhancing the flavour when fresh produced. The blending process according to the invention can introduce mature cheese taste into fresh-produced cheese by blending into a fresh-produced cheese a proportion of its mature version, or, perhaps, of the mature version of some other cheese.

The process is illustrated generally in Figure 1, which shows a process for blending three cheeses, 12, 13 and 14. The cheeses are fed in comminuted form, either as a crumbly cheese, or in diced or grated form, into a mixing chamber 15, where they are thoroughly mixed. The mixture is then fed to a blender 16 in which the mixture is homogenized. The homogenized cheese product is then fed to a cheese forming arrangement 17, where it is formed into cheeses of desired size and shape before being cooled in a cooling arrangement 18.

Mixing of cheeses is illustrated diagrammatical Iy in Figure 2, which simply shows pre- weighed cheeses 12, 13 being poured into a weighing hopper 21, which is then tipped into a feed hopper 22 for the blender 41, Figure 3.

In order to achieve a predetermined fat content for the finished cheese product, it is important to determine the proportions of the different cheese in the mixture. This may, in some cases, not be straightforward, inasmuch as, due to water losses and other reasons, the total fat content of the finished product may not be the average fat content of the starting cheeses. An iterative spreadsheet program is used to optimise the recipe to ensure that specific fat, moisture, salt, and additive requirements are met for a target specification.

It is important to consider temperature of the blending step. Traditionally, a cheese product that has been melted is classified as a processed cheese. Cheeses have a range of temperature, below the melting point, over which they soften so that they can flow and be blended to form a homogeneous product. The range will, of course, be different for different cheeses. In order for the finished product to be termed a cheese, rather than a processed cheese, none of the components must have melted during the blending process (or, indeed, at any other time) but this does not mean that the process

of the invention cannot be used to make cheese of which one or more of the components has exceeded its melt temperature. Generally, however, the temperature will be elevated above room temperature during the blending step, and will in most cases be in the range 35 - 85°C.

Blending can take place in a screw feeding blender 41, as is more particularly illustrated in Figures 4, 5 and 6. This comprises an input hopper 42 entering into a duct 43 containing two rotary screws 44 which feed the softened cheese mixture forward under low shear or no-shear conditions. The screws 44 can be varied in speed, dependent on the cheese processed but are typically in the order of one to ten revolutions per minute, and the screw "threads" do not touch each other or the wall of the duct 43. The duct 43 is heated by an external water jacket 45, and the screws 44 are themselves heated by means of circulating water through their hollow shafts 44a.

Mozzarella is cooked and stretched in similar screw feeder arrangements, but immersed in water. As this is not the case in the method of the present invention, it will be necessary, with many cheese products, to apply greater force than in used in mozzarella production, and the equipment will usually be constructed to be more robust, after the fashion of machinery used to make inherently more viscous product than mozzarella. The surfaces of the screw feeder against which the product flows are desirably coated with a non-stick coating, such as polytetrafluoroethylene.

The flowing cheese product, after about a 15 minute dwell time in the feeder blender 41 , emerges - see Figure 3, from a valve which is open or partially opened to provide, if required, a back pressure within the blender, to further the working action by the augers on the cheese mass as it passes through the blender. It emerges out of the blender valve at an elevated temperature into a feed arrangement 31 of a block making machine 32 which cools the outside of the moulded cheese for 10-30 minutes, making it shape stable.

As the hot cheese flows from the blender to the block making machine, further additives can be incorporated into the cheese, these can include items such as spring onions, pickles, health products, cholesterol reducing agents, etc.

The cheese is then placed into a cooling medium which can consist of brine or water for sufficient time to cool the cheese block down to a core temperature of below 12 ⁰ C.

At a typical exit temperature of 35-85°C, cooling of the moulded cheeses is required prior to packing and storing.

The temperature and pressure regime during the blending phase can be very important to the quality of the finished cheese product, and this stage of the process can be usefully under the control of a microprocessor or programmable logic controller (PLC) which can, inter alia, control the temperature and flow of water through the screws and water jacket.

A worked example is now described to make a <3% fat cheese (termed "CHS03") having a defined composition.

The ingredients used to make CHS03 are initially analysed for composition and to check that they meet microbiological standards. If suitable, the compositional results are entered into a recipe spreadsheet Table 1 (below) lists the composition of CHS03

Table 1: Composition of ingredients of CHS03

A spreadsheet is used to calculate the proportions of ingredients in order to produce the CHS03 cheese. The percentage target values of fat, water, and salt are predetermined, and the spreadsheet is used to calculate the weight in kg of each ingredient required. Table 2 (below) lists these target values together with the amount required of each of the ingredients in order to produce the desired cheese.

The recipe listed Table 2 is used to make the required quantity of cheese. The recipe is recalculated whenever the composition changes for new batches of existing ingredients - either extra ingredients are added, or the specification changes.

To make the cheese, the ingredients are shredded and weighed into a mixer which blends the cheese together to ensure even distribution. Computer software is used to compare the weighed amount of each ingredient with the actual amount required by the recipe. If out of tolerance, a warning alarm is sounded, and the mixer is locked until a Supervisor investigates the problem and clears the computer log.

The batch of cheese is placed in a blender where it is mixed and heated to make the cheese homogeneous. As the hopper of the mixer empties, the next batch is tipped in, and this process continues until the production run is completed. A computer records the operating parameters of the mixer. Parameters such as start time, stop time, pressure, maximum temperature, minimum temperature, and actual temperature are recorded, and are used to evaluate the operation.

The cheese is extruded into moulds of the correct shape, and then chilled with cold water for approximately 12 minutes. The cheese is then placed in water or brine baths, which complete the cooling.

The cooled cheeses are vacuum packed, placed in a cardboard box, labelled and palletised. They are placed in a chill store where they are tested for composition and microbiological content before being positively released. An example of such a specification for CHS03 is shown in Table 3.

Table 3: Specification summary for CHS03.

Product Low fat cheese 3%

Product code CHS03

Ingredients Skimmed milk, whole milk, lactic cultures, rennet and salt If coloured, E160b

Rennet Vegetarian type

Chemical standards

Test Typical Tolerance

Fat <3.0% Max 3.0%

Moisture 55% 53-57%

Salt 1.9% 1.7-2.0%

F.D.M. 5.3% 4.8-5.8%