A frozen pourable product typically comprises a base liquid such as water into which has been added a flavouring in the form of a solid which can dissolve within the base liquid. Suitable flavourings are, for example, sugar and Isosweet solids. Isosweet is the trade name of Amylum UK for isomerose syrup. This is a glucose syrup treated with enzymes to make it sweeter. The flavouring is mixed into the base liquid and the mixture is frozen. During the freezing process, the soluble solids in the non-frozen liquor increase in concentration.

The semi frozen pourable product is then consumed by drinking the non- frozen liquor containing the soluble solids"through"the ice. The ice may also be consumed.

It is known to manufacture partially pourable frozen product by mixing a suitable flavouring with a base liquid such as water at appropriate levels of dilution. The mixture is then poured into a freezer in the form of a container incorporating an agitator. The mixture is frozen to about-3°C until it forms a pourable semi frozen mixture, and is held at this temperature by a viscosity switch that controls a freezer element in the freezer. As is the case with most freezers, the temperature of the mixture is controlled to within a predetermined temperature range by causing the freezer unit to be switched on and off as appropriate. Conveniently, the freezer will comprise a sensor which senses the viscosity of the freezing mixture. As the viscosity

increases to a certain level, the freezer unit will be triggered to switch off in order to raise the temperature and hence reduce viscosity of the mixture.

Similarly once the mixture falls below a certain viscosity, the freezer unit will be triggered to switch on again to reduce the temperature and hence increase the viscosity of the mixture.

Such freezer units are often found in retail units such as newsagents, in which a range of products such as sweets and drinks are also sold. When a customer wants to purchase some of the partially frozen pourable product, an appropriate amount of the mixture is dispensed from the freezer by means of a tap into a smaller receptacle such as a paper cup.

A problem with this known method of forming and dispensing a partially frozen pourable mixture is that the mixture tends to freeze in the freezer from the surface of the mixture downwards leaving mixture towards the bottom of the freezer in the form of an unfrozen liquor containing the solid flavouring. This means that it is not possible to dispense all of the product from within the freezer since the tap must be positioned a predetermined distance from the bottom of the freezer. This in turn means that from time to time it is necessary to shut down the freezer, empty the freezer of mixture which is not dispensable, and then refill the freezer with a fresh mixture.

This results in substantial waste.

In addition, because the freezer has a relatively large capacity, of the order of 10 litres to 30 litres depending on the type of freezer, some of the mixture will remain in the freezer for several days. During this time ice crystals will grow, sometimes becoming unacceptably large.

Further, it is necessary to have a supply of individual containers such as paper cups, into which the mixture is poured, at the point of sale of the product. This results in potentially further waste.

Also, the known method of forming the mixture cannot be used with milk- based products for legal and hygiene reasons. Milk products suffer microbiological spoilage, and food poisoning organisms may grow from within the milk products. Preservatives may not be added. Machine dispensed milk products would require pasteurising daily, resulting in unacceptably high wastage spoilage due to over heating.

According to a first aspect of the present invention there is provided a method of forming a partially frozen pourable mixture, the method comprising the steps of : mixing a liquid containing a base liquid and a flavouring ; pouring the liquid into one or more containers each having a predetermined volume, and representing an individual portion of the mixture; placing the one or more containers within a temperature controlled chamber; causing the temperature to vary in a controlled manner to produce frozen pourable product in the one or more containers.

An advantage of the present invention is that a retailer wishing to sell the product may buy the product in pre-packed containers. Each container holds an individual portion size of the mixture. It is then necessary merely to store the containers in a temperature controlled chamber forming part of the invention. When a customer wishes to purchase the product, it is necessary only for the retailer to remove a container from the chamber and

present it to the customer. This results in a more convenient process and obviates the need to have separate individual containers for dispensing the mixture.

Preferably, the temperature is caused to fall to about-20°C for a first predetermined period of time and then caused to increase to about-3°C for a second predetermined period of time.

During the first predetermined period of time when the temperature drops to - 20°C, ice crystal growth is initiated by lowering the temperature of the mixture to below freezing temperature of the mixture.

The presence of the dissolved solids which provide the flavour to the liquid will depress the freezing point of water which is usually used as a base liquid, from 0°C to typically-3°C, in a situation where 50% ice formation is required.

As the product freezes ice is formed and soluble solids in the non-frozen liquor increase in concentration. This causes the freezing temperature to be lowered further.

During the second predetermined period of time where the temperature within the chamber is increased to-3°C, the mixture is held at a temperature which maintains the liquid in a partially frozen pourable state in which it is suitable for selling to consumers.

For any given mixture within a temperature range of approximately-1°C to - 10°C, an equilibrium ice to liquor ratio will be established. Thus, in order to ensure a particular ratio of ice to liquor, it is necessary to control the temperature within the chamber during the period within which consumers

may buy the product. This period is usually within the hours of 0900 to 1800 depending on the hours within which the retail unit selling the product trades.

Preferably the method comprises the further steps of thawing the mixture to a temperature of about +2°C for a third predetermined period of time.

During this third predetermined period of time, the chamber may be restocked to replace products which have been sold during the day, and products not sold are thawed before being refrozen during the first step of the cycle during which the temperature in the chamber is reduced to about - 20°C for the first predetermined period of time. This prevents growth of large ice crystals in product remaining in the chamber for more than one temperature cycle.

The resulting product will typically contain approximately 25% ice although a ratio of between 10% and 50% of ice is also feasible. The consistency of the product is preferably similar to that of slush from melted snow. If it is too thick, it cannot be consumed via a straw. If it is too thin it becomes mobile like water.

Conveniently, the method comprises a further step of rotating the one or more containers about a longitudinal axis for at least some of the time that the one or more containers are positioned within the chamber.

This has the effect of ensuring substantially uniform freezing of the product within the one or more container.

According to the second aspect of the present invention there is provided an apparatus for forming a partially frozen pourable mixture comprising:

a chamber ; receiving means for receiving one or more containers containing a mixture to be frozen; a temperature sensor for sensing the temperature within the chamber; temperature means for cooling and heating the chamber; control means for controlling operation of the temperature means such that the temperature within the chamber cycles through at least two predetermined temperatures for predetermined periods of time.

Preferably, the control means controls operation of the temperature means such that the temperature within the chamber is caused to fall to about - 20°C for a first predetermined period of time and then caused to increase to about-3°C for a second predetermined period of time.

Preferably, the control means controls the operation of the temperature means such that the temperature is raised to +2°C for a third predetermined period of time.

Conveniently, the temperature means comprises refrigerator coils, and a fan, and optionally a heater.

Advantageously, the apparatus further comprises rotating means for causing rotation of one or more container.

Conveniently, the rotation means comprise one or more rollers.

The invention will now be further described by way of example only with reference to the accompanying drawings in which:

Figure 1 is a schematic representation of a first embodiment of the invention, in the form of a temperature control chamber forming part of the apparatus according to the second aspect of the present invention used to carry out the method of the first aspect of the present invention; Under certain circumstances it has been found advantageous to be able to rotate one or more of the one or more containers containing the mixture to be frozen. However in other circumstances, for example, if a large number of containers is being processed simultaneously, it is preferable for the containers to remain stationary throughout the processing.

It has been found that, if a large number of containers is processed, for example, 80 or more containers, then the product within the containers cools more slowly. This may create a larger depression of the freezing point than occurs when a smaller number of containers are processed simultaneously.

It has, therefore, been found advantageous that when a large number of containers are processed simultaneously, that they should remain stationary through the process. In other words, the container should be processed statically. This means that when seeding occurs, the ice crystals tend to form a matrix which occupies all the original liquid space.

The mixture to be frozen can be held as a pseudo solid for several days of the temperature cycle. This eliminates the need for a thawing cycle. <BR> <BR> <P>A product processed in this way will become a slush, i. e. , a frozen pourable product, upon shaking the container prior to consumption of the mixture.

According to a third aspect of the present invention, there is provided a product formed using the method according to the first aspect of the present invention, or the apparatus according to the second aspect of the present invention.

Figure 2 is a schematic plan view of the chamber of Figure 1 showing the rollers on which containers may be supported; Figure 3 is a schematic representation of the chamber of Figure 1 with no containers present showing spindles on which rollers are supported; Figure 4 is a detail of Figure 3; and Figure 5 is a schematic representation of a second embodiment of the present invention.

Referring to the Figures 1 to 4, a temperature controlled chamber is designated generally by the reference numeral 2. The chamber can take any form in which it is possible to control temperature within the chamber, and may for example be in the form of an incubator.

The chamber is shaped and sized so that it can contain 16 individual containers 4. It is to be understood however that a chamber 2 according to the present invention may be proportioned to hold any number of containers 4 as appropriate.

Each of the containers 4 contains a mixture which will be sold as a semi frozen pourable product.

In this example each container 4 is positioned on rollers 6, although in other examples, the chamber 2 may not include rollers.

The chamber 2 further comprises a thermometer 8 which in this example comprises a platinum resistance thermometer, a heater 10 and a fan 12. The chamber also contains a source of refrigeration 15. This may be in the form of cooling coils or chilled air. In this example the source of refrigeration is coiling coils 15.

The product contained within the containers 4 comprises a base liquid such as water, and a predetermined proportion of a flavouring in the form of a solid. In this example the flavouring is a glucose syrup solid which is added to the base liquid water in a proportion of 10% glucose syrup solid to 90% water.

Each container 4 comprises a substantially cylindrical clear plastic bottle having a neck and a cap. The maximum capacity of each container 4 in this example is 390ml. Each container is filled with a mixture of water and glucose syrup solid to a capacity of 350ml to allow 40ml of head space which is used to stir the product. The rollers 6 on which each of the containers 4 are supported, allows each container to be rotated along its axis. In this example the speed of rotation is 2.5 bottle revolutions per minute.

The temperature within the chamber 4 is controlled so that it varies to produce a frozen pourable product within each of the containers. A temperature cycle within the chamber will now be described in more detail.

First Period, Period A

This period takes place between the hours of midnight and 2am. The temperature within the chamber is raised to +2°C and product within containers which has not been sold during the temperature cycle is thawed and remixed.

Second Period, Period B This period takes place between the hours of 2am and 4am. During this period the temperature within the chamber is lowered to-15°C. Old and newly supplied products are lowered to a temperature well below the initial freezing temperature. Initially, the product will cool to a temperature of, say-6°C which is significantly below the initial freezing temperature of the product. Small ice crystals will then quickly form throughout the containers and the temperature of the product will rise.

Third Period, Period C This period takes place between the hours of 4am and midnight. During this period the temperature is controlled within a range of approximately - 1. 5°C +/-0. 5°C. During this period, the product is maintained at a temperature that produces a suitable ratio of ice to liquor for the proportion of glucose solids within the base liquid.

In this example, as mentioned above, the mixture comprises 10% of glucose solids. This means at a temperature of-1°C there will be a minimal amount of ice. At a temperature of-1. 5°C there will be 25% ice and at a temperature of-2°C there will be 50% ice.

It is during period C that retailers will have the opportunity to sell the product to customers. As the day progresses, ice crystals become fewer and

larger and would continue to enlarge if the product was not completely thawed during period A when the incubator is also restocked.

The temperature may be controlled in such a way to produce the product having any proportion of ice from 10% to 50% as appropriate.

The invention further comprises a controller which controls the operation of the heater 10 and the fan 12 as appropriate in order to produce the required temperature at the appropriate time.

The temperature is controlled by an electronic control unit connected to the thermometer 8. If the freezer temperature is above the set point then the control unit admits refrigeration to the freezer to cool it down. When the temperature is sensed to be below the set point then the refrigeration is withdrawn.

The invention is adapted to cover temperature rise and falls of 0.1 to 2°C.

The time between set points (the hunt) is typically 20 minutes although the hunt time may be anything from 1 minute to 2 hours.

The thermometer 8 monitors the temperature at all times, and the controller causes adjustment of the temperature through operation of the refrigeration source 15, heater 10 or fan 12 as appropriate during the temperature cycle of the chamber.

Referring now to Figures 2 to 4, the chamber 2 is shown in more detail.

The chamber 2 comprises rollers 6 which are adapted to support the containers 4 and also to cause the containers to rotate. One of the rollers, in this case roller 14, is a drive roller and is driven by any means such as a

motor to rotate at a predetermined speed. Adjacent rollers are drivingly connected to one another by means of drive belts 16.

Figures 3 and 4 show details of the chamber 2. As can be seen, the drive portion of roller 14 and the drive belts are hidden behind a false back 18 to the chamber 2. This ensures that the drive mechanism does not interfere with the containers 6.

The chamber comprises, in this embodiment, two shelves, or layers of rollers as can been seen in Figure 1.

Turning now to Figure 5, a second embodiment of the invention is illustrated. In this embodiment, the invention comprises a temperature controlled chamber designated generally by the reference numeral 200.

Parts of the chamber 200 which correspond to parts of the chamber 2 illustrated in Figures 1 to 4 have been given corresponding reference numerals for ease of reference.

The chamber 200 is very similar to chamber 2, but there are no rollers 6 for causing rotation of the containers 4 (not shown in Figure 5). It has been found that chamber 200 is particularly useful for processing large numbers of containers 4 simultaneously. In particular, chamber 200 is useful for processing eighty to one hundred and sixty containers at a time.

On processing a large number of containers 4 at the same time, the product held within the containers will cool more slowly. This will create a larger depression of the freezing point compared to the depression of the freezing point created when a smaller number of packs of containers are processed at the same time.

Because there are no rollers 6 in the chamber 200, the containers will be processed statically. This means that ice crystals tend to form a matrix that occupies all of the original liquid space in each of the containers.

This means that the product can be held at as a pseudo solid for several days of the daily temperature cycle. This in turn means that there is no need for a thawing cycle.

In other words, the first period, period A as described hereinabove with reference to Figures 1 to 4 is not necessary when using the chamber 200 for processing a large number of containers 4 at the same time.

It is to be understood that the chamber illustrated in Figures 1 to 4 could be used to statically process containers by similarly not operating the rollers.

Exaii, zple Product Details A raspberry flavoured syrup was prepared with 15% glucose solids, 0. 3% citric acid, preservatives, colouring and flavouring.

This was filled into 120 P. E. T. bottles to 330ml. The brim full capacity of the bottles was 390ml. The bottles were placed on 4 shelves, 30 bottles to a shelf and with air space around each bottle i. e. , the bottles were not touching one another.

The Daily Cycle Seeding The temperature within the chamber 200 was set at minus 15° centigrade and kept at this temperature for 14 hours. After approximately 3 hours the air temperature in the display unit was about minus 6 degrees-centigrade.

The first bottles developed ice crystals which very quickly occupied most of the volume of the bottle. The temperature in the seeded bottles rose to minus two degrees centigrade. This rise in temperature means that the refrigeration cooling rate reduces, and the number of bottles seeding per hour falls. Also, in general, the longer a bottle takes to seed the greater the freezing point depression. However, after 14 hours all bottles had seeded and grown sufficient ice.

Holding The temperature in the chamber 200 was then set at minus 3 degrees centigrade for 10 hours. If the temperature detected was above minus 3 degrees, the refrigeration would cut in. If the temperature dropped to below minus 2.8 degrees centigrade, the refrigeration would cut out. If refrigeration dropped below minus 5 degrees centigrade the heater would cut in. As the temperature rose, more ice thawed. After 2 hours holding, the bottles were saleable as slush. On removing the bottles from the chamber, the product was found to imitate a solid with an ice crystal structure. On shaking the bottle the product assumed a typical slush pourable structure.

Restacking Sold product can be replaced by fresh product, typically stored at ambient, at any stage during the holding cycle.