WO2005120243A1

WO2005120243A1 - Method and apparatus for making an iced food or drink product

Info

Publication number: WO2005120243A1
Application number: PCT/GB2005/002285
Authority: WO
Inventors: Elizabeth Acton; George John Morris
Original assignee: Elizabeth Acton; George John Morris
Priority date: 2004-06-08
Filing date: 2005-06-08
Publication date: 2005-12-22
Also published as: GB2414915A; GB0511756D0

Abstract

The present invention provides a method of making a food or drink product, the method comprising the steps of (i) producing a ice slurry by forming ice within a concentrated solution of the unflavoured or uncoloured product; (ii) adding a desired flavour or colouring to the ice slurry; and (iii) diluting the ice slurry with chilled or supercooled solution to produce an iced product of the desired composition and ice fraction.

Description

Method and apparatus for making an iced food or drink product

This invention relates to a method and apparatus for preparing iced food and drink products, such as iced cream, frozen yoghurts etc, and particularly such a method and apparatus which allows a choice of multiple flavours and colourings at the time of serving.

Commercially produced iced beverages and desserts are produced using scrape surface heat exchangers of various types. The scrape surface heat exchanger can operate in continuous, batch, or semi-batch (semi-continuous) mode. The beverage or dessert is introduced into the scrape surface heat exchanger, with or without a gas such as carbon dioxide, and. ice is produced at the refrigerated walls and mixed into the product. When required, the iced product is dispensed and any entrapped gas will then expand producing a foamed product. This approach allows only one type of drink or dessert to be produced per barrel ofthe scrape surface heat exchanger.

Currently there is no satisfactoiy way to introduce a selection of flavourings or colours to an iced beverage when it is dispensed. One approach that has been examined is to start with a base syrup which contains sugars etc but no flavourings or colour. Ice is produced in the scrape surface heat exchanger and then a concentrate of flavouring or colour is introduced on serving. However, this is unsuccessful because there is no incoiporation of the flavour or taste molecules into the ice crystals and this results in a very poor quality product.

A method is described below by which it is possible to add a wide variety of flavourings to a base syrup which has been partially frozen.

We have realised that it is not beneficial or necessary to induce ice solely using the final product, and that if ice is formed within a "Concentrated Solution" (which may be a concentrated sugar solution, a concentrated solution of the beverage or dessert, or a concentrated ice cream solution, an alcohol solution or any other suitable concentrated solution), and then diluted, before serving, with a "Diluent" (which may be a dilute sugar solution, a dilute solution of beverage or dessert, a dilute ice cream solution, a dilute alcohol solution, any of which may be supercooled, chilled or partially frozen, or water which may be supercooled or chilled, or any other suitable diluent), then a number of benefits occur:

1. Ice crystal formation in a Concentrated Solution results in many very small ice crystals, which even with some growth on dilution will result in a product with a fine ice ciystal structure, which is a desired feature of ice beverages and desserts etc 2. Ice crystals formed within a Concentrated Solution are not as susceptible to regrowth and sintering as are ice crystals formed in a more dilute solution. An ice slush formed within a concentrated sucrose solution, for example, would be expected to have a long "shelf life". 3. The ice crystal structure in a Concentrated Solution would not cause as much abrasion of the barrel or the scraper blades of the scrape surface heat exchanger, a problem which occurs with ice slush formed in a more dilute solution. 4. During the ice ciystal growth, sintering and recrystallisation that will occur during addition of a Diluent, any added flavour molecules etc will be entrapped within the ice crystal structure. This will allow equipment to be developed in which it is possible to select from a multiple choice of flavours and colours to be added at the point of serving. 5. As only a portion of the delivered product will need to be processed in the scrape surface heat exchanger, there may be savings in the counter space occupied by the equipment.

Described hereinafter is a method of allowing the selection of multiple flavours and colours to be introduced at the point of serving of frozen beverages or desserts comprising the steps of forming ice within a concentrated solution of the unflavoui-ed beverage or dessert, dispensing a portion of tliis ice slurry into a mixing chamber and adding desired flavours and colouring, and then diluting this ice slurry with chilled or supercooled water to produce a iced beverage ofthe desired composition and ice fraction. A method of producing a frozen slush or dessert is also described which comprises the steps of forming ice within a concentrated solution of the beverage or dessert and then diluting this ice slurry before serving with chilled or supercooled water to produce a iced beverage of the desired composition and ice fraction. In these methods, the ice slurry produced in the concentrated solution may be diluted with an ice slurry of a dilute solution. Furthermore, the solute may be removed from the ice slurry by filtering or any other appropriate means, and the remaining ice may be added directly to a chilled or supercooled liquid.

A method of manufacturing a conventional iced beverage is also described in which an ice fraction is induced in a concentrate of the beverage and, when required, this is mixed under pressure with water.

A method of production of beverages with a low ice content is described in which the beverage is cooled or supercooled and a small volume of an ice slurry prepared in a concentrate of the beverage, or in a sugar solution, or an alcohol solution is then added under pressure to the beverage

A method of manufacturing an iced product with a wide variety of flavours is described below as comprising the steps of: inducing an ice fraction in a Concentrated Solution; when required adding a small volume of flavour or taste concentrate to this iced slush before or at the same time as mixing it with a Diluent. The compositions of the two solutions, (the Concentrated Solution and the Diluent), and the mixing ratios are selected to achieve the desired solute concentration in the final product. The temperature of these two solutions, (the Concentrated Solution and the Diluent), is controlled to give the desired ice fraction in the final product. Either one or both of the Concentrated Solution and the Diluent may be carbonated or otherwise gassed.

Two ice slurries (high and low solute concentration) may be produced in twin barrels within the same machine, the operating temperatures for the barrels being selected to achieve the desired ice fraction within the product. With carbonated products, carbon dioxide may be added to both sugar solutions and both barrels kept under pressure; alternatively CO may be added to the product in one barrel only.

In a preferred embodiment the ice slurry of Concentrated Solution is mixed with chilled or supercooled water, which is cooled immediately prior to use by passing it through a heat exchanger. The supercooled state may be stabilised by the application of pressure, the introduction of soluble gas etc. Different consistencies of the final product, for a given composition and Concentrated Solution exit temperature from the scrape surface, are achieved by modifying the temperature ofthe Diluent.

Concentrates of flavourings or colour are added, with mixing, to the Concentrated Solution ice slush in a mixing chamber, the Diluent is then added to the mixing chamber, which in the case of gassed products is pressurised. The final product may be further mixed; the product dispensed and the pressure released.

In a further embodiment the flavour or colour is added to the Diluent prior to addition of the Diluent to the Concentrated Solution ice slush.

The method described may also be used for the production of beverages, for example lager, with a low ice content. In this case the beverage is cooled or supercooled and a small volume of an ice slurry prepared in a concentrate of the beverage, or in a sugar solution, or an alcohol solution is then added under pressure to the beverage

In a further embodiment the partially frozen Concentrated Solution is further processed to remove solute by filtering or any other appropriate means to retain the ice component which is then added directly to a Diluent or final product, which may be chilled or supercooled. Flavouring may be added to the ice if required prior to its addition to the Diluent or final product, for example to produce a decorative or flavoured "head". Alternatively the ice may provide "seeds" for nucleating supercooled solutions.

hi a further embodiment, the flavour or colour is added to the concentrated solution before freezing and the Diluent added to the mixing chamber, which in the case of gassed products is pressurised. The final product may be further mixed; the product dispensed and the pressure released.

In a further embodiment the mixing chamber may take the form of an auxiliary chamber, a pipe, a valve channel or in any other suitable form.

In a further embodiment the mixing chamber is designed to achieve rapid mixing, by incorporation of a suitably driven mixer, impeller or screw or by appropriate jetting ofthe infeed Diluent or any other suitable means.

In a further embodiment the pressure is maintained in the mixing chamber by a piston or similar which moves to allow the mixing chamber to be filled by the iced Concentrated Solution and then further moves to allow the Diluent to flow into the mixing chamber.

In a further embodiment the pressure is maintained in the mixing chamber by appropriate flow restriction downstream ofthe first mixing point.

In a further embodiment the mixture is treated ultrasonically either in the mixing chamber or as it is being dispensed to induce grain refinement of ice crystals.

The mixing chamber is cleaned with a small amount of Diluent to minimise contamination of products with flavouring and/or colour from the previous product.

In a further embodiment the mixing chamber has a flexible surface such as a bag or tube which may be externally manipulated to achieve the desired mixing.

Various embodiments of the invention are now described by way of example only with reference to the following examples.

Example 1. Apparatus 2 for the direct addition of flavoured or coloured water to a slush is shown in Figure 1. For simplicity, the addition of the flavoured or coloured water is shown as being introduced from a single inlet 6, however to achieve a rapid mixing within the mixing chamber 8 it may be beneficial to have more than one inlet. Also, to reduce the cross contamination with different flavours or colours, it may be necessary to have multiple inlets, each one dispensing a single flavour or colour. The apparatus 2 also comprises a scrape surface heat exchanger 4 for producing an ice slurry (slush).

This configuration could also be employed for the addition of chilled water to a slush of a beverage concentrate to produce a "conventional" iced beverage.

Example 2. The addition of a concentrate of a flavour or a colour to an ice slush may be made simultaneously with (or, in an alternative embodiment, followed by) the addition of chilled water or a secondary ice slush of a dilute solution to the mixing chamber. Apparatus 102 for simultaneously adding diluent and flavour is shown in Figure 2.

Example 3. Apparatus 202 for the addition of chilled flavoured water into a mixing chamber is shown in Figure 3 as comprising a short pipe 204 and cylinder system 206. In this arrangement, a piston 208 is used to ensure that there is minimum drop in pressure during the addition of the flavoured Diluent. It is desirable to avoid a substantial drop in pressure otherwise gasses dissolved in a product (particularly the CO₂ in a carbonated beverage) are likely to cause the product to foam prematurely.

The Diluent is added to the concentrate by radial jets (only one jet 210 is shown) which ensure good mixing. The piston 208 moves to extract the final product via the exit pipe 204 fitted with a static mixing tube.

Example 4. Apparatus 302 is shown in Figure 4 which allows for the direct addition of chilled flavoured water into a mixing cylinder 303 as the concentrate is extracted from the freezing barrel 305. The pressure is maintained during extraction from the freezing barrel 305 by a moving piston 308.

Example 5. Production of a Standard product. Using the apparatus described in

Example 3, a standard product has been produced by freezing a concentrated fcb solution (17° - 18° Brix) at 2 - 3 bar pressure, to below -8°C, and adding a cold water Diluent. The final product brix was 13°- 14° brix, it peaked and had the characteristics of a standard fcb product, namely overrun ~100%, ice fraction ~ 50%.

Example 6 Apparatus 402, shown in Figure 5, mixes flavoured water diluent and Concentrated Solution downstream of the freezing ban-el exit as the product is dispensed. The pressure is maintained by a downstream flow restriction or valve 407. The flow path shown could be part of a suitably designed single exit valve with Diluent inflow ports.

The principle of the method is illustrated here for 100 ml of a drink, containing 10% sucrose, typical of a cola type drink (melting point -0.625°C). In Table 1 below, some examples of the sucrose solutions which could be mixed to produce a drink of 100ml final volume containing lOg sucrose are presented. An unexpected finding is that when mixing a concentrated sucrose solution at the temperature of its melting point with a more dilute sucrose solution, also at its melting point, the final mixture is below the melting point for the final composition.

Example 7. In Table 2 below, the ice fractions which may be obtained on mixing 25 ml of a 36% sucrose solution frozen to either of three different temperatures when added to 75 ml of a 2.5% sucrose solution frozen to either of three different temperatures are illustrated.

In Graph 1 below, the ice fractions obtained following freezing of a 10% glycerol solution to different final ice fractions and then diluting with an equal volume of water at 0°C are shown. This analysis demonstrates that at all ice fractions, addition of an equal volume of water results in >50% ofthe existing ice fraction, as would be expected by simple dilution ofthe existing ice. This occurs presumably by growth on the pre-existing ice crystals.

Final ice fraction of mixture following dilution of 10% glycerol stream with equal flow rate water stream at 0°C

1.0 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0.0

0.0 0.1 0.2 0.3 0.4 0.5 0.6 Final ice fraction of mixture

Graph 1: Graph to illustrate the effect of mixing a cold stream with given ice fraction with a chilled stream. The final ice fraction of the mixture is shown. It may be noted in this example that the temperature ofthe 10% glycerol solution at 0.52 ice fraction is -5°C and the final temperature ofthe mixture at 0.27 ice fraction is -1.4°C.

Calculation method for determining Concentrated solution properties to achieve required final product

The ideal process modelled is illustrated below

Concentrated Solution

Insulated Final oroduct mixer - no heat losses Diluent

The basic equation for mixing without heat loss is m_ch_c + m_wh_w = (m_c + m_w)h_m where m_c, m_ware the mass flow rates of the concentrate and diluent respectively; and h_c, h_w, and h_m are the enthalpies per unit mass of the concentrate, diluent and mixture.

We use this equation by dividing through by m_c and working in terms of the ratio of the water: concentrate flow rates, to give m m (1) m„ m„

This equation assumes that there are no heat losses in the mixing.

Example: Concentrated Solution at 17° brix, Diluent is flavoured water to give final mixture 13° brix, 50% ice fraction

1. Calculate the required amount of Diluent Noting that the brix is equivalent to the mass concentration in the solution, m then, — - is given by the following equation:

m which gives — ^ = 0.377 .

2. Calculate the required ice fraction in the concentrate using the enthalpy balance, equation (1)

Firstly we note that we have calculated the enthalpies with the enthalpy at 0°C being equal to zero in all cases, so that for example when the temperature of the water (no ice present) is at 0°C, h_w = 0

At 50% ice fraction in the final mixture we have calculated, using the enthalpy data given in Graph 2 below and taking the density at 13° brix as 1050 kg/m³ , that h_m = -171kJlkg

Case (a): diluent temperature at 0°C so that/z,,, = 0 , equation (1) gives h_c = (l + - ^}^)h_n, m_c

which leads to h_c = -223.6U/kg , which taking the density at 17° brix as 1067 kg/m³ and using the data given in Figure 7 below corresponds to an ice faction of 63.5%, temperature -8.4°C.

Case (b): diluent temperature at 2°C, so that/?,, = S.434U/ kg , equation (1) givesΛ_c = -226.1U Ikg , which corresponds to an ice fraction of 64.3%, temperature -8.7°C.

Comparison of these two cases shows that although the colder the water stream the better, i.e. the concentrate does not require as big an ice fraction, the difference is not significant over 2°C. Graph 2: Calculated ice fraction - temperature and enthalpy temperature relations at 13° and 17° brix.

-10 -9 -8 -7 -6 -5 -4 -3 2 -1 0 Temperature (°C) 17° enthalpy-temperature — — 13° enthalpy-temperature 17° ice fraction-temperature

Similar calculations may be carried out to determine the "ideal" conditions using different Concentrated Solutions to achieve particular concentrates and ice fractions in the final mixture using the data in Graph 3 below.

Calculated Enthalpy-Temperature & Ice fractions

-12 -11 -10 -7 -6 -S -4 -3 -1 1 Temperature (deg C) • 10° enthalpy - temperature - 12° enthalpy - temperature — — ^■ 13° enthalpy - temperature ^■ 17° enthalpy - temperature - 20° enthalpy-temperature — — 24° enthalpy - temperature - 28° enthalpy - temperature -10° ice fraction temperature ——— 12° ice fraction - temperature -13° ice fraction - temperature - 17° ice fraction - temperature 20° ice fraction - temperature -24° ice fraction - temperature -28° ice fraction - temperature The present invention is not limited to the specific embodiments described above. Alternative arrangements will be apparent to a reader skilled in the art.

Claims

CLAIMS:

1. A method of making a food or drink product, the method comprising the steps of: (i) producing an ice slurry by forming ice within a concentrated solution of the product without flavour or colouring; (ii) adding a desired flavour or colouring to the ice slurry; and (iii) diluting the ice slurry with chilled or supercooled solution to produce an iced product ofthe desired composition and ice fraction.

2. A method as claimed in claim 1, wherein the food product is an iced beverage or dessert.

3. A method as claimed in claim 1 or 2, wherein the ice slurry is dispensed into a mixing chamber.

4. A method as claimed in claim 3, wherein the desired flavour or colouring is added once the ice slurry has been dispensed into the mixing chamber.

5. A method as claimed in any of the preceding claims, wherein said chilled or supercooled solution is chilled or supercooled water.

6. A method as claimed in any of the preceding claims, wherein said chilled or supercooled solution is a dilute solution ofthe product without flavour or colouring.

7. A method as claimed in any of the preceding claims, wherein the ice slurry is diluted with said chilled or supercooled solution after the desired flavour or colouring has been added.

8. A method as claimed in any of the preceding claims, wherein the ice slurry is maintained under sufficient pressure, when the desired flavour or colour is added thereto, to substantially prevent gas dissolved in the ice slurry from expanding out of solution.

9. A method as claimed in any of the preceding claims, wherein the ice slurry is maintained under sufficient pressure when diluted with chilled or supercooled solution, to substantially prevent gas dissolved in the ice slurry from expanding out of solution.

10. A method as claimed in claim 8 or 9, wherein a piston, restriction or valve is used to maintain the ice sluny under said pressure.

11. A method as claimed in any ofthe preceding claims, further comprising the step of removing solute from the ice sluny.

12. A method as claimed in claim 11, wherein the solute is removed by filtering.

13. A method of providing a beverage with a low ice content, wherein a beverage is cooled or supercooled and a small volume of an ice sluny prepared in a concentrate of the beverage, or in a sugar solution, or an alcohol solution, is then added under pressure to the beverage.

14. A method of producing a frozen slush or dessert, the method comprising the steps of producing an ice sluny by fonning ice within a concentrated solution of the beverage or dessert; and then diluting this ice slurry before serving with chilled or supercooled water to produce an iced beverage ofthe desired composition and ice fraction.

15. A method as claimed in claim 14 wherein the ice slurry produced in the concentrated solution is diluted with an ice slurry of a dilute solution ofthe beverage.

16. A method as claimed in claim 14 or 15, wherein solute is removed from the ice sluny, and the remaining ice is added directly to a chilled or supercooled liquid.

17. A method as claimed in claim 16, wherein the solute is removed by filtering.

18. A method of manufacturing a conventional iced beverage as claimed in claim 1, wherein an ice fraction is induced in a concentrate of the beverage and, when required for use, is mixed under pressure with water.

19. Apparatus comprising means for freezing a liquid; a chamber for receiving an ice sluny produced by said freezing means; and means for mixing a flavoured or coloured liquid with said ice slurry.

20. Apparatus as claimed in claim 19, further comprising means for maintaining the ice slurry and flavoured or coloured liquid at a sufficient pressure during mixing to substantially prevent gas dissolved in the ice sluny from expanding out of solution.

21. Apparatus as claimed in claim 20, wherein said means for maintaining a said pressure comprises a piston, restriction or valve.