AU700297B3 - Ice confections - Google Patents

Description

f -2- ICE CONFECTIONS FIELD OF THE INVENTION This invention relates to ice confections which comprise a mass of a milk containing frozen confection, for example ice cream, with a surface covering of water ice.

Products of this form are usually referred to as "splits" and this term will be used. This product form provides two refreshing ice compositions within a single body.

BACKGROUND TO THE INVENTION Splits are usually sold with an ice cream core, as an example of a milk based frozen confection, with a stick for holding the product and an outer layer of water ice.

However, they are not limited to this geometry and may be in other shapes, eg spherical, and can be in a container for consumption. For example an ice cream could be produced in a standard tub with a layer of water ice on top. The term "split" is used herein to be a mass of ice confection having a layer of water ice in contact with it.

The milk containing frozen confection contains milk S 20 proteins and the class includes ice cream, frozen yoghurt, oooee sherbet, sorbet, ice milk and frozen custards. The usual **form of protein will be animal milk but vegetable sources, .eg soya milk, are also useable. There is no criticality in the source of the milk protein and it may be incorporated S 25 as liquid milk, cream, skimmed milk, milk powder and skimmed milk powder, as examples.

One known method of manufacturing split products is to partially freeze a water ice composition in the form of a cylinder closed at one end and then fill the centre core with liquid ice cream composition. Typically the water ice solution is placed in a cone in a freezing bath. The cone is inverted when the water ice contacting the cone wall is frozen and then an ice confection placed in the core. A stick for hand holding is placed in the core.

The manufacture of a two component ice confection by this route requires careful manipulation of the feedstocks 3 and the several stages of handling. There is usually a restriction in the product geometry which can be obtained.

The levels of overrun in the ice confection are limited because at higher levels the ice confection is more viscous.

GENERAL DESCRIPTION OF THE INVENTION In a first aspect of the present invention provides a method of preparing a two component ice confection including: taking a mass of milk-containing frozen confection and bringing at least a substantial portion of the surface thereof to a temperature of below -15 0

C,

contacting said substantial surface portion with a water ice solution for a time sufficient to allow a frozen layer of material from the water ice solution to form on and adhere to said surface portion, the water ice solution having a solids content in the range 15% to 50% by weight and the water ice solution being substantially of liquid phase material with any ice crystals present being 20 of such small size and constituting such a small proportion of the total water ice solution that the frozen layer is not significantly adversely affected in terms of overall crystal size and shape or adherence to the milk-containing frozen confection compared with a water ice solution which is entirely in liquid phase, and subjecting the frozen confection with the frozen layer thereon to hardening by exposure to a low temperature medium to a temperature of below -15 0

C.

In preferred embodiments the surface of the frozen confection is brought to below -40 0

C.

Preferably, steps and are conducted by immersion into a cryogenic liquid as a cooling agent to bring respectively the surface of the frozen confection and the whole two component ice confection to a temperature substantially less than -15 0

C.

A practical and advantageous method is one wherein 4 after step the two component ice confection is manipulated to allow excess material from the water ice solution to drip off and after step at least one further cycle of steps and is conducted to build up successive layers of frozen water ice.

In a second aspect, the present invention provides a two component ice confection comprising a mass of milkcontaining frozen confection having a frozen layer of material derived from a water ice solution adhered to a substantial surface portion of the ice confection, the frozen layer having an average ice crystal size (D( 3 of less than 100 microns, the ice crystal sizing and shape and the ice crystal adherence to the frozen confection having the characteristics of a two component ice confection made by a method comprising: taking a mass of milk-containing frozen confection and bringing at least a substantial portion of the surface thereof to a temperature of below -15 0

C,

contacting said substantial surface portion with 4* S20 a water ice solution for a time sufficient to allow a oo o frozen layer of material from the water ice solution to form on and adhere to said surface portion, the water ice solution having a solids content in the range 15% to 50% by weight and the water ice solution being substantially of 25 liquid phase material with any ice crystals present being of such small size and constituting such a small proportion of the total water ice solution that the frozen layer is not significantly adversely affected in terms of overall crystal size and shape or adherence to the milk-containing frozen confection compared with a water ice solution which is entirely in liquid phase, and subjecting the frozen confection with the frozen layer thereon to hardening by exposure to a low temperature medium to a temperature of below -150C.

Preferably the ice crystal size is below 80 microns immediately after manufacture.

The present invention can be embodied in products having a thickness from a substantial range, yet a water ice layer having a desirable and consistent texture can be provided.

The low temperature of the ice confection core can be obtained in a refrigerated volume, for example a blast cooler, or preferably by immersion in a cryogenic liquid, eg liquid nitrogen.

The product of this invention comprises two essential components, the ice confection mass and the water ice layer.

The amount of water ice solution picked after immersion is determined by the temperature of the ice confection core, while the ice crystal size is determined predominantly by the temperature of the hardening step.

Thus, if the core was at -15 0 C prior to immersion and the hardening step (iii) was obtained by immersion in liquid nitrogen then the water ice will have the desirable size of ice crystals but only a thin layer will be present.

S20 Hardening the product at -15 0 C provides a thin layer with o oo relatively large crystals. Similarly, a core cooled in liquid nitrogen but hardened at -15 0 C will give relatively large amount of pick-up but a water ice with relatively large crystals.

25 The preferred average ice crystal size D(3,0) of micron is generally obtained by using liquid nitrogen or other cryogenic liquid for both steps and (iii). Using temperatures of about -40 0 C provided for example by a blast *r freezer tunnel, in both steps and (iii) provides a water ice layer with ice crystals having a D(3,0) of below 100 microns.

Consumer tests have shown the presence of water ice crystals below about 80 microns provide a particularly soft texture.

The method of the invention uses process steps which are easy to operate sequentially and uses apparatus and 6 cooling materials which are either in wide use or are available commercially and are easily handled.

The surface of the milk containing ice confection is preferably brought to the desired low temperature by immersing it in liquid nitrogen or other liquified gas at low temperature, or contacting the desired surface with a heat exchanging surface cooled to an appropriate low temperature, for example with an innocuous liquid refrigerant such as liquid nitrogen or a solid refrigerant such as carbon dioxide.

In another method successive layers of water ice can be laid down on the surface of the mass of milk containing ice confection by immersing the mass in water ice solution and then in a suitable cryogenic liquid or in a refrigerated volume at low temperature to make another layer of water ice. These stages can then be repeated to build up a thicker layer of water ice.

The preferred viscosity of the water ice solution is up to poise to provide optimum generation of the water ice a.

20 layer. At 0.2% w/w aqueous solution of locust bean gum (LBG) has a viscosity of about 1 poise.

It is not necessary for the second cooling stage to be at the same temperature as the stage cooling the core.

Thus, dependent on the apparatus available and desired 25 product properties, it may be at a higher or lower temperature.

Usually the confection will include a stick penetrating the core to allow it to be held in the hand.

1* The relatively small ice crystal size and orientation 30 of the water ice and selection of the total solids provides a soft texture to the water ice when bitten. The texture of the milk protein containing ice confection is also very good because it is formed as the core by standard processing steps. There is no restriction or overrun which will usually be in the range from about 50% to about 150%.

Additionally, the use of standard processes allows the 7 usual components, eg fats to be present at the usual levels. Thus there is no restriction on the ice confection caused by viscosity requirements to allow feed into a quiescently formed water ice shell. A product formed by the quiescent process will have larger ice crystals, for example some in the order of millimetres. In general quiescently frozen products have dendritic ice crystals, while those produced according to the present invention have a more rounded shape comparable to those obtained in a freezer barrel. A complete quiescently formed split was found to be harder to bite, crunchier and less chewy. The water ice layer was less adhesive to the core.

A solids level of below about 15% in the water ice will give only a small amount of structuring and flavour while about 50% the solids content provide a very soft water ice layer.

The ice crystals formed by the process of the present invention provide a soft texture.

Test methods 20 Ice crystal size: a thin waiter ice sample was S"examined using a cold stage (-20 0 C) microscope in a white spirit matrix. Polarising filters were used at xl00 *900 magnification to obtain maximum contrast and a Zeiss particle size analyser used to obtain the average ice 25 crystal size as D( 3 ,0) SPECIFIC DESCRIPTION OF THE INVENTION Examples of the invention will now be given to :"illustrate but not limit the invention.

Example I An ice cream formulation with the following off composition was prepared using standard techniques.

Ingredient Weight skimmed milk powder 10.0 sugars 17.2 butter 10.5 8 flavour 0.1 water 61.5 emulsifier 0.4 stabiliser 0.25 The ice cream was prepared with an overrun of 100%, extruded through a shaped nozzle to give a cylinder of 56g and the stick inserted. It was then hardened in a freezing tunnel at -40 0 C. After leaving the tunnel the portions were dipped in liquid nitrogen for 8 seconds and then in a water ice solution at 5 0 C, which is the usual temperature of storage, for 15 seconds. This solution had a composition of: Ingredient Weight% sugars 21.5 stabiliser (LBG) 0.4 fruit solids 4.4 citric acid 0.2 colour 0.2 water remainder 20 The excess water ice solution was allowed to drip off and then the portions were immersed in liquid nitrogen to harden the external surface and complete the formation of the water ice layer. The product contained 25g water ice in the external layer.

25 The products were then stored at about -30 0 C in a cold store before distribution. The particle size distribution

(D(

3 in the water ice layer immediately after preparation was about 55 micron; this increased to about 75 microns on storage during distribution.

S.

*0 0. 30 Example II Samples of the ice cream core prepared as in Example I were cooled to temperatures of -15 0 C, -25 0 C, -30 0 C and 0 C in a refrigerated volume. They, were then immersed in the Example I water ice solution for 10 seconds and the products hardened at the above temperatures.

9 The results are shown in Table I with the Example I results included for comparison. It is seen the amount of water ice reduces as the core temperature rises. Increased amounts of water ice can be picked up by using more cycles of cooling/immersion.

Table I Temperature of Hardening Weight of core OC Temp OC water ice (g) Liq N2* Liq N2* -40 -40 18 (A) -30 14 -25 13 -15 8 (B) *8 seconds exposure The products using -40 0 C for the core temperature and hardening stage had a D( 3 of 85 microns, while the products using -15 0 C for the core temperature and hardening stage had a D( 3 ,0 of above 200 microns.

e *ooo o o oo• 10

i. A method of preparing a two component ice confection including: taking a mass of milk-containing frozen confection and bringing at least a substantial portion of the surface thereof to a temperature of below -15 0

C,

contacting said substantial surface portion with a water ice solution for a time sufficient to allow a frozen layer of material from the water ice solution to form on and adhere to said surface portion, the water ice solution having a solids content in the range 15% to 50% by weight and the water ice solution being substantially of liquid phase material with any ice crystals present being of such small size and constituting such a small proportion of the total water ice solution that the frozen layer is not significantly adversely affected in terms of overall crystal size and shape or adherence to the milk-containing frozen confection compared with a water ice solution which is entirely in liquid phase, and subjecting the frozen confection with the frozen layer thereon to hardening by exposure to a low temperature medium to a temperature of below -15 0

C.

2. A method as claimed in claim 1 and wherein steps and are conducted by immersion into a cryogenic 25 liquid as a cooling agent to bring respectively the surface of the frozen confection and the whole two component ice confection to a temperature substantially less than -15 0

C.

3. A method as claimed in claim 1 or claim 2 wherein Sr after step the two component ice confection is manipulated to allow excess material from the water ice solution to drip off and after step at least one further cycle of steps and is conducted to build up successive layers of frozen water ice.