It is known to aerate a mix for the preparation of an ice cream through the use of an aerating means comprising a rotating element that fits into the barrel of a continuous ice cream freezer. This aerating means is commonly referred to as a dasher. On rotation the dasher transfers mechanical energy into the mix in order to achieve aeration and generate a fat network by aggregating some of the fat droplets. This aggregation is necessary for product stability.
For many industrial continuous freezers there are a variety of dasher types available. These can be differentiated from each other by the volume displaced within the freezer barrel which can be assessed by simply filling the freezer barrel with a liquid, such as water, and measuring the volume of liquid displaced when the dasher is fitted therein. A dasher described as a series 80 indicates that this rotating element occupies 80% of the available internal volume of the freezer barrel so that only 20% of the space is available to be occupied by the mix to be aerated. By contrast a series 15 dasher, also known in the art, demonstrates a displacement volume of only 15% of the internal barrel volume, the remaining 85% being available to be occupied by a mix to be aerated.
In conventional ice cream processing it is generally accepted that higher displacement dashers such as the series 80 give rise to high quality ice cream being highly churned (Ice Cream 5th Edition, W. S. Arbuckle et al., page 183) thus showing optimal levels of fat de-stabilisation, while at the same time product dryness, good meltdown resistance and product hardness. These displacement dashers are therefore the standard form of aerating means used in ice cream manufacture.
The ice cream formulations prepared by conventional aeration comprise a fat phase with a relatively high melting point. This means that little if any liquid fat is present at the processing temperature.
The applicants have identified a need to extend the range of fats that can be applied to ice cream manufacture. In particular there is a need for the development of novel ice cream compositions having formulations that can comprise a fat component with a low melting point, thus imparting a higher level of liquid fat in the fat phase, at the processing temperature. At the same time formulations must maintain the high degree of stable aeration and low levels of destabilised fat and overrun loss, characteristic of conventional ice creams. The ability to use increasingly varied fats would also allow the manufacture of ice cream at reduced cost.
Unexpectedly it has been found that the full range of conventional techniques described above for processing ice cream are not suitable for this group of novel ice cream formulations. The use of high displacement aerating means has been found by the applicants to lead to the development of a product exhibiting over destabilisation of fat and overrun loss, phase separation, leading to a clearly unsatisfactory product.
The technical problem to be solved by the present invention is therefore derived from the finding that novel ice cream formulations comprising a fat phase with relatively high levels of liquid fat at the processing temperature cannot be processed to a high quality ice cream by conventional routes.
It has been surprisingly been found that a solution to this problem resides in the use of equipment which had never been used for this type of formulation before. There is no suggestion in the prior art that this type of equipment has any positive influence on the destabilisation of fat, phase separation or overrun loss during the processing of a composition. The present invention therefore seeks to provide a stable composition with at least 90% overrun, wherein said composition comprises a fat phase which has a high ratio of liquid fat to solid fat.