PLASTIC CONSISTENCY

TECHNICAL FIELD OF THE INVENTION

The present invention relates to a method of embossing or shaping a water-in-oil emulsion of plastic consistency, said method comprising the step of contacting the outer surface of the emulsion with a cooled stamp having a contacting surface temperature below -50°C. Examples of water-in-oil emulsions that may suitably embossed or shaped by the present method include spreads, butter, kitchen margarines, bakery margarines and skin creams.

BACKGROUND OF THE INVENTION Water-in-oil emulsions such as butter, kitchen margarines and bakery margarines are typically produced in the form of rectangular blocks that are packaged in a wrapper. These rectangular blocks are produced by extrusion and have a rather unexciting appearance. It would be advantageous if the appearance of these emulsion blocks could be made more attractive by providing the product surface with an appealing design or pattern.

In principle, the surface of a plastic water-in-oil emulsion might be embellished with a design or a logo by stamping the surface with an embossing member. However, with conventional stamping techniques it is not possible to produce well-defined images or patterns. In addition, these conventional techniques suffer from the problem that the emulsion tends to adhere to stamp.

Spreads are another category of plastic water-in-oil emulsions and usually have a softer consistency than the aforementioned plastic emulsions. This softer consistency makes most spreads unsuitable for wrapper packaging. Instead, spreads are usually filled into tubs, following which the tub is provided with a lid, optionally after the tub has been hermetically closed with a seal. Often, the upper surface of the spread is irregular as the product tends to congeal very rapidly when it is filled into the tub. As a matter of fact it is not uncommon for protruding parts of the product surface to come into direct contact with the seal or lid when the seal or lid is placed onto the tub.

Hence, it would be beneficial if the upper surface of tub-filled spreads could be levelled before a seal or a lid is applied.

The upper surface of a tub spread might be levelled by stamping said surface with a stamp having a flat stamp surface. However, also here adhesion of the emulsion to the flat member poses a major problem. EP-A 0 023 746 describes a process for packaging margarine and similar products in containers which are closed by closure parts which are in contact with the product, wherein before the closure parts are placed on the surface of the portion inserted in the container, a pattern of small cavities is made in this surface and subsequently a closure part with a smooth inner side is pressed down against the edges of the surface surrounding the cavities. The aim of this process is to decrease adherence of the product to closure parts.

US 5,948,456 describes a method of moulding a food product, the method comprising the steps of:

lowering the temperature of a food product so that the food product is plastic and pressing a mould against the food product to cause at least a portion of the food product to take up the shape of the

mould, the mould being at a sufficiently low temperature of -80°C or less such that when the mould is

pressed against the food products, the food product retains its moulded shape and the food product is

readily releasable from the mould. The product is especially suitable for confectionary food products such as ice cream. EP 0 864 256 describes that the adhesion of ice cream to moulds can be reduced, when the moulds are cryogenically pre-cooled to -100 degrees Celsius. GB 2 463 495 relates to the use of a cooled stamp for imparting a controlled surface finish to food products, such as aerated butter cream, without any of the product sticking to the stamping device. GB 2 463 495 further teaches that the stainless steel stamp may be cooled using liquid nitrogen.

SUMMARY OF THE INVENTION

The inventors have developed a method that enables embossing or shaping of plastic water-in-oil emulsions and that does not suffer from the aforementioned drawbacks. More particularly, the inventors have found that the aforementioned adhesion problems can be overcome very effectively by employing a stamp that has been cooled to cryogenic temperatures.

Thus, the present invention provides a method of embossing or shaping a water-in-oil emulsion of plastic consistency, said method comprising the step of contacting the outer surface of the emulsion with a cooled stamp having a contacting surface temperature below -50°C.

The present method offers the important advantage that well-defined images and patterns can be produced without difficulty. Furthermore, the present method can be operated for a prolonged period of time without the need for repeated cleaning of the stamp surface.

Although the inventors do not wish to be bound by theory it is believed that by cooling to the stamp to a temperature below -50°C adhesion of the emulsion to the stamp can be minimized effectively.

DRAWINGS Figure 1 a depicts a tub holding a spread shortly after filling of the tub, the top

surface of the spread showing clear traces of the filling operation Figure 1 b depicts the contacting of the top surface of the spread with a cooled stamp with a flat stamp surface Figure 1 c depicts the tub holding the spread after the contacting with the cooled stamp, showing that the traces of the filling operation have been erased.

Figure 2a depicts a wrapper margarine that is not yet packaged in a wrapper Figure 2b depicts the contacting of the surface of the margarine with a cooled

stamp carrying a design

Figure 2c depicts the margarine after the contacting with the cooled stamp,

showing that that an image has been embossed into the surface DETAILED DESCRIPTION OF THE INVENTION

Accordingly, the present invention relates to a method of embossing or shaping a water-in-oil emulsion of plastic consistency, said method comprising the step of contacting the outer surface of the emulsion with a cooled stamp having a contacting surface temperature below -50°C.

In the present method the emulsion has a plastic, i.e. non-liquid, consistency when the outer surface is contacted with the cooled stamp. In other words the present method does not emboss or shape the emulsion by congealing a liquefied emulsion against the cooled stamp surface.

The term "shaping" as used herein refers to any physical operation that changes the shape of the emulsion, e.g. by moulding or pressing. Preferably, the shaping of the emulsion in the present method involves pressing.

The term "embossing" as used herein, refers to the act of impressing a relief or a design onto the surface of the emulsion.

The terminology "plastic consistency" refers to a state in which the emulsion is non- liquid, is shape-retaining and at the same time deformable. The term "stamp" as used herein refers to a solid device having a flat, textured or image-carrying surface that is designed to engage with a plastic product to impress the surface characteristics of the stamp onto the surface of the plastic product. The term "stamp surface" refers to the part of the stamp that comes into direct contact with the outer surface of the emulsion during the contacting of said outer surface with the stamp.

The terms "oil" and "fat" as used herein, unless indicated otherwise, refer to a lipid material that contains at least 90 wt.% of a fatty acid esters. Examples of such fatty acid esters include triglycerides, diglycerides, monoglycerides, phospholipids and sucrose polyesters.

In the present process the emulsion has a substantially higher temperature than the stamp surface when the outer surface of the emulsion is contacted with said stamp. Typically, the surface area of the emulsion that it is contacted with the stamp has a surface temperature of at least -10°C, preferably of 0-40°C, when it is contacted with the cooled stamp. The stamp surface preferably has a contacting surface temperature of less than - 60°C, more preferably less than -80°C and most preferably of less than -100°C when it is contacted with the outer surface of the emulsion. Typically, the contacting surface temperature of the stamp surface exceeds -270°C when it is contacted with the emulsion.

The temperature of the stamp surface may increase during the contacting with the emulsion. Typically, however, the temperature of the stamp surface remains below - 50°C during the contacting with the emulsion surface. Even more preferably said surface temperature remains below -60°C, most preferably below -70°C during the contacting with the emulsion. The contact time between the surface of the emulsion and the cooled stamp preferably is less than 3 seconds. More preferably, said contact time is less than 1 second, most preferably, less than 0.5 second. According to a particularly preferred embodiment of the present method, the stamp surface is cryogenically cooled. Cryogenic cooling may suitably be achieved by contacting the stamp with, for instance, liquid nitrogen, liquid helium, liquid neon or solid carbon dioxide. Preferably, the cryogenic cooling is achieved by contacting the stamp with a liquid gas, most preferably liquid nitrogen.

Preferably, the stamp surface is cooled continuously whilst it is operated to shape or emboss an emulsion. Thus, it can be ensured that the surface temperature of the stamp surface remains sufficiently low to minimize product adhesion. The stamp surface is advantageously cooled by passing a cooling liquid, e.g. liquid nitrogen, through the stamp. In order to ensure that the surface of the stamp is cooled effectively it is preferred to employ a stamp that comprises a heat conducting material and that comprises a stamp surface that preferably is not covered by a coating such as paint. Even more preferably the stamp surface is made of a heat conducting material. Examples of suitable heat conducting materials include metals, such as aluminium, silver, copper, iron, steel and alloys of these metals, aluminium being most preferred.

It is preferred that the cooled stamp does not penetrate the outer surface of the emulsion by more than 10 mm. Even more preferably during the contacting of the outer surface of the emulsion and the cooled stamp, the cooled stamp does not penetrate said outer surface by more than 5 mm, most preferably by not more than 2 mm. The present method may suitably be employed to level off (flatten, egalise) the surface of the emulsion or to form an embossed image or design on the surface of the emulsion. In order to form an embossed image or design a cooled stamp carrying a relief or a design may suitably be employed. The present method may also suitably employ a cooled stamp having a largely flat stamp surface to level off the surface of the emulsion. As explained herein before, this embodiment of the invention is advantageously applied to level off the surface of an emulsion after it has been filled into a container and after it has congealed to a plastic consistency.

In accordance with this advantageous embodiment, the emulsion that is to be shaped or embossed is contained in a container and at least a part of the top surface of the emulsion is contacted with the cooled stamp. The stamp surface of the cooled stamp may be substantially flat so as to impress an essentially level surface. It is also feasible to level off the surface of the emulsion whilst at the same time embossing the emulsion with an image or a design. Advantageously, in the aforementioned embodiment at least 60%, more preferably at least 80% and most preferably at least 90% of the top surface of the emulsion in the container is contacted with the cooled stamp.

The levelling of the top surface of the emulsion in a container is particularly

advantageous if the top of the container is subsequently sealed off with a thin sheet of material as it ensures that the sheet does not come into contact with the emulsion. The levelling of the emulsion is also beneficial if the container comprises a tub and a lid (that can be used to close the tub) and if the tub and/or lid are transparent so that the emulsion can be viewed through the tub and/or the lid.

The water-in-oil emulsion of the present method typically contains at least 15 wt.% fat, said fat having a solid fat content at 20°C (N ₂ o) of at least 20%. More preferably, the emulsion contains 20-90 wt.% of fat. Most preferably, the emulsion contains 35-85 wt.% of fat.

Examples of water-in-oil emulsion that may suitably be embossed or shaped by means of the present method include spreads, butter, bakery margarines and kitchen margarines. The present invention also relates to a shaped or embossed emulsion obtained by a method as described herein before. There is a need to provide products which provide added consumer benefit, such as having a particular visual appearance such as for appeal and/or providing information. It was observed that by using the method according to the invention even intricate reliefs on the stamp surface could be embossed onto the surface of a water-in-oil emulsion, and be well-defined. For example, letters and/or numbers when embossed can be clearly read and symbols and/or depictions easily recognized. In contrast, when such intricate reliefs on the stamp surface are embossed onto the surface of an oil-in-water emulsion, such as an ice cream, they were less clear (i.e. did not lead images/designs on the surface, which were well defined). For example, in case of embossed letters and numbers these were poorly readable. It will be appreciated that the degree of how well an image is defined can be easily ascertained by visual inspection.

Preferably the surface of a water-in-oil emulsion obtained according to the method of the invention comprises one or more designs selected from the list consisting of symbols, letters, numbers and depictions; and more preferably one or more readable letters and/or numbers. Depictions are realistic or abstract representations leading to the recognition of one or more objects, such as plants, animals, vehicles. Symbols are defined as forms which do not correspond to specific letters, numbers, or depictions as defined, such as a musical notation, triangle and/or a decorative design.

Furthermore, it was observed that a flat patch of the stamp surface (e.g. flat area of the stamp surface in between symbols), after embossing, left a corresponding flat patch on the surface of a water-in-oil emulsion, which appeared smooth. Smooth indicates that the specific area appeared very flat with little or no observable coarseness, particles and/or surface cracks). A (partially) smooth surface of the product, such as a spread, can be preferred by some consumers to communicate the product was stored under stable (e.g. secure) conditions (e.g. not tampered with during storage). In contrast, after embossing, flat patches of the stamp the surface did not lead to corresponding smooth areas on the surface of an oil-in-water emulsion, such as ice cream.

Embodiments of the invention will now be described with reference to the

accompanying drawings.

Figures 1 a to 1 c describe an embodiment of the present method in which the top surface of a spread is egalised by contacting it with a cooled stamp. Figure 1 a shows the top surface 1 of a plastic spread that has been filled into a tub 2. The top surface 1 of the spread is irregular as a result of the filling of the product. Also shown in Figure 1 a is a cooled stamp 3 with a stamp surface 4 that is totally flat. Figure 1 b shows that the flat stamp surface 4 of the cooled stamp 3 is contacted with the irregular surface 1 of the plastic spread. Figure 1 c shows the flat surface 5 of the spread that results from the contacting of the cooled stamp 3 with the surface 1 of the plastic spread.

Figures 2a to 2c describe an embodiment of the present method in which an image is impressed in the surface of a wrapper margarine. Figure 2a shows a block of margarine 10 that is sitting on top of a sheet of wrapper paper 20. Also shown in Figure 2a is a cooled stamp 30 with a stamp surface 40 that carries a design. Figure 2b shows that the stamp surface 40 of the cooled stamp 30 is contacted with the top surface of the margarine block 10. Figure 1 c shows the image 50 that has been impressed in the margarine block 10 by the contacting with the cooled stamp 30. The invention is further illustrated by the following non-limiting examples. EXAMPLES

Example 1

A tub spread (Blue Band Goed Start®, Unilever, Netherlands) having a fat content of 38 wt.% was taken from the fridge and placed on a table. The surface of the spread showed the typical irregularities that result from the filling of the emulsion into the tub.

An aluminium stamp with a flat surface was immersed in liquid nitrogen for at least 5 minutes. Next, the stamp was taken out of the liquid nitrogen and softly pressed onto the top surface of the spread for 0.5 second before being removed. The surface irregularities were removed by the contacting with the cooled stamp leaving a smooth surface.

The operation described herein before was repeated several times, using contact times of 0.5-3 seconds. The results obtained were very similar.

Example 2

Example 1 was repeated, except that this time the stamp was cooled by placing it in a thermally insulated container with solid carbon dioxide. The results obtained were comparable to those described in Example 1 .

Example 3

A wrapper kitchen margarine (Blue Band®, Unilever, Netherlands) having a fat content of 79 wt.% was taken from the fridge and placed on a table. An aluminium stamp carrying a intricate image was immersed in liquid nitrogen for at least 5 minutes. Next, the stamp was taken out of the liquid nitrogen and softly pressed onto the top surface of the margarine for 0.5 second before being removed. The cooled stamp left a well-defined image on the margarine surface. Example 4

Example 3 was repeated except that this time the stamping operation was repeated 10 times within 20 seconds using the same stamp. In all cases a well-defined image was produced. The stamp was found to be absolutely clean after it had been used to emboss these products.

Comparative Example A

Example 3 was repeated, except that this time the stamp had been cooled to -18°C in a freezer. Irrespective of the contact time, the cooled stamp left a poorly defined image on the margarine surface. Furthermore, it was found that upon removal of the stamp pieces of margarine still clung to the stamp. Example 5

The following water-in-oil emulsions were taken from the fridge and placed on a table: a) wrapper kitchen margarine (Blue Band voor koken bakken en braden ®, Unilever, Netherlands) having a fat content of 79 wt.%;

b) spread (Bona voor op brood®, Unilever, Netherlands) having a fat content of 59 wt.

%

c) spread (Blue Band Idee®, Unilever, Netherlands) having a fat content of 39 wt. % d) spread (Blue Band Goede Start®, Unilever, Netherlands) having a fat content of 38 wt. %

e) spread (Becel light®, Unilever, Netherlands) having a fat content of 38 wt. % f) spread (Flora®, Unilever, Netherlands) having a fat content of 38 wt. %

g) spread (Latta extra fit®, Unilever, Netherlands) having a fat content of 30 wt. %

Emulsion a) was embossed with a stamp carrying an intricate relief in the form of the words 'Latta Frische', the number '100' and the '%' symbol on the stamp surface. Besides these markings the overall circular area of the stamp surface was flat.

Emulsions b) to e) were embossed with a stamp carrying an intricate relief in the form of the word 'FLORA' surrounded by decorative lines on the stamp surface. Besides these markings the overall circular area of the stamp surface was flat.

Emulsion f) was embossed with a stamp carrying an intricate relief in the form of a depiction of a flower with detailed petals on the stamp surface. Besides these markings the overall rectangular area of the stamp surface was flat. Emulsion g) was embossed with a stamp carrying an intricate relief in the form of the words 'Latta... und go!' on the stamp surface. Besides these markings the overall rectangular area of the stamp surface was flat. Said stamps were made of aluminium.

For each of said combinations of emulsions and stamps the embossing comprised the following method: the respective stamps were first immersed in liquid nitrogen for at least 5 minutes. Next, the stamp was taken out of the liquid nitrogen and softly pressed onto the top surface of the emulsion for approx 1 second before being removed.

In each case the relief of the stamp surface left a well-defined image (a.k.a. design) on the surface of the water-in-oil emulsion. Any letters and numbers, depictions and symbols engraved on the stamp surface were clearly visible, readable and/or recognizable on the surface of the water-in-oil emulsions. In addition, flat areas on the stamp surface resulted in corresponding smooth areas on the surface of the water-in- oil emulsions. Comparative Example B

The method of Example 5 was repeated, except that this time a tub of ice cream (Kwini, "Us met vanillesmaak") having a fat content of approx 6 wt. % was taken from the refrigerator, placed on a table and stamped. Said ice cream was embossed with a stamp carrying an intricate relief in the form of the words 'Latta Frische', the number '100' and the '%' symbol on the stamp surface. Besides these markings the overall circular area of the stamp surface was flat.

It was observed that the relief of the stamp surface did not lead to a well defined corresponding design on the surface of the oil-in-water emulsion. In particular, letters and numbers engraved on the stamp surface were poorly readable on the surface of the ice cream. In addition, flat areas on the stamp surface resulted in corresponding areas on the surface of the ice cream, which remained coarse in structure.