Food or edible material: processes – compositions – and products – Products per se – or processes of preparing or treating... – Gels or gelable composition
Reexamination Certificate
2001-11-14
2003-08-26
Bhat, Nina (Department: 1761)
Food or edible material: processes, compositions, and products
Products per se, or processes of preparing or treating...
Gels or gelable composition
C426S034000, C424S499000, C424S403000
Reexamination Certificate
active
06610348
ABSTRACT:
This invention relates to gelling agents, gels and to processes for preparing them. It also relates to products comprising the gels, in particular matrices for delivering active agent and food products.
BACKGROUND
Gels are formed from macromolecular hydrocolloids and have the ability to form non-deformable structures with low impact resistance. The classical gelling agent, which has been most widely studied, is gelatine. This is also the only known food grade hydrocolloid which is a protein. Gelatine is, nutritionally, a low quality protein and gels incorporating it have the disadvantages that they tend to harden on storage and may develop undesirable textural properties. Gelatine may also have negative religious and/or health connotations for some consumers, as it is produced in a manner destructive of animals and there may also be concerns arising from a perceived link with Transmissible Spongiform Encephalopathies such as Bovine Spongiforms Encephalopathy or Creutzfeld-Jacob Disease
It is an object of the present invention to provide a gelling agent which will go some way towards overcoming the above disadvantages, or at least to provide the public with a useful choice.
SUMMARY OF THE INVENTION
In a first aspect the present invention may broadly be said to consist in a gelling agent which comprises modified casein, the native structure of the casein having been disrupted sufficiently to cause a composition to which the casein is added in use to gel.
Preferably, the gelling agent comprises a dispersion of modified casein in water and a suitable plasticiser, preferably glycerol.
In a further aspect the present invention provides a method of preparing a gelling agent which comprises the steps of:
(a) forming a dispersion comprising casein and water; and
(b) heating the dispersion for a sufficient time and to a sufficient temperature to disrupt the native structure of the casein.
In another aspect the present invention may broadly be said to consist in a process of preparing a gelled product which comprises adding a gelling agent as defined above to a gellable composition.
In yet a further aspect the invention may broadly be said to consist in a process of preparing a gelled product which involves the use of casein as a gelling agent.
In still a further aspect the present invention may broadly be said to consist in a gelled product which includes a gelling agent as defined above.
In preferred embodiments, the gelled product is a food product.
In other alternative preferred embodiments, the gelled product is a delivery matrix which comprises (a) a matrix which includes the modified casein; and (b) an active agent incorporated in the matrix.
In yet a further aspect the present invention may broadly be said to consist in a method of preparing a gelled product which comprises the following steps:
(a) forming a dispersion comprising casein and water;
(b) heating the dispersion for a sufficient time and to a sufficient temperature to disrupt the native structure of the casein; and
(c) removing the source of heat, adding other gellable components and allowing the resulting mixture to set into a gel.
Preferably, the dispersion also comprises a plasticiser (preferably glycerol) and a suitable buffer to maintain the pH in the range of about 6.1 to about 10.10.
DESCRIPTION OF THE INVENTION
As outlined above, the invention relates generally to gelled products and to macromolecular gelling agents used in their preparation.
The ability of a macromolecule to gel depends on interaction between molecules at restricted points along the macromolecule. Portions of the molecule that do not interact disperse in the continuous phase (usually water). Energy is usually required to disrupt the native structures of hydrocolloids. For instance, gelatine is manufactured by applying heat to collagen. The applicants have discovered that the native structure of casein can be disrupted sufficiently for gel formation. This can be achieved, for example, by heating, generally to a temperature of about 95-110° C. or above. It is this finding by the applicants which forms the basis for the present invention.
In a first aspect, the invention provides a gelling agent which comprises modified casein, in which the native structure of the casein has been disrupted sufficiently to cause a composition to which the casein is added to gel. The gelling agent preferably comprises a dispersion of the modified casein in a suitable plasticiser (preferably glycerol or glycerol combined with propylene glycol (1,2-propanediol) and water, although other forms of the modified casein are by no means excluded.
The gelling agents of the present invention have a number of potential applications. For example, in some embodiments of the invention, the gelling agents may be used in food products. In other embodiments the gelling agents may be used in preparing non-edible gels. For example, they may form part of a delivery matrix in which a matrix containing the modified casein encapsulates an active agent.
The preferred formulation of a particular gelling agent of the present invention will depend on the desired end use of the gel.
For example, alteration of the amount of plasticiser, if any present will change the characteristics of the resultant gel. Similar changes can be effected by changing the identity of the plasticiser. By way of illustration, using 1,2-propanediol as a plasticiser instead of, or partially instead of glycerol, results in a softer gel with a lower melting point. This may be desirable for some applications, for example where volatiles are to be entrapped or encapsulated by the gel matrix.
It is also possible to produce a lower melting point gel matrix through the addition of excess water during formation of the matrix. The excess water can then be removed again after the volatiles are encapsulated by gently drying over silica.
A still further approach to modifying the properties of the gel matrix is to replace a small amount of modified casein with gelatine (between 10% and 20%). This produces a lower melting point gel matrix which is softer than the equivalent matrix using casein alone.
Various embodiments of the invention are described in more detail below.
Food/Confectionery Applications
As noted above, in some preferred embodiments the gelling agents of the invention are used in preparing food products. In these embodiments, the gelling agents, and gelled products containing them, may be prepared by first forming a dispersion comprising water and preferably an edible plasticiser, most preferably glycerol, with the dispersion having a pH in the range of about 6.1 to about 8.0. It is preferred that the pH is about 7.5. It is generally desirable that the pH be within the above range when the gelling agent is to be incorporated into a food product, as the resulting gel may be waxy and brittle if the pH is lower than this, or may be unpalatable if the pH is above the upper limit of the range.
Suitable buffers to achieve this pH will be apparent to those skilled in the art. However, a preferred buffer is a combination of sodium citrate, calcium carbonate and sodium carbonate. It is preferred that the sodium citrate is present in an amount of about 1.0% to 2.0%, more preferably about 2.0%, by weight of the resulting gel, that the sodium carbonate is present in an amount of about 0.2% to 0.8%, more preferably about 0.4%, by weight of the gel, and that the calcium carbonate is present in an amount of about 0.4% to 1.0%, more preferably about 0.8% by weight of the gel.
It should also be noted that the calcium carbonate, as well as acting as a buffer, acts as a texture modifier, resulting in a gel with a firmer texture, which is desirable when the gel is to be used as a confectionery product such as a wine gum. The firmer texture is believed to result from interaction between the calcium ion and the casein.
In one preferred embodiment of the invention, glycerol is present in an amount of about 40% to about 55% by weight of the gelled product. Glycerol is a humectant and acts as a plasticiser in the gel. Thus, the more glyce
Beyer Richard
Silcock Patrick J.
Bhat Nina
Fonterra Tech Limited
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