Chemistry: natural resins or derivatives; peptides or proteins; – Proteins – i.e. – more than 100 amino acid residues – Blood proteins or globulins – e.g. – proteoglycans – platelet...
Patent
1993-10-21
1996-01-02
Russel, Jeffrey E.
Chemistry: natural resins or derivatives; peptides or proteins;
Proteins, i.e., more than 100 amino acid residues
Blood proteins or globulins, e.g., proteoglycans, platelet...
426305, 426573, 426657, 427414, 530365, 530367, 530411, 530829, 530833, A23J 300, A23L 10562, A23P 108, C07K 1113
Patent
active
054809738
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to novel protein gels and related products and to a process for making them.
It is known that aqueous solutions or dispersions of so-called functional proteins or proteinaceous materials, such as blood plasma, egg albumin or whey protein, can be coagulated by heat to form opaque solid gels which are thermally irreversible. It is also known that other proteins, for example gelatine, can form clear but thermally reversible gels.
The present invention in one aspect now provides a stable, substantially clear, thermally irreversible gel formed by the reaction product of protein and reducing sugar. Furthermore, it is possible to dry a sheet of the solid gel to form a clear film, which may have a variety of applications in place of existing film materials.
Surprisingly, gels formed by this invention retain their clarity, even after substantial further best processing or other treatment to render them commercially sterile, and for this reason may be described as `stable`.
By a "substantially clear" gel is here meant a gel which, but for the possible inclusion of extraneous heterogeneous components, is essentially transparent in that light can pass therethrough without substantial scattering or dispersion by the gel-forming protein content. The gels may be substantially colourless or coloured, depending upon the starting materials and the reaction conditions, if only by reason of a Maillard type reaction between the protein or associated aminoacids and the sugar.
It will be appreciated that, if the gel has a deep colour, it may not give the appearance of transparency to a casual observer owing to absorption of light, but yet, by the low level of scattering, be substantially clear within the meaning of this term intended here. By way of example, transmission of light at appropriate wavelengths can be used to estimate the degree of clarity or transparency of gels. This is illustrated in Example 9 below.
In accordance with another aspect of this invention, a process for producing a galled aqueous phase comprises reacting an aqueous solution or dispersion (hereinafter referred to as a `dispersion`) of a protein or proteinaceous material with a reducing sugar or source thereof in the presence of a denaturing agent and/or denaturing conditions and forming therefrom a substantially clear, thermally irreversible gel structure.
It is contemplated that any protein may be employed that is capable of solubilisation in aqueous dispersion and can be formed by heat or the lapse of time into a gel structure under the conditions of the present invention. The preferred proteins, especially where a solid gel is required, are globular proteins such as blood plasma, whey protein or egg albumin but it may be acceptable to use other proteins such as plant storage proteins (e.g. soya), casein, mycoprotein or muscle proteins. For commercial applications it is desirable to use cruder forms of protein, for example crude blood plasma, fish offal or yeast, rather than expensive purified proteins such as bovine serum albumin or lactoglobulin.
The concentration of the functional protein in the aqueous dispersion may vary with the type of product required and the purity or functionality of the protein, but is preferably in the range of 2-25% by weight of the dispersion. Most commonly, the protein concentration will be in the range of 4-15% but for gels produced from purified proteins may be as low as 2%, while for crude, less active protein materials may be as high as 25%.
The reducing sugar may be any sugar capable of entering into a Maillard reaction. Examples include lactose, xylose and glucose. For commercial applications it may be desirable to use crude source of reducing sugar such as whey powder rather than expensive purified sugars such as lactose. Nevertheless, certain purified sugars such as xylose are effective at such low concentrations that they may be economically competitive in commercial applications.
The reducing sugar concentration is preferably in the range of 1-6% by weight of the aqueous dispersi
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Cant Jonathan R.
Goodlad John S.
Harford Stephen
Nadreph Limited
Russel Jeffrey E.
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