- 1 - Egg Substitutes

The present invention is concerned with egg sub¬ stitutes and, in particular, substitutes for egg yolk or whole egg.

Eggs and egg yolks are basic ingredients of many

5 cooked products, such as cakes, custards, pastry, sauces, quiches, biscuits, souffles and the like. Although there have been many attempts to provide substitutes for egg yolk or whole egg, these have not generally been very successful, largely because of difficulties in reproducing the whole

10 range of properties of natural egg and egg yolk. These prop¬ erties include emulsifying capacity, leavening action, protein- fat - and water - binding, the provision of nutritional value and organoleptic properties. Many proposed βgg olk and whole egg substituteswouldmore

^^> accurately be described as egg extenders, because they have little or no protein content and therefore little nutritional value. More recently, various high protein substitutes for egg yolk or whole egg have been proposed and in some cases, marketed. Examples of previously proposed substitutes for

20 egg yolk or whole egg are given in U-«IO. patent specificat¬ ions 1405078 and 1533084, and U.S. patents 3864500 and 4214010.

U.S. patent 4214010 discloses a whole egg replacement, comp¬ rising 40 to 60S. of whey solids (such as whey protein concen¬ trate), and 60 to 40J_ of lactylated shortening. The whey solids contain 0.5 to 5.055 of carboxymethyl cellulose, which is believed to function as a thickener and/or emulsifier.

The whey solids disclosed inevitably contain lactose, which would not be acceptable for persons suffering from diabetes : or lactose intolerance; furthermore, since lactose is sweet, it may impart an undesirable flavour to some savoury dishes. Carboxymethyl cellulose is not absorbed by the human body; it is not a naturally occurring material and is therefore a foreign substance as far as the human digestive system is concerned. With increasing awareness of natural products, many people avoid food products containing materials which are not naturally occurring.

A further egg yolk repla'cer" is disclosed in British specification 1533084. The egg yolk replacer is a lipoprotei emulsion comprising an edible protein (such as soy protein isolate) together with oil and lecithin. The soy protein isolates described would contain some soya oil, so it may be difficult to control the amount of oil in the final compo¬ sition. The specification described also discloses the use of whey protein concentrates instead of soy protein isolates; such concentrates inevitably contain lactose, which is undesi able n some circumstance-s, as described above with refer¬ ence to U.S. patent 4214010.

Known egg yolk replacers, when they are used to replace whole egg, are generally mixed with egg albumen; it would be desirable to have a versatile egg yolk replacer which could be used with ingredients not derived from egg to make a whole egg replacer.

We have now devised an egg yolk substitute which is based on substantially pure, naturally derived functional protein material, and which overcomes some of the problems of prior art egg yolk substitutes.

According to the invention, therefore, there is provided a cholesterol-free egg yolk substitute, which comprises :

(a) an aqueous solution of pH 7.0 to 9.5 consisting entirely of materials of known composition (rather than complex naturally-derived concentrates), which solution contains water-soluble substantially undenatured functional protein of purity at least 88% by weight (dry basis) obtained from a natural source said protein source containing not more than 10% lactose, and a dietetically acceptable emulsifier which is either a natural product or a synthetic equivalent thereof, the solution containing no more than 2.5% by weight of dietetically acceptable salt; and

(b) an edible fat or oil which is homogenised or emulsified with said aqueous solution.

The soluble functional protein material may be provided in the form of a salt (such as an alkali metal salt) thereof. The solids may be provided in powdered or other solid form for dissolution in water to produce the egg yolk substitute according to the invention.

Exemplary ranges of proportions of the various ingredients are

6 to 20% by weight of the water-soluble undenatured functional protein, 1% to 3% by weight of the dietetically acceptable emulsifier and 0.5 to

2.5% by weight of the dietetically acceptable salt, together with no more than 15% by weight of fat or oil.

The protein material may be isolated from the protein source by precipitation followed by redissolution thereof.

It is, however, preferred that the protein material be obtained from the protein source by complexing protein material present in the protein source with ion-exchange material, and recovering protein therefrom. Such an ion-exchange method is described in U.K. patent specifications 1227906 and 1436547-

Such an ion-exchange method can result in highly pure protein material from sources such as soya whey and dairy whey. Typical analyses of such protein ma erials for use in the ;qq yolk substitute accordinq to the Invention 5 are as follows:

Source .ό Protein ϊ of Ash % of Lactnse ?ό of Fa

Soya Whey 95.1 3.4 - ^' 1.5

Dairy Whey 96.8 3.1 <0.5 <0.5

Dairy Whey 93.6 4.2 1.5 0.5

10

Dairy Whey 90.0 5.4 3.5 0.5

The protein material preferably has a purit of at least 90% by weight (dry basis), more preferably at least 94?ό by weight, and is preferably substan ially fat-free. -

15 The protein material is most preferably a hi hly pure protein is lated from dπiry whey by ion-exrhnnqp extract¬ ion. Such a protein material is commercially available from Bio-Isolates Ltd under the trade mark BIPRO and typically has an analysis as follows:

20 Protein 95-97?ό; carbohydrates .less than Q. *.; fats less than 0.5?ό; and mineral salts approxima ely 3?i (all ^' percent ages bεinq on a dry weight basis). The protfiire in such a ^• protein material are basically lactoglobuIin, lactalbumen and serum albumen.

25 The dietetically acceptable emulsifier is na urally occurring (that is either the natural product itself or a synthetic equivalent thereo ), preferabl a material of vege¬ table origin, such as vegetable lecithin.

The dietetically acceptable salt may be a sodium

30 salt, such as sodium chloride; as an alterna ive., it may be a potassium salt, such as potassium chloride. In some cases, there may be a dietetically acceptable salt present in the protein material; the percentage of salt quoted in the total amount present (not just the amount of added salt).

35

e egg yo su s u e accor ng o e nven on may contain, as optional ingredients, tnickeners ; colouring agents (which should of course, be yellow/orange), preferabl of vegetable origin; vitamins; mineral supplements; preserv- n 5 atives; or flavouring agents. All such optional ingredients should, of-course, be dietetically acceptable and consist

^" ' entirely of materials of known composition.

The egg yolk substitute according to the invention may be dehydrated to produce a comestible concentrate which

10 can be dissolved in water prior to use (or used in dried for when the recipe is suitable for powdered dried egg yolk).

The egg yolk substitute according to the invention may be contained in conventional receptacles, such as bottle or sachets. It is, however, particularly preferred that the

15 substitute be free of preservatives and stored in an airtigh container, such as a sachet (typically of air-impermeable polymer film or sheet). According to a further aspect of th invention, therefore, there is provided an airtight containe containing an egg yolk substitute according to the invention

20 which is preferably preservati e-free .

The container is preferably a unit pack (that is a container which contains one egg yolk equivalent, or about 15 to 30 ml o the egg substitute according to the invention at a protein content of about 12?ό) . The provision of such a unit pack enables accurate direct

25 replacement of an egg yolk in an existing recipe; this is so thing which has not, so far as we are aware, been previously suggested for known egg yolk substitutes.

According to a further aspect of the invention, there is provided a receptacle containing a plurality of 30 separate containers, each containing one or more egg yolk equivalents as described.

The egg yolk substitute according to the invention may be provided together with natural egg-white or an egg- ^ white substitute; a suitable egg-white substitute comprises

35 an aqueous solution containing 7 to 1 ?ά by weight of water- soluble substan ially, undenatured functional protein (as

described above) and up to 4% by weight (preferably 3 to 4% by weight) of a dietetically acceptable salt (again as described above). The egg-white substitute should be substantially free of emulsifiers such as lecithin, and added fat or salt. The egg-white substitute may also be provided in dehydrated form, when the egg yolk substitute according to the invention is provided in dehydrated form.

The egg-white substitute may be provided in a container together with the egg yolk substitute; they may be either separate (which is preferred) or mixed together.

Such a container preferably contains at least the equivalent of the white of one egg; that is, about 20 to 40 ml at a protein content of about 12%. Such a container can be a unit pack (as described above with reference to one egg yolk equivalent), which again permits the use thereof as a direct replacement of an egg in a recipe.

When the egg-white substitute is mixed with the egg yolk substitute according to the invention, the mixing ratio is preferably 1:2 to 2:1. The total volume of a whole egg substitute is preferably 35 to 70 ml at a protein content of about 12%. The egg yolk substitute and the whole egg substitute according to the invention are useful in a whole range of food products in which egg yolk or whole egg is normally used. The present invention accordingly further comprises a prepared food product prepared using either egg yolk substitute or the whole egg substitute.

In order that the present invention may be more fully understood, the following Examples (in which all percentages are by weight) are given by way of illustration only. Example 1

3.2 grams of powdered dairy whey protein of 96% purity (dry basis), as commercially available from Bio-Isolates Ltd under the trade mark BIPRO, was added to 20 ml water with agitation. The volume of water was then made up to 40 mis, and 0.2 g of salt was added. Vegetable lecithin (0.6 grams) dissolved in 5 ml of water was then added and the mixture was

agitated for 30 seconds.

The resulting solution (Solution A) was thoroughly blended with

_*

^* one tablespoon of vinegar, a quarter teaspoon of sugar, 1 50 ml of sunflower oil and pinches of mustard, black pepper, and salt, to give an

5 acceptable egg-free mayonnaise.

Example 2

A further batch of Solution A was emulsified with 4 grams of sunflower oil, to produce Emulsion A. Emulsion A was mixed with an equal 10 volume of Emulsion A from which lecithin was omitted (as egg-white replacement), to produce a whole egg replacement.

The whole egg replacement was used as a replacement for 2 eggs in a standard quiche recipe (Good Housekeeping World Cookery, Ebury Press 15 1962, p 89). The resulting quiche browned well and had excellent organoleptic properties (in fact the taste was judged to be better than a parallel quiche made employing whole eggs).

Example 3 20 Example 2 was repeated, with 6.2 grams of sunflower oil ^" being added to Solution A. Excellent results were obtained once again.

Example 4

Soya protein containing 90.2% dry matter (85.08% protein, 3.05% 25 ash) was isolated from soya whey by ion-exchange interaction using a cellulosic ion-exchange medium.

18 grams of the soya isolate was added with 50 grams of water to

12 grams of lecithin and the mixture thoroughly homogenised. 20 grams sa flower oil were added dropwise with thorough mixing to form an emulsion, and 0.5 gram of salt was added to the emulsion.

Two-fifths of the resulting mixture was used as a replacement for i-

* two egg yolks in a cup custard recipe (Good Housekeeping Cookery Book,

35 National Magazine Company 1954, p 300). A thick, smooth and creamy custard with an acceptable flavour was produced. '

Examp le 5

Example 4 was repeated using the dairy whey protein as used in Example 1 instead of the soya protein isolate; similar results were obtained.

Emulsion A was further used as a replacement for 2 egg yolks in cream of cucumber soup, cold lemon souffle and Hollandaise sauce, with very acceptable results in terms of flavour. Tie whole egg replacement of Example 2 was used in sponge cakes and plain biscuits, again with acceptable results.