METHOD FOR PREPARING GLUTEN-FREE DOUGH AND BATTER

The invention relates to a method for preparing gluten-free dough and batter used for example to produce gluten-free pasta, bread or gnocchi, to dough and batter produced by such a method and to products prepared therewith.

Traditionally, flour used in the preparation of dough and batter (hereafter referred to as "dough") for pasta, gnocchi, bread and other food, contains gluten, which plays a major role in the texture of the dough. Indeed, gluten transforms the final dough into a nice workable paste.

However, there is a strong demand for gluten-free products for people suffering from gluten intolerance and allergy. Where gluten- free flour is used, the texture of the final dough is detrimentally affected and is usually solid, crumbly and difficult to work, for example, into a desired shape and consistency. Thus, texture and, ultimately, taste is affected.

It is therefore an object of this invention to mitigate problems such as those described above.

According to a first aspect of the invention, there is provided a method for preparing gluten-free dough comprising the step of foaming egg white wherein the foaming is carried out in absence of egg yolk, oil, fat and detergent in a receptacle comprising a material capable of forming a complex with egg protein.

According to preferred embodiments, the receptacle is made of silver or copper. Alternatively, the inner surface of the receptacle is silver-plated or copper-plated.

According to one embodiment, the egg white is foamed with at least one foaming ingredient. The foaming ingredient may be selected from the group consisting of milk, preferably with a high protein content, potatoes, water, or mixtures thereof. Preferably, the temperature of the foaming ingredient ranges between 0 to 25°C, more preferably from 4 to 10 ⁰ C.

The foaming step may be carried out using a mixer, which may be a hand held electric mixer.

The method may further comprise the steps of processing egg yolk in a second receptacle; and/or processing gluten-free flour in a third receptacle; and mixing the content of the first, second and third receptacle, in a fourth receptacle.

The egg yolk processing step preferably comprises mixing the egg yolk with at least one other ingredient, which may be oil, other saturated ingredients or mixtures thereof.

The gluten-free flour processing step preferably comprises mixing said gluten-free flour with at least one other ingredient, which may be water or salt or mixtures thereof.

Thus, the invention seeks to provide a method comprising an egg white foaming step to obtain a workable, non-crumbly dough devoid, or at least substantially devoid, of gluten. The method is based on the separation and

pre-processing of certain ingredients before being mixed together.

Indeed, it has been discovered that when egg white, egg yolk and oil are mixed in the receptacle, the presence of the yolk and the oil prevents the foam from being light and stable. It is thought that these ingredients compete with the egg white proteins for a place at the gas-water interface, thereby preventing the formation of any structural reinforcement. The exclusion of these ingredients from the egg white foaming process leads to a thick body foam, with a homogeneous dispersion of gas bubbles throughout the foam. Traditional gluten-containing dough does not require such a separate egg white bubble foaming step to assist the final outcome of the dough texture.

In addition, an important feature of the method is the use of a silver or copper receptacle or a receptacle with a silver-plated or copper-plated inner surface. Indeed, it has been observed that when egg whites are whipped in a glass ^' receptacle, the resulting foam was grainy and dry. However, when egg whites are whisked in a copper or silver bowl, some copper or silver ions migrate from the bowl into the egg whites. The copper or silver ions form a complex with one of the proteins in eggs, conalbumin. The conalbumin-ion complex is more stable than the conalbumin alone, so egg whites whipped in a copper or silver bowl are less likely to denature or unfold.

When air is whisked into egg whites, the mechanical action denatures the egg white proteins, which will then coagulate, thereby stiffening the foam and stabilising the gas bubbles. If the foam is over-beaten in a non-copper or non- silver bowl, the proteins become completely denatured and coagulate into clumps. Where a copper or silver bowl is used, fewer protein molecules are free to denature and coagulate, because some have tied up in conalbumin-ion complexes.

In addition to forming complexes with conalbumin, the copper or silver may

also react with sulphur-containing groups on other proteins, further stabilising the egg proteins.

The use of an alternative material will influence the foaming process and the final consistency of the foam. The present invention is not limited to the use of silver and copper. Other materials having similar properties may also be used.

Furthermore, the choice of said at least one foaming ingredient is not restricted and may be chosen from any foaming ingredients commonly used in food preparation, such as milk, water, or potatoes. Where milk is the foaming ingredient, those with added protein content, reduced-fat and skimmed milks are preferred. Indeed because the whey proteins are stabilisers, milks, which are fortified with added protein, are most easily foamed.

The foaming ingredient is preferably cold when added to the egg white. Indeed, the temperature will affect the foaming process. Thus, the foaming ingredient is preferably at a temperature ranging from 0 to 25 ⁰ C, more preferably from 4 to 1O ⁰ C.

The preparation of the egg white foam is essential for obtaining a workable dough in the absence of gluten. Gluten-free dough prepared using the method of the invention will hold on its own when mixed (raw) and cooked. The greater the number of bubbles produced throughout the foam, the more fine and tender the resulting dough and food.

The mixture of egg white and at least one foaming ingredient may be foamed by any known manner known in the art by using, for example, a hand-held mixer, an electric mixer, an industrial mixer, or any other foaming or mixing device. Preferably, the foaming is carried out using a hand held electric mixer. The foaming should not be carried out roughly as this may break the structure

of the foamed mixture. Thus, preferably, the mixing is carried out at low speed, as a faster movement will damage the foam structure. Furthermore, where an electric mixer is used, the foaming is preferably carried out for no more than 4 minutes, as longer beating time will change the texture and volume of the foam. However, the time and speed of beating may be varied in order to obtain the desired foam structure and consistency.

In another embodiment, egg yolk is processed in a second receptacle, preferably by mixing with one or more ingredients. The further ingredients in this second receptacle may be any ingredients known in the art, but preferably comprise oil or saturated ingredients or mixtures thereof. Where oil is used, it is preferably olive oil, for the taste, and unfϊltered oil, which contains 30% more antioxidants compared with filtered oil. Preferably, salt is not introduced in the second receptacle, as, when mixed with egg yolk, the latter has a tendency to burn or overcook when being cooked or baked.

In another embodiment, gluten-free flour is processed in a third receptacle, preferably by mixing with one or more ingredients. The further ingredients in the third receptacle may be any ingredients known in the art, but preferably ^■ comprise water or salt. The gluten-free flour is preferably sieved for a better texture.

Once the ingredients have been processed in the first, second and third receptacle, the contents of the receptacles may be mixed together for further processing. Thus, using the method according to the invention, based on the use of separate receptacle and pre-processing steps, a nice workable dough may be prepared, which is not solid or crumbly.

There now follows a number of examples illustrating the results of performing methods for preparing gluten-free dough, both in accordance with, and with deviations from, the preferred embodiments.

Example 1

The Example is illustrated in Figure 1.

1) The silver plated bowl contains non GM large fresh egg whites and fresh skimmed milk at approximately 4 to 1O ⁰ C. The contents of the silver- plated bowl is foamed using an electric mixer, for 4 minutes at low speed.

2) The second bowl comprises non GM large fresh egg yolks, processed by being mixed with unfiltered olive oil.

3) The third bowl comprises gluten-free flour, which is sieved then mixed with mineral water and salt.

4) The contents of the second and third bowls are mixed together in a fourth bowl. 5) The foamed mixture of the silver-plated bowl is added to the fourth and mixed with the contents from the second and third bowls, with care being taken not to break the foam structure. It is very important to carefully fold the foam into the main mixture of ingredients in order to maintain the bubble structure of the egg white foam. 6) The mixture is kneaded until a dough with a smooth texture is obtained. 7) The dough is allowed to stand for 45 minutes, then passed, for example, through a pasta machine for cutting.

The invention may also be used to prepare other food products such as gnocchi, where the foaming ingredient is steamed potatoes is added to egg whites in a silver-plated bowl to prepare a foam as described above.

It has also been shown that the dough or batter obtained according to the method of the invention could sustain freezing, that is, the defrosted dough still has a smooth texture and is easily workable. This unique foaming process may be used in a wide variety of recipes from bread to dolce, where egg

whites can be foamed following the specific method as claimed to alter the texture and taste of gluten-free food products.

Comparative Example 1

The same ingredients as in Example 1 were mixed together in a silver or copper bowl. The resulting foam is unstable, loses its gas content and its general structure would collapse. The resulting mixture was a solid, unworkable dough, which is hard to knead.

Comparative Example 2

Step (1) of Example 1 was repeated, but using a high speed electric mixer instead of a low speed mixer. The resulting foam was unstable and lost volume and structure, as the increased speed led to the disintegration of the foam bubbles.

Comparative Example 3

Step (1) of Example 1 was repeated, but using a bowl made of plastic instead of a bowl or receptacle as defined in claim 1. The resulting foam was unstable and lost its bubble capacity, volume and structure. In addition, it should be noted that plastic retains traces of fat and washing detergent to a certain extent and is thus more toxic and will lead to the disintegration of the foam bubbles.

Comparative Example 4

The method of example 1 was repeated using warm milk 30 ⁰ C instead of cold milk at 4 to 1O ⁰ C. The resulting foam was unstable and lost its bubble capacity, volume and structure because of the heat of the milk. In addition, the cooked dough obtained using the foam prepared with warm milk tasted sour.

It can be seen from the above-description that embodiments of the present invention allow for the preparation of a limitless variety food products devoid of gluten, for gluten-intolerant people, while maintaining a good texture and taste.