GB2111367A - Production of a stable protein- sugar foam with a high gas content - Google Patents

Abstract

In the production of stable protein-sugar foam with a high gas content, the prepared or boiled components, such as protein solution, sugar and optionally further components, are mixed and foamed in the presence of air at a pressure of 0.3 to 0.8 N/mm<2> in a dispersion tube fitted with a macrofibril system of unbranched, intertwining, strong threads of circular cross-section having a diameter of 0.4 to 2.0 mm. <IMAGE>

Description

SPECIFICATION Process for the production of a stable proteinsugar foam with high gas content The present invention is concerned with a process for the continuous production of proteinsugar foam, which may be employed in the baking industry, biscuit and cracker industry and in the confectionary industry for filling various products (such as so-called "negro kisses", i.e. proteinsugar masses on a wafer base, covered with chocolate) and for making special wafers.

It is known that protein-sugar foams can be produced by two different basic processes: 1. in a single-stage procedure, the protein and boiled sugar solution are foamed together; 2. in a two-stage procedure, the protein solution is foamed, followed by carefully mixing or dispersing with boiled sugar solution.

The two processes may be carried out continuously or discontinuously. In the discontinuous single-stage process, the two components are foamed in an open foaming machine with the help of a beater. The quality of the protein-sugar foam thus obtained does not fulfil the requirements for the production of several products, such as "negro kisses" and special wafers, because the required specific foam volume is not achieved (see Zucker- und Süsswarenwirtschaft, 30 (12), 448/1977).

This disadvantage is also observed in all the known continuous single-stage processes in which the protein-sugar mix is foamed in special dispersion devices, such as rotating mixer heads, The foams thus obtained may be used, for example, for the production of marshmallows (see Zucker- und Süsswarenwirtschaft, 28, 57/1975).

In the discontinuous two-stage process, single batches of the protein solution are foamed in open foaming machines, such as planetary paddle mixers. The protein solution is produced from spray-dried egg white and water in a ratio of 1:7.

The sugar is preferably heated to 110 to 1200C and, in accordance with the particular recipe, contains starch syrup and a gelling agent, such as sugar-agar, gelatine or pectin, and is added in small amounts to the protein foam and intensively dispersed in the foaming machine and thereby cooled to about 500C so that a voluminous foam is obtained with a density of about 0.2 g/cm3. The foam thus obtained is well-suited to the production of so-called "negro kisses" and of foam fillings for wafers (see Zucker- und Süsswarenwirtschaft, 30 12, 448/1 977).

In the continuous two-stage process, the protein foam is produced with compressed air in known pressure beaters or narrow spaced homogenisators which are fitted with slotted metal inserts, wire-mesh sieves of special shape, cylindrical metal inserts, structured baffles, such as balls, Raschig rings, saddles, spirals or the like.

The foam is carried continuously into a second dispersion device, where it is carefully mixed with boiled sugar and all the other necessary components. The mix is cooled in an appropriate cooler and fed to a finishing machine.

The disadvantage of the known two-stage processes include the high cost of energy and equipment for the production of a stable voluminous protein-sugar foam, which are due to the separate foaming of the protein solution and of the protein-sugar mix for variable periods of time and by the spatial and instrumental separation of the foaming processes for the two main components.

Furthermore, after the addition of the boiled sugar, the foam volume of the whipped protein solution decreases significantly as a result of the denaturation and partial destruction of the foam.

Thus, the foam volume has to be increased again by a subsequent intensive foaming.

It is an object of the present invention to provide a process for the production of a stable protein-sugar foam of a high volume and foam yield, which can be used for a large variety of baked goods, biscuits and confectioneries and sweetmeats, such as wafers with voluminous foam filling and so-called "negro kisses".

A further object of the present invention is to provide a process which has a low requirement for energy and apparatus.

According to the continuous single-stage processes as described in the literature, it is possible to produce protein-sugar foams for marshmallows. For the production of so-called "negro kisses", high foam volumes and increased foam stabilities are required. To fulfil these requirements, high expenses for apparatus and energy are necessary in the single-stage processes.

Therefore, the present invention is concerned with the problem of providing a process by means of which it is possible to produce, in a continuous single-stage process, protein-sugar foams of high volume yield and foam stability. The production of a stable, voluminous protein-sugar foam for socalled "negro kisses" and special wafer fillings can be carried out in a continuous single-stage process when a mixture is produced from protein solution and boiled sugar, leavened with air, transported by a pump into a dispersion tube of special design (see German Democratic Republic Patent Specification No. 233,586-8) and thereby foamed.

Thus, according to the present invention, there is provided a process for the production of stable protein-sugar foam with a high gas content, wherein the prepared or boiled components, such as protein solution, sugar and optionally further components, are mixed and foamed in the presence of air at a pressure of 0.3 to 0.8 N/mm2 in a dispersion tube fitted with a macrofibril system of unbranched, intertwining, strong threads of circular cross-section having a diameter of 0.4 to 2.0 mm.

The denaturation of the proteins during the mixing with sugar boiled at 110 to 1 200C causes a decrease of the foaming characteristics which can be compensated by this special dispersion procedure in that the remaining film-forming properties of the proteins and the flexibility of the laminae present are utilised for the formation and progressive dispersion by the directed action of shear forces.

The shear forces activate the foam formation and dispersion in that the flowing mixture is led through a dispersion tube which is fitted with thin strong threads of circular cross-section. The threads bring about a progressive disintegration and mixing of the gas bubbles by flow swirl and adhesive forces.

The mixture of protein solution and sugar, preferably boiled at 110 to 1200C, may be produced continuously or discontinuously in a conventional mixing or stirring device. Depending upon the temperature of the components, the mixing temperature is adjusted to 40 to 900C, a mixing temperature of 60 to 70oC preferably being used. The preferred temperature may be maintained by providing the mixing vessel with a temperature-regulating device.

If the temperature is below the preferred temperature range, the viscosity increases, which results in an increased energy requirement for the dispersion process. If the temperature exceeds the preferred range, a foam with unsatisfactory properties is obtained from the dispersion process.

After the finishing step, there are no increased cooling requirements.

Depending upon the temperature of the protein-sugar mix, upon the throughput, the shear gradient within the dispersion tube and upon the composition of the raw materials, a definite internal pressure is established, which is preferably kept at 0.3 to 0.8 N/mm2.

The following Example is given for the purpose of illustrating the present invention, reference being made to the accompanying drawing, which schematically illustrates the apparatus which can be used.

In accordance with the present invention, which relates to a process for the production of protein-sugar foam with a high gas content, sugar boiled to 110 to 1200C (5), a prepared protein solution (6) and further components, if necessary, (7), are fed into a mixing vessel (1) which is equipped with a stirrer. The mixing vessel may be temperature-controlled. The mixing temperature is preferably adjusted to 60 to 700 C. The proteinsugar mix is fed through a pipe containing a sieve (2) and appropriate control elements into a conveying pump (3). The pump, the speed of which can be regulated, forces the mixture into a dispersion tube (4). At the tube inlet, purified compressed air is introduced through appropriate control elements. The pressure of the air is preferably adjusted to 0.3 to 0.8 N/mm2. The exit end of the tube serves to discharge the mass for further processing, for example in a depositing machine (9).

According to the process of the present invention, protein-sugar foam with a high gas content may also be produced without using purified compressed air when the protein-sugar mix and filtered air are together sucked up by a pump and forced through the dispersion tube (see German Democratic Patent Specification No.

233,664-3).

Claims (4)

1. Process for the production of stable proteinsugar foam with a high gas content, wherein the prepared or boiled components, such as protein solution, sugar and optionally further components, are mixed and foamed in the presence of air at a pressure of 0.3 to 0.8 N/mm2 in a dispersion tube fitted with a macrofibril system of unbranched, intertwining, strong threads of circular crosssection having a diameter of 0.4 to 2.0 mm.

2. Process according to claim 1, wherein the boiled sugar is added to the protein solution at a temperature below 1200C and the protein-sugar mix has a temperature of at least 4000.

3. Process according to claim 1 for the production of stable protein-sugar foam with a high gas content, substantially as hereinbefore described and exemplified.

4. Stable prdtein-sugar foam, whenever produced by the process according to any of claims 1 to 3.