NL1024433C2 - Manufacturing monodisperse foam involves forming monodisperse coarse prefoam from unfoamed liquid starting product, and passing prefoam through membrane with particular pore diameter - Google Patents

Abstract

Manufacturing a substantially monodisperse foam involves forming a relatively insufficiently monodisperse coarse prefoam from an unfoamed liquid starting product; and passing the prefoam through a membrane having a particular pore diameter to form a foam which is substantially monodisperse.

Description

Title: Method for obtaining a monodisperse foam and product obtainable by such a method.

The invention relates to a method for obtaining a monodisperse foam. A monodisperse foam is understood to be a foam in which the bubbles present therein have substantially the same dimensions.

5 There is a widespread need for healthy food products with a unique taste and mouthfeel. In recent years, low-fat products have become popular due to health issues. However, such products often lack the taste and mouthfeel of full products.

It is known that the perception of taste and the mouthfeel of foodstuffs can be considerably influenced by the presence of gas bubbles. The addition of gas bubbles to a product also provides the possibility of low-fat products with improved sensory properties. The sensory properties can be controlled inter alia in the areas of creaminess, freshness, softness or lightness. Which sensory characteristic is influenced in which way and to what extent depends, among other things, on the size and the number of bubbles. The attribute creaminess in a mousse is thus strengthened more when smaller bubbles are present in a not too high number. The attribute airiness in mousse is more enhanced when larger bubbles are present in a higher number. In this light, see for example Kilcast & Clegg in Food Quality and Preference 13 (2202), 609 * 623.

The appearance of a foamed product is also determined by the amount of bubbles and the hell size in the foam.

25 Foamed products have been known in the market for decades. Examples of this are mousses, whipped cream, ice cream, shakes and desserts. Such products generally have a more or less 1024433

I 2 I

I fixed structure whereby the bubbles during the required at least I

I desired storage time of a few weeks to months in the product can I

I being detained. Donable, foamed products are less I

I known. In general, such products, for example I

Soft drinks, a foam stability on the order of a few seconds instead of I

I a few weeks. To prepare foamed, pourable products in which the I

I calling for a few weeks to months remaining, are small I

I call required. I

It is often preferable that a foamed product is stable I

I 10 is, at least during the time it uses, and in the case of I

I foods can be consumed. I

I The term "stability" in this context refers to the possibility of the I

I to store foamed product for a long time without I

I lead to ongoing changes in the size of the gas bubbles present I

To unwanted coarsening and / or possibly to creaming up the gas bubbles

I and / or other undesirable structural changes. I

I Foamed products are thermodynamic by definition

I unstable. The three most important destabilization processes that occur are the I

I cream, coalescence and disproportionate the foam-forming I

I 20 gas bubbles. I

I The creaming of bubbles can in practice be controlled by I

I have a good ratio between the bubble size and the product viscosity

I argue. I

I Coalescing, or merging, of two bubbles into one larger one

Bubble occurs mainly when the product film is very thin between two bubbles. I

I In products where relatively little gas is distributed, such as pourable I

I foamed products, coalescence is usually not a big problem. I

I Disproportionation, also known as Ostwald Enlargement, is the I

I grow out of larger bubbles at the expense of smaller bubbles. It is a consequence I

Of gas diffusion between bubbles of different sizes, and between bubbles and I

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3 the environment. Due to the coarsening of the gas bubbles present, the appearance changes significantly and, moreover, the driving force for rising is increased. This can dramatically deteriorate the stability of the foam.

Stabilization of pivotable foamed products against disproportionation will in practice not or hardly be achieved by the rheological properties of the continuous phase, as is the case, for example, with mousse where stabilization is partly determined by the gelatin network present. In the case of pourable foamed products, the longer-term stabilization against disproportionation can be achieved by the surface properties of the bubble surfaces. The patent application filed simultaneously with the title "Method for stabilizing an edible foam; the stable foam, as well as compositions comprising this foam" (reference P58079NLOO) provides a solution for this. The content of that patent application is deemed to be incorporated herein by reference.

Another possibility to increase the stability of a foamed product can be realized by making the variation in the size of the foam as small as possible.

The present invention contemplates a method with the aid of which a foam is obtained whose bubbles are substantially the same size. The aim is to achieve this goal with the lowest possible energy consumption.

According to the invention, a method for manufacturing a substantially monodisperse foam is provided, wherein from a non-foamed starting product in a first foaming step a (relatively coarse) pre-foam is formed that is insufficient mono-dispersers, the pre-foam passing through a membrane with a specific pore diameter is fed to form a foam that is essentially monodisperse. Incidentally, as a membrane, any permeable 1024433 can in fact be used

4 I

material, the perforations being such that an I

monodiepers foam remains. I

The beauty of the method according to the invention is that the I

the size of the foam obtained by the process can be controlled I

5 on the basis of the correct choice of the pore size of the membrane. I

Therefore, if the starting product is a food, I

with the method according to the invention the desired sensory I

properties are obtained. Moreover, the method according to I

invention very little energy. When a front foam with I

10 bubble sizes between 30 and 250 micrometers through a membrane I

with an average pore size of 8 microns, I

the energy required for this is approximately 2.5 kJ per liter of foam. To I

obtain such a decrease in bubble size using I

of the Mondomix rotor-stator mixer known per se, an amount is I

15 energy of 500 kJ per liter of foam required. Previous numbers show I

clear that a substantial saving of energy is obtained with the I

method according to the invention in addition to the other advantages which are above I

described. I

According to a further elaboration of the invention, the I

The average pore diameter of the membrane is essentially ten times I

smaller than the desired bubble diameter of the main I

monodisperse foam. Thus, by choosing the correct pore size, the I

Bubble size of the foam can be determined. The invention provides I

I also a method for providing certain sensory I

Characteristics of an edible foamed product using I

The method described above, wherein the sensory properties I

I are set by a suitable choice of the bubble size of the I

I foam, this bubble size being determined by the pore size of I

I select the membrane approximately ten times smaller than the desired I

I 30 bubble size. I

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The pre-foam can be produced according to a further elaboration of the invention by a standard commercially available foam device. For example, the well-known Mondomix rotor-stator mixer can be considered. However, it is also possible that the pre-foam is produced by any other method that forms a non-monodisperse foam.

According to a further elaboration of the method, it is preferable that the denaturing and the compression of the bubbles take place after the foam has passed the membrane. This can be realized, for example, by heating the foam after it has passed the membrane for a time and a temperature selected such that denaturation occurs.

Incidentally, this embodiment is described in detail in the patent applications filed simultaneously with the present application with the following references: - "P58079NL00" - "P63301NL00"; and - "P63303NL00".

The contents of these patent applications are considered to be incorporated herein by reference. Particularly when applying the methods from the patent applications filed simultaneously, it is achieved that after or during foaming of the product, proteins from the unfoamed starting product denature after adsorption on the bubble surfaces, whereafter the protein layer thus formed compresses by causing the bubble to shrink so that an undeformable, or at least rigid, surface is formed around the gas bubbles.

According to a further elaboration of the invention, the pore size of the membrane is in the range of 0.1 - 20 microns, more particularly in the range of 0.2 - 10 microns. With such a membrane, a monodisperse foam is obtained, the 1024433 of which

6 I

average hell size varies between 1 and 100 microns, more preferably between I

3 and 30 μιη, starting from a pre-foam where the average I

bell sizes vary from 30 to 250 micrometers. I

According to a further elaboration of the invention, the viscosity I

5 of the pre-foam are increased by thickening agent I thereto

such as xanthan gum. Such an I

thickener prevents the bubbles from creaming and thus the product I

leave. According to a further elaboration of the method, the I

pre-foam has at least substantially 20% gas. However, lower or higher I too

10 storage percentages can be applied. The starting product is included in I

generally a solution of surfactants that bubbles I

stabilize and, in particular, combat disproportionation. Examples are I

sugar esters, TWEEN ®, and stabilizing proteins. I

According to a further elaboration of the invention, the I

Membrane that is used, for example, a sintered metal membrane I

to be. Also an application of a ceramic membrane or a polymer I

membrane is possible. I

According to a further elaboration of the invention, it deserves the I

preferred to make the minimum hell size in the pre-foam approximately 5 times greater I

20 than the average pore size. That way I

causes all bubbles in the pre-foam in the membrane I

break open and be transformed into smaller bubbles. This has the advantage I

that the bubble size in the monodisperse foam can be very accurately measured I

are controlled by the correct choice of the hell size of the pre-foam I

25 and the pore size of the membrane. I

According to a further elaboration of the invention, it deserves the I

preferably that in the foamed product is about 3 to 10 milligrams of protein I

included per m2 of calling surface. In addition, at least approximately I

0.1 wt% protein in the solution, so that the proteins that are on the I

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7 bubble surface can possibly be supplemented from the solution.

The method is particularly advantageous when the starting product is an edible liquid containing milk protein.

The invention also relates to a product obtainable with the method according to the invention.

Such a product retains its foam structure for a longer period of time because the bubbles have substantially the same size, so that disproportionation proceeds more slowly. Moreover, in the case of an edible product, by applying the method a product can be obtained which has the desired taste and structural properties.

The invention will now be elucidated with reference to a number of examples.

15

Example 1

Figure 1 shows a foam produced with a Mondomix rotor-stator mixer, which is a standard device available in the market for foaming products. With this device, gas is injected into a mixing chamber in which a rotor rotates at high speed and divides the gas into fine bubbles. Figure 1 clearly shows that the bubbles have different dimensions. In Figure 1, 20% storage is produced by adding gas to protein solution (3% whey protein concentrate). The solution was thickened with 0.7% xanthan gum to prevent creaming of the gas bubbles. In Figure 1A the rotor speed was 1000 revolutions per minute. The pre-foam produced in this way was then pumped through a membrane with an average pore size of 4 microns at a rate of approximately 40,000 liters per m2 per hour.

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This led to a pressure drop of 25 bar and the resulting monodisperse

foam is shown in figure 2. I

Example 2 I

In a second example, the pre-foam from Figure 1 was pumped I

through a membrane with an average pore size of 8 microns. I

A pressure drop of 10 bar occurred at a flow rate of 40,000 l

liters per m2 per hour. The resulting monodisperse foam is shown I

in Figure 3a. I

10 I

In the example from Figure 1, I presses through the membrane

2.5 kJ per liter of foam requires energy. To an I

to achieve a similar decrease in bubble size with the Mondomix is I

approximately 500 kJ per liter of foam is required. The foam thus produced I

15 is shown in Figure 3b. I

When comparing FIG. 3b and FIG. 3a it can be seen that both foams I

have a comparable average bellexi size, but I

foam made with the membrane and narrower distribution in bubble size I

20 knows. This is quantified in FIG. 3c. More particularly, FIG. I

3c a quantification of the bubble size distribution. Herein it refers I

caption "Mondomix" to the foam as shown in Figs. 3b and I

"membrane foaming" to the foam as shown in FIG. 3a. On the y-axis I

is the number of bubbles in a certain size category as a percentage of I

25 the total of the total number of bubbles. Because of both peaks, a normal I is

distribution fitted, it follows for the average hell size and I

standard deviation therein: I

Membrane foam: 30.4+ 12.9 μιη I

Mondomix: 35.4 + 21.2 μπι I

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9

Membrane foams therefore provide a significant improvement in mono-dispersity (i.e., significantly reduce the (relative) standard deviation).

Figure 4 shows the monodisperse foam from Figure 2 after it has been stored for 3.5 hours.

Figure 5 shows how the pre-foam from Figure 1 has changed its structure after one day of storage. It should be noted here that the foam is stabilized against further disproportionation with the help of denaturation of proteins that are on the bubble surface and subsequent compression as a result of disproportionation. The bubbles can therefore only shrink to a certain minimum size and remain stable thereafter. It is clearly visible that there is a broad distribution in the hell size.

Finally, figure 6 shows a foam stabilized in a similar manner after a day of storage, but starting from the foam from figure 2 which has been passed through a membrane with a pore size of 4 micrometres. Figure 6 clearly shows that the hell size in this foam is much more uniform and that there are only a limited number of large bubbles in the foam. As a result, the stability of the foam of Figure 6 is particularly good.

It will be clear that the invention is not limited to the examples described and that various modifications are possible within the scope of the invention as defined by the claims.

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Claims (17)

1. A method for manufacturing a substantially I monodisperse foam, wherein a relatively coarse I foam is formed from a non-foamed liquid I product in a first foam-forming step which is insufficient monodisperses, wherein the I foam is passed through a membrane with a specific pore diameter. I to form a foam that is essentially mono-disperse. I 2. Method according to claim 1, wherein the average pore diameter of the membrane is chosen to be substantially 10 times smaller than the desired bubble diameter of the substantially mono-disperse foam. I A method according to claim 1 or 2, wherein the pre-foam is produced by a standard commercially available foam device. I 4. Method as claimed in any of the foregoing claims, wherein at least substantially 20% gas is included in the pre-foam. I The method according to any of the preceding claims, wherein the starting product is a surfactant-containing composition. I 6. A method according to any one of the preceding claims, wherein the viscosity of the pre-foam is increased by adding a thickener to the starting product I, such as, for example, xanthan gum. I A method according to any one of the preceding claims, wherein the I membrane is a sintered metal membrane, a ceramic or a polymer I membrane. I 8. A method according to any one of the preceding claims, wherein the pore size of the membrane is in the range of 0.1-20 micrometers, more particularly in the range of 3-10 micrometers. I 1 024433 - I A method according to any one of the preceding claims, wherein the minimum hell size in the pre-foam is greater than approximately 5 times the average pore size. 10. Method as claimed in any of the foregoing claims, wherein the foamed product comprises approximately 3-10 mg of protein per m2 of bubble surface. 10 I CONCLUSIONS I The method of claim 10, wherein the protein in the bubble surface is in equilibrium with at least about 0.1% by weight protein in the fluid surrounding the bubble. 12. A method according to any one of the preceding claims, wherein the starting product is an edible liquid containing milk protein. 13. A method according to any one of the preceding claims, wherein the non-foamed starting product contains proteins which, after foaming of the product, are able to form a surface that is non-deformable under the prevailing conditions around the gas bubbles by denaturing after adsorption on the bubble surfaces followed by compression of the product. bubble surface. The method of claim 13, wherein the denaturation and compression of the bubble surface takes place after the foam has passed through the membrane. The method of claim 13 or 14, wherein the rigid surface around the gas bubbles is formed by heating the foamed product followed by compression. 16. Method for providing a specific taste sensation to an edible foamed product using the method according to any one of the preceding claims, wherein the taste sensation is adjusted by a suitable choice of the bubble size of the foam, this bubble size being determined by the pore size of the membrane approximately 10 times smaller than the desired bubble size. 17. Product available with the method according to any one of the preceding claims. 1024433