Field of the invention

The present invention relates to a process of stabilizing the interface between two phases. In particular, the present invention relates to a stabilizing agent and to the use of said stabilizing agent for stabilizing the interface between a gas phase and an aqueous phase of a product.

Background of the invention

Foams can be used to create an exciting and pleasurable food experience by altering the perception of colour, texture and flavour. In packaged food, one of the chief challenges associated with foams is to generate edible products that either maintain their structure over the desired shelf-life or can conveniently produce the foam at the targeted point-of-consumption.

Foam stability is governed by a range of mechanisms, including the

microstructural geometry of the dispersed gas phase, the viscoelastic properties of the continuous liquid phase and the physico-chemical properties of the interfacial layer.

The most traditionally used approach for stabilizing the foam interface involve the use of either low or high molecular weight surfactants (sometimes referred to as emulsifiers) or a combination of the two. Examples include mono- and diglycerides of fatty acids for low molecular weight surfactants and milk proteins for high molecular weight surfactants. Surfactants can be molecularly dissolved in liquids although they may locally associate to form mesophases for certain concentration ranges.

Hence, there is a need in the industry for a new and/or an alternative way for stabilising the foam of food products. This stabilisation also needs to result in a food product having a pleasurable food experience in respect of perception of colour, texture and flavour. Summary of the invention

Thus, an object of the present invention relates to the provision of a stabilizing agent and the use of such stabilizing agent for stabilizing the interface between a gas phase and an aqueous phase.

A further object of the present invention relates to the provision of a method for the preparation of a product having improved stability between at least two phases of the product. Thus, one aspect of the invention relates to a method for stabilizing the interface between at least two phases of a product, the method comprising the steps of:

(i) providing a composition comprising :

(a) at least one gas phase,

(b) at least one aqueous phase,

(c) a stabilizing agent comprising particles of a plant material and

(ii) mixing the composition in order to stabilize the interface between the at least gas phase and at least one aqueous phase of a product.

Another aspect of the present invention relates to a product obtainable by the above method.

Yet another aspect of the present invention relates to a stabilizing agent comprising micronized particles of a plant material, wherein the particles of the plant material have a particle distribution size in the range from 1-100 Mm.

Still another aspect of the present invention relates to the use of said stabilizing agent for stabilizing the interface between a gas phase and an aqueous phase of a product. The present invention will now be described in more detail in the following. Description of the drawing

Figure 1 shows the particle distribution size of the foam stabilizers described in Table 1. MRC represents micronized roasted coffee; EMRC represents exhausted micronized roasted coffee; DMRC represents defatted micronized roasted coffee; and DEMRC represents defatted exhausted micronized roasted coffee.

Detailed description of the invention

Definitions

Prior to discussing the present invention in further details, the following terms and conventions will be defined :

Crema

The term "crema" refers to the foam or froth covering the surface of a high quality cup of espresso the colour of which varies from reddish brown to beige. Crema is very important in making a good espresso. The presence of crema is the main difference between drip coffee and espresso. Crema releases potent coffee aroma and flavour compounds remaining in the mouth and throat long after drinking the espresso.

Polyphenols

In the context of the present invention "polyphenols" refers to a structural class of organic chemicals characterized by the presence of large multiples of phenol units.

Polysaccharide molecules

Polysaccharides are polymeric carbohydrate structures, formed of repeating units (either mono- or disaccharides) joined by glycosidic bonds. The structure of polysaccharides is often linear, but may also display various degrees of branching . Polysaccharides are often quite heterogeneous, containing slight modifications of the repeating unit. In an embodiment of the present invention the term

"polysaccharide molecules" refers to mannan and galactomannan

Nitrogenous compounds

In the context of the present invention, "nitrogenous compounds" refers to a structural class of natural organic chemicals characterized by the presence of large amounts of nitrogen atoms within their structure. Dry weight

The dry weight refers to the measurement of the mass of matter when completely dried and all fluids are completely removed from the matter. The dry weight % of a substance refers to the relative amount of said substance in the total dry weight matter. In the description of the present invention dry weight % is termed "w/w %".

Beverage product

In the context of the present invention, a beverage product refers to a liquid prepared for human consumption. A powdered beverage product refers to a dry matter product (such as an instant powder) which may be reconstituted into a beverage by the addition of a liquid such as water. A beverage may be served hot or cold. The term hot beverage product refers to a beverage which is served heated. A hot beverage product may be obtained by the addition of a heated liquid (for example in the form of water or milk) or by heating the beverage as such.

Other definitions and/or explanations are present in the detailed description below.

Stabilizing process

It has surprisingly been found by the present inventor that an increase in foam stability (or preservation of foam stability) may be obtained by adding a stabilizing agent comprising particles of a plant material to a composition comprising at least one gas phase and at least one aqueous phase.

As mentioned above an aspect of the present invention relates to a method for stabilizing the interface between at least two phases of a product and the product obtained by said process.

Thus, in one embodiment the present invention relates to a method for stabilizing the interface between at least two phases of a product, the method comprising the steps of:

(i) providing a composition comprising : (a) at least one gas phase;

(b) at least one aqueous phase;

(c) a stabilizing agent comprising particles of a plant material; (ii) mixing the composition in order to stabilize the interface between the at least one gas phase and at least one aqueous phase of a product.

A foam stabilizer comprising particles of a plant material may be seen as a food source ingredient, in particular as a plant source ingredient. Accordingly such a stabilizer creates a competitive advantage as it meets the need of the modern consumer who demands food comprising natural and sustainable food ingredients (such as stabilizers).

Stabilizers may be added to many types of food products to increase foam stability. Foam stability may decrease over time thus it may also be advantageous to preserve the initial foam stability. From an industry perspective it may be advantageous to replace synthetic stabilizers with a "food source ingredient". In the present context the term "synthetic stabilizers" relates to ingredients produced using non-food source ingredients. "Food source ingredient" stabilizer on the other hand is to be understood as vegetable source ingredients, animal source ingredients, microbial source ingredients and/or fungi source ingredients. These vegetable source ingredients, animal source ingredients, microbial source ingredients and fungi source ingredients may be derived from a vegetable source, an animal source, a microbial source and/or a fungi source, respectively, primarily through physical processing, e.g. separation, filtration centrifugation, ion exchange, and/or sometimes facilitated by simple chemical reactions such as acidification, basification, hydrolysis, or salt formation.

The gas phase may comprise nitrogen, oxygen, air, carbon dioxide and any combination thereof. From a cost perspective it may be preferred that the gas- aqueous interface is an air-water interface.

The aqueous phase may be any kind of liquid comprising water. It may be preferred that the aqueous phase is a dairy based aqueous product or a beverage product. In the present context the term dairy based aqueous product is to be understood as a product comprising ingredients which are fully or partly of dairy origin. The dairy based aqueous product may be selected from the group consisting of ice cream base, cream, milk, or milk fractions, such as whey, lactose, casein and/or milk proteins, and any combination hereof.

It may be advantageous to increase the stability between the at least one aqueous phase, such as the at least one dairy based aqueous product, and the at least one gas phase in order to provide a light textured and/or creamy product. As part of the total volume of such a light textured product is gas, the product comprises fewer calories compared to a similar product of the same volume comprising no or merely a limited amount of gas. Such a product meets the needs of the modern consumer who demands products which simultaneously are low in calories and comprises a light textured product having a great mouth feel.

In an embodiment of the present invention the mixing in step (ii) may involve shaking with low or high energy input and/or stirring with high or low energy input, whipping with high or low energy input, gas sparging, decompression of a compressed mixture of a gas phase and a aqueous phase, de-solubilisation of a soluble gas phase inside a aqueous phase.

Following step (ii) a product comprising an improved stability between at least two phases is obtained. Obviously, the present invention also pertains to such a product which is obtainable by the method of the present invention.

As the product obtained is intended for human consumption the taste is of outmost importance. Thus, it may be preferred that the pH of the composition is adjusted to a pH value above 4, e.g. a pH value above 5, such as a pH value above 6, such as a pH value above 7, e.g. a pH value of pH 8 or above, such as in the range from pH 4-8, e.g. in the range from pH 5-7, such as in the range from pH 6-8, preferably in the range from pH 7-8 either before mixing, during mixing or following mixing of the composition. In one embodiment the product or at least part of the product obtained is a foam. The foam may be crema if the product obtained is a coffee based product, such as espresso. In one embodiment the product or the foam of the product comprises particles of a plant material. As taste is one of the key attributes driving consumer preference, it may be contemplated that pH of the product or the aqueous phase of the foam of the product has a pH value above 6, e.g . a pH value above 7, such as a pH value of pH 8 or above, e.g. between pH 6-8, preferably between pH 7-8.

Lipid(s) are generally known to reduce foam stability. Thus, it may be preferred that the product or the foam of the product comprises substantially no lipid(s). In a particular preferred embodiment the product or the foam of the product comprises no lipid(s) originating from the micronized plant material. In the present context the term "lipid(s)" is to be understood as a compound comprising at least 3 fatty acids. An additional advantage of providing a product and/or a foam of a product comprising no lipid(s) is that the calorie intake per serving of such a product may be decreased.

In an embodiment of the present invention the product may be selected from the group consisting of a chilled dairy product, an ambient diary product, an ice cream product, a confectionery product pet-care product and a beverage product The beverage product may be a coffee based product (such as but not limited to espresso, cappuccino, iced coffee or ice blended coffee, instant coffee, instant espresso coffee, and coffee mixes, coffee mixtures, mixes of roast and ground coffee and instant coffee, and ready-to-drink coffee beverages).

Stabilizing agent

Another aspect of the present invention pertains to a stabilizing agent and the use of such a stabilizing agent for stabilizing the interface between a gas phase and an aqueous phase.

In an embodiment of the present invention the stabilizing agent comprising micronized particles of a plant material. It may be preferred that at least 75%, such as at least 85%, e.g. at least 95% of the particles of the plant material in the stabilizing agent have a particle size in the range from 1 - 100 Mm (percent by volume).

As the stabilizing agent is intended for human consumption it may be preferred that the stabilising agent has a pH value above 4, e.g . a pH value above 5, such as a pH value above 6, such as a pH value above 7, e.g . a pH value of pH 8 or above, such as in the range from pH 4-8, e.g. in the range from pH 5-7, such as in the range from pH 6-8, preferably in the range from pH 7-8. Due to the negative effects of lipid(s) on the foam stability it may be desired that the stabilizing agent is defatted or substantially defatted . In particular it may be preferred that the stabilizing agent is defatted or substantially defatted before being added to a composition. Thus, in a preferred embodiment the stabilizing agent comprises substantially no lipids(s). In an even more preferred embodiment the stabilizing agent comprises no lipid(s) originating from the micronized plant material. In the present context the term "defatted" is to be understood as a stabilizing agent comprising less that 5 w/w% lipids, such as less than 1 w/w% lipids, e.g . in the range of 0.01-5, such as in the range of 0.1-3, e.g. in the range of 0.5-2, e.g. in the range of 0.75-1.

The stabilizing agent of the present invention may be used for stabilizing the interface between a gas phase and an aqueous phase of a product. In a preferred embodiment the product may be selected from the group consisting of a chilled dairy product, an ambient diary product, an ice cream product, a confectionery product pet-care product and a beverage product. The beverage product may be ice tea, chocolate drinks, fruit beverages, sport beverages, energy beverages, healthy drinks, dairy beverages, soups, sauces, alcohol containing beverages and milkshakes, ice coffee, coffee flavoured beverages, other coffee based products (such as but not limited to espresso, cappuccino, iced coffee or ice blended coffee, instant coffee, instant espresso coffee and coffee mixes, coffee mixtures, mixes of roast and ground coffee and instant coffee, and ready-to-drink coffee beverages). The plant material of the stabilizing agent

It may be contemplated that the plant material is derived from a seed- or bean bearing plant. Preferably, the seed or bean comprises at least 0.1 w/w% oil, such as at least 1 w/w% oil, e.g. at least 5 w/w% oil, e.g. in the range from 0.1-5 w/w %. As the stabilizer is intended for human consumption it may be preferred that the plant material comprises an acceptable taste which does not negatively affect the taste of a product comprising the stabilizer. Thus, a preferred embodiment the plant material may be selected from the group consisting of Coffea and

Theobroma cacao. Stabilizers comprising plant materials may be seen as food source ingredients thus, fulfilling the needs of the consumer and thus the food industry.

In an embodiment the particles of a plant material may be a micronized plant material. In the present context the term "micronized plant material" (MPM) is to be understood as particles of an untreated plant material. In the present context the term "untreated plant material" is to be understood as the plant material has not been subjected to physico-chemical modification such as but not limited to extraction, fractionation or concentration prior to being micronized. The plant material may however be subjected to a heat treatment (e.g. roasted) prior to being micronized.

Thus, in an embodiment of the present invention the MPM comprises substantially the same compounds as the plant material from which they are derived. Such compounds may for example be nitrogenous compounds, polyphenols and polysaccharide molecules. Thus, the MPM may be water insoluble or at least partially water insoluble due to their substantially intact composition.

In an embodiment the plant material comprises components that are water- insoluble, or water soluble compounds such as but not limited to nitrogenous compounds, polyphenols and/or polysaccharide molecules. The water-insoluble compounds may be fibrous material from the plant material.

MPM may be provided by subjecting a plant material to a process selected from the group consisting of milling, grinding and pulverization. As the overall texture of the product comprising the stabilizer may be affected by the size of the MPM it may be preferred that the MPM may comprise a volume average particle size (PDS) in the range from 1 - 100 Mm. It may be further preferred that at least 75%, such as at least 85%, e.g. at least 95% of the particles of the MPM have a particle size in the range from 1 - 100 Mm (percent by volume).

The particle distribution size may be determined by a standard analytical method, e.g. using light scattering such as by using a Malvern light scattering instrument. This method is commonly used by people skilled in the art.

The particles of the plant material may be subjected to an extraction which may be a high degree of extraction prior being added to a composition. In the present context the term "extraction" is to be understood as a separation process comprising the separation of a substance from a matrix using an aqueous phase where the substance to be separated is soluble (e.g. separation of water soluble compounds from a plant material). The term "high degree of extraction" is to be understood as a substantially exhausted separation of a substance from a matrix using a liquid phase where the substance to be separated is soluble.

In a preferred embodiment of the present invention the particles of the plant material are not subjected to a high degree of extraction or extraction of water soluble compounds prior to being added to the composition. Examples of such water soluble compounds may be polyphenol compounds, nitrogenous compounds and polysaccharide molecules.

It should be noted that embodiments and features described in the context of one of the aspects of the present invention also apply to the other aspects of the invention.

All patent and non-patent references cited in the present application, are hereby incorporated by reference in their entirety.

The invention will now be described in further details in the following non-limiting examples. Examples

Materials and Methods

Foams were generated as described below. Coffee Ingredients

Four ingredients from coffee were tested as foam stabilizers and prepared as described in Table 1 below. The particle size distributions of the foam stabilizers described in Table 1 are shown in figure 1. Additional Materials

Foams were generated using the following additional materials:

• MilliQ water,

• Hydrochloric acid (Merck) (for making aqueous solutions at pH 2, 4, 6),

• Sodium hydroxide (Merck) (for making aqueous solutions at pH 8),

· Disodium hydrogen phosphate/potassium dihydrogen phosphate pH 7

buffer solution (Merck).

Experiments were performed to test the ability of coffee ingredients to stabilize interfaces.

Table 1

# Sample Preparation

Foam Stability Experiments

Samples 1 - 4 (5mg and 50mg) were dissolved in MilliQ water (3.5ml) and the pH of the solutions was adjusted to pH 2, 4 and 6 using hydrochloric acid and pH 8 using sodium hydroxide. The volume was completed to 5ml_ yielding two solutions of 0.1 weight percent (wt %) and 1 wt% respectively. Foams at 0.1 wt% of coffee extract were also formed at pH 7 using buffer solution. The foams were prepared in 15 ml polypropylene Falcon tubes (BD Biosciences). The samples were placed in glass test tubes and vigorously shaken by hand for approximately 5 seconds. They were then placed vertically in a test tube stand . The foaming performance was evaluated by visual inspection of the foam height and recorded by digital photography. Results and Discussion

Foams were prepared by vigorously shaking aqueous solutions of samples 1 - 4 at pH 2 - 8. The foams formed by the coffee samples were compared through visual inspection. The result showed an increasing foam height and increasing foam stability with increasing pH for sample 3 (i.e. the defatted MRC). The same trend was noted for samples 1, 2 and 4.

A comparison between foams formed at pH 7 for samples 1-4 was also conducted. The results showed that the defatted micronized coffee (samples 3 and 4) stabilized air-water interfaces better than samples still containing lipids (samples 1 and 2). Also the exhausted micronized coffee (samples 2 and 4) did not provide the same foam stabilization as non-exhausted micronized coffee (samples 1 and 3) even though some stabilization was provided.

The proposed explanation for the above foam stability observations are as follows: the absence of lipids confers a higher stability to the foam as lipids are generally known to reduce foam stability. Secondly, contrarily to samples 2 and 4 which are exhausted (i.e. extracted to a high degree), sample 3 still contains more soluble coffee solids including surface active melanoidines. Surface active melanoidines lead to a decreased surface tension. Since they also contain complex phenolic moieties, a pH change will lead to the physico-chemical changes that favour foam stabilization. Additionally foaming properties of micronized coffee could also be augmented by stabilization due to small particles (Pickering stabilization).

Conclusion

In simple air-water foam experiments all samples created greater foam heights and improved stabilisation of the foam at natural and mildly basic conditions (pH 7-8) compared to acidic conditions (pH 2-4). The de-fatted micronized roasted coffee was the most efficient at stabilizing foams.