TECHNICAL FIELD

The invention relates in general to a dairy composition suitable for making a foamed dairy product, to its manufacture process, and to a process for preparing a foamed dairy product.

BACKGROUND OF THE INVENTION

Any discussion of the prior art throughout the specification should in no way be considered as an admission that such prior art is widely known or forms part of common general knowledge in the field.

Yoghurt is a common dairy product consumed globally. Its organoleptic properties have a large effect on consumer acceptability. Whipped yoghurts (also called yoghurt mousses) evolved as a new category of dairy products due to their ability to provide new and unique textures, mouth-feels and product appearances.

Currently, the large majority of texturized chilled products that are consumed at home, such as whipped yoghurt, are bought chilled or frozen at the selling point, and are consumed at home without the need of any additional preparation. However, these products have several drawbacks. Among others, the cold chain must remain unbroken for such products, from the manufacturing point to the transporters, retailers, through to the consumer's refrigerator. Transport at chilled temperature is costly, and temperature fluctuations during transport, loading and unloading impact the product quality. At the selling point and at home, the products must be stored in a refrigerator, which imposes limits on the diversity of the product offering, considering the standard refrigerator volume.

Whipping or foaming consists in dispersing and stabilizing a gas phase (usually nitrogen or air) in the form of tiny bubbles into the continuous yoghurt matrix. Foaming processes can be performed batchwise or continuously. For instance, foaming may be performed by batch with standard kitchen mixers, such as a HOBART or a KITCHENAID mixer. Continuous foaming is generally performed on an industrial scale, for instance using equipment described in WO 2013/068426 Al. The properties of the foamed yoghurt depend on the foaming operation, gas fraction (expressed as the overrun), the bubble size distribution, as well as on the distribution of the ingredients between the bulk and the gas-yoghurt interface. Usually, the manufacture of commercial yoghurt mousses is based on a continuous process. The foams are characterized by on overrun of about 100% which remains stable for 1 month under refrigerated storage conditions.

Patent application WO 2010/122033 A2 discloses fermented dairy products with reduced caloric values, in particular to low-fat milkshakes and smoothies having reduced amounts in sugar. The dairy product contains gelatin. It also contains live probiotic bacteria. The compositions which contain an emulsifier exhibit a foaming rate of less than 50%, lower than the compositions which do not contain the emulsifier. The compositions which contain gelatin having a bloom index of 125 or 130, without emulsifier, exhibit a foaming rate above 50% or 70%. Patent application WO 2010/122376 Al relates to a similar product. This document also discloses a composition which contains alive probiotics.

Patent application WO 2011/084570 Al discloses a whippable composition suitable for making a topping. The composition comprises yogurt and a whip topping emulsion. The yoghurt and the whip topping emulsion are prepared separately, and then combined at low temperature (3 to 15°C). The composition is manufactured in a manner that preserves the microflora of the yogurt. It has a shelf life of up to one year when frozen. The whippable composition must be thawed for at least 12 hours in a refrigerator (4 to 7°C) before whipping in a mixer. The finished whipped product may be stored for up to 5 days in a refrigerator.

Patent application US 2003/068406 Al discloses a chilled whipped yogurt product and its method of preparation. In particular, a hydrated pasteurized emulsifier blend is added after fermentation of the yogurt product, before aeration. The hydrated emulsifier blend contains a wetting agent such as polysorbates or sodium stearyl lactylate, and an emulsifier blend of lactylated mono- and di- glycerides. The yogurt product also contains gelatin. A gas in injected into the product, and then it is whipped with a standard continuous whipping equipment. The whipped product is stored, distributed and sold under refrigerated conditions.

Patent application US 2011/020512 Al discloses a method to enhance the foam retention property of a beverage. Enhanced foam retention properties in a beverage are achieved with a fermentation-derived cellulose complexed with a high- molecular substance such as xanthan gum, guar gum, and carboxymethylcellulose.

JP 2007 006738 A discloses a method for producing a fermented milk beverage having a good storage stability.

As outlined above, foaming agents, stabilisers, and gelling agents are used in industrial processes. In general the foaming agents are emulsifiers such as mono- and di-glycerides and their derivatives, which are not always well perceived by consumers. Gelatin is a common stabilizer in commercial products. Gelatin is produced by partial hydrolysis of collagen extracted from animal tissues, such as cattle or pig. Gelatin replacement represents a major consumer requirement in the recent years, as well as for the vegetarian, halal and kosher markets. Similarly, hydrocolloids such as xanthan gum, guar gum, or cellulose derivatives are not always well perceived by consumers.

It is desirable to overcome or ameliorate at least one of the disadvantages of the prior art, or to provide a useful alternative. Especially, it is desirable to provide a foamed dairy product comparable to a foamed yogurt, without gelatin or other food additives generally used to stabilise foamed yogurt. It is also desirable that such product be prepared and exhibit consistent organoleptic characteristics upon consumption by the consumer, despite the absence of undesired foaming or gelling agents.

SUMMARY OF THE INVENTION

To this end, a first embodiment of the invention proposes a liquid dairy composition suitable for making a foamed dairy product, wherein said liquid dairy composition is shelf-stable under ambient storage conditions, has a pH between 3.8 and 4.4, and comprises fermented milk, up to 0.12% by weight of hydrolysed whey protein based on the weight of the total composition, up to 5% by weight of fat based on the weight of the total composition, up to 1% by weight of high methylester pectin based on the weight of the total composition. Preferably, the liquid dairy composition is suitable for making a foamed dairy product having an overrun of 50% to 150%.

Such compositions may be used in the preparation of a foamed dairy product, for instance a foamed yogurt-type product, in less than 5 minutes, starting from the liquid composition at an ambient temperature.

It was quite surprising for the inventors to achieve the preparation of a cooled, single portion of a foamed yogurt-type product, with such a high overrun, a pleasant mouthfeel, while starting from a low-fat acid fermented dairy composition, and without using texture agents, all in less than 5 minutes.

A second embodiment of the invention proposes a pack comprising at least two containers, preferably single-portion containers, wherein at least one of said containers contains a liquid dairy composition according to the first embodiment of the invention, and wherein each of the remaining containers contains a liquid composition selected from the group comprising: a liquid dairy composition according to the first embodiment of the invention, a liquid composition which is shelf-stable under ambient storage conditions and is suitable for making a frozen confection, and a liquid composition which is shelf-stable under ambient storage conditions and is suitable for making a chilled beverage containing a dairy component and a sweet flavour component.

A third embodiment of the invention proposes a process of manufacturing a liquid dairy composition suitable for making a foamed dairy product, comprising the steps of:

a) providing a liquid milk blend comprising milk and up to 5% by weight of fat based on the weight of the total composition,

b) homogenising and pasteurising the milk blend,

c) inoculating the milk blend with ferment, and fermenting said milk blend until it reaches a pH between 3.8 and 4.4, to obtain a fermented milk, d) adding up to 1% by weight of high methylester pectin based on the weight of the total composition, to the fermented milk,

e) homogenising and pasteurising the fermented milk base, to obtain said liquid dairy composition which is shelf-stable under ambient storage conditions ,

f) packing said liquid dairy composition,

wherein up to 0.12% by weight of hydrolysed whey protein based on the weight of the total composition is added during step a), between steps d) and e), or between steps e) and f).

A fourth embodiment of the invention proposes a process of preparing a foamed dairy product, comprising the steps of

a) providing a liquid dairy composition according to the first embodiment of the invention, at ambient temperature, preferably at a temperature between 10°C and 25°C

b) cooling the liquid dairy composition to a temperature between 1°C and 5°C for a period below 10 minutes, preferably below 5 minutes, even more preferably about 3 minutes, and simultaneously,

c) aerating the liquid dairy composition to an overrun in the range from 50% to 150% by stirring the composition with a stirring member.

These and other aspects, features and advantages of the invention will become more apparent to those skilled in the art from the detailed description of embodiments of the invention, in connection with the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The figures are provided as black-and-white pdf documents after conversion from a coloured pre-conversion document. The pre-conversion document is filed together with this patent application as the "pre-conversion archive".

Figure 1 is a diagram showing embodiments of the process of manufacturing a liquid dairy composition.

Figure 2 shows a Turbiscan analysis of the foamed compositions Rl (Figure 2A) and RC4 (Figure 2B) of Example 1. In the pre-conversion figure, the curves are coloured (curve 1, magenta: 0 min; curve 2, blue-green: ~10 min; curve 3, green: ~20 min; and curve 4, red: ~lh).

Figure 3 shows air bubbles dispersions using a quantitative image analysis, from foamed compositions Rl and RC4 of Example 1.

Figure 4 shows the mean and median diameters of the air bubbles of Figure 3.

Figure 5 are confocal microscopy pictures showing simultaneously the distribution of fat (in red in the pre-conversion figure) and proteins (in green in the pre-conversion figure), in foamed recipes Rl and RC4 of Example 1.

Figure 6 are confocal microscopy pictures showing the distribution of fat (in red in the pre-conversion figure) at the air bubbles interface, in foamed recipes Rl and RC4 of Example 1.

DETAILED DESCRIPTION OF THE INVENTION

Unless the context clearly requires otherwise, throughout the specification, the words "comprise", "comprising" and the like are to be construed in an inclusive sense, that is to say, in the sense of "including, but not limited to", as opposed to an exclusive or exhaustive sense.

As used in the specification, the singular forms "a", "an", and "the" include plural referents unless the context clearly dictates otherwise.

Unless noted otherwise, all percentages in the specification refer to weight percent, where applicable.

Unless defined otherwise, all technical and scientific terms have and should be given the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

In a first embodiment, the invention relates to a liquid dairy composition suitable for making a foamed dairy product. The liquid dairy composition is shelf- stable under ambient storage conditions. In the context of the invention, "ambient" refers to an ambient temperature, for instance between 15°C and 25°C. More specifically, in the context of the invention, "shelf-stable under ambient storage conditions" means that the composition does not undergo spoilage, and maintains its organoleptic properties, in particular its foaming capacity, for up to 6 months, preferably up to 9 months, when stored at a temperature of up to 20°C, and preferably up to 25°C. In a preferred meaning, the liquid dairy composition is shelf stale for up to 9 months at 25°C. To achieve the desired shelf life, the liquid dairy composition is heat-treated. For instance, the liquid dairy composition is heat-treated at a temperature lower than 100°C as it has a pH lower than 4.4. The pasteurisation temperature could range from 75°C to 95°C for 2 to 180 sec depending on the composition. Thus, the ferments in the liquid dairy composition are inactivated.

In this context, the invention relates in part to a liquid dairy composition which is shelf-stable at storage temperatures ranging from 15°C to 25°C, for up to 6 months, and even up to 9 months. In particular, the liquid dairy composition comprises fermented milk, where ferments are inactivated. Preferably, inactivation of the ferments is performed by heat treatment, such as pasteurisation.

The liquid dairy composition has a pH between 3.8 and 4.4, preferably between 4.1 and 4.3, and more preferably about 4.2. The pH of the composition results from fermentation of milk by a starter culture, during manufacture of the composition, as will be explained below and is illustrated on Figure 1. An acidic pH is a usual component in the flavour of a yogurt-type product.

In an embodiment, the liquid dairy composition is a liquid fermented dairy composition, such as a liquid yogurt-type composition.

Usually, foamed dairy products must be stored under chilled conditions, and they contain foaming agents, stabilisers, and gelling agents, all of which do not derive from milk. The liquid dairy composition does not contain gelatin. The liquid dairy composition does not contain foaming agents that do not derive from milk. The liquid dairy composition is shelf-stable under ambient storage conditions, and it can be used to prepare a foamed dairy product, preferably a yogurt-type foamed product, in less than 5 minutes. This is quite an exceptional achievement.

The liquid dairy composition contains fermented milk. While bovine milk is preferred, other milks can be used instead of, or in addition to bovine milk. Examples of alternative milk include camel, goat, sheep and equine milk. Alternatively, milk can comprise vegetable milk, such as soy milk. Various milk ingredients can be used, including skim milk, semi-skim milk, full-fat milk, in a liquid or powder form, condensed milk, as well as milk fractions. Preferably, milk is inoculated with standard yogurt ferments, namely Lactobacillus bulgaricus and Streptococcus thermophilus. Most jurisdictions provide a regulatory definition of "yogurt", depending on the presence of live or inactivated yogurt ferments, on the presence or absence of other ferments, or on their respective ratios. However, the invention should not be limited by such regulatory definitions. Indded, milk can also be inoculated with and fermented by other ferments, such as bacteria from a genus selected from Lactobacillus, Leuconostoc, Streptococcus, Lactococcus, Bifidobacterium, Enterococcus, and Pediococcus. For instance, the ferment may be selected from Lactobacillus acidophilus, L. plantarum, L. casei, L. lactis, L. helveticus, L. paracasei, L. cremoris, L. rhamnosus, L. delbrueckii, L. reuteri, L. johnsonii, L. brevis, Streptococcus thermophilus, Lactococcus lactis, Bifidobacterium longum, B. breve, B. bifidum, B. infantis, and B. lactis. The liquid dairy composition comprises from 60% to 85% by weight of fermented milk based on the weight of the total composition, preferably from 65% to 80% by weight of fermented milk based on the weight of the total composition, more preferably from 70% to 80% by weight of fermented milk based on the weight of the total composition. Preferably, the fermented milk is prepared from bovine milk.

In addition to fermented milk, the liquid dairy composition comprises up to 0.12% by weight of hydrolysed whey protein based on the weight of the total composition. In an embodiment, the liquid dairy composition comprises at least 0.01% by weight of hydrolysed whey protein based on the weight of the total composition. Preferably, the liquid dairy composition comprises from 0.02% up to 0.12% by weight of hydrolysed whey protein based on the weight of the total composition, more preferably from 0.03% up to 0.09%, and even more preferably from 0.04% up to 0.08% by weight of hydrolysed whey protein based on the weight of the total composition. Hydrolysed whey proteins are used to increase the foaming capacity of the liquid dairy composition. Hydrolysed whey protein can be found from various suppliers, at various levels of hydrolysis. Usually, whey protein hydrolysates (WPH) contain non-hydrolysed whey protein and hydrolysed whey protein. Examples of WPH include WPH917 from Fonterra, Vitalarmor H80LB from Armor Proteins, Lacprodan range from Aria, BioZate range from Davisco. Addition of whey protein, of hydrolysed whey protein (via whey protein hydrolysate) in the liquid dairy composition improves its foaming capacity. The liquid dairy composition comprises up to 3.5% by weight of whey protein, including hydrolysed whey protein, based on the weight of the total composition. Whey proteins are natural components of milk. Hence, in the liquid dairy composition, whey proteins may come from the fermented milk, and from whey protein hydrolysate. Unless indicated otherwise, "whey protein content" includes non-hydrolysed whey protein and hydrolysed whey protein. Preferably, the liquid dairy composition comprises at least 1% by weight of whey protein based on the weight of the total composition. For instance, the liquid dairy composition comprises from 1% up to 3.5% by weight of whey protein, preferably from 1.2% up to 3% by weight of whey protein, more preferably from 1.3% up to 2.5% by weight of whey protein, and even more preferably from 1.4% up to 2% by weight of whey protein, based on the weight of the total composition.

As mentioned above, the liquid dairy composition is heat-treated, for instance it is pasteurised. Proteins, in particular whey proteins and hydrolysed whey proteins must be protected against pasteurisation, so that they retain their foaming properties after heat-treatment. This is achieved by the addition of high methylester (HM) pectin based during manufacture of the liquid dairy composition. HM pectin have a degree of methyl esterification (DE) higher than 50. Hence, the liquid dairy composition comprises up to 1% by weight of high methylester pectin based on the weight of the total composition. Examples of HM pectin include Pectin Genu Type HM-115-H from CP Kelco, Grindsted Pectin AMD Series from Dupont Dansico. Alternatively to HM pectin, carboxynnethylcellulose (CMC) can be used. Examples of CMC include Cekol HVD from CP Kelco, Grindsted AMD 258 from Dupont Danisco, Walocle CRT 1000 from Dow. The liquid dairy composition also contains up to up to 5% by weight of fat based on the weight of the total composition. Preferably, the liquid dairy compostion contains less than 4%, or less than 3%, or less than 2% by weight of fat based on the weight of the total composition. Usually, mouthfeel and foam structure are achieved thanks to a relatively high fat content, for instance above 6% by weight, especially in fermented milk products. Indeed, the low pH of such products is detrimental to foaming, and this is counterbalanced by the high fat content or the presence of gelatin. The liquid dairy composition has a low fat content, even as low as 0.05% of fat based on the weight of the total composition. Despite this low fat profile, the liquid dairy composition can be used in the preparation of a foamed dairy product, such as a foamed yogurt-type product, with an appealing mouthfeel and a rather high overrun of 50% to 150%. For instance, the liquid dairy composition comprises from 0.05% up to 2% by weight of fat based on the weight of the total composition. Preferably, the liquid dairy composition comprises from 0.1% up to 1.5% by weight of fat based on the weight of the total composition.

Preferably, the fat is milk fat, although vegetable fat could also be considered, especially to improve the fat profile of the liquid dairy composition, from a nutritional perspective. For instance, the content in mono-or poly-unsaturated triglycerides could be adjusted to provide a better balanced fat profile. Milk fat can be added from various ingredients, such as cream, or whole milk. Non-milk fat can be added from various vegetable oils, such as coconut oil, palm oil, sunflower, rapeseed oil. Mixes of milk fat ingredients and vegetable oils are also useful.

The liquid dairy composition can further include sweeteners, such as nutritive carbohydrate sweetening agents. Examples of nutritive carbohydrate sweetening agents include sucrose, high fructose corn syrup, various DE corn syrups, beet sugar, cane sugar, malt extract, honey, or maple syrup.

The liquid dairy composition can contain further ingredients such as minerals and vitamins, flavours and aromas, such as fruit extract, fruit juice, fruit syrup, cereal ingredients, fruit flavour, cereal flavour, vanilla, chocolate, coffee, or caramel. Preferably, the liquid dairy composition is essentially or completely free of any artificial or non-natural emulsifier or stabilizer. Examples of artificial and non-natural ingredients which are avoided in a particular embodiment of the invention include for example the following emulsifiers: mono- and diglyceride of fatty acids, acid esters of mono- and diglycerides of fatty acids such as acetic, lactic, citric, tartaric, mono- and diacetyl tartaric acid esters of mono- and diglycerides of fatty acids, mixed acetic and tartaric acid esters of mono- and diglycerides of fatty acid, sucrose esters of fatty acids, polyglycerol esters if fatty acids, polyglycerol polyricinoleate, polyethylene sorbitan mono-oleate, polysorbate 80 and, chemically extracted lecithins.

Chemically modified starches which are used in the art as stabilizers are also preferably avoided. These include for example modified starch, monostarch phosphate, distarch phosphate, phosphate or acetylated distarch phosphate, acetylated starch, acetylated distarch adipate, hydroxyl propyl starch, hydroxypropyl distarch phosphate, acetylated modified starch. Hydrocolloids such as xanthan gum, guar gum, carboxymethylcellulose or other cellulose derivatives, are also preferably avoided. Usually, these hydrocolloids are used in the art as texture agents.The products of the present invention are preferably essentially free of the preceding synthetic esters, modified starches, and hydrocolloids.

In the context of the invention, "essentially free" means that these material are not intentionally added for their conventional property imparting abilities, e.g. stabilizing, although there could be unintended minor amounts present without detracting from the performance of the products. Generally and preferably, the products of the invention will not contain any non-natural materials. By the term "essentially or completely free" is therefore meant that the product comprise 1% by weight or less of a given compound.

For instance, the liquid dairy composition is essentially free of xanthan gum, or guar gum, or carboxymethylcellulose, or other cellulose derivatives, or synthetic esters, or modified starches, or their mixtures. The liquid dairy composition has a total solid content from 10 to 30% based on the weight of the total composition. Too high a total solid content may impact negatively the viscosity and foamability of the liquid dairy composition.

The liquid dairy composition may be packed in a container, preferably a single- portion container. Preferably, packing of the liquid dairy composition is done aseptically, to avoid any contamination with environmental bacteria, spores, or moulds, and prevent spoilage during storage. The single-portion container can be used, as will be explained below, in the preparation of a foamed dairy product. In the context of the invention, "single-portion container" encompasses any container suitable for being disposed after being used for the preparation of the single-portion of foamed dairy product. Thereby, the containers are preferably at least partially recyclable. "Single-portion" also means that the container contains the amount of liquid dairy composition sufficient to prepare one portion of foamed dairy product. For instance, one portion of foamed dairy product represents any amount of product from 50g to 180g, such as 50g, 60g, 70g, 80g, 90g, lOOg, HOg, 120g, 130, 140g, 150g, 160g, 170g, or 180g of product. Alternatively, one portion can represent any volume between 50mL and 150mL of liquid dairy composition, such as 60mL, 70mL, 80mL, 90mL, lOOmL, llOmL, 120mL, 130, 140mL, or 150mL of liquid dairy composition.

Further, the container may also be designed for being used as process container, i.e. a container in which the foamed dairy product is prepared, as well as serving container, i.e. a container from which the consumer may directly consume the resulting foamed dairy product. Preferably, the packaging container comprises an identification means containing a recipe code related to the type of foamed dairy product to be prepared. In a preferred mode, the identification means comprises at least one barcode.

As will be described below, the liquid dairy composition can be used in the preparation of a foamed dairy product, such as a foamed yogurt-type product. Preparation of the foamed dairy product can be executed in less than 5 minutes, preferably in about 3 minutes. As the liquid dairy composition is shelf-stable under ambient storage conditions, it does not need to be stored at refrigerated temperatures, contrary to current foamed or whipped dairy products. In addition, the foamed dairy product can be prepared easily and directly from an ambient temperature liquid composition, as a single portion, which reduces losses which typically occur in standard whipping devices. The foamed product has a low fat content, and it does not contain gelatin, which is very interesting from a nutritional standpoint. Because whipping can be performed at the moment of consumption, instead of several days or weeks before with standard whipped yogurts, it becomes possible to overcome issues associated with transport, the cold chain or the fragile structure of whipped products. For instance, the product does not show structure/texture changes, or syneresis. In fact, it becomes possible to offer a foamed dairy product, with consistent and high quality, to be prepared at home for instance.

Therefore, in an embodiment, the invention relates to a pack comprising at least two containers, preferably single-portion containers, wherein at least one of said containers contains a liquid dairy composition as described above. The remaining containers contain a liquid composition selected from: a similar liquid dairy composition, a liquid composition which is shelf-stable under ambient storage conditions and is suitable for making a frozen confection, and a liquid composition which is shelf-stable under ambient storage conditions and is suitable for making a chilled beverage containing a dairy component and a sweet flavour component. In other words, the pack comprises one or several categories of containers, preferably single-portion containers. Said frozen confection could be selected from a smoothie, a frappuccino, a sorbet, or an ice-cream. Examples of liquid compositions suitable for making a frozen confection are described in co-pending European patent applications EP 14 167233 and EP 14 167326 filed on May 7, 2014. Said chilled beverage, such as a chilled dairy beverage, could be selected from caffe latte, tea latte, cereal-based dairy beverage, milk-shake type beverages, including milk-shake flavoured with fruit, cocoa, coffee, caramel, vanilla, malt, or tea.

Either all of the containers, or only some of them contain a liquid dairy composition as described above, which are suitable for making a foamed dairy product, such as a foamed yogurt-type product. In that situation, the liquid dairy composition in each container may be flavoured differently from one another, or may all have the same flavour, or may have other combinations of flavours. When only some of the containers contain such a liquid dairy composition, the remaining containers are any combination of containers containing a liquid composition suitable for making a frozen confection, and a liquid composition suitable for making a chilled beverage containing a dairy component and a sweet flavour component. Preferably, the pack comprises only single-portion containers. For instance, the pack comprises only containers which contain a liquid dairy composition suitable for making a foamed dairy product, such as a foamed yogurt-type product. For instance, the pack is for on-shelf disposal. In this event, the pack preferably comprises a single category of containers, for instance from 10 to 50 containers. Alternatively, the pack may be to be bought by consumers. In this event, the pack may comprise a mix of containers, for instance from 2 to 20 containers.

An example of a process of manufacturing the liquid dairy composition will be described with reference to Figure 1. The process for manufacturing the liquid dairy composition begins with preparing or providing a liquid milk blend comprising milk and up to 5% by weight of fat based on the weight of the total composition. Preferred or alternative milk sources, and fat contents are described above. Sweeteners can be added in the liquid milk blend at this stage. Sweeteners can be added in the dry blend, when relevant, or as an aqueous solution into the liquid milk blend. The ingredients are mixed to form a homogeneous liquid blend. The blend can be stored overnight for complete hydration, especially when using milk powder. The milk blend is then heated from the typical milk storage temperature of 4-5°C, to about 70°C prior to homogenization in a conventional homogeniser. Homogenisation further disperses the fat component and other ingredients. To ensure that no biological contamination occurs before fermentation, the milk blend is pasteurised typically at 92°C for 6 minutes. Alternative heat-treatments are known to the person of ordinary skill in the art. Then the homogenised and pasteurised milk blend is cooled to the fermentation temperature. The fermentation temperature depends on the ferment. Typically, it varies between 37°C and 45°C.

A ferment is added to the milk blend, for instance as a freeze-dried culture. The starting conditions (pH, water content, inoculation ratio) as well as the fermentation condition (temperature, duration) are generally known. Fermentation of the milk blend is performed until a pH between 3.8 and 4.4 is reached. Preferably, the target pH is from 4.1 to 4.3, and even more preferably, about 4.2.

Thereafter, the fermented dairy product - "the curd" - is broken, smoothed, and cooled to about 20°C. As explained above, this is where HM pectin may be added to the composition. Preferably, pectin is added as an aqueous solution. A sweetener can be added in the fermented dairy product at this stage also, preferably as an aqueous solution. Preferably, the composition is let to rest for sufficient time, such as 15 to 30 minutes, before a second pasteurisation is performed to inactivate the ferments. Conventionally, the composition is pre-heated to about 70°C, then it is homogenised, pasteurised typically at 94°C for 3 minutes, then cooled down to about 20°C for final storage in aseptic conditions.

A fruit preparation can be added to the composition during aseptic storage. The fruit preparation must also be aseptically treated. The pasteurised fermented dairy composition is then filled aseptically into a container, preferably a single- portion container, before storage in ambient conditions.

As shown on Figure 1, the whey protein hydrolysate may be added at several steps during the manufacture of the liquid dairy composition. Preferably, the whey protein hydrolysate is added in the liquid milk blend, at the very beginning of the process. Alternatively, or in addition to it, whey protein hydrolysate can be added during storage, just before the final pasteurisation, for instance together with the pectin ingredient. Finally, but this is less preferred due to the risk of contamination, aseptically treated whey protein hydrolysate may be added in the aseptic storage. In that case, it is preferred that the whey protein hydrolysate be added as a blend in liquid milk. Another embodiment of the invention is a process of preparing a foamed dairy product, comprising the steps of

a) providing a liquid dairy composition as described above, at ambient temperature, preferably at a temperature between 10°C and 25°C

b) cooling the liquid dairy composition to a temperature between 0°C and 5°C for a period below 10 minutes, preferably below 5 minutes, even more preferably about 3 minutes, and simultaneously,

c) aerating the liquid dairy composition to an overrun in the range from 50% to 150% by stirring the composition with a stirring member.

Preferably, the liquid dairy composition is aerated to an overrun from 80% to

140%, more preferably from 100% to 135%. The overrun is defined in the examples below.

In particular, this is achieved with a single-portion whipping and cooling device as described in co-pending application PCT/EP2013/072692 filed on 30 October 2013 and published as WO 2014/067987, or in co-pending application PCT/EP2015/059930 filed on 6 May 2015.

Preferably, the foamed dairy product is prepared in its container. For this purpose a container is having a heat exchange contact surface through which the liquid dairy composition is cooled may conveniently be used. This allows for a quick cooling of the liquid dairy composition when the container is brought into contact with cooling means during the aeration.

In a preferred process for preparation of a foamed dairy product, the aerating is done by means of a stirring member and by contacting the composition during cooling with the stirring member wherein said stirring member has a planetary movement with an angular velocity ω2 between 40 and 120 rpm, such as 40 rpm, 50 rpm, 60 rpm, 70 rpm, 80 rpm, 90 rpm, 100 rpm, 110 rpm, or 120 rpm, and a rotation about an axis with an angular velocity ωΐ of 500 to 1200 rpm, such as 500 rpm, 600 rpm, 700 rpm, 800 rpm, 900 rpm, 1000 rpm, 1100 rpm, or 1200 rpm. The angular velocities ωΐ and ω2 of the stirring member may be varied during the preparation process. In a preferred process for preparation of a foamed dairy product, the cooling rate of the liquid dairy composition during a first cooling period is greater than the cooling rate during a subsequent cooling period. For instance, if the whole preparation period, ie the period during which the liquid dairy product is cooled and whipped, lasts 3 minutes, then the liquid dairy product can be cooled at a greater rate during the first minute or the first 90 seconds (first cooling period), then at a lower rate during the last two minutes or the last 90 seconds (subsequent cooling period). The cooling rate can be constant during each cooling period, or it could evolve continuously over the whole preparation period.

Advantageously, the process mentioned above may be performed in a single- portion whipping and cooling device as described co-pending application PCT/EP2013/072692 filed on 30 October 2013 and published as WO 2014/067987, or in co-pending application PCT/EP2015/059930 filed on 6 May 2015. This machine comprises:

- a receiving seat, for accommodating a container, comprising a heat exchange element having a heat exchange contact surface arranged to be in contact with an outer surface of a side wall of the container when the container is placed in the machine,

- a cooling unit arranged for cooling the heat exchange element and,

- a stirring unit connectable to a stirring member and arranged for driving the stirring member in at least one rotational movement;

wherein it comprises

- means for measuring the temperature of the product while being prepared,

- a control unit for automatically setting output parameters according to input parameters received by the control unit and compared to threshold values stored in the unit;

- wherein the output parameters comprises: at least one rotational velocity of the stirring member and the cooling power of the cooling unit, and

- wherein the input parameters comprises any one or a combination of: the measured product temperature and the stirring time. The machine preferably has a stirring unit being arranged for driving the stirring member according to a combination of movements, wherein the combination of movement comprises a first rotational movement of the stirring member about its longitudinal axis which is arranged offset to a central longitudinal axis of the receiving seat and/or of the container and wherein the second rotational movement comprises an orbital or planetary rotational movement about the central longitudinal axis of the container or seat and wherein the output parameters comprise the first velocity (ωΐ) of the first rotational movement and the second velocity (ω2) of the second rotational movement of the stirring member.

An advantage of such a device is that it does not require injection of a gas under pressure to reach a desired overrun, and it can process a single-portion.

A machine of the above-mentioned type was used in the examples identified with the letters SP. EXAMPLES

The following illustrate various embodiments of the invention by way of example, and not limitation.

Example 1: Yogurt-type compositions

Three yogurt-type compositions (Recipe Rl, R2 and R3) are prepared according to several embodiments of the invention. A comparative composition (Comparative recipe CR4) is prepared according to a similar process. The final composition and nutritional composition is indicated in Table 1 below. The manufacturing process is shown at Figure 1.

Recipes 1-3 differ by the step where whey protein hydrolysate (WPH) is introduced in the composition during its manufacture. In recipe Rl, WPH is added in the milk base, before fermentation. In recipe R2, WPH is added to the fermented milk, before the final pasteurisation. In recipe R3, WPH is added aseptically to the pasteurised fermented milk. Comparative recipe RC4 does not contain whey protein hydrolysate, contrary to recipes Rl, R2 and R3. Table 1 - Final connpositions and nutritional analysis

Recipe Rl was prepared first by mixing the milk ingredients and WPH. After fermentation, an aqueous HM pectin solution (5% pectin by weight) and an aqueous sugar solution was added to the fermented during storage, before the post- fermentation pasteurisation, as shown on Figure 1.

Recipe R2 was prepared first by mixing the milk ingredients. After fermentation, a solution of WPH (10% WPH by weight) in liquid skimmed milk, an aqueous HM pectin solution (5% pectin by weight) and an aqueous sugar solution was added to the fermented during storage, before the post-fermentation pasteurisation, as shown on Figure 1.

Recipe R3 was prepared first by mixing the milk ingredients. After fermentation, an aqueous HM pectin solution (5% pectin by weight) and an aqueous sugar solution was added to the fermented during storage, before the post- fermentation pasteurisation. After the post-fermentation pasteurisation, a sterilised solution of WPH (10% WPH by weight) in liquid skimmed milk, was added aseptically in the pasteurised fermented milk, as shown on Figure 1.

Comparative recipe RC4 was prepared using a process as shown on Figure 1, but without addition of WPH. Also, RC4 has a higher fat content than either of recipes Rl, R2, and R3. This is to ensure better foaming of the comparative recipe RC4.

The yogurt-type compositions are shelf-stable under ambient storage conditions. They can be used to produce a foamed dairy product using a Kitchen Aid device or a device described in co-pending application PCT/EP2013/072692 filed on 30 October 2013, or in co-pending European patent application EP 14 167344 filed on 7 May 2014.

Example 2: Overrun (%)

"Overrun" refers to the increase in volume of a product due to whipping or foaming. It is also referred to as "foaming capacity". The overrun is measured according to the following equation: (volume of the product after aeration - volume of the product before aeration) / (volume of the product before aeration). It is reported as a percentage value. Whipping of the compositions mentioned in Table 1 was performed with a KITCHENAID Artsan K45 (stainless steel bowl of 4.2L, 250W, voltage: 220/240V) (KA) or with a single-portion whipping and cooling device (SP).

Because the KA device does not have a cooling function, it was necessary to cool down the composition to 4°C in the refrigerator before whipping. In addition, a minimum of 500 g of composition must be poured into the bowl. Whipping was done at speed 5, using the metal whisk during the time mentioned in Table 2 below. If the room temperature was too high, ice packs were placed on the outside wall of the bowl to keep it cool during whipping.

When using the single-portion whipping and cooling device, a volume of 90 mL of the composition was poured in a single-portion container, inserted into the device. An 8-wire metal whisk was used for whipping (planetary speed of the whisk oo2: +100 rpm, axial speed of the whisk col: -1000 rpm). The temperature of the composition was reduced from ambient temperature (15°C to 20°C) to a temperature of 1°C to 5°C in 3 minutes. The maximum temperature decrease was performed during the first minute of the whipping and cooling process.

The overrun was measured immediately after whipping.

Table 2 - Overrun

Recipe Equipment Time (min) Overrun (%)

Rl KA 3 88

Rl SP 3 115

R2 KA 3 88

R2 SP 3 124

R3 KA 3 117

R3 SP 3 129

RC4 KA 20 96

RC4 KA 10 39

RC4 KA 3 26

RC4 SP 9 48 KA: KITCHEN AID Artsan K45

SP: Single-portion whipping and cooling device described co-pending application PCT/EP2013/072692 filed on 30 October 2013 and published as WO 2014/067987, or in co-pending application PCT/EP2015/059930 filed on 6 May 2015

With a single-portion whipping and cooling device, compositions Rl, R2 and R3, can reach an overrun above 100% in about 3 minutes. With each of these compositions, the single-portion whipping and cooling device provides a greater overrun than the KA device after a 3-minute whipping.

Recipe RC4, which does not contain whey protein hydrolysate, yields an overrun of 48% after 9 minutes of whipping with the single-portion whipping and cooling device.

Hence, it appears that compositions which contain hydrolysed whey protein can be whipped to an overrun of more than 80% in less than 5 minutes (about 3 minutes) and cooled to a chilled temperature of less than 5°C. A foamed yogurt-like product, with a very interesting texture and mouthfeel, can be produced, using the single-portion whipping and cooling device, for immediate consumption and enjoyment. Example 3: Foam assessment

A foamed yogurt-type product was prepared under the following conditions with the compositions mentioned in Example 1 and the equipment mentioned in Example 2:

Table 3 - Whipping conditions

Recipe Mass Equipment Whipping Temperature (°C)

(g) time (min) Initial Final

Rl 500 KA (speed 5) 20 4 5.5

Rl 80 SP 3 5 1

RC4 500 KA (speed 5) 20 4 5

RC4 80 SP 3 4 1 3.1 Foam stability

The Turbiscan Lab Expert (Formulaction, France) was used to characterise the foam stability over a period of time by laser light inspection. A special cylindrical glass tubes is used for foam. Measurement tubes (27.5 mm outer diameter) are purchased from Instrumat SA (Switzerland).

The foam volume, corresponding to a height of 5cm, was introduced gently in the tube from its bottom part of the tube. The tube was then closed at the bottom with the stopper and on the top by the screw cap.

This measurement tube was introduced in the Turbiscan Lab Expert instrument at 25°C and analysed with the "scan" mode. This instrument is equipped with two detectors, one analyzing the transmitted light, the second one the scattered one. The foam stability of each sample was assessed by measuring light transmission and backscattering as a function of sample height at several times (0, 10 min, 20 min and 1 h). The stability kinetic of the foam coarsening was then assessed by calculating the transport mean free path, I*, of each sample at mid-height (5 mm) of the measurement tube. L* is a function of the bubble diameter, oil droplet diameter and of the inverse of the volume fraction of the disperse phase in the foam. Table 4 gives the transport mean free path, I* (μηη) at 5 minutes and 60 minutes.

The results are shown in Figure 2A (composition Rl) and Figure 2B (composition RC4). As can be seen on Figure 2A, the curves overlap. It means that the foam is quite stable during a period of time of 1 hour, irrespective of the whipping device used, for recipe Rl. However, the foam made with the comparative recipe RC4 was not very stable, as can be seen from the separation of the curves over time on Figure 2B. This is confirmed by the values given in Table 4.

An improvement of the stability is observed for Rl in spite of the more marked structural change obtained with SP. Table 4 - Transport mean free path, I* (μιτι)

3.2 Rheology: rigidity and viscosity

Rigidity or viscosity can impact the whipping capacity of the recipes in kitchen beaters. Rigidity was measured on different recipes having different spoon textures and whey protein content.

Rigidity was measured with a Anton Paar MCR 101 rheometer, applying small- amplitude oscillation (amplitude sweep from 0,01% to 500% strain, IHz, shear stress range 0,01 to 110 Pa) with a sanded 50mm plate-plate configuration and a gap of 1mm, at 8°C. G' was captured in the linear range. The yield stress was recorded, where the samples began to flow significantly.

Viscosity was measured by flow measurement, using a sanded plate-plate configuration, with a gap of 1mm, at 8°C, applying a logarithmic increase of the shear rate from 1 to 300s ^"1 . The viscosity was measured at 116s ^"1 .

The results are shown in Table 5. RC5 corresponds to Rl to which 2% starch and 2.28% whey protein were added, to adjust for viscosity. Both whipping systems have an impact on the rigidity and viscosity of the tested recipes. Equipment SP however has a more destructive impact than device KA.

An overrun close to 100% could still be achieved within 3 minutes in spite of the high level of viscosity and rigidity. Table 5 - Rheology measurements

3.3 Air bubble dispersions analysis by quantitative image analysis

Air bubbles dispersion are prepared as follows:

- Disperse and dilute the foam in a dispersion medium, using from 0.2 to 4 g of product in 20 g dispersion medium). The dispersion medium is made with 5% of solution A (3 parts pure acetone + 1 part glacial acetic acid) in solution B (glycerol 87%).

- Spread an aliquot of the dispersion in an observation chamber.

- Adjust the microscopy settings to get highly contrasted images.

- Capture images to get a sufficient number of air bubbles (about 2000)

- Carry out the dispersion in triplicate.

- Launch the batch analysis.

- Collect the data in a Excel file

Figure 3 shows air bubbles dispersions using a quantitative image analysis, from foamed compositions Rl and RC4, obtained with either the KA device or with the SP device. Figure 4 shows the mean and median diameter of the air bubbles of Figure 3, reported in Table 6.

The air bubbles in the foamed recipe Rl are bigger than in the foamed comparative recipe RC4, irrespective of the whipping device used. However, while the mean and median diameter of the air bubbles increase when using the SP device to whip the comparative recipe RC4, using the SP device instead of the KA device yields smaller air bubbles with the recipe Rl.

Table 6 - Bubble size measures

3.4 Protein, fat and air distribution imaging by confocal microscopy

Fats are stained with Nile red (Sigma # Sigma N3013), 5 mg/100 ml absolute ethanol. Proteins are stained with Fast green FCF (Serva electrophoresis # SVA2129502) 1% in ethanol. An aliquot of the stained whipped product is placed in a 5 mm deep observation chamber and covered with a cover slide. Confocal imaging is done as follows:

- Nile red: Excitation wavelength = 488 nm; Emission bandwidth= 510-600 nm

- Fast green: Excitation wavelength = 633 nm; Emission wavelength = 640-700 nm

Figure 5 are confocal microscopy pictures showing simultaneously the distribution of fat (in red in the pre-conversion figure) and proteins (in green in the pre-conversion figure), in foamed recipes Rl and RC4 of Example 1.

When whipping the compositions with the SP device, the protein and fat signals are separate. Fats constitute the major component of the air bubbles interfaces. Proteins are mostly in the continuous phase. In addition, in the foamed comparative recipe RC4, proteins appear both as purely protein aggregates and as fat protein aggregates in the continuous phase.

When whipping the compositions with the KA device, the protein and fat signals seem to overlap: fats and proteins are both present at the air bubbles interfaces. Figure 6 shows are confocal microscopy pictures showing the distribution of fat (in red in the pre-conversion figure) at the air bubbles interface, in foanned recipes Rl and RC4 of Example 1. It seems that the fat globules at the air bubble interface are far larger in the foamed comparative recipe RC4 than in the foamed recipe Rl.

It shows that the SP device imparts a different fat and protein distribution than commercial whipping equipment such as a KA device. SP device is leading to a separated location of proteins and fat in the whipped structure which can be identified by confocal microscopy. Although preferred embodiments have been disclosed in the description with reference to specific examples, it will be recognised that the invention is not limited to the preferred embodiments. Various modifications may become apparent to those of ordinary skill in the art and may be acquired from practice of the invention. It will be understood that the materials used and the chemical details may be slightly different or modified from the descriptions without departing from the methods and compositions disclosed and taught by the present invention.