Patent Description:
It is known to provide texture and mouthfeel to food and beverage product by protein aggregation and there continue to be a need for food and beverages products exhibiting nutritional balance of macronutrients while delivering great taste and texture.

Mouthfeel and creaminess, as well as reduction of fat, are key drivers of liking for milk based products such as cream and products derived from cream. Today, there is a challenge to increase the mouthfeel/creaminess of present creams, in particular to achieve such increase in mouthfeel/creaminess using all-natural formulations or ideally by acting on the product matrix itself, instead of adding ingredients to the product. This is particularly true in low and no fat products.

<CIT> describes a process to obtain a heat convection drying protectant preparations for lactic bacteria or probiotics consisting in heat treating at <NUM> a milk preparation enriched with calcium in order to induce protein aggregation and subsequently submitting the preparation to a mechanical homogenization treatment. This patent application does not relates to dairy concentrates. <CIT> describes the production of an ingredient exhibiting high content in milk-derived complex lipids. It is obtained by precipitating the protein fractions of butter serum at pH <NUM> - <NUM> in presence of calcium and filtering the supernatant in order to concentrate the complex lipids.

<CIT> disclosing the production of a free divalent cations-rich liquid food product in which <NUM>% of the lysine residues carried out by the proteins have been glycosylated in order to increase their resistance to aggregation in presence of calcium. Therefore, <CIT> is related to preventing protein aggregation in presence of divalent cations, calcium among others.

<CIT> is describing a process for the production of a milk protein concentrate which is enriched with whey proteins. Skimmed milk is heated in the pH range <NUM>-<NUM> in order to promote aggregation of whey proteins together with caseins. The heated product is subsequently submitted to filtration in order to concentrate protein aggregates and to remove lactose.

] describe the effect of addition of free calcium on the viscosity of superphosphorylated caseins. It was shown that the viscosity of a <NUM> wt. % superphosporylated caseins (<NUM>% phosphorylation) increased by addition of <NUM> calcium at pH <NUM>. This study does not relate to dairy concentrates. Further, for dairy concentrates the superphosporylated caseins are not desirable relevant as chemically modified and expensive ingredient.

<NPL>] reported that the amount of free calcium ions in bovine milk at pH <NUM> was <NUM> and that this value decreased to <NUM> when milk pH decreased to <NUM>.

<NPL>] investigated the effect of calcium chloride addition to skimmed milk reconstituted at <NUM> wt. % in the pH range <NUM> - <NUM> and the subsequent effect on viscosity when the milks were heated for <NUM> minutes at <NUM>, <NUM> and <NUM>. They reported a critical instability pH of <NUM> for the milks upon heating at <NUM> for calcium chloride content up to <NUM>.

<NPL>] determined the impact of calcium chloride addition into full fat milk (<NUM>% fat) upon heating at <NUM>. It was reported that calcium chloride addition below <NUM> was leading to viscous dispersions while higher calcium chloride concentrations induced formation of stronger gels. Interestingly, pre-treatment of the milk at <NUM> for <NUM> minutes before calcium chloride addition and subsequent heating at <NUM> was leading to the strongest gels. Gel formation is not desirable in many semi-solid food and beverage products.

] reported when treating <NUM>% whey protein (beta-lactoglobulin) with an addition of calcium chloride at pH <NUM> it was leading to microgels or gel formation upon heating at <NUM> or <NUM> when calcium content was <NUM>-<NUM> for a protein concentration of <NUM> wt. Again gel formation is not desirable in many semi-solid food and beverage products.

<CIT> discloses the production of dairy-based RTD. The milk component comprises casein and whey proteins. The milk proteins are partially aggregated in the presence of hydrocolloids as stabilizing system and chelated calcium salts can be added to fortify the products.

<CIT> relates to a heat-treated liquid nutritional composition comprising <NUM> to <NUM> of protein per <NUM> of the composition, wherein at least <NUM> wt. % of the protein is micellar casein and at least <NUM> wt. % of the protein is hydrolysed whey protein.

<CIT> relates to a milk concentrate comprising caseins and whey proteins in the ratio <NUM>:<NUM> to <NUM>:<NUM>, wherein the casein/whey protein aggregates have a volume based mean diameter value Dv50 of at least <NUM> as measured by laser diffraction.

<CIT> relates to a beverage product comprising a partially denatured protein system including kappa-casein and beta-lactoglobulin, wherein said product has a pH comprised between <NUM> and <NUM>.

The prior art teaching shows that although viscosity may be obtained with calcium addition gelling of is a well-known effect which may be undesirable in food production.

Furthermore, the pH of the product may vary and influence process and may lead to instability of the product. The prior art does not show how to provide food and beverage products delivering desirable taste and texture.

Thus, there is a need for food and beverage products exhibiting nutritional balance of macronutrients while delivering great taste, texture and shelf stability.

It is thus the object of present invention to provide a dairy concentrate with improved texture and mouthfeel and a method of making it according to the appended claims.

The present invention provides the improvement by the use of milk protein-based aggregates by specific heat treatment in the presence of a specific concentration of added divalent cations. It was surprisingly found that there is a critical range of divalent cations addition leading to optimum protein aggregation without precipitation or gelation of the formed aggregates upon heating.

In a first aspect, the invention relates to a method of producing a dairy concentrate, comprising the steps of:.

When carrying out experiments on the effect of divalent cations addition, in particular calcium, to full fat milk on protein aggregation and viscosity built up, it was surprisingly found that there is a critical range of divalent cations addition leading to optimum protein aggregation without precipitation or gelation of the formed aggregates upon heating. When this optimum concentration of calcium is passed, the system either exhibited over-aggregation with precipitation or a decrease of aggregate size.

Without being bound to theory, it is likely that calcium chloride addition to proteins is leading to an exchange between the protons adsorbed at the surface of the proteins and the calcium ions which have a higher affinity. This phenomenon resulted in a decrease of the pH of the dispersion and thereby a decrease of electrostatic repulsions between proteins. In these conditions, subsequent heat treatment of milk or milk based dispersions and emulsions is leading to a controlled aggregation of the proteins which was shown to affect positively the textural and sensorial properties of the finished products.

A major advantage of this invention is that it allows to texturize reduced fat milk-protein based concentrates and enables a reduction or elimination of the use of additional hydrocolloids and/or emulsifiers.

In the present context the agglomerates created with the method according to the invention and present in the product of the invention have a size of <NUM> - <NUM> microns, preferably <NUM> - <NUM> microns, more preferably <NUM> - <NUM> microns, as measured by D(<NUM>,<NUM>) mean diameter. The agglomerate particle size distribution is measured (PSD) using a laser granulometer such as a Mastersizer <NUM> (Malvern Instruments, UK). For the measurements a sample may e.g. be dispersed in the Hydro SM measuring cell until an obscuration rate of <NUM>-<NUM>% is obtained and then analysed in the Mastersizer.

Further in the present context the free divalent cations may be measured by means of a selective electrode. For example, free (ionic) calcium concentration is determined a Mettler Toledo calcium selective electrode perfection™ DX series half cells with BNC connector P/N <NUM> connected to a 692pH/Ion meter (Metrohm Switzerland).

Further in the present context unless otherwise indicated % of a component means the % of weight based on the weight of the composition, i.e. weight/weight %.

In addition by "dairy concentrate" may be a dairy culinary product, a soup or soup base, a dessert, a whipping cream, a tea or coffee creamer or enhancer, a dairy component in coffee mixes and dairy component for use in a beverage system such as a beverage vending system.

Furthermore, in the present context "stirring" means moving the ingredient composition. The stirring may result in a shearing of the ingredient composition. If it does it is preferred that this is done without destroying the agglomerates.

In a preferred embodiment of the invention the aggregates are <NUM> - <NUM> microns, preferably <NUM> - <NUM> microns. This give a desirable mouth feel to the product without the aggregates providing grittiness.

The divalent cations are calcium cations.

Advantageously, the divalent cations are added until the free divalent cations concentration is <NUM> - <NUM> divalent cations. It has been found that amounts that need to be added in dairy concentrate are <NUM> - <NUM>.

Furthermore, it is preferred that the divalent cations are added in form of a calcium mineral salt, selected from the group consisting of calcium chloride, calcium lactate calcium gluconate or calcium phosphate. In a particular preferred embodiment of the invention the calcium salt is calcium chloride.

In an all-natural embodiment of the invention the calcium is obtained from concentrated minerals from milk after separation of the protein, fat and lactose by e.g. membrane fractionation.

In accordance with the invention the pH of the ingredient composition is preferably <NUM> - <NUM> before adding the calcium cations.

The content of soluble protein in the ingredient composition is preferable below or equal to <NUM>% in relation to the total protein content indicating that the majority of the proteins are in the form of aggregates.

In one embodiment of the invention the ingredient composition comprises from <NUM> - <NUM> wt. % fat, preferably <NUM> - <NUM> wt. %, more preferably <NUM> - <NUM> wt. %, most preferably <NUM> - <NUM> wt. It has been found that even with low amounts of fat the texture of the product is still perceived as creamy due to the agglomeration created within the product.

The caseins and whey protein in the ingredient composition are preferably provided in a form selected from the group consisting of raw milk, pasteurized milk, low heat concentrated milk, low heat milk powder, milk protein concentrate, milk protein isolate in liquid or powder format or a combination thereof while the additional whey proteins are provided in a form selected from the group consisting of sweet dairy whey, whey protein concentrates, whey protein isolates in liquid, concentrate or powder format or a combination thereof.

It has been found that the method according to the invention is particular useful for making dairy concentrates. The ingredient composition is a concentrate comprising <NUM> - <NUM>, preferably <NUM> - <NUM> wt. % milk solids.

In a particular preferred embodiment of the invention the concentrate is dried into powder by means of freeze drying, spray drying or roller-drying.

It was surprisingly found that the addition of divalent cations and the process conditions of the present invention form agglomerates with the casein micelles, which results in increased colloidal particle size, water binding and overall viscosity. Surprisingly the structure and function after drying the composition is maintained. It was observed that current high pressure spray drying conditions for standard milk powder manufacture resulted in high shear effect that destroyed the controlled aggregation of proteins and thus the functionality during spray drying process. Several types of atomization are known for spray drying such as centrifugal wheel, hydraulic (high) pressure-nozzle, pneumatic (two phase nozzle) and sonic atomization. The term "low pressure drying system" refers to centrifugal wheel or pneumatic atomization systems which protects the structure of the casein-whey protein aggregates. It has been observed that high pressure atomizers such as hydraulic (high) pressure-nozzle atomization results in shearing effect thus destroying the casein-whey protein aggregates and thus its unique functionality. Such high pressure atomizers are useful for making conventional milk powders; however such a high-pressure system is not suitable for producing samples of the present invention. It has however been found that spray drying using low pressure drying system preserves the functionality of the product. The low pressure nozzles may operate below <NUM> bars, more preferred below <NUM> bars, preferably below <NUM> bars.

Milk protein-based aggregates obtained by calcium chloride addition in heated full fat milk.

Chilled pasteurised and microfiltered full fat milk (<NUM> wt. % fat) was provided by Cremo S. (Le Mont-sur-Lausanne, Switzerland). It had an initial pH of <NUM> as measured at <NUM>. For calcium addition a solution of CaCl2, <NUM>(H20) (Merck, Darmstadt, Germany) was prepared at <NUM> in MilliQ water. A volume <NUM> of milk were introduced in a Pyrex glass bottle of <NUM> (Schott Duran type, Germany) for each calcium chloride solution addition to cover a free calcium addition ranging from <NUM> - <NUM>. Magnetic stirring was performed <NUM> rpm and at room temperature <NUM>-<NUM>.

After calcium chloride addition, <NUM> of milk were introduced in a <NUM> sealed glass tube containing a magnetic barrel. The closed tubes were partially (<NUM>/<NUM>) immerged for <NUM> in a water bath regulated at <NUM> in order to reach a product temperature of <NUM> in <NUM> minutes. The incubation was done under magnetic stirring (<NUM> rpm) to ensure shearing of the samples. After incubation the tubes were transferred in iced water for cooling.

The capillary viscosity was determined using Rheotest LK <NUM> (Medingen GmbH, Dresden, Germany) and the particle size distribution (PSD) using Mastersizer <NUM> (Malvern Intruments, UK).

The direct visual appearance of the tubes was done to detect the first free calcium chloride concentration where protein aggregates were formed. Ionic (free) calcium concentration after heating was determined a Mettler Toledo calcium selective electrode perfection™ DX series half cells with BNC connector P/N <NUM> connected to a 692pH/Ion meter (Metrohm Switzerland).

It can be seen from Table <NUM> that the original milk already contained <NUM> free ionic calcium in the form of soluble colloidal calcium. The addition of CaCl2 in milk was leading to an increase in free ionic calcium but also to a decrease of pH after heating. Up to an added calcium chloride concentration of <NUM> (corresponding to <NUM> measured free calcium) the particle size in the heat milk remained around <NUM> for D43 and <NUM> for D32 which is corresponding to the size of protein coated milk fat droplets and to the casein micelles. Above this critical CaCl2 value, larger particles are being formed reaching hundreds of microns for D43 and D32. These aggregates are visible on the surface of the glass tubes in <FIG>. Surprisingly, the size of protein-based aggregates reaches a maximum at about <NUM> CaCl2 and then decreased steadily while more calcium was present in the system. The viscosity of the system increases with the increase of the calcium chloride content. Systems did not gel proving that the interactions between the protein aggregates could be controlled by applying shearing in the tubes while heating.

The stock solution of micellar caseins dispersion was prepared at a protein concentration of <NUM> wt. Micellar caseins concentrate Promilk852B (batch <NUM>) was purchased from Ingredia (Arras, France). The powder composition was (g/<NUM> wet powder): protein (Nx6. <NUM>) <NUM>, Ca <NUM>, Mg <NUM>, Na <NUM>, K <NUM>, Cl <NUM>, P <NUM>. The mass of powder needed to prepare the dispersion was calculated as a function of the protein content in the powder.

Micellar casein powder was hydrated in MilliQ water for <NUM> hours under stirring at the room temperature. After <NUM> hours, the protein dispersion was homogenized with an EmulsiFlex C-<NUM> high pressure, single-stage homogenizer (Avestin®, Canada). This treatment decreased the average particle size of micellar caseins and the amount of non-sedimentable caseins (κ, αs1; and αs2) in serum increases, it allows to stabilize the solution and avoids the sedimentation of the MCI.

The average particle diameter was determined after the homogenization using a Nanosizer ZS (Malvern Instruments®, UK) and it was monodisperse and around <NUM>.

O/W emulsions were prepared by the addition of high oleic sunflower oil (Oleificio Sabo, Manno, Switzerland) to the proteins dispersions so that total sample resulted in oil content of <NUM>, <NUM> and <NUM> wt. % and a constant protein content of <NUM> wt. The mixtures were subsequently pre-homogenized using an Ultra-Turrax T25 basic (IKA®, Switzerland) at <NUM>,<NUM> rpm/min during <NUM> minute for a volume of <NUM>. The pre-homogenized emulsions were after homogenized at High Pressure with a PandaPLUS HomoGenius <NUM> (GEA®, Germany) adjusted at <NUM> bars for the first valve and at <NUM> bars for the second one, to obtain a pressure total of <NUM> bars.

Emulsions were homogenized twice by this method. After homogenization, pH and concentration of CaCl2 were adjusted to defined target values. Samples with different pH were heated up at <NUM> during <NUM> in a hot water bath just after have been prepared and <NUM> hour after for different concentration of CaCl2. Emulsions were after cooled in iced-water during <NUM> and stored at <NUM> during <NUM> hour.

The samples were afterward sheared at <NUM>,<NUM> rpm during <NUM> using a Ultra-Turrax T25 basic (IKA®, Switzerland) in a beaker for a volume of <NUM>, thirty circles were applied in order to have the same shearing for all the volume. Emulsions were after stored at <NUM> until the analyses were done.

In order to assess particles size distribution, dispersions and emulsions were analyzed after shearing by dynamic light scattering using a MasterSizer <NUM> (Malvern Instruments Ltd®, UK). The emulsion sample was dispersed in the Hydro SM measuring cell until an obscuration rate of <NUM>-<NUM>% was obtained. Non-heated and heated samples were analyzed. Measures were performed three times and the average of the three replications was reported.

Cryogenic cuts were done in order to analyze samples by CLSM. To this aim, sucrose and formaldehyde were added at the samples in order to conserve them (PRICE and JEROME, <NUM>). Percentage are for the sucrose <NUM> wt. % of the total volume and <NUM> wt. % for the formaldehyde. Samples were homogenized using a vortex and stored overnight at <NUM> before beginning analyses.

Afterwards, samples were fixed. This step consisted of adding <NUM> of the sample in <NUM> of Optimum Cutting Temperature (OCT) Compound for Cryostat Sectioning, Tissue-Tek®. The composition was homogenized and <NUM> were added in the cryostat sample holder, itself containing already OCT Compound for Cryostat Sectioning, Tissue-Tek®.

The cryostat sample holder was immersed in a plastic vial containing <NUM> of <NUM>-Methylbutane (<NUM>% from Sigma Aldrich®, US), itself immersed in Sagex box of nitrogen liquid. The solution of <NUM>-Methylbutane ensures a good freezing of the sample and protects it from the drying.

Samples were then placed in a Cryostat CM <NUM> (Leica®, Switzerland). Microtome cuts were afterwards done at <NUM> of thickness at -<NUM>. Microscope slides were conserved in a freezer at -<NUM> until the analyses were performed.

Microscope slides were previously treated with HistoGrip (<NUM>× concentrate from ThermoFisher Scientific®, US) for adhering tissue to glass slides and avoid to remove tissues during harsh processes.

In order to distinguish proteins and fat globules, individual samples <NUM>/<NUM> (MCI/SPI) and <NUM>/<NUM> (MCI/SPI) were labelled with dyes.

Fast Green was used to color proteins and Nile Red for fat globules. According to FOWLER et al. , <NUM>, Nile Red is an excellent dye for the detection of intracellular lipid droplets by fluorescence microscopy, it is highly hydrophobic and fluorescent. <NUM> of Nile Red was solubilized in <NUM> of ethanol. The excitation wavelength was achieved using the <NUM> emission from the diode laser and the emitted light was collected between <NUM> and <NUM>.

Fast Green is an organic dye, electrostatically attracted to charged groups on proteins (MERRIL and WASHART, <NUM>). It can bind non-covalently to the biopolymer of interest by electrostatic interactions (AUTY, <NUM>). The excitation wavelength was set using the <NUM> emission from the diode laser and the emitted light was collected between <NUM> and <NUM>. The Fast Green used was at <NUM> wt. % in water.

Samples were dyed with a mix of Nile Red (<NUM>µL) and Fast Green (<NUM>). The mix was put on the microscope slides for <NUM> and rinsed. Slides were mount with a set mounting Vectashield Hard Set Mounting Medium (Vector Laboratories®, US).

Microscope slides were after analyzed using a Zeiss® LSM <NUM> Confocal Scanning Microscope (Zeiss®, Germany). The CLSM is equipped with lasers allowing the excitations of several fluorescent probes at the same time, this capability allows multi-imaging of a sample by selecting the correct excitation wavelength and filters to collect the emission light from a particular dye. A <NUM>×/<NUM> ∞/<NUM>/PL APO and <NUM>×/ <NUM> oil/DIC <NUM>-<NUM>/ PL APO was used for all images.

One day after shearing, flow experiments were performed using a controlled stress rheometer Physica MCR501 (Anton Paar®, Austria) with concentric cylinders geometry CC27-SS/S (diameter = <NUM>, gap= <NUM> by Anton Paar®, Austria).

Steady state flow measurements were conducted in a constant temperature of <NUM>, a shear stress of <NUM><NUM>/s was applied to the samples during <NUM>, following by four shear rates, one from <NUM> - <NUM><NUM>/s and one other from <NUM> - <NUM><NUM>/s, these were done twice; <NUM> measurements each <NUM> were done. The apparent viscosity was recorded as a function of the shear rate.

For each measurement, an aliquot (<NUM>) of the emulsion sample was poured into the cup. Measures were performed three times and the average of the three replications was reported.

In order to characterize content in soluble proteins in the products from the invention, emulsions were centrifuged at <NUM>,<NUM> at room temperature for <NUM> using an Eppendorf® centrifuge <NUM> (Vaudaux-Eppendorf AG®, Switzerland), one day after production. Supernatant was carefully withdrawn and stored at <NUM> in order to be analyzed by Reverse Phase-Ultra Performance Liquid Chromatography (RP-UPLC).

The UPLC system (Waters Corp Milford Ma, USA) consisted of a binary pump, a temperature controlled auto-sampler (sample manager-UPSMPM6R) and a photodiode array detector (UPPDA-E). The equipment was controlled by the Empower® <NUM> software, Pro version.

Separations were performed on a reversed-phase analytical column Acquity UPLC® BEH300 C4 <NUM> <NUM>. 1x150 mm (Waters Corp Milford Ma, USA) and on VANGUARDTM Pre-column BEH300 C4 <NUM> <NUM> × <NUM> (Waters Corp Milford Ma, USA). UPLC vials were kept at constant temperature <NUM>± <NUM> and injected by the sample manager system. A <NUM>µL injection syringe and a <NUM>µL injection loop were used.

Standards of caseins were prepared at concentrations of <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> wt. % by dilution in milliQ water from a <NUM> wt. % reference solution. In a <NUM> Eppendorf® microtube, <NUM>µL of the sample and <NUM>µL of buffer {Guanidine-HCl <NUM>,<NUM> ; Trisodium Citrate <NUM> ; DTT <NUM>} were added. The sample's and buffer's masses were accurately weighted. The composition was then homogenized using a vortex and incubated in an Eppendorf® Thermomixer Compact (Vaudaux-Eppendorf AG®, Switzerland) at <NUM> for <NUM> at <NUM> rpm.

After incubation, samples were homogenized and centrifuged at <NUM>,<NUM> for <NUM> at room temperature using Eppendorf® centrifuge <NUM> (Vaudaux-Eppendorf AG®, Switzerland). Supernatant was then carefully withdrawn and introduced in a UPLC Vial, watching out for the fat layer and also to not suspend the pellets if presents. The injection volume was variable from <NUM>µL - <NUM>µL, adapted to the sample's protein content (determined by Kjeldahl method, Nx6. <NUM>) to have sufficient signal. The standards were also injected with adjusted volumes in order to consider variability.

A gradient elution was carried out with two solvents mixed during the elution. Solvent A consisted of <NUM>% TFA in water and solvent B was <NUM>% TFA in acetonitrile/water (<NUM>/<NUM>) (v: v). Separations were performed with a linear gradient from <NUM> - <NUM> % B in <NUM> (<NUM>% B. min-<NUM>), <NUM> - <NUM>% B in <NUM> (<NUM>% B. min-<NUM>) and from <NUM>% B - <NUM>% B in <NUM> (<NUM> % B. min-<NUM>). This was followed by an isocratic elution at <NUM>% B during <NUM>. Then returned linearly to the starting condition in <NUM>, followed by the rebalance of the column for <NUM>.

The flow rate was <NUM>. min-<NUM> and the column temperature was kept constant at <NUM> ± <NUM>. The acquisition was achieved at λ = <NUM> (resolution <NUM> - <NUM> points/sec - Exposure time automatic).

Each chromatogram was manually integrated. For calibration curves, the total area was plotted as a function of proteins amount injected. The soluble protein content was calculated from the ratio of protein amount present in the supernatant after centrifugation and the total amount of protein present in the emulsion without centrifugation and expressed in percentage.

<FIG> shows that upon heat treatment and shearing, the size distribution of the emulsions at pH <NUM> exhibit a peak around <NUM>-<NUM> for the <NUM> sunflower oil content tested. On the contrary, larger particles are formed when the heat treatment in achieved in presence of <NUM> added fee calcium. Hence, there is a clear shift of the size distribution to around <NUM>-<NUM> microns, indicating that the initial oil droplets had aggregated into larger protein based particles.

The microstructure of the protein based aggregates is clearly shown on <FIG>. More numerous aggregates were obtained when the oil content in the emulsion was increased (<FIG>). Interestingly, larger magnification of the particles show that these are composed by oil droplets tightly included in a surround protein matrix (<FIG>). The higher the sunflower oil content in the emulsion, the more compact and spherical the shape of the particles was (<FIG>). On the contrary, more branched and elongated particles were obtained for the lowest oil content (Figure A). The soluble protein content in the emulsion at <NUM> wt. % oil was found to be <NUM>% at pH <NUM> while upon heat treatment in presence of <NUM> calcium chloride, it was found to be about <NUM>% as revealed by UPLC analysis.

The flow properties of emulsion produced with <NUM> wt. % oil was compared after heat treatment and shearing at pH <NUM> and after addition of <NUM> CaCl2. The flow properties are shown in <FIG>.

The emulsion produced at pH <NUM> exhibited a Newtonian flow behaviour with an independence of the viscosity as a function of shear rate. This is explained by the fact that viscosity is mainly driven by the oil volume fraction and that the oil droplets are not interacting. In the sample of the present invention containing <NUM> calcium, the flow behaviour is shear thinning, which is an indication that shear sensitive particles have been produced, affecting the overall flow behaviour. The sample viscosity is compared for the <NUM> sunflower oil contents tested at a shear rate of <NUM>-<NUM> which is relevant for in-mouth conditions (see <FIG>). It can be seen that at pH <NUM>, the viscosity slightly increases with increasing the oil content. For samples of the present invention prepared in presence of calcium, the viscosity was about <NUM> to <NUM> times larger than the corresponding sample at pH <NUM>. This clearly indicates that the particles of the present invention enables to build viscosity at a much lower oil content, enabling fat lowering in food products, see <FIG>.

A set of <NUM> samples were produced according to the following procedure, involving: concentration of a commercial whole milk to <NUM>% total solids (TS) content, adding a variable amount CaCl2 (<NUM> and <NUM>) in the milk concentrate, standardized heat processing including a direct steam injection step, and spray drying to obtain a functionalized milk powder.

Commercially available, pasteurized and microfiltered, homogenized whole milk (<NUM>% fat content, Cremo, Le Mont-sur-Lausanne, CH) is concentrated to a total solid content as indicated in the table <NUM>, with a Centritherm® CT1-<NUM> thin film spinning cone evaporator (Flavourtech Inc.

The concentration process is done in recirculating batch mode, starting with milk at <NUM>. The milk is pumped with a progressing cavity pump, from a buffer tank through a plate heat exchanger set to <NUM> outlet temperature and the Centritherm® CT1-<NUM> evaporator, back into the buffer tank. The milk in the buffer tank thereby gradually increases in solid concentration and temperature. When a critical concentration threshold is reached, the milk is brought to the desired total solids content by a final evaporator pass without remixing, and collected in a separate holding tank.

The following process parameters are used: flow rate <NUM>/h, evaporator inlet temperature <NUM>, evaporator vacuum pressure <NUM> - <NUM> mbar, evaporator steam temperature <NUM>. This results in concentrate outlet temperatures of around <NUM>, and evaporate flow rates which decrease gradually from about <NUM>/h - <NUM>/h with increasing milk concentration. High product flow rates around <NUM>/h and a stable product inlet temperature of <NUM> are important to avoid fouling of the milk concentrate on the heat exchange surface of the Centritherm® device.

The milk concentrate is cooled to <NUM> and the required amount of CaCl2, 2H2O powder (Merck, Darmstadt, Germany) was added, under agitation, to the milk. The typical timeframe for calcium powder addition to a <NUM> batch is about <NUM> minutes.

The cooled, calcium loaded milk concentrate was heat-processed in semi-continuous mode on a commercially available OMVE HT320-<NUM> DSI SSHE pilot plant line (OMVE Netherlands B. Processing steps are: preheating in the OMVE tubular heat exchanger to <NUM>, direct steam injection to <NUM> outlet temperature, <NUM> sec hot holding period at <NUM> in the two scraped surface heat exchangers of the OMVE line, connected in series and running at maximum rpm, and subsequent cooling to about <NUM> product outlet temperature the OMVE tubular heat exchanger cooled with ice water. The flow rate is set to <NUM>/h to obtain a sum of approximately <NUM> sec residence time in the scraped surface heat exchanger units. Residence time in the OMVE cooler is about <NUM> minutes. The residence times are averages from volumetric flow rates and dead volume of line elements (tubular heat exchanger, scraped surface heat exchanger).

Clogging of the DSI injector is a critical phenomenon, and the line must be carefully controlled in this respect. No flash evaporation is applied and condensing steam remains entirely in the product.

The heat-processed milk concentrate with <NUM> calcium added was spray-dried on a Niro SD <NUM> pilot plant spray tower (GEA NIRO Process Engineering, DK), equipped with a FS1 rotary atomizer. Operating parameters are: Product feed rate <NUM> - <NUM>/h, product inlet temperature in the rotary atomizer <NUM> - <NUM>, rotary atomizer speed <NUM> rpm, airflow <NUM> - <NUM>/h (mass flow control), air inlet temperature <NUM>, exhaust air temperature <NUM> and exhaust air relative humidity <NUM>%. The finished powder product is packed immediately in air-tight bags and has a residual humidity below <NUM> %.

The same methods as those used in example <NUM> were used to characterize sample size distribution, microstructure and flow properties. For the experiments carried on spray dried powder containing <NUM> CaCl2, sample was reconstituted to <NUM> or <NUM>% TS before measurements. Distilled water was poured into a beaker and heated up to <NUM> - <NUM> with a water bath. A volume of <NUM> distilled water at <NUM> - <NUM> was measured and transferred into a glass beaker using a volumetric cylinder. An amount of <NUM> milk powder is added to the <NUM> distilled water at <NUM> and mixed with a spoon for <NUM>.

It can be seen from table <NUM> that the samples of the present invention were exhibiting a marked increase in particle size after heat treatment leading to an increase in viscosity. It can be seen that in the presence of <NUM> calcium chloride addition, the D(<NUM>,<NUM>) increased to <NUM> microns which was leading to a slight sandiness of the sample. For this milk concentration, the best conditions and aggregation profile were obtained with <NUM> CaCl2 addition which can be inferred also by the higher viscosity reached (<NUM> mPa. s) compared to <NUM> CaCl2 addition (<NUM> mPa. After spray drying, the samples have been characterized upon reconstitution in MilliQ water.

The distribution of particles upon reconstitution is exhibiting a peak at about <NUM> microns (see <FIG>) which is very close to the particle size obtained before spray drying (D(<NUM>,<NUM>) = <NUM> microns, Table <NUM>). The slight reduction in particle size might be due to the shearing effect occurring during the spray drying of the product. Surprisingly, the soluble protein content obtained after reconstitution of the powder at <NUM>% TS was <NUM>% of the total proteins, indicating that the majority of the milk proteins were involved in the aggregate structure.

The microstructure of the particles can be seen on <FIG>. Aggregates were rather compacts and were composed of proteins and fat droplets with no sign of non-reacting proteins which is confirming the low amount of soluble proteins. Higher magnification of the particles on <FIG> shows well embedded fat droplets with an average size of <NUM>-<NUM> microns embedded in a dense protein matrix. There is little sign of fat droplet coalescence indicating that aggregate formation arose from a flocculation mechanism.

The milk spray dried powder according to the present invention was reconstituted to <NUM>% TS which is generally the TS at which full fat milk is spray dried. It can be seen of <FIG> that the flow behavior is strongly shear thinning, exhibiting a steep negative slope and a high low shear viscosity. This is a sign that the product upon reconstitution had built some structure and that protein aggregates were able to interact between each other. Surprisingly, the structure could be recovered upon releasing the stress on the sample as the up and down curves were almost superimposed.

Commercially available, pasteurized, homogenized whole milk (<NUM>% fat content, Emmi, Lucerne, CH) was concentrated by a Scheffers <NUM> effects falling film evaporator (from Scheffers B. ) to <NUM>% total solids. The milk concentrate is cooled by a plate heat exchanger to <NUM> and pH of homogenized liquid milk concentrate was measured to be <NUM>. The composition is preheated again to <NUM> by a plate heat exchanger and subsequently heated to <NUM> by direct steam injection system (self-construction of Nestlé) with a holding time of <NUM> seconds. After the heat treatment, the milk concentrate is rapidly cooled down by a 3VT460 CREPACO scrape heat exchanger (from APV Invensys Worb) to <NUM>. The milk concentrate is then spray dried on a Nestlé <NUM> Egron (self-construction) by a two-phase nozzle system (<NUM> nozzle) to maximal moisture content of <NUM>% and packed into air tight bags. Conditions of spray drying were: product flow of <NUM>/h at <NUM> product temperature, hot air inlet temperature of <NUM> and an air flow of <NUM>/h, outlet air temperature of <NUM>.

Commercially available, pasteurized, homogenized whole milk (<NUM>% fat content, Emmi, Lucerne, CH) was concentrated by a Scheffers <NUM> effects falling film evaporator (from Scheffers B. ) to <NUM>% total solids. The milk concentrate is cooled by a plate heat exchanger to <NUM> and <NUM> calcium chloride is added. The calcium adjusted milk concentrate is preheated again to <NUM> by a plate heat exchanger and subsequently heated to <NUM> by direct steam injection system (self-construction of Nestlé) with a holding time of around <NUM> seconds. After the heat treatment, the milk concentrate is rapidly cooled down by a 3VT460 CREPACO scrape heat exchanger (from APV Invensys Worb) to <NUM>. The milk concentrate is then spray dried on a NIRO SD6 3N spray dryer by a rotary disc nozzle system at <NUM>,<NUM> rpm to maximal moisture content of <NUM>% and packed into air tight bags. Conditions of spray drying were: product flow of <NUM>/h at <NUM> product temperature, hot air inlet temperature of <NUM> and an air flow of <NUM><NUM>/h, outlet air temperature of <NUM>.

The milk powders of the present invention were compared to the above references and were characterized by laser diffraction in order to determine particle size distribution (PSD = Particle Size Distribution).

Powdered samples were reconstituted before measurements. Distilled water was poured into a beaker and heated up to <NUM> - <NUM> with a water bath. A volume of <NUM> distilled water at <NUM> - <NUM> was measured and transferred into a glass beaker using a volumetric cylinder. An amount of <NUM> milk powder is added to the <NUM> distilled water at <NUM> and mixed with a spoon for <NUM>.

Dispersion of the liquid or reconstituted powder sample in distilled or deionised water and measurements of the particle size distribution by laser diffraction.

Measurement settings used are a refractive index of <NUM> for fat droplets and <NUM> for water at an absorption of <NUM>. All samples were measured at an obscuration rate of <NUM> - <NUM>%.

Samples were reconstituted to <NUM>% TS using the process described above. Flow experiments were performed using a controlled stress rheometer Physica MCR501 (Anton Paar®, Austria) with concentric cylinders geometry CC27-SS/S (diameter = <NUM>, gap= <NUM> by Anton Paar®, Austria). Steady state flow measurements were conducted in a constant temperature of <NUM>, a shear stress of <NUM><NUM>/s was applied to the samples during <NUM>, following by four shear rates, one from <NUM> to <NUM><NUM>/s and one other from <NUM> to <NUM><NUM>/s, these were done twice; <NUM> measurements each <NUM> were done. The apparent viscosity was recorded as a function of the shear rate.

For each measurement, an aliquot (<NUM>) of the emulsion sample was poured into the cup. Measures were performed three times.

The size distribution of full fat milk spray dried at <NUM>% TS was determined after reconstitution to <NUM>% TS (<FIG>). It can be seen on <FIG> that a major peak was found <NUM> micron, followed by a tailing up to <NUM> microns. This indicates that the milk fat droplets and the micellar casein from milk are concomitantly measured that that no significant aggregation had occurred in the system. For the sample of the present invention that was treated in presence of <NUM> added calcium chloride, the size distribution was shifted to larger particle diameters. The D(<NUM>) reached <NUM> microns accounting for the presence of protein aggregates, while a small residual peak about <NUM> microns probably accounted for unreacted micellar caseins (<FIG>). The levels of soluble proteins were <NUM>% in the control milk sample while it was <NUM>% in the sample produced in the presence of added calcium. This shows again that the present invention favors the protein aggregation and the entrapment of oil droplets in the protein aggregates.

Claim 1:
A method of producing a dairy concentrate, comprising the steps of:
providing an ingredient composition comprising micellar caseins and whey proteins and having a pH of <NUM> - <NUM> and a concentration of <NUM> - <NUM> wt.% of proteins, and wherein the ingredient composition has a casein to whey protein ratio of <NUM>/<NUM> - <NUM>/<NUM>,
adding <NUM> - <NUM> divalent cations to provide a concentration of <NUM> - <NUM> free divalent cations in the ingredient composition,
homogenising the ingredient composition; and subsequently
pasteurising and stirring the ingredient composition at a temperature of <NUM>°- <NUM> for a period of <NUM> - <NUM> to form agglomerated proteins comprising caseins and beta-lactoglobulin from the whey proteins, the agglomerates having a size of <NUM> - <NUM> microns as measured by D(<NUM>,<NUM>) mean diameter, and wherein the ingredient composition is a concentrate comprises <NUM> - <NUM> wt.% milk solids, and wherein the divalent cations are Ca.