Gas-injection extrusion for producing infant formula products

Abstract

The present invention concerns a process for manufacturing an infant formula product comprising: (a) subjecting an aqueous mixture having a protein component and a carbohydrate component to a heat treatment step; (b) mixing the aqueous mixture with a lipid component; (c) subjecting the aqueous mixture comprising the lipid component, the carbohydrate component and the heat-treated protein component to a homogenization and emulsification step to obtain a homogenized oil-in-water emulsion having a total solids content in the range of 45-80 wt %; (d) conveying the homogenized emulsion into an extruder, independently adding digestible carbohydrates and optionally dietary fibres to the extruder and extruding the contents of the extruder wherein a gas is injected into the extruder, to obtain an extruded aerated material (e) preparing an infant formula product from the extruded aerated material. The invention further concerns Infant formula product obtainable by the process according to the invention and to a modular system suitable for performing the process according to the invention.

Claims

1. Process for manufacturing an infant formula product comprising the following steps: (a) subjecting an aqueous mixture having a protein component and a carbohydrate component to a heat treatment step, (b) mixing the aqueous mixture with a lipid component, (c) subjecting the aqueous mixture comprising the lipid component, the carbohydrate component and the heat-treated protein component to a homogenization and emulsification step to obtain a homogenized oil-in-water emulsion having a total solids content in the range of 45-80 wt %; (d) conveying the homogenized emulsion into an extruder, independently adding digestible carbohydrates and optionally dietary fibres to the extruder and extruding the contents of the extruder wherein a gas is injected into the extruder, to obtain an extruded aerated material; (e) preparing an infant formula product from the extruded aerated material.

2. The process according to claim 1, wherein step (e) involves spray-drying of the extruded material.

3. The process according to claim 1, wherein the protein component of the infant formula has a weight ratio of whey protein to casein in the range of 9/1 to 1/9.

4. The process according to claim 1, wherein the total solids content of the homogenized oil-in-water emulsion of step (c) is in the range of 53-68 wt %.

5. The process according to claim 1, wherein the digestible carbohydrates, such as lactose and/or maltodextrin, are added in step (d) as a dry powder and the dietary fibres are added as a dry powder or as a concentrated liquid.

6. The process according to any of the preceding claims, wherein the extrusion of step (d) is performed at a temperature below 75° C., preferably wherein the entire process, with the exception of the heat-treatment of step (a), does not exceed 75° C.

7. The process according to claim 1, wherein the heat treatment of step (a) is designed to obtain a microbial safe protein component and preferably is carried out by pasteurization, UHT, HTST or ESL.

8. The process according to claim 1, wherein the aqueous mixture of step (a) has a total solids content in the range of 15-40 wt %.

9. The process according to claim 1, wherein the aqueous mixture subjected to step (b) has a total solids content in the range of 35-60 wt %, prior to the mixing with the lipid component.

10. The process according to claim 1, wherein the total solids content of the aqueous mixture obtained in step (a) is increased, preferably by an evaporation step, prior to mixing with the lipid component.

11. The process according to claim 1, wherein skim milk and/or whey protein concentrate (WPC) are used as source of the protein component and carbohydrate component of the aqueous mixture subjected to step (a).

12. The process according to claim 1, wherein the carbohydrate component in step (a) comprises lactose, which lactose constitutes between 15 and 75 wt % of the total lactose contents of the infant formula product prepared in step (e).

13. The process according to claim 1, wherein the digestible carbohydrate that is added during step (d) comprises lactose and the amount of lactose added during step (d) lies between 0 and 80 wt % (on dry weight basis) of the total amount of lactose contained in the infant formula product obtained in step (e).

14. The process according to claim 1, wherein the digestible carbohydrate that is added during step (d) comprises lactose and the amount of lactose that is added during step (d) lies between 0 and 40 wt % of the total dry weight of the infant formula product obtained in step (e).

15. Infant formula product obtainable by the process according to claim 1.

16. The infant formula product according to claim 15, which is an infant formula, a follow-on formula, a toddler milk or a growing-up milk.

17. A modular system for carrying out the method steps according to claim 1 for manufacturing an infant formula.

18. A modular system for manufacturing an infant formula comprising: a heat-treatment module for heat-treating an aqueous mixture having a protein component and a carbohydrate component, a mixing module for mixing the aqueous mixture with a lipid component, a homogenization and emulsification module for subjecting the aqueous mixture comprising the lipid component, the carbohydrate component and the heat-treated protein component to homogenization and emulsification to obtain a homogenized oil-in-water emulsion, an extrusion module comprising an inlet for receiving the homogenized oil-in-water emulsion, a separate inlet for adding digestible carbohydrates and optionally dietary fibres into the extrusion module, an outlet for exiting of the extruded material, and a gas injection inlet, a drying module for drying the extruded material, and optional modules for milling and/or packaging the obtained material.

Description

FIGURES

[0121] The invention is illustrated by FIGS. 1 and 2, depicting preferred embodiments of the process according to the invention.

[0122] FIG. 1 depicts a preferred embodiment of the process according to the invention, wherein (a), (b), (c), (d) and (e) represent steps (a), (b), (c), (d) and (e) as defined herein. (1)=introduction of a source of protein and digestible carbohydrate; (2)=optional introduction of a second source of protein and digestible carbohydrate; (3)=introduction of a lipid component (4) introduction of a digestible carbohydrate component; (5)=optional introduction of a dietary fibre component; (6)=discharge of the infant formula product. Gas injection into the extruder is not shown.

[0123] FIG. 2 depicts a preferred embodiment of the process according to the invention, wherein (a), (b), (c) and (d) represent steps (a), (b), (c) and (d) as defined herein, (a′) represents a step wherein the aqueous mixture is increased in total solid content as defined herein; (e1) represents a drying step as defined herein; and (e2) represents a milling step as defined herein. (1)=introduction of a source of protein and digestible carbohydrate; (2)=optional introduction of a second source of protein and digestible carbohydrate; (3)=introduction of a lipid component (4) introduction of a digestible carbohydrate component; (5)=optional introduction of a dietary fibre component; (6)=discharge of the infant formula product. Gas injection into the extruder is not shown.

EXAMPLES

[0124] The following examples illustrate the invention.

Example 1

[0125] A process flow was generated for production of an infant formula intended for infants with an age of between 0 and 6 months. In a first step, demineralized whey (Demin Whey, flowrate 3166 kg/h), liquid whey protein concentrate 80 (WPC80, flowrate 430 kg/h), water (flowrate 677.2 kg/h) and the required amounts of micronutrients (i.e. vitamins and minerals) were compounded into an aqueous liquid with a total solids content (% TS) of 25 at a temperature of 35° C., and processed at a flowrate of 4419 kg/h.

[0126] The aqueous liquid was subsequently heat treated at 121.0° C. with a residence time of 2.89 seconds to achieve an F.sub.0 of 2.4. After cooling, the heated solution is subsequently fed into an evaporator for concentration purposes during which water was removed at a flowrate of 1943.5 kg/h. After evaporation, the aqueous solution has a % TS of 44.6 and is conveyed with a flowrate of 2475.5 at a temperature of 60° C. to the oil injector. Oils necessary to produce the infant formula are injected into the aqueous stream at a flowrate of 2337.32 kg/h to reach a % TS of 71.5. The solution is subsequently fed into a homogenizer for homogenization and emulsification at 60° C. using a flowrate of 4812 kg/h. The homogenized oil-in-water emulsion is conveyed to the extruder.

[0127] During extrusion, whey protein concentrate (WPC35, flowrate 388.8 kg/h), whey protein concentrate powder (WPC80, flowrate 91.2 kg/h), skim milk powder (SMP, flowrate 1349.3 kg/h), lactose (1417.4 kg/h) and GOS (Vivinal GOS; concentrated liquid at 75 wt %, flowrate 1685.9 kg/h) were added. GOS is added as the final ingredient during the extrusion process. Extrusion is performed at 63° C. at a flowrate of 9745.6 kg/h. The extrudate as obtained contained 80% TS and was ready for drying using known technologies, such as flash or vacuum belt drying, to end up with a nutritional composition with a % TS of 97.5 which was produced at a flowrate of 7996.4 kg/h. No dry blending of further ingredients is required. A powdered composition was obtained that was ready for packaging.

Example 2

[0128] A process flow was generated for production of an infant formula intended for infants with an age of between 6 and 12 months. In a first step, liquid whey protein concentrate 35 (WPC35, flowrate 1019.4 kg/h), water flowrate 3140.7 kg/h) and the required amounts of micronutrients (i.e. vitamins and minerals) were compounded into an aqueous liquid with a total solids content (% TS) of 25 at a temperature of 35° C., and processed at a flowrate of 4236.5 kg/h. Protein content of the aqueous liquid was 8.44 wt %.

[0129] The aqueous liquid was subsequently heat treated at 121.0° C. with a residence time of 2.89 seconds to achieve an F.sub.0 of 2.4. After cooling, the heated solution is subsequently fed into an evaporator for concentration purposes. After evaporation, during which water was removed with a flowrate of 1703.1 kg/h, the aqueous solution has a % TS of 41.8 and is conveyed with a flowrate of 2533.4 at a temperature of 60° C. to the oil injector. Oils necessary to produce the infant formula are injected with a flowrate of 2029.82 kg/h into the aqueous stream to reach a % TS of 67.69. The solution is subsequently fed into a homogenizer for homogenization and emulsification at 60° C. using a flowrate of 4563.2 kg/h. The homogenized oil-in-water emulsion is conveyed to the extruder.

[0130] During extrusion, skim milk powder (SMP, flowrate 1633.45 kg/h), lactose (2472.24 kg/h) and GOS (Vivinal GOS; concentrated liquid at 75 wt %, flowrate 1084.8 kg/h) were added. GOS is added as the final ingredient during the extrusion process. Extrusion is performed at 65° C. at a flowrate of 9753.68 kg/h. The extrudate as obtained contained 80% TS and was ready for drying using known technologies, such as flash or vacuum belt drying, to end up with a nutritional composition with a % TS of 97.5 which was produced at a flowrate of 8003.0 kg/h. No dry blending of further ingredients was required. A powdered composition was obtained that was ready for packaging.

Example 3

[0131] Data mentioned in example 1 and 2 were generated using the gPROMS gFormulatedProducts 1.2.2 simulation model from Process Systems Enterprise (PSE). Mass balance models used were steady state, meaning no accumulation in time is applied. Models were applied on a macro level without applying any discretization method.

[0132] For evaporation/concentration the mass balance of equation (1) was applied.

[00001]$\begin{array}{cc}0={\phi }_m^{in}-{\phi }_m^{out}-{\phi }_m^{evap}& \left(1\right)\end{array}$

It states that the amount of evaporated water or water otherwise removed

[00002]$\left(\frac{\mathrm{kg}}{s}\right)$

from a stream, plus the outlet from a stream should be equal to an inlet stream. From this perspective the outlet total solids

[00003]$\left(\frac{\mathrm{kg}}{\mathrm{kg}}\right)$

were calculated via equation (2):

[00004]$\begin{array}{cc}{x}_{s\mathrm{olids}}^{out}=\frac{x_{s\mathrm{olids}}^{in}{\phi }_m^{in}}{{\phi }_m^{out}}& \left(2\right)\end{array}$

This was applied under the assumption that extracted water, extracted via evaporation or any other technology, is pure water.

[0133] The same approach was used for mixing of different streams either within compounding (i.e. preparation of an aqueous mixture prior to heat treatment step a), fat injection (i.e. step b) or extrusion (step d). Equation (3) applies for the total mass balance:

[00005]$\begin{array}{cc}{\phi }_m^{out}=\underset{i=1}{\overset{N_{\mathrm{streams}}}{.Math.}}{\phi }_{m_i}^{in}& \left(3\right)\end{array}$

The solids outlet of any mixer and/or extruder was calculated by adapting equation (3) in case multiple inlet streams were applied:

[00006]$\begin{array}{cc}{x}_{s\mathrm{olids}}^{out}=\frac{{.Math.}_{i=1}^{N_{\mathrm{stream}s}}{x}_{\mathrm{solids},i}^{in}{\phi }_{m_i}^{in}}{{\phi }_m^{out}}& \left(4\right)\end{array}$

For the drying step, independent of the drying technology, equations 1 and 2 were applied to calculate the water evaporation capacity.

[0134] These equations were applied in a flowsheet construction. The information passed between models in a product flow are the mass flowrate and the composition (kg/kg).

Example 4

[0135] A process flow was generated for production of an infant formula intended for infants with an age of between 0 and 6 months. First, 40 kg of a mixture of demineralized whey and minerals (95% TS) was compounded into 35 kg water to obtain a solution having a total solids content of 51% at a temperature of 29° C. The wet phase was subsequently fed into an oil injector and homogenizer. 39 kg of Oil necessary to produce the infant formula was injected into the aqueous stream to obtain 113 kg of an emulsion at 68% TS. The solution is subsequently homogenized at 60° C. The viscosity of the homogenized emulsion was determined to be 107 kcP (determined at 42° C. in a rotational viscometer).

[0136] The homogenized oil-in-water emulsion is conveyed to the extruder at a flow rate of 12.2 kg/h. During extrusion, GOS (Vivinal GOS; concentrated liquid at 75% TS, flowrate 3.3 kg/h), lactose (95% TS; 2.6 kg/h) and skim milk powder (SMP, 95% TS, 1.8 kg/h) were added. Extrusion is performed at 550 rpm and a temperature gradient of 55° C..fwdarw.65° C..fwdarw.4 T.sub.g, using 30 L/h N.sub.2 or 50 L/h CO.sub.2 as aeration gas. The gas was injected at T.sub.g, which was 60° C. for N.sub.2 and 35° C. for CO.sub.2. The viscosity of the N.sub.2 aerated extrudate was determined to be 4.2 kcP (determined at 53° C. in a rotational viscometer), and of the CO.sub.2 aerated extrudate was determined to be 8.4 kcP (determined at 46° C. in a rotational viscometer). The extrudate as obtained contained 75% TS and was spray-dried at 125−130° C. and 8 bar atomization air pressure, at a rate of 20 kg/h to end up with an infant formula base powder with 98% TS.

Example 5

[0137] The bulk volume and particle density of the infant formula base powder obtained in Example 4 and a control infant formula base powder not subjected to extrusion were measured. The bulk volume was determined following IDF guideline IS08967, and the particle density using gas pycnometer UltraPyc1200E.

[0138] The bulk volume represents the amount in ml that 100 g of the powder takes up in volume, while the particle density provides an indication of the porosity of the powder. Both serve as an indication for the wettability of the powder. The table below shows that the poured and loose bulk volume of the aerated powders compared to the spray dried control powder are not strongly affected by the process according to the invention. Further, aeration with N.sub.2 does not affect the particle size density of the powder, while powder aerated with CO.sub.2 has a lower particle density and thus a higher porosity.

Powder Property Analysis

[0139]

TABLE-US-00001 Average bulk volume (ml/100 g) Average particle Poured loose density (g/ml) N.sub.2 gas injection 216 158 1.25 CO.sub.2 gas injection 285 215 0.88 Control 229 181 1.20

Example 6

[0140] The free fat content of the infant formula base powder obtained in Example 4 and a control infant formula base powder not subjected to extrusion were measured following guidelines in GEA Niro analytical methods Nr. A 10 b.

[0141] It is preferred that the amount of free fat is low as possible as free fat is prone to oxidation during storage. From the table below it can be observed that both powders aerated with either N.sub.2 or CO.sub.2 have free fat levels lower than 2% and thus meeting the preferred requirements of a stable infant formula powder.

Free Fat Analysis

[0142]

TABLE-US-00002 Free fat (%) N.sub.2 gas injection 1.5 CO.sub.2 gas injection 1.9 Control 0.5

Example 7

[0143] The wettability and reconstitution characteristics of the infant formula powder obtained in Example 4 and a control infant formula not subjected to extrusion were measured following guidelines in GEA Niro analytical methods Nr. A 5 b and IDF guidelines.

[0144] The wettability refers to the time needed for the powder to sink through the water upon reconstitution, and represents an important feature for the user experience (cf. Example 9 below). Powder aerated with CO.sub.2 gas had a wettability over 120 seconds, while powder aerated with N.sub.2 has an improved wettability compared to the control. In addition, the reconstitution analysis showed that reconstitution behaviour was sufficient for all tested powder, with the aerated powders according to the invention performing slightly better than the control powder. Reconstitution values of 1 or lower correspond to excellent reconstitution properties. All in all, the powders obtained by the process according to the invention show desirable reconstitution behaviour without undesirable lumping or sticking.

[0145] Wettability and Reconstitution Characteristics

TABLE-US-00003 Average wettability (s) Average reconstitution N.sub.2 gas injection 7 1 CO.sub.2 gas injection >120 0.5 Control 12 1

Example 8

[0146] The infant formula powder obtained in Example 4 and a control infant formula not subjected to extrusion were further tested in a user experience evaluation. A dedicated milk panel of 8 members developed specific language for testing 16 attributes. In total 5 sessions for attributes generation and training were done, followed by 1 profiling session wherein the three products were blindly assessed for the 16 attributes.

[0147] In most attributes, the three tested formula did not perform significantly differently, however some noteworthy differences were observed in foaming behaviour and sinking speed. Foam formation after reconstitution of the powder is undesirable for the user, as the foam for a large extent remains in the bottle during a feeding event. Also, a faster collapse of the foam is preferred, as the user typically does not wait for the foam to collapse before starting to feed the infant. From the table below, it can be concluded that the aerated powders obtained according to the invention result in a reduced total amount of foam compared to the control formula. Also, it appears that the foam is less stable using the process according to the invention as the amount of foam quickly reduces over time. Both aerated formulae according to the invention outperformed the control formula, with a slight better performance for the CO.sub.2 aerated one over the N.sub.2 aerated one.

[0148] The sinking speed of the powderous infant formula is comparable to the wettability as described above. The sinking speed was measured as the speed with which the powder sinks through the water in the bottle after the sixth scoop is added. The lower the sinking speed, the faster the powder sinks in the fluid. The sinking speed of powder aerated with CO.sub.2 gas is the highest, i.e. sinks the slowest, while powder aerated with N.sub.2 gas sinks the fastest. These results are in accordance with the results obtained from the wettability experiment.

User Experience Results

[0149]

TABLE-US-00004 Foaming (%, 100 max, 0% min) Sinking speed After after after (100 high, shaking 2 min 5 min 0 low) N.sub.2 gas injection 68 53 40 77 CO.sub.2 gas injection 59 37 25 11 Control (spray dry 82 76 68 58 only)