METHOD FOR MAKING YOGURT OR ANOTHER FERMENTED MILK-BASED PRODUCT

Abstract

Method for making yogurt or another fermented milk-based product comprising the steps of: adding to the milk an enzyme preparation based on transglutaminase at a concentration of 0.5-3 units per gram of protein contained in the milk, the transglutaminase being supported on vegetable fibres; homogenising the milk by forcing it through a gap afforded between a lower annular chamber (9) and an upper annular chamber (10) of a homogenising valve (1).

Claims

1. Method for making yogurt or another fermented milk-based product, comprising the steps of: pasteurising the milk; homogenising the pasteurised milk; subjecting the homogenised milk to fermentation, characterised in that it further comprises a step of adding to the milk an enzyme preparation based transglutaminase at a concentration of 0.5-3 units per gram of proteins contained in the milk, said transglutaminase being supported on vegetable fibres, said homogenising step comprising forcing the milk through a gap afforded between a lower annular chamber (9) and an upper annular chamber (10) of a homogenising valve (1), said homogenising valve (1) comprising an annular passage head (11) and an annular impact head (12) interposed between said lower annular chamber (9) and said upper annular chamber (10), said gap being defined between the passage head (11) and the impact head (12).

2. Method according to claim 1, wherein the step of adding said enzyme preparation to the milk takes place before the step of pasteurising the milk, with transglutaminase at a concentration of 2-3 units per gram of proteins contained in the milk.

3. Method according to claim 1, wherein the step of adding said enzyme preparation to the milk takes place after the step of pasteurising the milk, with transglutaminase at a concentration of 0.5-2 units per gram of proteins contained in the milk.

4. Method according to claim 1, wherein the step of subjecting the milk to fermentation takes place by inoculating a predefined bacterial culture at a temperature comprised between 42° C. and 44° C.

5. Method according to claim 1, wherein said vegetable fibres are obtained from potato (Solanum tuberosum) and psyllium seeds (Plantago ovata).

6. Method according to claim 1, wherein said vegetable fibres are present in a weight percentage comprised between 5% and 10% of the enzyme preparation.

7. Method according to claim 1, wherein said enzyme preparation is obtained by a granulation step in which it is used gum arabic as a coating agent.

8. Method according to claim 1, wherein said enzyme preparation comprises demineralized buttermilk.

9. (canceled)

10. Use of an enzyme preparation based on transglutaminase supported on vegetable fibres for making yogurt or another fermented milk-based product, said milk being added with said preparation with transglutaminase at a concentration of 0.5-3 units per gram of proteins contained in the milk and being subjected to a forced passage through a gap afforded between a lower annular chamber (9) and an upper annular chamber (10) of a homogenising valve (1), said homogenising valve (1) comprising an annular passage head (11) and an annular impact head (12) interposed between said lower annular chamber (9) and said upper annular chamber (10), said gap being defined between the passage head (11) and the impact head (12).

Description

BRIEF DESCRIPTION OF DRAWINGS

[0027] Further characteristics and advantages of the present invention will become more apparent from the following indicative, and hence non-limiting, description of a preferred, but not exclusive, embodiment of a method for making yogurt or another fermented milk-based product, wherein the homogenisation step is performed in a homogenising valve illustrated in FIG. 1, in a sectional view.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

[0028] In particular, the description proposed herein will refer to the production of yogurt. For example, the method can be used both for making set yogurt (i.e. full coagulation) and for making creamy yogurt. Furthermore, the method can also be used for making animal or vegetable cream or fermented milk.

[0029] The method comprises the steps of: [0030] pasteurising the milk; [0031] homogenising the pasteurised milk; [0032] subjecting the homogenised milk to fermentation.

[0033] In particular, the milk is pasteurised according to known techniques which are not the subject matter of the present invention.

[0034] The pasteurisation is followed by the homogenisation step, which is performed by forcing the milk through a gap afforded between a lower annular chamber 9 and an upper annular chamber 10 of a homogenising valve 1.

[0035] In the preferred embodiment described and illustrated herein, the homogenising valve 1 comprises a valve body 2 defining a through hole with an axial extension with respect to the valve body 2.

[0036] Preferably, the valve body 2 is formed by the assembly of a lower valve body 3 and an upper valve body 4, which are axially aligned.

[0037] The valve 1 comprises a lower piston 5, inserted in a first section of the through hole at the lower valve body 3, and an upper piston 6, inserted in a second section of the through hole at the upper valve body 4. The lower piston 5 and the upper piston 6 are integrally coupled.

[0038] The valve 1 presents an inlet 7 for the fluid (in this case milk) at high pressure and an outlet 8 for the homogenised fluid at low pressure. The inlet 7 can be connected to a high pressure pump (not shown).

[0039] Between the valve body 2 and the lower piston 5, the lower annular chamber 9 is afforded, into which the inlet 7 for fluid at high pressure opens.

[0040] Between the valve body 2 and the upper piston 6, the upper annular chamber 10 is afforded, into which the outlet 8 opens. In particular, the upper annular chamber 10 transfers the homogenised fluid at low pressure to the outlet 8 of the valve 1.

[0041] The valve 1 comprises an annular passage head 11 and an annular impact head 12, which have axial symmetry and are interposed between the lower annular chamber 9 and the upper annular chamber 10.

[0042] The passage head 11 is integral with the valve body 2.

[0043] The impact head 12 is integrally coupled to the lower piston 5 and to the upper piston 6 so as to form an assembled member. For example, the coupling is performed by means of a screw 13, which is part of the assembled organ.

[0044] The valve 1 is provided with means for moving the assembled organ in the axial direction towards the passage head 11 so that the impact head 12 defines with the passage head 11 a gap for the passage of fluid (in this case milk) from the lower annular chamber 9 to the upper annular chamber 10.

[0045] In particular, the movement of the assembled member towards the passage head 11 contrasts the pressure exerted by the fluid contained in the lower annular chamber 9 on the impact head 12.

[0046] Originally, the method also comprises a step of adding to the milk an enzyme preparation based on transglutaminase at a concentration of 0.5-3 units per gram of protein contained in the milk. The transglutaminase is supported on vegetable fibres.

[0047] The vegetable fibres supporting the enzyme have high water retention capacity coupled with the presence of glycoproteins. In fact, they contain a special quantity of specific amino acids (in particular lysine) which represent the optimal substrate for the transfer reaction performed by the transglutaminase.

[0048] The vegetable fibres therefore act as an active support for the enzyme becoming interposed and covalently bonding between the various caseins and whey proteins thanks to the action of transglutaminase, causing an increase in the water retention of the milk proteins as well as an improvement in the overall structure of the curd.

[0049] In the preferred embodiment, the vegetable fibres that support the transglutaminase enzyme are obtained from potato (Solanum tuberosum) and psyllium seeds (Plantago ovate). This choice allows the best performance levels to be obtained in terms of viscosity of the finished product.

[0050] Preferably, the vegetable fibres are present in a weight percentage comprised between 5% and 10% of the enzyme preparation.

[0051] Preferably, the enzyme preparation comprises demineralized buttermilk as a bulking agent.

[0052] In the preferred embodiment, the enzyme preparation is a commercial product known as Reactyn YO+ by the company Campus S.r.l. having its registered office in Via Sala Baganza 3, Quartiere Industriale “I Filagni”, 43033 Collecchio (Parma), Italy.

[0053] In a first implementation of the method, the addition of this enzyme preparation to the milk takes place prior to the pasteurisation step. In this case, the concentration of transglutaminase is 2-3 units per gram of proteins contained in the milk.

[0054] In a second implementation of the method, the addition of this enzyme preparation to the milk takes place after the pasteurisation step. In this case, the concentration of transglutaminase is 0.5-2 units per gram of protein contained in the milk.

[0055] The method for making yogurt just described and the use of an enzyme preparation based on transglutaminase supported by vegetable fibres for making yogurt homogenised with a valve having the characteristics described above allows: [0056] the energy consumption and wear on the components of the homogenising valve to be reduced, thanks to a significant reduction in homogenisation pressure; [0057] the yogurt production times to be reduced;
the rheology characteristics of the yogurt (such as viscosity and texture) to be preserved without increasing the cost of the recipe.

[0058] Such properties have been demonstrated fully by the following three tests performed in a laboratory.

[0059] In a first test, the viscosity of the following products was compared: [0060] A—fresh pasteurised semi-skimmed milk [0061] B—fresh pasteurised semi-skimmed milk with the addition of the enzyme preparation based on vegetable fibres and transglutaminase at a concentration of 0.5-2 units per gram of proteins contained in the milk (after the milk pasteurisation step).

[0062] Specifically, the enzyme preparation is Reactyn YO+ by Campus S.r.l.

[0063] The aim of this first test is to check if the addition of the enzyme preparation based on transglutaminase supported by vegetable fibres allows the homogenisation pressure to be lowered with the same rheology characteristics.

[0064] The pasteurisation step, performed in a known way, is followed by the homogenisation step in the homogenising valve 1 described above.

[0065] During the subsequent fermentation step, the products were kept at the temperature of 42° C. for about 7-8 hours, therefore the pH was lowered to 4.4-4.5. Subsequently, the products were brought to a temperature of about 4° C. for storage.

[0066] Any curds were broken and smoothed with a 850 micron filter.

[0067] The comparison took place after the products had been homogenised in two steps: [0068] first homogenisation step at different pressures: 80, 150 and 300 bar; [0069] second homogenisation step at the pressure of 50 bar.

[0070] The viscosity, expressed in Cps in the table below, was measured every second for a minute using a Brookfield viscometer with RV03 probe, maintaining a constant temperature of about 4° C. The viscosity values expressed in the table represent the mean of the measured values.

TABLE-US-00001 Homogenisation pressures Viscosity of Viscosity of during the first step (bar) product A (Cps) product B (Cps) 80 360 3119 150 906 6804 300 1733 6686

[0071] As can be noted from the experimental data obtained, to increase the viscosity of product A (without the enzyme preparation based on transglutaminase supported by vegetable fibres) it is necessary to subject the product to higher homogenising pressures, up to 300 bar.

[0072] Instead, for product B, which contains the enzyme preparation based on transglutaminase supported by vegetable fibres, already at 80 bar a higher viscosity is obtained than that obtained with product A at 300 bar.

[0073] In a second test, the viscosity of the following products was compared: [0074] C—fresh pasteurised semi-skimmed milk with added proteins [0075] D—fresh pasteurised semi-skimmed milk with added proteins and the enzyme preparation based on vegetable fibres and transglutaminase at a concentration of 2-3 units per gram of proteins contained in the milk (before the milk pasteurisation step)

[0076] Specifically, the enzyme preparation is Reactyn YO+ by Campus S.r.l.

[0077] The addition of proteins to products C and D took place as per the tables below.

TABLE-US-00002 Ingredients of Product C Percentage Semi-skimmed milk (1.5% fat, 2.3% protein) 95.00 Semi-skimmed powdered milk 2.80 Powdered whey 2.20 Enzyme preparation based on 0.00 transglutaminase supported by vegetable fibres

[0078] The percentage of proteins in product C is equal to 4.26.

TABLE-US-00003 Ingredients of Product D Percentage Semi-skimmed milk (1.5% fat, 2.3% protein) 97.62 Semi-skimmed powdered milk 0.50 Powdered whey 1.82 Enzyme preparation based on 0.06 transglutaminase supported by vegetable fibres

[0079] The percentage of proteins in product D is equal to 3.51.

[0080] The aim of this second test is to check if the addition of the enzyme preparation based on transglutaminase supported by vegetable fibres allows the homogenisation pressure to be lowered and the protein content to be reduced with the same rheology characteristics.

[0081] The pasteurisation step, performed in a known way, is followed by the homogenisation step in the homogenising valve 1 described above.

[0082] During the subsequent fermentation step, the products were kept at the temperature of 42° C. for about 7-8 hours, therefore the pH was lowered to 4.4-4.5. Subsequently, the products were brought to a temperature of about 4° C.

[0083] Any curds were broken and smoothed with a 850 micron filter.

[0084] The comparison took place after the products had been homogenised in two steps: [0085] first homogenisation step at different pressures: 80, 150 and 300 bar; [0086] second homogenisation step at the pressure of 50 bar.

[0087] The viscosity, expressed in Cps in the table below, was measured every second for a minute using a Brookfield viscometer with RV03 probe, maintaining a constant temperature of about 4° C. The viscosity values expressed in the table represent the mean of the measured values.

TABLE-US-00004 Homogenisation pressures Viscosity of Viscosity of during the first step (bar) product C (Cps) product D (Cps) 80 3144 6605 150 3038 3529 300 4458 4470

[0088] Compared to the first test, the viscosity differences are less marked. This is due to the fact that product C has about a 0.75% higher protein content than product D, whereas in the first test products A and B have the same protein content. Furthermore, the enzyme preparation based on transglutaminase supported by vegetable fibres was added prior to the pasteurisation step.

[0089] In any case, it can be noted that—with the same pressure and homogenisation—product D still has a higher viscosity than product C.

[0090] In particular, the increased viscosity effect for product D is more marked at the minimum pressure of 80 bar. This effect is however less evident at higher pressures since at such pressures the protein complexes formed by the added enzyme preparation are broken up, hence reducing the viscosity.

[0091] In a third test, the viscosity of the following products was compared: [0092] E—fresh pasteurised semi-skimmed milk with added proteins [0093] F—fresh pasteurised semi-skimmed milk with added proteins and the enzyme preparation based on vegetable fibres and transglutaminase (supported by vegetable fibres) at a concentration of 1-2 units per gram of proteins contained in the milk (after the milk pasteurisation step, precisely during the inoculation of the bacterial mixture).

[0094] Specifically, the enzyme preparation is Reactyn YO+ made by Campus S.r.l.

[0095] The addition of proteins to products E and F took place as per the tables below.

TABLE-US-00005 Ingredients of product E Percentage Semi-skimmed milk (protein content 3.1-3.4%) 78.98 Semi-skimmed powdered milk 5.19 Cream 45% 8.33 Sugar 7.50 Enzyme preparation based on 0.00 transglutaminase supported on vegetable fibres

[0096] The percentage of proteins in product E is equal to 4.41.

TABLE-US-00006 Ingredients of product F Percentage Semi-skimmed milk (protein content 3.1-3.4%) 78.98 Semi-skimmed powdered milk 5.19 Cream 45% 8.33 Sugar 7.50 Enzyme preparation based on 0.06 transglutaminase supported on vegetable fibres

[0097] The percentage of proteins in product D is equal to 4.41.

[0098] Compared to the second test, here the two products E and F have the same protein percentage, therefore the only variable effectively comes from the addition of the enzyme preparation based on transglutaminase supported on vegetable fibres after pasteurisation.

[0099] The aim of this third test is to check if the addition of the enzyme preparation based on vegetable fibres and transglutaminase allows the homogenisation pressure to be lowered with the same rheology and protein characteristics.

[0100] The pasteurisation step, performed in a known way, is followed by the homogenisation step in the homogenising valve 1 described above.

[0101] During the subsequent fermentation step, the products were kept at the temperature of 42° C. for about 7-8 hours, therefore the pH was lowered to 4.4-4.5. Subsequently, the products were brought to a temperature of about 4° C.

[0102] Any curds were broken and smoothed with a 850 micron filter.

[0103] The comparison took place after the products had been homogenised in two steps: [0104] first homogenisation step at the pressure of 180 bar; [0105] second homogenisation step at the pressure of 50 bar.

[0106] The viscosity, expressed in Cps in the table below, was measured every second for a minute using a Brookfield viscometer with RV03 probe, maintaining a constant temperature of about 4° C. The viscosity values expressed in the table represent the mean of the measured values.

[0107] For product E a viscosity of 21347 Cps was measured, whereas for product F a viscosity of 29773 Cps was measured.

[0108] From the tests performed, the characteristics of the method for making yogurt, according to the present invention, are clear, as are the advantages.

[0109] In particular, the addition to the milk of the enzyme preparation based on transglutaminase supported on vegetable fibres at the indicated concentration and the performance of the homogenisation step in a valve with a double annular chamber allows: [0110] processing at lower homogenisation pressures (e.g. 80 or 150 bar compared to 300 bar), hence reducing the energy expenditure and the wear on the components of the homogenising valve; [0111] the yogurt production times to be reduced; [0112] for the same homogenising pressures, the viscosity of the yogurt to be increased;
for the same homogenising pressures, the protein content to be reduced without affecting the viscosity (which is actually improved), hence also reducing the cost of the recipe.