Method for the demineralisation of whey and whey thus obtained

Abstract

The invention relates to the field of dairy products and particularly concerns a method for the demineralization of whey. The method according to the invention comprises the following steps: obtaining a whey, electrodialysis of the whey at a temperature of 30° C. to 60° C., acidification of the whey to a pH of between 2 and 3.5, pasteurization of the acidified whey, electrodialysis of the pasteurized acidified whey at a temperature of 30° C. to 60° C., and neutralization of the demineralized whey to a pH between 6.7 and 7.2. The method according to the invention makes it possible to achieve the whey demineralization using only the method of electrodialysis while avoiding the problems conventionally encountered with this method, namely a limited demineralization rate, fouling of the membranes, and an insufficient service life.

Claims

1. A method for demineralizing whey, comprising the following steps: a first step of obtaining whey, electrodialysis of said whey at a temperature of 30° C. to 60° C., acidification of the whey to a pH between 2 and 3.5 thereby obtaining acidified whey, pasteurization of the acidified whey thereby obtaining pasteurized acidified whey, electrodialysis of the pasteurized acidified whey at a temperature of 30° C. to 60° C. thereby obtaining electrodialysed pasteurized acidified whey, and neutralization of the electrodialysed pasteurized acidified whey to a pH between 6.7 and 7.2.

2. The method according to claim 1, wherein the whey obtained in the first step is concentrated whey of 18 to 25% of dry extract.

3. The method according to claim 1, wherein the step of electrodialysis of the whey is carried out so as to obtain a conductivity of said whey of between 4.0 and 5.0 mS/cm.

4. The method according to claim 1, wherein the step of electrodialysis of the pasteurized acidified whey is carried out so as to obtain a conductivity of said pasteurized acidified whey of between 2.0 and 3.0 mS/cm.

5. The method according to claim 1, wherein the step of electrodialysis of the pasteurized acidified whey is carried out so as to obtain a conductivity of said pasteurized acidified whey of between 1.0 and 1.5 mS/cm.

6. The method according to claim 1, wherein the pasteurization is carried out for 1 to 20 min and at a temperature of between 80 and 120° C.

7. The method according to claim 1, wherein the electrodialysis steps are carried out at a temperature of 35° C. to 55° C.

8. The method according to claim 1, wherein the neutralization step is carried out concurrently with the electrodialysis step on the pasteurized acidified whey.

9. The method according to claim 1, wherein the pasteurization is carried out for 1 to 10 minutes and at a temperature of between 90 and 100° C.

10. The method according to claim 1, wherein the pasteurization is carried out for about 5 minutes and at a temperature of about 95° C.

11. The method according to claim 1, wherein the electrodialysis steps are carried out at a temperature of 40° C. to 50° C.

Description

EXAMPLES

(1) The ash content is determined according to standard NF 04-208.

Example 1: Preparation of Demineralized Whey According to the Invention

(2) Test 1: For this test, 3 solutions were prepared and placed in tanks, their contents listed below: Tank 1: solution of 20 L of concentrated sweet whey at 19.63% dry extract. The solution has a temperature of 30.8° C. and a conductivity of 13.71 mS/cm. The solution was pasteurized at 95° C. for 5 minutes. Tank 2: brine solution prepared with 20 L of tap water at 40° C. and acidified with a few drops of 37% HCl. The pH of the solution is 2.89. Tank 3: electrolyte solution prepared with 18 L of tap water at 30° C. and a few drops of 95% H.sub.2SO.sub.4 to adjust the conductivity between 15 and 18 mS/cm (at 20° C.). The solution has a conductivity of 16.37 mS/cm (at 20° C.), a pH equal to 1.43, and a temperature of 27.6° C.

(3) The electrodialysis is started and the pH and the conductivity are checked continuously by means of previously calibrated probes.

(4) When the conductivity of the whey reaches 4.52 mS/cm, the electrodialysis is stopped. 15 L of brine are then removed and replaced with tap water whose pH has been adjusted to 2.79 by adding HCl, and the electrodialysis is restarted.

(5) Finally, the electrodialysis is stopped again when the solution of acidified demineralized whey has a conductivity of 2.56 mS/cm.

(6) To carry out the neutralization, 75 mL of 40% NaOH are added to tank 1 to adjust the pH to 6.6; the conductivity is 3.88 mS/cm. 15 L of brine are removed and replaced with tap water at 40° C. whose pH has been adjusted to 2.86. The electrodialysis is restarted for a duration of approximately 30 minutes until the solution of demineralized whey has a conductivity of 2.74 mS/cm.

(7) Samples are collected after the first electrodialysis is stopped (sample 1) and after the second electrodialysis is stopped at the end of the method (sample 2), in order to perform analyses on the characteristics of the demineralized whey obtained. The results are shown in Table 1 below.

(8) TABLE-US-00001 TABLE 1 Parameters analyzed Total nitrogenous Na.sup.+ K.sup.+ Ca.sup.2+ Mg.sup.2+ ES Ash matter Cl.sup.− P pH mg/100 g dry extract % %/dry matter mg/100 g dry extract Sample 1 3.8 84 166 265 16 18.8 2.2 13.8 299 255 Sample 2 6.5 486 115 236 15 18.7 2.2 13.8 107 229 Demineralization 73% rate

(9) A mass balance was assessed in order to verify the transfer of ions (sodium, potassium, calcium, magnesium, and chlorine) through the membranes. This assessment confirms that the quantities of ions that have disappeared from the whey are found in the brine solution, with a relative difference between the quantities of less than 15%.

(10) The whey demineralized according to the method of the invention has a demineralization rate of 73% and the mineral composition is in accordance with the specifications.

(11) Test 2: This test was reproduced under the same operating conditions as test 1, but with slightly different starting solutions. Three new solutions were therefore prepared and placed in tanks, their contents listed below: Tank 1: solution of 20 L of concentrated sweet whey at 19.58% dry extract. The solution has a temperature of 29.9° C. and a conductivity of 13.85 mS/cm. The solution was pasteurized at 95° C. for 5 minutes. Tank 2: brine solution prepared with 20 L of tap water at 29.5° C. and acidified with a few drops of 37% HCl. The pH of the solution is 3.09. Tank 3: electrolyte solution prepared with 18 L of tap water at 30° C. and a few drops of 95% H.sub.2SO.sub.4. The solution has a conductivity of 18.49 mS/cm (at 20° C.), a pH equal to 1.24, and a temperature of 30.7° C.

(12) Each of the tanks is connected to an electrodialyzer having the same characteristics as that of test 1.

(13) The electrodialysis is started and the pH and conductivity are checked continuously by means of previously calibrated probes.

(14) When the conductivity of the whey reaches 4.49 mS/cm, the electrodialysis is stopped. 20 L of brine are then removed and replaced with tap water whose pH has been adjusted to 2.88 by adding HCl, and the electrodialysis is restarted.

(15) Finally, the electrodialysis is stopped again when the solution of demineralized acidified whey has a conductivity of 2.77 mS/cm.

(16) To carry out the neutralization, 86 mL of 40% NaOH are added to tank 1, bringing the pH of the serum to 6.65; the conductivity of the serum is then 4.33 mS/cm.

(17) 20 L of brine are removed and replaced with tap water at 40° C. whose pH has been adjusted to 2.87. The electrodialysis is restarted for a duration of approximately 30 minutes until the solution of demineralized whey has a conductivity of 3.02 mS/cm and a pH of 6.50.

(18) Samples are collected after the first electrodialysis is stopped (sample 1) and after the second electrodialysis is stopped at the end of the method (sample 2), in order to perform analyses on the characteristics of the demineralized whey obtained. The results are shown in Table 2 below.

(19) TABLE-US-00002 TABLE 2 Parameters analyzed Total nitrogenous Na.sup.+ K.sup.+ Ca.sup.2+ Mg.sup.2+ ES Ash matter Cl.sup.− P pH mg/100 g dry extract % %/Dry matter mg/100 g dry extract Sample 1 3.4 92 182 266 87 18.8 1.8 13.7 370 266 Sample 2 6.5 645 124 229 79 18.7 2.4 13.8 114 235 Demineralization 70% rate

(20) A mass balance was assessed in order to verify the transfer of ions (sodium, potassium, calcium, magnesium and chlorine) through the membranes. This assessment confirms that the quantities of ions that have disappeared from the whey are found in the brine solution, with a relative difference between the quantities of less than 15%.

(21) The whey demineralized according to the method of the invention has a demineralization rate of 70% and the mineral composition is in accordance with the specifications.

(22) To increase the demineralization rate of this whey.

(23) Test 3: This test was reproduced under the same operating conditions as tests 1 and 2, but with slightly different starting solutions. Three new solutions were therefore prepared and placed in tanks, their contents listed below: Tank 1: solution of 20 L of concentrated sweet whey at 19.7% dry extract. The solution has a temperature of 29.9° C. and a conductivity of 13.85 mS/cm. The solution was pasteurized at 95° C. for 5 minutes. Tank 2: brine solution prepared with 20 L of tap water at 33.5° C. and acidified with a few drops of 37% HCl. The pH of the solution is 3.01. Tank 3: electrolyte solution prepared with 18 L of tap water at 30° C. and a few drops of 95% H.sub.2SO.sub.4 to adjust the conductivity to between 15 and 18 mS/cm (at 20° C.). The solution has a conductivity of 17.28 mS/cm (at 20° C.), a pH equal to 1.23, and a temperature of 36.1° C.

(24) Each of the tanks is connected to the electrodialyzer having the same characteristics as that of test 1.

(25) The first electrodialysis step is started and the pH and conductivity are checked continuously by means of previously calibrated probes.

(26) When the conductivity of the whey reaches 4.51 mS/cm, the electrodialysis is stopped.

(27) 20 L of brine are then removed and replaced with tap water whose pH has been adjusted to 2.92 by adding HCl, and the electrodialysis is restarted.

(28) Finally, the electrodialysis is stopped again when the solution of demineralized whey has a conductivity of 2.26 mS/cm.

(29) To carry out the neutralization, 84 mL of 40% NaOH are added to tank 1, bringing the pH to 6.8 and the conductivity to 3.8 mS/cm. 20 L of brine are removed and replaced with tap water at 40° C. whose pH has been adjusted to 2.87. The electrodialysis is restarted for a duration of approximately 30 minutes until the solution of demineralized whey has a conductivity of 2.78 mS/cm and a pH of 6.7.

(30) Samples are collected after the first electrodialysis is stopped (sample 1) and after the second electrodialysis is stopped at the end of the method (sample 2) in order to perform analyses on the characteristics of the demineralized whey obtained. The results are shown in Table 3 below.

(31) TABLE-US-00003 TABLE 3 Parameters analyzed Total nitrogenous Na.sup.+ K.sup.+ Ca.sup.2+ Mg.sup.2+ ES Ash matter Cl.sup.− P pH mg/100 g dry extract % %/Dry matter mg/100 g dry extract Sample 1 3.7 73 132 222 75 19.1 3.7 13.0 210 257 Sample 2 6.7 576 99 195 72 19.1 2.5 13.0 96 225 Demineralization 69% rate

(32) A mass balance was assessed in order to verify the transfer of ions (sodium, potassium, calcium, magnesium and chlorine) through the membranes. This assessment confirms that the quantities of ions that have disappeared from the whey are found in the brine solution, with a relative difference between the quantities of less than 15%.

(33) The whey demineralized according to the method of the invention has a demineralization rate of 69% and the mineral composition is in accordance with the specifications.

Example 2: Preparation of a Whey Demineralized to about 90% According to the Invention

(34) Using the same operating conditions as Test 1 of Example 1 and with the same solutions in the tanks, electrodialysis is started until the conductivity of the acidified whey reaches 3.02 mS/cm.

(35) Neutralization is performed with a mixture of sodium hydroxide:potassium hydroxide (1:3) to achieve a pH of 6.7 and a conductivity of 5.37 mS/cm. 5 L of brine are removed and replaced with a 40° C. tap water solution. Electrodialysis is restarted for about 2 hours and then stopped again when the solution of demineralized whey has a conductivity of 1.04 mS/cm and a pH of 6.5.

(36) Samples are collected after the first electrodialysis is stopped (sample 1) and after the second electrodialysis is stopped at the end of the method (sample 2) in order to perform analyses on the characteristics of the demineralized whey obtained. The results are shown in Table 4 below.

(37) TABLE-US-00004 TABLE 4 Parameters analyzed Total nitrogenous Na.sup.+ K.sup.+ Ca.sup.2+ Mg.sup.2+ ES Ash matter Cl.sup.− P pH mg/100 g dry extract % %/Dry matter mg/100 g dry extract Sample 1 3.7 91 189 323 95 18.2 1.7 13.9 316 143 Sample 2 6.6 93 171 138 67 18.0 0.9 14.0 26 137 Demineralization 89% rate

(38) A mass balance was assessed in order to verify the transfer of ions (sodium, potassium, calcium, magnesium and chlorine) through the membranes. This assessment confirms that the quantities of ions that have disappeared from the whey are found in the brine solution, with a relative difference between the quantities of less than 20%.

(39) The whey demineralized according to the method of the invention has a demineralization rate of 89% and the mineral composition is in accordance with the specifications.