DE2653003A1 - Clarification of liquids containing whey protein - Google Patents

Description

Dr. Fnp. Wa'trr M * i * z 3

Di r- ^! -'- rr ν'- '", ²² November 1976

Dr. Hans-Α. Brauns BO 5395 MdR

8 Mürtsn-, 3 tu, ftenzenauerstr. 28

STICHTING BEDRIJVEN VAN HET NEDERLANDS INSTITUUT VOOR ZUIVELONDERZOEK

Kernhemseweg 2, Ede, Holland

Clarification of liquids containing whey protein

The invention relates to a method for clarifying whey protein-containing Liquids by demineralizing the liquids and adjusting their pH to values in the range of 4.2 to 4.8.

One of the most important liquids containing whey protein is whey, which occurs in large quantities in the production of cheese and casein. Because of the high nutritional value of those proteins, the whey is and in particular a concentrate thereof is an attractive raw material for food. In addition to protein, whey also contains milk salts, Lactic acid and lactose as well as fatty components and microorganisms, both of which cloud whey and its concentrates to lead.

It is known that the proteins from whey and whey concentrates by ultrafiltration or filtration through a molecular sieve or can be obtained by obtaining them by forming insoluble complexes of the same with other substances. Solutions of proteins obtained in this way are slightly cloudy and can form a ring of fatty material on the surface

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and moreover take on a bad taste after storage in contact with the air for a certain period of time due to the oxidation of fatty materials still present. In NL-OS 73.1095 it is therefore recommended to adjust the pH of a liquid subjected to ultrafiltration, which is subjected to gel filtration if necessary, to the range from H _s h to 5.0, and the precipitate thus formed by microfiltration separate and isolate the filtrate containing the soluble protein fraction. A disadvantage of this recommended method is that the appropriate equipment is not generally available in dairies and that microfiltration is a time consuming process.

It has been found that this disadvantage can be eliminated by demineralizing the whey protein-containing liquid to be clarified until an ash / protein ratio of up to 0.08 is reached, taking care that after the demineralization stage the protein content is up to 1.5 wt.% and that the pH value of the liquid in the range 4.2 to 4.8 is located, and finally separates the sedimenting material from the liquid.

Preferably, the demineralization is first applied, then adjusted the protein content and finally adjusted the pH.

If necessary, the clarified liquid, e.g. B. at a neutral pH, concentrated by means of membrane filtration, in this case the flow rate is considerably greater than in the case of ultrafiltration according to the above known ones Method is. Naturally, other concentration methods in which the protein does not denature are also suitable will.

Liquids containing whey protein, according to the invention clarify, are sweet and sour whey, as they can arise in the production of cheese, ouark, casein or similar Products. Under "whey" in this case both

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first and second whey as well as mixtures thereof to understand. Preferably, the whey is thoroughly freed from fat and coagulated fines. The whey can under such conditions be pasteurized so that protein denaturation did not occur. In addition to fresh whey, you can use the mother liquor work that remains when lactose crystallizes out of concentrated whey, as well as with whey concentrates, demineralized whey and solutions of whey powders of various Kind that are made from these.

To reduce the ash content of the liquid to be used Various methods known per se can be used to a sufficiently low value, such as

1. Demineralization using successive cation and anion exchange resins,

2. Demineralization using dialysis or electrodialysis,

3. gel filtration,

4 <Ultrafiltration until the required ash / protein ratio is reached in the retentate and then rediluted with water.

The ash content is preferably reduced by passing the liquid to be demineralized over ion exchangers. The demineralization is preferably down to an ash / protein ratio of 0.05 performed.

According to the method according to the invention, formation takes place. of complexes of - probably globulin-like - proteins, fatty substances and bacteria at a pH value close to the ■ isoelectric point of whey proteins.

Furthermore, the ash concentration is reduced to such an extent that the complexes formed form a sediment (probably due to reduced solubility). Along with the substances that cause unwanted cloudiness (fatty substances and bacteria), whey protein is also lost. It is essential to choose conditions so that as little protein as possible is lost y. but at the same time as much as possible of fatty materials

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and bacteria (or their spores) are made to disappear with the sediment or by entering the same. Avoid during or after the demineralization stage that the solutions to be clarified are kept in the pH range from 3.5 to 5j5 in which sedimentation occurs can.

In experiments, dilutions were prepared from whey protein solutions which were obtained by ultrafiltration and had an increasing protein content, all of which had a whey protein content of 1 % and therefore a variable ash / protein ratio.

Portions of all of these solutions were adjusted to pH values of 3 to 6. In the direct determination of the turbidity present in these, the strongest flocculation appeared to have occurred at pH values in the range from 3.5 to 5.5. After eliminating the flakes, the transmittance of the transparent solution to light of 600 nm was determined - as in all the clarity and turbidity determinations mentioned later - in comparison with an empty cuvette (ie a cuvette containing only air). Solutions with a pH value in the range from 4.2 to 4.8 and in addition an ash content of 0.04 or 0.05 % showed a permeability of over 90 %. These solutions were essentially water clear. Thus, most of the opacifying substances had been removed with the sediment, while the protein content appeared to be reduced by only about 10%. At an ash / protein ratio of 0.08 the permeability still appeared to be about 70 % , but if this ratio were to exceed 0.10 the permeability would decrease to 50% or less.

After setting the correct pH value, the turbidity first increases (formation of complexes) and then decreases (due to sedimentation the aggregates), the higher the temperature, the faster this happens. In the grand scheme of things is but the clarification of the liquid at 50 ° C is slightly less than at 25 ° C and 5 ° C. This may be due to the fact that at 50 ° C

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the kinetic energy is too high, which in turn causes the complexes are not too persistent. Accordingly, it could happen that a sufficiently clear solution does not form at 50 ° C can be achieved if sedimentation can only occur under the influence of gravity. The flaked good could however, even at 50 ° C it can in fact be separated from the clear liquid by using a centrifuge.

Aside from the pH and ash / protein ratio, the protein content of the solution is also essential for proper clarification. If the protein content is 2 wt.% Or more, the clearance extends less favorable than with a protein content of 1% or less. This has been shown by experiments in which whey which had been concentrated by ultrafiltration was again diluted to a protein content of 1% by weight and then concentrated again by continued ultrafiltration until protein solutions of 2, 3 and 4 % were also present. The pH of the four protein solutions was adjusted to 4.6, whereupon slowly settling, flocculent material formed. After 24 hours, the permeability of the top layer was determined and the fat and protein losses were calculated using a material balance. Results:

T a belle A Degreasing, % ■ Protein, Influence on the clarification of the 76
63
53
44 Weight % Asehe / Pro
tein, % 5 protein content 1.05
2.00
3.04
4.00 0.070
0.050
0.043
0.035 Head layer characteristic values after -24 hours-
ger clarification Permeable
speed, % 78
29
10
3

For optimum clearance adjustment of the protein content is desired to up to 1.5 wt.%. A reduction to under

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0.5 wt. £ on the other hand hardly leads to any further improvement-- However, it means that the whey used should first be diluted and then concentrated again. As a matter of fact the protein content of the liquid to be clarified is preferably 0.5 to 1.5 wt. ^.

The method according to the invention enables production clearer whey protein solutions without the need for an expensive facility or one unusual in dairy operations Furnishings. The whey protein solutions obtained can be used as such as a basis for protein-enriched soft drink beverages or nutritional drinks are used or concentrated or dried in a manner known per se, if necessary, after previous ρ H-fourth modification. Concentration by ultrafiltration is beneficial. The flow rate is then in fact that of the ultrafiltration of a non-clarified whey far superior.

If necessary, the solutions can be pasteurized beforehand. From the whey, however, a considerable amount of the bacteria is eliminated in sedimentation by the method according to the invention as such. A · lgew./Sige solution of demineralized whey protein powder had a germ count of 2k 000 / ml; After overnight clarification at k ° C, this bacterial count was only 210 / ml.

After aggregation with whey protein, not only bacteria but also their spores are eliminated. This has been shown in an experiment in which an igew.iSige solution of demineralized whey protein powder was mixed with spores of B. subtilis. After acidification to a pH of k.6 , 7 ^ 0 spores / ml were present. After storage for 1, 3,> 6 and 24 hours at k C, this number had dropped to 12, 6, 3 and 1, respectively, in the case of this clear liquid due to sedimentation. On the other hand, if the spores were added after the clarification, the majority of these spores were still present in the clear liquid 2 hours later.

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Soft-DrinK beverages which contain 3% by weight of the whey protein obtained according to the invention can be pasteurized for at least 20 minutes at 70 ° C. and a pH of 2.5 to 3> 5 without any risk of precipitation and There is cloudiness.

The whey protein obtained by the process according to the invention is not only indicated for use in nutritional beverages, but also has improved foaming properties. This is based probably that foam-inhibiting substances are also removed during the clarification.

If one "50 Hobart N" (for dough) proposes to determine the foaming an aqueous solution of 10 wt.% Whey protein on a percussion device of the type for 5 minutes at full speed and transfers the resulting foam to a measuring cylinder, is obtained as the usefulness of the clarified Whey protein for whipping (percentage increase in volume) two or three times the increase in volume for unclarified whey protein. The foam stability (fraction of the amount of liquid that is still present in the foam after standing for one hour) is 80 to 100 % and is maximally superior to that of foam of unclarified protein. This is e.g. B. essential when clarified whey protein is used instead of egg protein for meringue or foam pastries and other confectionery products.

example 1

Centrifuged and pasteurized whey - a mixture of first and second whey from Gouda cheese preparation - was passed one after the other over a cation exchanger and an anion exchanger for demineralization. The desalted whey obtained in this way had a pH of 5> 1 _s, a protein content of 0.70 wt / S, an ash content of 0.03 wt% and a fat content of 0.03 wt %. With this whey, which had a temperature of 5 ° C. and was adjusted to a pH value of 4.5, a transparent cylinder 1 m high with drainage pipes was filled, which were arranged at a distance of 15 cm from one another or from the floor

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was. The coarse aggregates that formed settled quickly; the finer ones needed a little more time to clear the sediment layer to reach. Whey samples were taken from each tube at intervals and these were determined for permeability The thickness of the sediment layer was also determined at intervals. The results are summarized in Table B. The· Clarification appeared to be essentially complete after just 4 hours.

Tabel

Settling
Time,
hours Permeability values (%)
of the liquid in a
from the head of cm 30 cm 45 cm 60 , measured in
distance Sediment-
thick, cm 15th 52 42 43 cm 75 cm 1 61 69 64 63 24 8 1/2 2 77 . 80 79 80 66 6 1/2 4th 83 81 82 82 81 5 1/2 6th 81 83 5

Example 2

A considerable part of the fat and the coagulation fines were removed from the first whey from the Gouda cheese production by centrifugation, after which the whey was pasteurized and demineralized as in Example 1. The demineralized whey had upon emerging from the anion exchanger has a protein content of 0.85 wt.% And an ash content of 0.04 wt. ^, While the ash content of the original whey was 0.48 Gevi.%. The pH of the collected, demineralized whey was 5.3. The fat content was invariably 0.07 % the formed, flocculated material could settle for 24 hours at 5 ° C. After that, a sediment layer 0.3 m thick had formed, of which the protruding. clear liquid was separated. As a clarification rate leaves

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a value of at least 0.13 ni / h can be calculated from this. The protein content of the clarified liquid was still 0.75% by weight, so that about 12 % of the protein was lost with the sediment.

r.

The fat content, on the other hand, was only 0.003 wt. SS, so that 95 % of the fat was removed with the sediment. The protein content of the layer in which the sediment had settled was 3.26 wt. and the fat content of the same 0.76 wt. The sediment, together with the liquid attached to it, could be used as food.

Example 3

Portions of the demineralized whey from Example 1, the pH of which had been adjusted to 4.6, were passed through a sludge centrifuge at 5 ° C. As a result of changes in the flow rate, the average residence times in the drum were adjusted to between half a minute and four minutes. The clarified whey emerging from the centrifuge was determined for protein content and light transmission. The acceleration in the centrifuge was 4600 g. The results are summarized in Table C. The table values show an average protein loss of 14 %. In the case of longer residence times, the loss is somewhat greater than, for example, 1 minute, but at 0.6 minutes the whey emerging was still a little bit cloudy. As a result of the clarification, the number of germs in the whey was reduced from 220,000 to 4,200. "

Table C.

Spin declaration of demineralized whey at pH 4.6

Average 4.0 3.5 1.8 1.5 1.0 0.6 residence time, minutes

Translucency 86 85 82 84 82 76, %

Protein content, 0.60 0.58 0.60 0.60 0.62 0.6l

Weight %

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Example 4

Hurled first-time cheese cheeses with a pH value of β ₃ β were demineralized in a dialysis tube against ten times the amount of distilled water. The pH of some of the dialysate present after 15 hours was adjusted to 4.6. The resistance measured in a cell between 1 cm electrodes at a distance of 1 cm had increased from 137 ohms to 2000 ohms; the protein content was 0.85% by weight and the ash content was 0.06% by weight . After standing for 24 hours, the clear liquid was removed from the settled flocculated material with the siphon. This clarified whey as well as the original, non-dialyzed whey were subjected to ultrafiltration in an ultrafiltration module at pH values of 4.6 and 6.5. The flow rate was regularly determined and the volume reduction (VR) achieved was recorded. The flow of the clarified whey was much higher than that of the non-clarified whey (see drawing). This was true for both pH values both after one and the same permeation period and when comparing the same concentrations (VR).

From this example it can be seen that in the manufacture of a whey protein concentrate by means of membrane filtration processes it is advisable to clarify the whey first and only then concentrate the protein. Indeed, then there is the filtration output higher, and the membranes are less contaminated.

Example 5

Whey was concentrated to 95% VR using ultrafiltration. A portion of the retentate was further concentrated in a circulation evaporator at 68-70 ° C. and then spray-dried to a powder "A" (inlet temperature 175 and outlet temperature 84 ° C.). The remaining concentrate was diluted to a protein content of 1% by weight with an ash content of 0.05% by weight and acidified to a pH of 4.6.

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After standing overnight, the clarified liquid was separated off and concentrated again to 95% VR by means of ultrafiltration. Under the conditions described, the concentrate was further treated to a "clarified" powder "B". Powders A and B were stored in contact with the air at 20 ° C. for 10 months and then evaluated for taste by a number of experienced inspectors; The evaluation was carried out on the basis of a scale from 3 to 8, in which 5 means unsatisfactory, 6 sufficient and 7 good, the average evaluation for powder A being 5.1 for taste and for powder B 6.9. The "unclarified" powder A showed deficiencies in taste originating in oxidation, while the "clarified" powder B showed no deficiencies.

A foaming test was carried out with both powders in the manner described above. The increase in volume and foam stability were found to be 1600 and 70 % when using powder A and 3400 and 95 % when using powder B.

From the powders vrässrige solutions with a protein content of 10 wt were. Prepared # and this with a chicken egg protein concentrate (C) with a protein content of 10 wt.% Compared. With these 10% by weight solutions, at a ratio of 65 parts by weight of sugar to 20 parts by weight of protein concentrates A, B or C, foam was whipped in the usual way. The foam was then "quirted" in the required shape and then first kept at a temperature of 125 ° C. for 30 minutes and finally dried at 100 ° C. for 30 minutes. The foam made with the "clarified" protein powder B (according to the invention ")" was not distinguishable from the foam made with the chicken egg protein concentrate C, neither in appearance nor in taste.

Foam prepared from the "unclarified" whey protein A, also used for comparison, was subject to baking ■ Process a bulged out to an amorphous mass.

Example 6

The powders from Example 5 were dissolved in water and mixed with

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Orange concentrate mixed in the usual way in the production of soft drink beverages, but in this case nutritional beverages with a protein content in the range from 1 to 4 wt% SS were obtained, which also contained 5 wt % sugar, 2 wt % citric acid and 0, 1 wt. Contained sodium benzoate. The drinks were heated in bottles up to 70 ° C for 20 minutes, stored at 5 ° C for three months and finally rated. Each bottle containing unclarified Protein A, prepared for comparison, had protein exuded and settled during the heating. In addition, a ring of fatty components had deposited on the top of the bottle. Again, there was an invariable taste difference based on oxidation. There was no difference in taste in the bottles containing the nutritional drinks produced with powder B clarified according to the invention, and there was no sediment or a ring of fatty substances on the head.

Example 7

The demineralization of the whey described in Example 2 was continued. Samples were taken regularly from the whey emerging from the anion exchanger, the pH of which gradually decreased. Samples with values between 4.0 and 5j2 were stored for 24 hours at 2 ° C. and their permeability was determined after 1, 3 and 20 hours. The sample with a pH of 5 * 2 did not clear; the permeability remained essentially unchanged. The other samples, and particularly those with pH values in the 4.2-4.8 range, as the permeability values of Table D show, clearing occurred. In each case, the permeability was only 2 % immediately when the sample was taken.

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Table D 1% by weight whey protein solution storage time, permeability at a pH of

hours 5.2 3 5.0 4.8 4.6 4 _? 4th 4.2 4.0 1 2 10 36 59 62 59 17th 3 2 26th 67 80 78 83 33 20th 40 68 80 84 86 40

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Claims (11)

BO 5395 MdR Claims Γϊ \ Process for clarifying liquids containing whey protein by means of demineralization of the same and adjustment of the pH value to the range from 4.2 to 4.8, characterized in that that a liquid containing whey protein is demineralized to an ash / protein ratio of up to 0.08, Care should be taken that after the demineralization stage the protein content is up to 1.5% by weight and the pH is in the required range, and the sedimenting Separates material from the liquid. 2. The method according to claim 1, characterized in that whey is used as the whey protein-containing liquid. 3. Method according to claim 1 or 2, characterized in that that the demineralization stage can be reached by passing the to demineralizing liquid effected via ion exchangers. 4. The method according to one or more of claims 1 to 3, characterized in that the demineralization stage is effected in such a way that there is an ash / protein ratio of up to 0.05 results. 5 × The method according to one or more of claims 1 to 4, characterized in that adjusting the protein content in the range of 0.5 to 1.5 wt.%. 6. The method according to one or more of claims 1 to 5, characterized in that the demineralized liquid stored at a pH value outside the range from 3.5 to 5.0 before clearing. 7. The method according to one or more of claims 1 to 6, - 14 - 709821 / 09A8 BO 5395 MdR β characterized by first going through the demineralization stages then adjusts the protein content and finally adjusts the pH value. 8. The method according to one or more of claims 1 to 7, characterized in that the sedxmentierenden material removed by spinning. 9- The method according to claim 8, characterized in that the resulting liquid is concentrated by means of ultrafiltration. 10. A process for the production of protein-rich beverages, characterized in that one component is the Liquid used, which is obtained by the method according to claims 1 to 9. 11. Process for the production of meringue products, characterized in that one component is the liquid used, which is obtained by the process according to claims 1 to 9. - 15 - 709 821/0948