CA1094868A

CA1094868A - Process for the production of high protein whey products

Info

Publication number: CA1094868A
Application number: CA294,585A
Authority: CA
Inventors: Harold T. Pederson, Jr.; Leo H. Francis
Original assignee: Patent Technology Inc
Current assignee: Patent Technology Inc
Priority date: 1977-01-10
Filing date: 1978-01-09
Publication date: 1981-02-03
Also published as: SE7800243L; FR2376630A1; NL7800265A; SE427982B; IE46362B1; NZ186139A; GB1551594A; AU510551B2; FR2376630B1; AU3231078A; IE780048L

Abstract

PROCESS FOR THE PRODUCTION OF
HIGH PROTEIN WHEY PRODUCTS
of which the following is a specification.
Abstract of the Disclosure A process for the treatment of whey to produce products containing whey protein to a desired predeter-mined level. Whey is subjected to treatment for removing a portion of its lactose content by lactose crystalliza-tion and the resulting mother liquor, which has a protein level higher than that of the original whey, is then sub-jected to ultrafiltration carried out in such a controlled manner as to produce a protein rich fraction having the desired protein content. The process produces products standardized with respect to protein content, irrespect-ive of variations in the protein level of the source whey, which may vary from time to time.

Description

~C~9~868 Background of the Invention This invention relates generally to processes for the treatment of whey to produce products having whey protein to desired predetermined levels.
It is recognized in the food industry that edible whey contains valuable nutrients, lncluding whey protein. Wheys such as are produced in the manufacture of Cheddar cheese (e.g~, sweet whey) and other types of cheeses, have relatively high mineral salt contents which in many food formulations cannot be tolerated.
Various processing treatments can be applied to re-move some of the mineral salts whereby the whey is more acceptable in various formulations. Particular reference can be made to reduction in the mineral salt content (i.e., ash content) by ion exchange columns or electro-dialysis. Removal of say 50% or more of the mineral salt content also serves to increase the protein level (e.g., from 12 to 14.5% dry solids basis [DSB]~. There is a cornmercial demand for whey derived products haVing a relatively high protein content, as for example ~rom 25 to 80% (DS~).
It has also been known that whey can be frac-tionated by ultrafiltration to produce a permeate that is rich in lactose and a fraction rich in protein (see Canadian Patent 996,361 dated April 22jl975). By applica-tion of ultrafiltration it is possible to produce whey products having protein levels well above 25%. Ultrafil-tration tends to be subject to some difficulties when ap-plied to whey, such as rapid reduction in the flux rate and relatively short life for the membranes. In general

- 2 -~'~

8~

it has been found that to a-ttain a given protein level in the 25 to 35~ range (DSB), it is more economical to employ removal of lactose by crystallization. A complicat-ing factor in the production of high protein whey products is that the protein content of raw natural whey available for processing varies from day to day and from season to season~ whereas it is important for a commercial high protein whey product to have a fixed predetermined protein content which complies with product specifications. It is difficult to control a lactose crystallizlng operation, f ollowed by removal of lactose crystals, in such a manner as to provide a mother liquor having a predeter-mined pEOtein level, since the protein level tends to vary dependent upon variations in the pro-tein level of the natural whey and other processing factors such as those that affect the lactose yield.
Objects of the Invention and Summary ~; It is an object of this invention to provide a ' process fc,rthe treatment of whey which makes possible pro-duction of products that are standardized with respect to their protein levels, irrespective of variations in the protein level of the source whey.
Another object is to provide a process which ` attains standardization with respect to protein level by application of processing operations which are relatively simple, economical and readily controllable.
Anothe. object is to provide a whey treatment process which ma~es use of ultrafiltration as a means for attaining standardization of the protein level(s) of the resulting product~s).

4~,8 Another object is to provide a whey treatment process which facili-tates fractionation of ~ey by ultrafiltration, thereby providing an accept-able and economical flux rate and relatively long operating cycles before it is necessary to replace or regenerate the ultrafiltration membrane.
According to the present process, whey is treated to produce a pro-tein containing product having Nhey protein at a desired predetermined protein level (dry solids basis), The whey being treated is subject to variations in protein level. A mother liquor is produced from such wheys by concentrating the whey and removing a substantial portion of its lactose content by crystal-lization and removal of lactose cry~stals from the mother liquor. The amount -~
of lactose thus removed ranges from about 45 to 55% of the lactose content of the concentrate. The protein level o~ the mother liquor solids ranges from about 25 to 50% and IS subject to vari:ations. Thereafter, the mother liquor is subjected to an ultrafiltration operation by use of ultrafiltration equip-ment operating and proceeding under controlled conditions to produce a protein rich fraction and a lactose rich permeate. The ultrafiltration operation is carried out continually over a period o~ time during ~hich there is continual increas-e in the protein level of said fraction until the desired predetermined protein level that is higher than that of the mother liquor is at~ained.
In general, according to the present process a substantial portion of the lactose content of whey is removed by crystallization of lactose, fol- -lowed by removal of the lactose crystals, where~y the resulting mother liquor has a protein level greater than the untreated whey, m ereafter the mother liquor is subjected to ultrafil~ration to produce a protein rich fraction and a lactose rich fraction, with the ultrafiltration operation keing controlled in such a manner as to provide a desired protein level that is substantially higher than that of the feed material.
Additional objects and features of the i~nvention will appear from the following description in which the preferred embodiments have been set forth in detail in conjunction w~th the accompanying drawi~ng.

4~

BRIEF DESCRIPTION OF THE DRAWING
Referring to the drawing:
Figure 1 is a flow diagram illustrating one procedure for carrying out the process.
Figure 2 is a flow diagram illustrating another embodiment of the process.
Figure 3 is a flow diagram illustrating another embodiment of the process.
Flgure 4 IS a diagram illustrating ultrafiltration equipment.

- 4a -18~i8 Description of the Preferred Embodiments The source material employed is whey such as is produced as a by-product in the manufacture of cheese.
It is considered preferable ~o use so-called sweet whey such as that produced in the manufacture of Cheddar cheese Typical sweet wheys range from about pH 5.7 to 6.4, where-as acid wheys such as are produced in the manufacture of co-ttage cheese range from pH 4.3 to 4.8. Cottage cheese wheys have an ash content which may range from about 9.5 to 13.0~ (DSB). Sweet wheys such as are produced in the manufacture of Cheddar cheese may have ash contents ranging from about ~.0 to 10.0~, and lactose contents from about 65 to 76% (DSB). As previously mentioned, the general composition of whey produced in a particular cheese plant may vary from day to day and from season to season, due to variations in the milk used in the cheese man-ufacturing process. Likewise the protein level varies with the type of processing used in the cheese manufac-turing plants in which the wheys are derived. Particu-larly, when products are being produced for human consump-tion, it is necessary for the whey to be of edible quaI-ity, and it is desirable that the heat denaturable pro-tein remains subs-tantially undenatured(i.e., low heat whey.
In the procedure outlined in Figure 1, it is assumed that the whey is a low heat sweet whey of edible quality produced in the manufacture of Cheddar cheese.
In step 10 the whey is concentrated, preferably by vacuum evaporation, to a solids concentration of about 20 to 30O.
It is then subjected to clarifying in step 11, which can 6~3 be carried out by passing the whey through a suitable centrifuge capable of removing any undissolved solids, such as curd fragments. The clarified concentrate is then partially demineralized in step 12, which can be carried out by known me-thods, such as contact with ion exchange resins or electrodialysis. Electrodialysis is preferred because it is relatively economical and sub-ject to control ~ore particularly, it is desirable to utillze the electrodialyzing process and apparatus dis-closed in U.S. Patents 3,544,436 dated December 1,1970 and 3,755,134 dated August 28,1973. In step 12, a predetermined amount of mineral salts are removed, depend-ing upon the specifications for the finished product being manufactured. In general, from 20 to 90% of the ash con-tent can be removed.
T~ partially demineralized whey from step 12 has a solids cc,~itent somewhat less than the solids con-tent of the concentrate produced in step 10. For example, the solids content may range from 19 to 25% where the whey in step 10 is concentrated to a solids content of from 20 to 30%. In step 13 the partially demineralized whey is further concentratedr preferably by vacuum evap-oration,to a solids content of about 50 to 60%. The concentrate is then subjected to lactose crystallization in step 14 which can be carried out by known methods involving cooling the concentrate to effect lactose crystallization, after which the lactose crystals are removed as by screening, hydraulic separation or centrifuging. The amount of lactose removed in th.i.e manner depends upon various controlling factors of the crystal-lizing operation, inc]uding particularly the concentration of the whey before cyrstallization, and may range from about 45 to 55% of the lactose content of -the concentrate.
Removal of lactose results in a corresponding increase int~le proteln content. Thus, whereas the whey supplied to the process may have a protein level of the order of 12% (DSB), after reducing the lactose content by some 45 to 55%, the protein level in the remaining solids may range from about 25 to 40%. According to the present process, step 14 is carried out under such conditions as to remove an amount of lactose which will result in a protein level of the remaining solids that is less than that required in the finished product, but is as high as can be economically produced by the step 14. For example, if the specifications call for a protein level of 35% for the finished product, then the amount of lactose removed in step 14 may be such that the protein level of the remaining mother liquor is about 20 to 32%. -~
In step 15 the mother liquor from step 14 is sub- ~
jected to separating as by use of a suitable centrifuge for removing a portion of the butterfat that may be present.
- Generally, wheys derived from the manufacture of cheese have a fat content of the order of 1.0 to 2.5% (DSB). In step 15 it is desirable to reduce the fat content to a level of the order of 0.3 to 0.35% (DSB). Centrifuging also serves to remove a sludge containing relatively fine sized lactose crystals that are not removed in step 140 ~ollowing step 15, the material is subjec-ted to ultrafiltration in step 16. It is desirab]e that the material being supplied to and dùring ultrafiltration be at a temperature level of the order of 110 to 120F.
Ultrafiltration equipment can he obtained from a number of manufacturers, and is characterized by membranes through which the liquid material is forced under con-trolled pressure to remove water and smaller molecules present,and resulting in the concentration of the larger molecules on the pressure side of the membrane. An equipment unit may consist of a plurality of serially connected modules manifolded in such a manner that the feed flows successively from one module to the next, while the liquid (i.e., permeate) expressed from all the modules is merged together for sep-arate discharge. There are a number of ultrafiltration membrane concepts available - tubular, hollow fibers, plate and frame, leaf deslgn and spiral wound. Any of these should be suitable for this application. With the proper selection of pressures and membranes, ultrafiltration can be applied to produce a lactose rich permeate and a protein rich fraction. Most of the various kinds of mineral salts , present are removed with the lactose permeate, whereby on a dry solids basis the level of mineral salts in the protein rich fraction is less than the mineral salt levelof the feed material. For example, if the mineral salt level of the mother liquor from step 14 corresponds to an ash content of 4.0%
(DSB), then step 16 may produce a protein fraction having an ash content of 3.0% (DSB). Good results have been ob-tained by use of equipment made by A~COR,INC. of Cambridge, Massachusetts sold under the trade designation ABCOR.
In operation of ultrafiltration equipment,there are certain factors which can be varied to control the protein level of the protein rich fraction. These factors lnclude the pressure at ~Jhich the feed is supplied to -the membranes, the temperature of 'che feed, and the duration of -the operating ;

86~

cycle. The equipment is usually operated -to process prede-termined measured batches of the feed material, with re-circulation of the protein fraction back to the feed, and with the duration of the cycle being such as to attain -the desired protein level. Making use of the ABCOR equip-ment previously mentioned, one can obtain protein levels in one stage as high as 50%, or any lesser level which one may desire to comply with the product specifications. The equipment may include a feed tank of sufficient size to accommodate the batch of feed material, a feed pump which supplies the feed material to the modules of the ultrafil-tra-tion equipment at a predetermined pressure or pressures, and means for recirculating the protein fraction. The equipment may also include a heat exchanger for heating or coollng the feed material to a desired temperature level. Such equipment can be operated on either a batch or continuous cycle.
In some instances the protein fraction from a first equipment stage may be routed to a second equipment stage 17, with the second stage operating in the same manner as the first stage. When two or more equipment stages are used the protein fraction from a preceding stage may be diluted with water to provide the feed to the next stage. The amount of diluting water can be another controlling factor to determine the protein level of the protein fraction produced.
By way of example, the amount if diluting water may be about the same volume as the volume of protein fraction supplied as feed to step 17. An increase in the amount oE dilution serves to increase the protein level produced by the second stage. Assuming that care is taken throughout processing to ~09~ 8 avoid heating to temperatures of the order of 150F. or higher for prolonged periods, the protein of the products obtained is substantially undena-tured.
The protein frac-tion from step 16 produces product A whieh ean be used as sueh, or whieh ean be subjeeted to drying 18 to produce the dry produet B. Known methods of spray drying ean be used to produce product s in powdered form. Likewise, the protein fraction from a seeond staye 17 produees product C, which again can be dried at 19 to produce product D.
Assuming that the products produced by the process of Figure 1 are to be supplied to various food manufacturers for formulating with other ingredients, the lactose crystal-lizing and removal step 14 and the ul~rafiltration step 16 can be eontrolled to meet sueh speeifications. For example, the specifications may call for a series of products ranging from 25 to 80% protein. Also the speeifieations for each such product may call for ash contents ranging from 1.5 to 6.0%.
Such specifications of ash content can be met by control- -ling the demineralizing step 12. Thus although steps 12, 14 and 16 are interrelated, they can be accurately controlled to meet the desired specifications to a high degree of aceuracy. The process is economical, partieularly in that a substantial part of the protein level increase is obtained by removal of crystallized lactose in step 14, and the remaining increase is attained to a high degree of accuracy by ultrafiltration. The process can be operated to accommodate variations in the protein content of the incoming whey. Thus analyses ean be made of the whey received by the processing plant, and depending upon the percentage of protein present in the whey solids, the process can be controlled to meet the de-sired specifications. Ultrafiltration as used in the process not only serves -to increase the protein level, but in addi-tion functions as a method of standardization of the finished product to meet the specifications.
As is understood by those familiar with ultra-filtration equipment, economical operation is dependent in part upon the flux rate that can be maintained. With the present process, relatively high flux rates can be main-tained, due in part to the absence of a substantial amount of ash which is removed in step 12, and also to the re-duction in the fat content by step 15. Also it has been found that undesirable fat present in the whey can most economically be removed after the crystallization and removal of lactose in step 1~, as distinguished from removing the undesired fat by centrifuging the incoming whey.
Figure 2 illustrates another embodiment of the process in which crystallization of lactose and removal of lactose crystals is carried out before demineralizing.
Thus the incoming whey is concentrated at 21, preferably by vacuum evaporation, to a solids content of from 50 to 60% or higher. In step 22 this concentrate is subjected to lactose crystallization and removal of lactose crystals, and the mother liquor subjected to separating and clari-fying in step 23. This material is then supplied to the electrodialyzing operation 24 for reducing the mineral salt content to the desired level. Thereafter it is sub-jected to ultrafiltration 25 -to produce the product E.
Also this material can be spray dried at ~6 to produce the 1C~!3~8$~

produ~ F. The separating step 23 serves to remove fine lac-tose crystals not removed in step 22, and also removes a certain amount of fat which may be in excess of that de-sired.
In both the processes of Figures 1 and 2, making use of sweet whey, it is generally unnecessary to adjust the pH of the material being supplied to the demineralizing step. However,in the event acid wheys are used, it is desirable to neutraliæe acid by the addition of a suitable neutralizing agent, such as sodium or potassium hydroxide.
It is desirable to neutralize to a pH level of the order of 6~1 to 6.5, with the incoming whey being neutralized before processing.
Another embodiment of the process is shown in Figure 3. This is applicable whexe the product specifications do not call for a reduction in the mineral salt content. Thus with such products, the incoming whey is concentrated in step 31 to 40 to ~0% solids, and subjected to crystallizing and removal of lactose crystals in step 32. Thereafter the mother liquor is subjected to separating and clarifying in step 33, and then to ultrafiltration 34. Both the steps 32 and 34 are controlled to produce the desired pro-tein level in the final products. Product G is the protein fraction from step 34, and product H is the same material after drying 35. By the use of the process shown in Figure

3, it is possible to produce final products having protein levels ranging from about 22 to 75%.
~igure 4 schematically illus-trates one way in which ultrafiltration equipment has been operated. The equipment includes a feed tank 41 which is of sufficient 86~3 size to accommodate a batch of material to be processed introduced through the feed line 42. Pump 43 delivers ma-terial from tank 41 to the ultrafiltration equipment 44 at a predetermined pressure. The pro-tein fraction is recir-culated by line 45 and pump 46 to the discharge side of the pump and permeate is discharged through line 47. The draw off of the protein fraction through line 48 is con-trolled by the three-way valve 49.
The equipment shown in Figure 4 can be operated continuously. Thus whey is pumped from tank 41 at a con-tinuous rate and delivered to the ultrafiltration unit 44 at a fixed predetermined rate and temperature. Pump 46 continuously recirculates the protein fraction with flow rates such as to maintain the desired flux performance.
When the protein level reaches the desired value, the ~roduct is bled off at a controlled rate through valve ; 47 and line 48. If it is desired to employ a second equip-ment stage, the fraction bled off through line 48 is de-livered by a pressure pump to a second equipment stage operating in the same manner as just described. The feed to the second equipment stage may be diluted as previously described.
Examples of the invention are as follows~
The source material was sweet whey of edible quality obtained from the manufacture of Cheddar cheese.
Its protein level was 11.5% (DSB), and the ash content of the solids was 10%. As received for processing, it was at p~ 5.8. By use of a vacuum evaporator it was concentrated to 20% solids, after which the concentrate was clarified by centrifuging. It was then subjected to elec-~ 13 -tr odialyzing, making use of the method and apparatus dis-closed in said U.S. Patents 3,544,436 and 3,755,134. The pH was adjus-ted to pH 6.1 with sodium hydroxide and during electrodialysis it remained be-tween the limits of 6.1 to 6.5~ Also it was at a temperature between the limits of 100 to 110F. Electrodialyzing was carried out to the extent of reducing the ash content to 4.5% (DSB). The elec-trodialyzed material had a solids content of 20%. This material was then subjected to concentration to 50 to 55%
and then crystallization of lactose by cooling, after which ~actose crystals were removed by hydraulic separation.
The amount of lactose thus removed reduced the lactose content of the mother liquor to 55% (DSB). The mother liquor was then subjected to separation by centrifuging to reduce the fat content to 2.5%. Thereafter the batch was diluted ~ to 15% solids and subjected to ultrafiltration, maXing use ; of equipment manufactured by ~BCOR,INC. of Cambridge, Massachusetts, identified as AB COR UF 480. The equipment was operated with recirculation of the protein fraction in the manner described in connection with Figure 4. The product specifications to be met in this instance was a dry powdered product having an ash content of ~3%, and a protein level of >35% (DSB). The controlling factors of the ultrafiltration operation were controlled whereby these specifications were met accurately both with respect to mineral salt conten-t and protein level. Control in-volved maintaining the inflow pressure constant, and con-trolling the duration time of the cycle. During the course of this example, it was observed that the ultrafiltration equipment maintained a relatively high flux rate, which is attributed to the fact that the whey had been partially 1 ~ _ 9~8~

demlneralized and had a relatively low fat level. The final product in this instance corresponded with Product B of Figure 1.

Example 2.
Example 1 was repeated, but control of the cry-stallization of lactose and its removal and of the ul-tra-filtration operation were modified to produce a product of higher protein value, namely ~50% (DSB). Thus in this instance crystallization of lactose and lactose removal were carried out to remove a higher percentage of lactose, whereby the lactose remaining in the mother liquor was 50% (DSB). This was done by increasing the concentration of the whey before crystallization. The resulting mother liquor had a protein level of 232%. Ultrafiltration was then carried out under controlled conditions to meet the specification of ~50% protein in the final product.
Example 3.
To carry out the process illustrated in Figure 2, the whey employed can be the same as in Example 1. It is concentrated by vacuum evaporation to 55% solids content, after which it is subjected to crystallization and removal of lactose crystals to the extent of providing a mother liquor having a lactose content of 5.0%j and a protein level of 1~.
The mother liquor is then subjected to the separating and clarifying step 23 carried out by use of a centrifuge, and the clarified material then subjec-ted to eiectrodialyzing 24 carried out in the same manner as in Example 1. Electro-dialyzing i9 continued to reduce the ash content to the level of 4~(DSB).
~he electrodialyzed material is then ~ed to the 8~

ul-trafiltration step 25 which is con-trolled to meet the product specifications. These specifications may call for an ash content of ~3~ and a protein level of ~35%.
The specifications as to protein level can be readily at-tained by controlling the ultrafiltra-tion operation. The product produced in this example would correspond with the product F of Figure 2.
Example 4.
The product specifications in this instance called for a mineral salt content corresponding to that present in untreated whey, and a protein level of 12%. In othex words, the product specifications did not require reduction in the ash content. The whey in this instance was the same as employed in Example 1. It was concentrated by vacuum evaporation to a 55% solids, after which it was subjected to crystallization of lactose and removal of lactose crystals to reduce the lactose content of the mother liquor to 50%. Also the level of protein in the mother liquor was increased to 18% (DSB). The mother liquor was then subjected to separating and clarifying by use of a centri-fuge, which served to remove fine lactose crystals as a sludge, together with some fat. The clarified material was then subjected to ultrafiltration carried out as previously described to produce a protein fractlon having a protein level corresponding to the specifications, namely ~35%. This product when spray dried corresponded with the product H of Figure 3. Here again there was no difficulty in accurately manufacturing to the desired protein speci-fications.
~7ith respect to the procedure of Example ~, the ~L0~4~

protein fraction produeed by ultrafiltration can be sub-jected to demineralizing as by electrodialysis to reduce the ash eontent to a desired level to meet produet specifications.
Li]~ewise in carrying out proeedures as in Figures 1 and 2, or as in Examples 1, 2 or 3, demineralizing ean be applied to the protein fraetion produced by ul-trafiltration. However, when demineralizing is employed, we prefer that it be applied before removal Of lactose and before ultrafiltra-tion as in Figure 1. Such pr~ctiee reduees the amount of mineral 1~ salt contamination of the lactose crystals removed in step 14 and the salt level in both the protein fraction and per-meate from step 16.

Claims

WHAT IS CLAIMED IS:

1. A process for the treatment of wheys to produce a protein containing product having whey protein at a desired predetermined protein level (dry solids basis) the whey being treated being subject to variations in pro-tein level, comprising producing a mother liquor from such wheys by concentrating the whey and removing a sub-stantial portion of its lactose content by crytallization and removal of lactose crystals from the mother liquor, the amount of lactose thus removed ranging from about 45 to 55% of the lactose content of the concentrate, the protein level of the mother liquor solids ranging from about 25 to 50% and being subject to variations, and thereafter subjecting the mother liquor to an ultrafil-tration operation by use of ultrafiltration equipment operating and proceeding under controlled conditions to produce a protein rich fraction and a lactose rich permeate, the ultrafiltration operation being carried out continually over a period of time during which there is continual increase in the protein level of said fraction until the desired predetermined protein level that is higher than that of the mother liquor is attained.

2. A method as in Claim 1 in which some of the mineral salt content is removed from the whey before removal of part of the lactose by crytallization.

3. A process as in Claim 1 in which some of the mineral salt content is removed from the mother liquor after removal of some of the lactose from the whey by crystallization and before subjecting the material to ultrafiltration.

4. A process as in Claim 1 in which the ultrafiltration equipment is operated with controlled continuous recirculation of the protein rich fraction, the operation continuing until the protein level of the protein rich fraction increases to the desired value.