CA1077472A - Process for the treatment of whey and whey permeate and products resulting therefrom - Google Patents

Abstract

Abstract of the Disclosure Whey permeate produced by membrane ultrafiltration is treated to produce various usable products, including lactose of various selected purities, and mineral salts of high calcium content. Also processing of whey permeate to produce an edible flavoring material having the proper-ties of soy sauce.

Description

~ :; 1077472 Background of the Invention Processes are presently in cor~ercial use which treat whey for the separation and production of various ~: useful products, including whey protein products and lactose.
One such process makes use of membrane ultrafiltration which serves to sèparate the whey into two fractions, one being 'S! a protein-rich fraction, and the other being a permeate rich in lactose. Such a process is disclosed in Canadian Patent 965,361 dated April 22,1975. The composition of a typical ~ 10 wbey permeate obtained by application of membrane ultra-- filtration depsnds upon a number of factors, including the character and source of the whey, and the manner in which the membrane ultrafiltration is carried out. The princi-pal constituents include lactose, mineral salts, protein, non-protein nitrogen (NPN), and a small amount of fat.
The mineral salts include both the natural buffer salts of milk, and also mineral salts resulting from the cheese ma~ing proc2ss from which the whey is derived. A general ;~ ~ composition range (dry solids basis) for permeate derived from acid and sweet wheys is as follows:
Lactose 68.0 to 87.0%`-Protein 3.0 to 5.5 ~¦~ NPN 0.4 to 0.8 Fat 0-1 to 0.2 Ash 8.5 to 14.0%
Titratable acidity2.0 to 14.0~
The high level of mineral salts tends to impart ~ undesirable flavor characteristics. When processed for '' the removal of lactose by crystallization, which involves : :!
, 30concentration of the permeate, certain of the salts pre-~. .j ,.,.,~ ~
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cipitate out, together with crystallization of the lactose, and this tends to reduce the lactose yield and decrease its -- purity. While the permeates include substances of value, their disposal without processing poses a serious problem ~; 5 since it is an ecological pollutant.
Commercial processes for the manufacture of lactose generally remove lactose from whey concentrate by crystalli- -'~ zation (see U.S. Patent 2,439,612 dated April 13,1948).
Such lactose is relatively impure, since it contains some whey i 10 protein and mineral salts. Resolution and recrystallization - -is employed to obtain products of higher purity. The remain-ing mother liquor is not suitable for human consumption and ~,/ cannot be discarded to waste because of adverse ecological `~~ effects.
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Summary of the Invention and Objects This invention relates generally to the treatment of cheese whey to produce various usable products, and ' more particularly to processes making use of membrane ultra-filtration and to the treatment of the resulting whey per-meate.
An object of the invention is to provide a pro-cess capable of converting whey permeate into one or more products of marketable value without undue expense.
Another object is to provide a process for the treatment of whey permeate which will produce a high yield -of relatively pure lactose.
~ Another object is to provide a process which -~
`,' yields one or more mineral salt products of marketable '' value.
' 30 Another object is to provide a permeate treatment .'' :' :
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process which facilitates elimination of disposable materials which are objectionalbe as ecological pollutants.
In general the present process involves production of a whey permeate by membrane ultrafiltration of whey. As indicated above, such permeate may have a lactose content of from 68 to 87% (dry solids basis), and 3.0 to 5.5%
whey protein. The permeate is subjected to a treatment step in which certain ~ -of the mineral salts are precipitated, after which the precipitated material is removed and the remaining material subjected to further treatment to provide purified lactose and possibly other marketable products.
The present process treats whey derived from the manufacture of cheese which has titratable acidity. The whey is subjected to membrane ultra-filtration to form a protein-rich fraction and a permeate fraction. The per-j. ..j .
meate fraction has a solids content of the order of 5.0 to 7.5% and a lactose content of about 68 to 87%. Also it has a protein content of not more than ;, about 6% and a mineral salt content including calcium and citrate salts, together with phosphate and monovalent salts. Calcium and citrate salts are precipitated from the permeate without substantial precipitation of phosphate ~i salts by concentrating the unneutralized permeate to a solids content of about 40 to 45% and by holding the concentrate at a temperature level of about 180 to 200F. for a holding period of from 30 to 90 minutes to effect precipitation of calcium and citrate salts without substantial precipitation of phosphate salts, ::.
the precipitated salts amounting to about 5.0 to 15.0% of the total mineral salts of the permeate. The precipitated solids are then removed from the per-meate and the permeate further concentrated and some of the lactose crystallized ;., ~
and removed from the same.

~- Additional objects and features of the invention will appear from the following description in which the preferred embodiments have been set forth in - detail in conjunction with the accompanying drawing.

Brief Description of the Drawing ~ 30 Figure 1 is a flow diagram illustrating one em~odiment of the process.

,`~ Figure 2 is a flow diagram illustrating another embodiment of the ~ process making use of alkaline precipitation.

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Figure 3 is a flow dia8ram illustrating another embodiment in which lactose is purified in two stages.
Figure 4 is a flow diagram illustrating another embodiment.
Figure 5 is a flow diagram illustrating a procedure for manufacturing a flavoring material like soy sauce.
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Description of the Preferred Embodiments In Figure 1 it is assumed that the whey being treated is an edible grade acid cheese whey, although the process is deemed applicable to other types of wheys, ' 5 such as Cheddar cheese whey. Preliminary to its process-; ing, the whey may be treated in any one of various ways, ~; f , as or example by pasteurlzation or chemical treatment to ;~ control bacterial contamination. The whey is shown being subjected to membrane ultrafiltration in step 10, thereby producing a protein-rich fraction and a whey permeate. Ultra-filtration may be carried out in a single stage, or in more than one stage, depending upon the protein level desired for the protein fraction. In any event, it is desirable ; that ultrafiltration be carried out in such a manner that the residual protein in the permeate does not amount to more '-l than about 6.0~ of the total solids content. The permeate ., .
j is shown being subjected to a precipitating step 11 which ~ serves to selectively precipitate certain of the mineral ;l salts. More specifically, in this instance precipitation is carried out by heating the permeate,which as it is obtained from step 10 has a solids content of the order of 5.0 to 7.5%, to a temperature level of the order of from , 180 to 200F., and concentrating the permeate by evaporation to a solids content of about 40 to 45%. The sequence of these steps can be altered by first concentratin~ the permeate by vacuum evaporation and then heating and holding for promoting precipitation. For example, the material may be held at the indicated temperature level and concentration ~, for a period of 30 to 90 minutes. As a result of this " l treatment, certain of the mineral salts are selectively :

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`~ precipitated, including particularly the natural buffer salts of the whey. More particularly, the calcium and ; ; citrate salts of the buffering system are precipitated, ~,l whereas the phosphate salts of the buffering system do not tend to be precipitated by this treatment. Likewise, this treatment does not precipitate the simpler monovalent ,r"~,~ i salts such as sodium chloride.
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By application of the treatment described above, from about 5.0 to 15.0% of the total mineral salts of the permeate are precipitated. The precipitate is removed in ,.,. ,j, .
~ step 12 and the remaining permeate is clarified and treated ";"~,., : -~I for the removal of lactose. Step 12 preferably is carried out `- 'J
~; while the permeate is at an elevated temperature of 180 to 200F. The filter medium may be iron free or reduced diatoma-ceous earth (e.g., acid washed Celite), which serves to remove precipitate and to clarify the material. In step 13 `
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the lactose is crystallized from the mother liquor, collected, ~.,`,,,1 `;~,; and subsequently subjected to washing in step 14. The crystal-lizing step 13 can be carried out with the permeate at ~` 20 a sufficient concentration for effective crystallization, as r exampIe, a concentration of the order`of 50 to 60%
total solids. Concentration to levels which cause further precipitation of mineral salts should be avoided. Thus it is desirable to effect some further concentration of ~; ~ 25 the permeate following the filtering step 12, without further precipitation of salts, in order to provide an -effective yield of lactose for the crystallizing operation.
The lactose crystals from washing step 14 may be subjected to drying by conventional methods to produce the lactose product A.

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Water of proper purity may be used for washing in step 14, although we prefer to use acidified water.
,, For example, the wash water may contain a small amount of ~` hydrochloric or other acid, whereby the wash is slightly acid at a pH of from 2.5 to 3.5. It has been found that this serves to more effectively remove protein and other impuri-, ties from the collected lactose crystals.
` The process as described above produces lactose ~' of a purity of the order of 99.1% or better. The lactose .~., .
yield may be of the order of 35 to 55%. The motherliquor from step 13, with or without being blended with ,f wash water from step 14, may be subjected to further treat-ment to increase the yield of lactose and to provide ~` another lactose product of high purity. Thus the liquor ~15 from step 13 is shown being subjected to a further precipi-`i~ tating step 15 which in this instance is preferably carried ,l out by adjusting the pH to a value of the order of 7 to 10, by adding an alkali neutralizing agent such as sodium or f~ potassium hydroxide. Following or at the time the neutral-f 20 lizing agent is added, the material is heated to a tempera-! ~ ture of the order of 140 to 150F., whereby a substantial percentage of the mineral salts present, which are not ¦ precipitated and removed in steps 11 and 12, are precipitated.
The solids concentration at the time of this treatment J
may be of the order of 20 to 30%. The salts precipitated in this manner are mainly salts other than the natural 1 buffering salts. However, the phosphate buffer salts are precipitated and also a substantial amount of non-protèin nitrogen. Following step 15 the material is treated for the removal of the precipitate as by the step 16 carried . ~ .

`` ` `^ "- ~077472 P `''''';`' ., out like step 12 of Figure 1. Both steps 12 and 16 may also be carried out by centrifuging to remove the precipitate ~;i followed by decolorizing by passing the material through a decolorizing carbon filter while at a temperature of about 180 to 200F. Lactose is then removed by crystallizing and collecting in step 17, with or without further washing, to produce the lactose product B. Here again it may be necessary to further concentrate the material (e.g., 50 to 65% solids) following the filtering step 16 and before o crystallizing in step 17, taking care to avoid concentrating , .- . , , to a solids level sufficient to cause further precipitation - of residual mineral salts.
Assuming that the process includes the second stage of lactose crystallization and removal, the overall yield of lactose for the process may be of the order of 80% or higher. Also the product B may have a purity of 97% or higher.
In some instances it may be desirable to spray dry the filtered permeate from step 12. Thus, the permeate may be concentrated and spray dried in step 21 to produce the spray dried lactose product C. Because of the removal ~, of whey protein and a substantial amount of buffer salts in the precipitating step 11, the flavor of the spray dried product is superior to that of untreated spray dried whey ~l~ 25 permeate, and therefore product C can be used in formulating various food and feed products.
The buffer salts removed in the filtering step 12 may be subjected to drying 22 to produce the dry product D.
This is a high calcium and mineral salt content product which has value as an additive to various formulations including ~';1 '~

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-~ - animal feeds. An analysis of a typical product D is as -~ follows:
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Water 5.805 Total Nitrogen 0.23%
Ash 31.09 Calcium 14.3 , ,,, ;
Phosphorous 0.43 Magnesium 0.07 Sodium 0.25%
-` 10 Potassium 0.8%
Citrate 43.4%
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~ Lactose 25.5%
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Titratable Acidity 2.0%
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pH 5.3 According to the process of Figure 2, the whey .: :;
.~ is subjected to ultrafiltration 31 as in Figure 1, and the :l perm eate is then subjected in step 32 to precipitation at - an adjusted pH of the order of 7 to 10. This step is carried out li]ce step 15 of Figure 1 by introducing a suitableneutralizing alkali such as sodium hydroxide.
After or at the time the pH is adjusted, the material is -.
heated to a temperature level of the order of from 180 to 200F. and held at this temperature level for a time , . . .
sufficient to substantially complete precipitation, as for 25 example from 30 to 90 minutes. The precipitate is then removed in the clarifying or filtering step 33, which pre-:;;:
ferably is carried out as described for step 16 of Figure 1 with the material at an elevated temperature of 180 to 200F.
For the purpose of producing products of varying purity, 30 further processing may involve concentrating the clarified , . ~ .
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`: ~0'77472 permeate in step 34 to a solids eontent of the order of from ~` 20 to 30% and then subjeeting it to a demineralizing step ~` 35, which ean be earried out by any one of several known methods, ineluding contact with ion exehange resins, or preferably by electrodialysis. By such treatment a desired amount (e.g., lO to 90%) of the residual mineral is removed.
The deminralized permeate is shown being further concentrated in step 36, after which it can be spray dried in step 37 to produce the spray dried product E. This product may have a lactose content of the order of 90 to 98%, and the lactose -yield for the process may be from 70 to 85%. Eleetrodialy- -sis is effeetive for the removal of from lO to 90% of the . . , . -, mineral salt content. Ion exchange resins are effective to , remove up to 98~ of the salt eontent .,., . - , Instead of direetly spray drying the material from the demineralizing step 35, the eoneentrated and deminerali-. .
zed permeate may be subjeeted to the erystallizing and eolleet-ing step 38, with the eolleeted lactose crystals being subjeeted to washing in step 39, followed by drying 40 to produee the laetose produet F. This produet may have a pur-ity of the order of 99%. As diselosed in eonneetion with ).,~ , Figure 1, the wash employed in step 39 may be slightly ~, aeidified water at a pH of from 2.5 to 3.5.
,;l Clarified permeate from step 33 of Figure 2 may ;i ,' 25 be eoneentrated in step 41 and subjeeted to spray drying 42.l to produce the produet G. Also a eoncentrate of the elari-fied permeate may be subjected to a lactose crystallizing and eolleeting step 43, with the eollected crystals being subjeeted to washing in step 44, and drying 45 to produce the purified laetose product H. This produet has a purity similar ., , , :, : ' ., ,- , .. . . .

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to product A of Figure 1, and this procedure provides a lactose yield of from 50 to 60%.
The process of Figure 3 employs a precipitating step together with lactose refining. Thus in this in-stance whey is subjected to membrane ultrafiltration 51 to remove whey protein, and the resulting permeate is subjected to the precipitating step 52 which is carried out by heating and concentrating in the manner described in --- connection with step 11 of Figure 1. After step 52 the material is subjected to step 53 which can be carried out ~ .
by filtering and clarifying the material while it is at an elevated temperature of the order of 180 to 200F. to remove precipitate and to clarify the permeate. The clarified ;l peremeate is then concentrated in step 54 to a solids content of the order of 50 to 60% and subjected to the lactose ` crystallizing step 55. The lactose crystals collected in ; ~ step 56 are subjected to washing, which can be carrled out ' by acidified wash water at a pH of from 2.5 to 3.5. The lactose from step 56 may be dried in step 57 to produce the ; 20 dry lactose product I. The mother liquor from step 56 .~ ~
l is shown being subjected to pH adjustment and precipitating i instep 58 which can be carried out in the same manner as step 32 of Figure 2. After filtering and clarifying in step ~1 59 the material may be concentrated at 60 (e.g., to 50 to 60~ solids), subjected to crystallizing 61, and the crystals :"1 -~l collected and washed in step 62, preferably with acidified wash water. Drying 63 provides the lactose product J.
~! Precipitate from step 53 may be dried at 64 to provide the ~-mineral salt product K. Li~ewise precipitate from step 59 -, 30 can be dried at 66 to produce the mineral salt product L.

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` 1077472 , Concentrated mother liquor from step 60 may be directly dried :: :
at 67 to produce the lactose product M.
~- The process described in connection with Figure 3 produces lactose products of high purity, and in addition, lactose yields can be obtained of the order of 70% or higher.
...~. . , ; Lactose products I and J may have purities of a~out 99% and 97% respectively.
~; For a product of lesser purity (e.g., 90%), con-y centrate from 54 can be spray dried at 68 to produce the lactose product N.
In the various embodiments of the invention .:
s; ~ described above, removal of whey protein and precipitation ~ .. . .
; ~ and removal of precipitated salts is carried out before .;
;~' removal of lactose by concentratlon and crystallization.
; 15 To effect crystallization of a substantial amount of the .... . .
lactose present (e.g., 40 to 60%) the permeate should be ; concentrated by evaporation to solids contents of 50 to 65%.
Since evaporation to such concentrations requires some heat ~i treatment, some of the mineral salts, if not previously removed, precipitate and are removed with the collected ~, lactose crystals, thus reducing the purity of the lactose product. By previous removal of a substantial amount of ~!~
~; the mineral salts (e.g., 10% or more) such contamination of .,.. i .
the recovered lactose is avoided. In addition, when precipi-tation of mineral salts is carried out in the manners and under the conditions described, lactose remains in solution and therefore no appreciable amount of lactose is removed with ~ the precipitated salts.
;~l The process shown in Figure 4 employs both precipi-~1 30 tation of mineral salts and electrodialysis. The permeate :
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from ultrafiltration step 71 is subjected to precipitation `~ step 72 carried out by heating and concentration as for step 11 of Figure 1. This serves to precipitate particularly the calcium and citrate salts of the buffering system. The partially demineralized permeate is then treated in step 73 ;` for removal of the precipitate and clarification, as described for step 12 of Figure 1. Further mineral salts '~ are removed to the extent desired in the electrodialyzing step 74. Before electrodialyzing, the pH and concentration may be adjusted for optimum operation (e.g., to pH 3.9 ~, to 4.2 and 30% solids). Thereafter the material may be further concentrated at 75 and spray dried at 76 to produce ~- the dry lactose product o. A purer lactose product can be obtained by concentrating 77, crystallizing and collecting lactose crystals 78, washing of the crystals 79 and drying :::
80 to produce the lactose product P. It should be noted that electrodialysis operates more effectively on monovalent salts, ~ which are not removed by the precipitating steps 72 and 73.
```1 All of the above procedures first remove the whey protein and then a substantial portion of the mineral salt , content, leaving a material consisting mainly of lactose.
~ This is exemplified in its simplest form by steps 10, - 11 and 12 of Figure 1, which remove whey protein and reduce the ash content, leaving a material comprising mainly lactose 'l 25 which can be concentrated and spray dried. Precipitation in ,!r,, , ' such a simplified process can be carried out either by step 11 or step 32 of Figure 2.
Figure 5 illustrates a treatment process which ~ produces a product having the flavor characteristics of soy `; 30 sauce. Here the permeate produced by ultrafiltration 81 of ','.'.

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: . : , : , `~ - 1077472 -- whey is neutralized at 82 by the addition of an alkali to pH
7 to 10.5. It is then subjected to heat treatment 83 :;
~; at an elevated temperature of the order of from 180 to .,, 200F. for an extended period of time of the order of 2 to ; 5 3 hours or more. During this time certain changes in compo-i~`i sition take place due to the alkali treatment at the elevated ~ temperature, and a substantial amount of the mineral salts :.
-~- is precipitated. The heat treated permeate is then subjecced , to filtering 84 carried out at an elevated temperature of the order of 180F., after which it is cooled in step 85 as by flashing in a partial vacuum. The cooled material, ; which may be at a temperature level of from 90 to 110F., is .,.. ~
then re-acidified at 86 as by the addition of any edible acids, such as hydrochloric, to a pH level of the order j.!~,i': .
lS of 4.0 to 5.0 pH. Thereafter it is concentrated in step 87 and spray dried at 88 to produce the dry product O.
This material has unique flavor characteristics, and when slurried with water it is suitable for use in place of soy ~il sauce. The composition of the dry product in a typical in-stance is as follows:
Moisture 3.2%
Protein 4.08 Non-protein nitrogen 0.66%
Ash 20.45%
Titratable acidity 2.44% -Lactose 66.64%
The precise reasons for the flavor characteristics cannot be adequately explained, but are presumably due to the alkali treatment at an elevated temperature which causes certain complex changes to take place.
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~;S~ Examples of the process are as follows:
~; EXAMPLE 1.
.i~ The procedure was generally as shown in Figure 1.
The source whey was an acid whey produced by the manufacture of cottage cheese. The whey was subjected to membrane ultrafiltration, making use of equipment manufactured by Westinghouse Company. The resulting permeate had a total ~ , ~`~ solids content of 6.6~ and analyzed as follows (dry solids basis) ~i; 10 Protein 6.3 Ash 11.1 ?,'': Titratable Acidity 10.0 ~ Lactose 70.0 t ~ : .
With respect to the ash content, 13.34% of the ash comprised calcium. The permeate was first passed through a filter of activated carbon while at a temperature of ~;; 120 to 130F., to decolorize the material and to remove a 3~1 part of the protein. Thereafter the permeate was heated to "t"~ 180 to 200F., and concentrated to 40% solids. This treatment caused a floc to be precipitated. The material was then filtered making use of acid-washed diatomaceous earth filter medium (Celite). At the time of filtering the material was at a temperature of 180F., which served ~l ~ to maintain the lacto~ in solution. The filtrate was then further concentrated to 48~ solids, and cooled to effect crystallization of lactose. The resulting crystals were collected and subjected to washing in a basket centrifuge.
The resulting lactose crystals were dried to produce the lactose product A of Figure 1.
The filtrate from step 12 of Figure 1 had a total :';
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solids content of 46.46% which analyzed as follows:
` Nitrogen 0.37 ~ Ash 5.15%
- Lactose 33 95%
:~ 5 Titratable acidity 0.35%
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The reduced acidity was due to the removal of buffer salts.
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;~ The purity of the lactose crystals collected in ,:~..................................................................... . .
step 13, without washing, was 98.3%. After washing with aci-;.:~ dified water, the purity was 99.3%.
;;' 10 Some of the filtrate from step 12 was subjected ~;...................................................................... .
to spray drying to produce a product C. Also it was con-; firmed that the precipitate from step 12 could be dried -~~ to produce a mineral salt product D suitable for use as an ;:q .
-1 animal feed supplement. Mother liquor from the crystal-lizing step 13 of Figure 1 and wash effluent from the washing ;`:'1 . .
step 14 were merged, concentrated to 20.5% solids, and sodium hydroxide added to adjust the pH to the level of 1l 9. This resulted in some further precipitation after which `: ,'I .
-~ the material was filtered in step 16, the filtrate acidi-, 20 fied to pH 4.5 and after further concentration to 68% solids, ;,J~
r;'."' was cooled to produce crystallization of lactose in step -17. The collected lactose crystals were washed to produce pro-duct B, which was lactose having a purity of 89%. -~
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It was confirmed by analysis that the treatment ~ -~ 25 in step 11 served to precipitate the calcium and citrate ;'~ buffer salts and that the product D was a mineral product -comprising mainly the calcium and citrate buffering compounds.

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,~ Also it was confirmed that additional mineral salts were ' removed in step 15, including the buffer phosphates.
.~ 30 The foregoinq example was repeated using sweet "~ ' .
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Example 2.
The permeate employed was one resulting from the membrane ultrafiltration of acid cottage cheese whey. It had a total solids content of 6.3% and analyzed (dry solids basis) as follows:
Protein 6.3%
Ash 11.07%
Titratable acidity 10.0%
Lactose 70.7%
Following generally the procedure of Figure 3, the permeate was heated to 180F., and evaporated to 20% total solids. While being maintained at 180F., sodium hydroxide was added sufficient to adjust the pH to 9. After holding at 180F., for a period of about 60 minutes, precipitated solids were removed in step 33 by passing through an acid 3` washed diatomaceous earth filter medium (Celite). Like-; wise while at about 180F. the material was passed through an activated carbon filtering medium for decolorizing. The ~ filtrate was then concentrated to 68% solids, and lactose .... .
- crystals removed as indicated in step 43 of Figure 2. The ~, lactose crystals were collected and subjected to washing and drying to produce the product H. This product had a purity of 99.8%. It was found that the same procedure, ,~ but without using a carbon filter, provided a product H
having a purity of 98%. Some of the filtrate was concentrated and spray dried as indicated by steps 41 and 42 of Figure 2 ~`l to produce product G. This product was estimated to con-tain 85% lactose, the remainder being mainly mineral salt.
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To produce a spray dried product having a higher ; level of lactose and reduced mineral salt content, a portion of the effluent from step 33 was concentrated to about 25% solids and subjected to demineralization by ~ .
electrodialysis to remove about 90% of the mineral salt content. The resulting partially demineralized material was concentrated to a~out 50% solids, and then spray dried, as indicated by steps 36 and 37 of Figure 2, to produce - the product E. This product contained about 98% lactose, the remaining solids being mineral salt.
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To produce a lactose of higher purity than product -H, some of the partially demineralized permeate from step 35 was concentrated to 65% solids, and lactose removed ~ -- by crystallization, as indicated by steps 38, 39 and 40 of Figure 1 to produce the dry lactose product F.
Thls product had a purity of 99.9%.
Example 3.
The procedure was generally that of Figure 3.
' Acid whey was subjected to membrane ultrafiltration to pro-~, ., I 20 duce a permeate analyzing generally the same as in Example `, 2. The permeate was then treated to heating and concentrat-ing for precipitating buffer salts (calcium and citrate), followed by clarifying in step 53, substantially as : ! explained in Example 1. Following this treatment the per-meate, after concentrating to 50% solids, was subjected to ~,~ crystallizing 55, collection and washing of the crystals in step 56 and drying 57 to provide a lactose product cor-~; responding generally to product A of Figure 1 and Example 1. To attain a product of higher purity and to increase the , 30 yield of lactose, the mother liquor from 56 may be subjected . , , .. -- 1~ --~,,, '.'~
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to the further steps 58, 59, 60, 61 and 62, and the collected ~` crystals dried to provide product J. Washing in step 62 ,..,~ .,., ~
may employ acidulated water (pH 2.5). Product J produeed in this manner may be a lactose having an estimated purity of 97%.
Some of the clarified coneentrated filtrate from , ~'' step 59 may be spray dried as indicated by step 67 of ~ Figure 3 to produce the spray dried product K, which may ,l~i5`~ contain 90~ 1actose.

~ Example 4.
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~,` This example illustrates the process of Figure ~ 5 which produces a product having flavor eharacteristies ";' like soy sauce. Acid whey was sub~eeted to ultrafiltra-~ tion and mineral salts precipitated by adjusting the pH to , ~,. . . .
.5 and by holding at a temperature of 180F., as in-dicated by steps 72 and 73 of Figure 5, for a period of 90 minutes. Precipitate was then removed by filtering as indicated by step 74, the filtrate cooled to 105F., ~51 and suffieient hydrochlorie aeid added to adjust the pH
to 4.5. This was then concentrated to 40% solids, and may be used as such or spray dried to produee the produet Q.
This produet could be slurried with water to produee a material having the flavor properties of soy sauce.
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Claims (6)

What is claimed :

1. A process for the treatment of whey derived from the manufacture of cheese and having titratable acidi-ty, the steps of subjecting the whey to membrane ultrafil-tration to form a protein-rich fraction and a permeate fraction having a solids content of the order of 5.0 to 7.5% and having a lactose content of about 68 to 87%, a protein content of not more than about 6% and a mineral salt content, the mineral salt content including calcium and citrate salts together with phosphate and monovalent salts, precipitating calcium and citrate salts of the per-meate without substantial precipitation of phosphate salts by concentrating the unneutralized permeate to a solids content of about 40 to 45%, and by holding the concentrate at a temperature level of about 180 to 200°F. to effect precipitation of calcium and citrate salts without sub-stantial precipitation of phosphate salts, the precipitated salts being about 5.0 to 15.0% of the total mineral salts for a holding period of from 30 to 90 minutes, removing the precipitated solids from the permeate, and then further concentrating the permeate and crystallizing and removing lactose from the same.

2. A process as in Claim 1 in which the removed lactose is subjected to washing with acidulated water.

3. A process as in Claim 1 in which the mother liquor remaining after crystallization and removal of lac-tose is subjected to a second precipitating operation to precipitate a substantial amount of mineral salts, remov-ing the mineral salts so precipitated, and then crystallizing and removing lactose from the liquor.

4. A process as in Claim 3 in which the second precipitating operation is carried out by adjusting the pH
to 7 - 10 by addition of a neutralizing agent and by holding at a temperature of about 140 to 150°F. for a time sufficient to effect precipitation of a substantial amount of mineral salts.

5. A process as in Claim 1 in which some of the mineral salts of the whey are removed by electroldialysis before removal of crystallized lactose.

6. A process as in Claim 5 in which some of the mineral salts of the permeate are removed by electrodialysis after removal of the precipitated solids and before said further concentrating of the permeate.