CA1038226A - Method of separating protein from cheese whey - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
A dry, food quality protein powder is produced from cheese whey by an ultrafiltration process which includes the steps of removing water and dissolved sugars from whey to concentrate the protein solids, pasteurizing the resultant concentrate to inhibit bacterial growth, and evaporating the protein concen-trate to produce a powdered protein substance which is palatable, highly soluble in water and rich in essential amino acids. The temperature of the whey and protein concentrate is carefully controlled throughout the process to optimize product yield and to avoid clogging the filtration media.

Description

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. I BACKGROUND OF THE INVENTION
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; Th1s lnvention relate~ generally to the art of ultrafil- j .~. tratlon, and ln partlcular to a proces~ of uslng ultrafiltration !
to s~parate valuable proteins from cheese whey. It h~s been . ~stlmate~ that well ln excess of twenty blllion pounds of whey 75. i8 pro~uced in the United States each year as a by-product of . the chbose industry. In manufacturing chee~e, the curd i5 .. separ~t~ from the whey and the former ls cured to produce I; che~ he curd ~t~elf conta$ns up to ~bout ninety percent I ¦
l¦ of ~h~ ~lglnal milk protein, while the b~lance of ~uch proteln 20. '~ rem~lRh ln the whey. I ~
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i 1l Cheese factories are con~ronted wlth tho problem of dis-`~ 1, posing of the whey, a~ no co~mercially practical methods have been developed ~or separatlng whey'~ valuable con3tituent~, \ 11 l.e., protelns and lactose, even though it has been known for 5. ~l' yeaxs that an important source of protein and lacto~e 1~ being ~i~ wasted. A great amount of xesearch time and money has heen I
spent attempting to solve the problem. For example, see ¦¦ McDonough and Mattingly, "Pilot Plant Concentration of Cheese ¦!~ Whey by Revers~e Osmosis," Food Technology, 24:194, 1970.
10~ Ir Some benefit has been derived from whey by merely concen-¦ trating the proteins and lactose to provide an impuxe powder for animal and human consumption, but this procedure can be profitable only in times of rising meat prices. ~or the most I part, then, the whey is dumped onto ~ields, in ditches, or into 15. ' river~ and streams. However, due to the high BOD of cheese , whey, ~erious pollution problems re~ult from dumping whey, and , the USDA, ~DA and federal and state environmental agencies have launched an attack on the cheese industry for its whey ' dlsposal practices. Some cheese plants have been forced to 20. ~' close because of the whey pollution problems. I
At the same time that literally million~ of pounds of protein are belng discarded with cheese whey, scientific ; researchers and nutritionist~ are searching fox suitable mil~
¦ replacers for infant formulas, high protein diet supplements 25. and animal food enhancer~. It is known that the proteins contained in cheese whey are highly desirable. Such protein~
are l~terally "power-packed~ in that they are rich in e~ential amino acidi which cannot be found elsewhere in natural food ! products. In addit~on, the proteins are soluble in watox 3nd 30. ,j the resultant "milk" ~s quite palatable. It i8 cleAr then an ocorom1c~lly inacible procecs for separ~ting checcc whey i -2 : .
l' , 1038Z;a6 ¦¦ prote~ns would benefit several ma~or food proce~slng indu~tries ¦ in thi~ country and throuqhout the world.
Ii Some discus~ion of prior attempts at separatlng cheese ; whey proteins from other ingredlents will be helpful. The 5. 1 earliest methods u~ed chemical separatlon techniques such as p~ ad~ustment, hoat treatment~, flocculation, e~c. to produce low yields of highly denatured protein. The products from such proce~ces do not posses3 the deslrable solubllity and i taste qualities required for milk replacer~. Electrodialysis 10. ~ has al~o been employed to ~eparate salts from cheese whey jl proteins, but this process 15 810w and expensive, ma~nly due ¦I to high powex requirements.
; i The most recent efforts to separate protein from cheese - ,1 whey have employed the prlnciples of ultrafiltration or reverse 15. ; osmosis. The osmosis process utilize3 a sem~permeable membrane !I flanked on either side by a concentrated solute solution and a .
~i le85 concentrated ~olution. Natural osmotic forces will tend to equalize the solute ~oncentration by passing water through the membrane, while the 801ute cannot pass through the membrane.
20. i By applying a pre~sure to th~ concentrated solution, pure water can be forced back through the membrane, oppositely to the normal osmotic flow, thereby concentrating the solute. In ultrafiltration, on the other hand, pre~sure i8 applied to a solutlon to force the ~olvent through a semipermeable membrane.
- 25. Recent attempts at employing these processes for cheese whey i sQpaxation have used a membrane which i5 selected so th~t protein ¦ will not pass through the membrane, but throuqh which lactose and other constituents of whey will pass. Membrane~ have been I de~lgned in various shapes, ~ncluding flat plates and hollow 30- ,l tubes. Tubular membranes are not particularly desirable becau~e !l of the high rate of membrane clogging ~rom whey solid~ leading ¦ to freguent repair3 of replacement o~ the co~tly membr~ne~.
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o~a6 ¦l S~MMARY OF THE INVENTION

'~ A prlmary ob~ect of the present ~nvention i8 to provldo a proces3 for separatlng protein~ from cheese whey.
Another ob~ect of the pre~ent invent~on i~ to prov~de a l, method for separating high purlty protein~ fxom cheese whey in 5. I~ an economically feasible manner.
further ob~ect of the present invent~on i~ to provide a process for separating proteins from cheese whey in which ,~ filtration membrane clo~ging i8 minimized.

!i Yet another ob~ect of the present invention is to provide 10. ~l a method for separating protein~ from cheese whey in which the solid content of the protein concentrate may be carefully regulated.
Another object of the present invention is to provide a method for ~eparating protein~ from cheese whey in which 15. ; denaturization and bacterial growth are minimized.
, In the process of the pre~ent invention whey ls cooled to : ` I!
- , below 80 and is pumped through an ultrafiltration ~ystem ,, including spirally-wound ultrafiltration module~. Micrometer ¦ Yalves are provided so that the solids content of the prote~n 20. ¦ concentrate may be carefully brought to the de~ired level at I which time product ~8 bled from the modules. The temperature ¦ of the product 1~ then raised to pasteurization temperature ' ¦ for a time sufficient to kill bacteria, but for a time insuf-¦ ! ficlent to sub~tantially denature the product. Th~ prote~n 25. ~ concentrate ~s cooled and then later evaporated and spray dried. Thc particulars of the process variables for the system will be di~cussed herein.

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I DESCRIPTION OF THE DRAWI1'1GS
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FIGURE 1 ~ 8 A sectional vlew ~howlng a cheese whey separation apparatus u~eful with the process of the present inventlon: ;
FIGURE 2 18 a fragmentary, cross-sectional v~ew o~ the . , apparatus shown in PIGURE ls " FIGURE 3 is a fragmentary, vertlcal, longitudlnal ~ect~onal view showing a preferred membrane filter module useful in the ,~ ~pparatus of FIGURE l;
I! FIGURE 4 ~ 8 a fragmentary~ ~ide elevation view, paxtly 10. I cut away and ln sect~on, ~howing an end portlon of a membrane f~lter module a~ ~hown ~n FIGU~E 4;
.FIGURE 5 i~ a perspect~ve view showing a spirally-wound .- membrane module as shown in FIGURES 4-57 ; FIGURE 6 ~ 8 an exploded, perspectlve view ~howing a 15. ~pirally-wound membrane module and associated pressure vessel of ~ f~lter according to the present invention; and !'M GURE 7 i~ a schematic flow diagram of the cheese whey : !, ` ¦' proce3s according to the present invention.
-:. DE5CRIPTION OF A PREFERRED EM~ODIMENT
.' . . FIGU~ES 1 an~ 2 of the drawings ~how an ultrafiltratlon 20. un~t 10 constructed from a plurality of horizontal bank~ 12, 14 ~nd 16 of individual filter tubes 18, 20 and 22. The filters are connected to and arranged with input manifold~ 24, 26 and - 28 on banks 12, 14 and 16, respectively, for introducing whey ~nder pre~ure into filter tubes 18, 20 and 22.
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The individual filter tubes are best shown in FIGURE
3 of the drawings where filters 18, 20 and 22 each include a cylindrical pressure vessel 30 having a tubular wall 32 and open ends 34 and 35 (FIGURE 1). A plurality of spirally-wound membrane modules 36 are arranged serially in eachpressure vessel 30. Modules 36 are connected to one another through a perforated tube 40 forming the core of each individual module. This core, as will be more fully described hereinafter, serves as the permeate collector in the ultrafiltration process.
Adjacent ends of modules 36 are connected by a rubber lined connecting sleeve, shown generally at 42, details of which can be found in copending Canadian Application Serial No. 230,338, filed June 27, 19750 A resilient member (not shown) is provided between i 15 adjacent ends of tubes 40 to absorb hydraulic shock as is more fully discussed in said copending application. A
membrane 44 (FIGURE 5) is spirally-wound around perforated tube 40 so as to foxm, in effect a flat envelope open at one end to aid in the transfer of lactose solution passing through the membrane to the permeate collection tube 40. Membrane 44 is preferably constructed of cellulose acetate, however, other materials providing the desired selectivity between protein and the remaining constituents of cheese whey may also be used.
Membrane 44 may have a backing constructed in a known manner from a synthetic or glass fabric material (e.g. dacron) capable of withstanding the high pressure encoun~ered inside pressure vessels 30. Seals 46 (FIGURE 6) surround the outer perimeter of the spirally-wound membrane 44 and serve to prevent the passage of solution around the modules along walls 32 of pres~
sure vessels 30. As will be more fully discussed hereinafter, specially constructed end caps are provided for pre~ure vessel 30. Ves~els 30 ar~ preferably con~tructcd entirely of 3-A USDA
approved dairy stainless steel. All mctall~c componcnt3 of the l ~ystem to be described belol~ are also constructed of ~uch sta~n-5. ~, less steel, which construction is preferred and/or required by ,I both federal and state regulatory agencie~ for apparatus to be ! used in producing human foods. The membrane modules 36, except 'i for the means interconnecting them, are described in the paper !!~ entitled, "Reclamation and ~e-Use of Waste Products From Food 10. 'ij Processing By Membrane Processes," by D. Dean Spatz, presented ¦ to the American Institute of Chemical Engineers on May 24, 1972.
It should ~e made clear at the outset that the number o~
banks of pressure vessels shown in the figures is illustrative . ii i' rather than limiting. Any number of vessels may be employed 15. depending on the desired purity of the final product and the ',' de~ired output from the system. In addition, the number of .j ~;
` , serlally arrangcd modules 36 in each of pressure vessel~ 30 may . ~ ., i, be varied. For example, individual modules may be 26-1/4 inches long or 39 inches lon~ and be specially designed for the 20. j~ present invention so that they have an outside diameter of ¦ 3,83 inches thereby fitting into pressure vessels ~0 snugly.
¦ Each end of the module may lnclude a plastic support wheel 45 ¦ with a plurality of, for example, 1/8 inch holes through which ¦ product can flow. Preferably however, an antitelescoping 25. device such as described in the aforementioned copending ¦ application Serial No.23~330 i8 used. These are designe~ to ¦ facilitate cleaning of the apparatus as are the rubber-lined stainle~s steel sleeve lnterconnectors 42. The support wheel~
or other antitelescoping device~ may also be turned to an 30. ¦ outside diameter of 3.83 inches to fit inside, for examiple, 4-inch stainless dairy tubing formlng the cylindrical walls 32 Il 7 ., \~, '~ !

~Q38Z2~' 1 ¦l of pressure vessel~i 30. Perforated tub~ 40 may extend approximately 2 incheis beyond the support wheel~ 45 or other ¦ antitelescoping d~vlce Six 26-1/4 inch modules as de~cribed I above may be connected together inside pre~3ure vessel 30 5- Il glving a total length of approximatély 157 inche~. Also by way of example only, FIGURE 2 ~how~ thAt there are 10 filters il 18 in bank 12, 8 ~lter~ 20 in bank 14 and 6 filter~ 22 in i bank 16. This arrangement 1~ preferxed as the de~lred flow 1! pres6ures are most easily maintained in apparatu~ havlng thi~
lO. I¦ pyramid-type arrangement. However, each bank of modules 30 ¦¦ could include the same number of filters.
ll At each end of pressure ve~sel 30, a CIP cap ii~ held to il pressure ve~sel 30 with a ~uitable known CIP dairy clamp and ¦ i8 drilled for the stainless 6teel fitting~ to be described 15. , hereinafter. At the input end, end cap 48 is pxovided with fitting 52 constructed of l-inch ~tainles~ piping and arranged 80 that it enter~ pressure vessel 30 at the lower portion thexeof. At the other end, end cap 50 i~ proyided with two Il fittings to allow pas~lng permeate to a collecting means and to 20. , allow further product flow to the next bank of membrane modules.
Fittings 52 of end cap 48 axe connected to it~ re~pective mani-fold 24, 26 or 28. End cap 50, on the other hand, covers end 3S which is spaced apart from manifold~ 24, 26 and 28 and has ~n opening 54 arranged adjacent the cylindrical wall 32 and a 25. connector 56 sp~ced from opening S4 and connected to a tube 40 of the ad~acent module 36 connectlng sleeve 42 in a manner ~imilar to that descrlbed for connecting ad~acent module~. An elbow 58 is connected to connector 56 wh~le a length of tubing 60 1~ arranged in opening 54 to facilitate connection of a ho~e 30. 1 to opening 54. Openings 54 of end caps 50 are ~ttached to I outlet manifold 64, 66 or 68 i~o that protein concentrate may I i ' 'I j .
ll l be collected for tran~er to the next ~erle6 of f~lter bank~.
i A pipe 70 carries protein concentrate from outlet manlfold 64 of the fir~t bank o~ filters to inlet manifold 26 of the next ~ bank. A pipe 72 per~orms a 6imllar function between outlet 5. l~ manlfold 66 and the inlet manifold 28 of the uppermost bank of ' filters. A plpe 74 extends from outlet manifold 68 of said uppermo~t bank of filters to dairy valve 76 and pxessure gauge il 78. A pipe 80 i~ in turn connected to valve 76 and is anchored ¦ at the end of unlt 10 spaced from valve 96 by valve 90 which 0. ~ al50 attached to another pressure gauge 92.
~¦ Filter ban~s 12, 14 and 16, together w~th the various manifolds, transfer pipeY and fittlngs, are mounted together on a support frame 62 of suitable con~truction and may ~e ¦ retained on frame 62 by brackets 19 which can be best ~een in 15. ' FIGURE 2. Arranged along pipe 80 somewhere along lt~ length .. ..
ls a T-fitting 81 leading to a pair of long stemmed micrometer valve~ 82 and 84 connected respectively to plpes 86 and 88. A
'¦ flow path i8 then established from pipe 80 into either pipes ¦¦ 86, 88 or continuing along pipe 80, depending on the degree 20. , micrometer valves 82 and 84 are opened.
I ¦ A pump 96 i8 also shown ln ~IGURE 2 for pumping the whey l through the banks of membranes, and pump 96 may be a ~uitable I ¦ known type of positive displ~cement or centrifugal pump which I feeds whey under pres~ure through a p~pe 98 to a conventlonal 25. ¦ dalry valve 100. Another plpe 102 connects valve 100 to another ~onventional valve 194 which i~ connected to a pipe 106 extend~ng ¦ to the f~rst ~nlet manifold 24. Another pipe 108 is connected ¦ between valve 90 at one end of pipe 80 and valve 104 wh~le a - ! ~till further pipe 110 extenas from valve 100 to pipe 74 3G. 1 (connecting the ~lnal output manifold 68 to val~e 76). ~ motor l 112 which may be of conventional de~ign i~ ~ounted on frame 62 I g I ~ I

¦ to selectively actuate pump 96. The plping ~y~tem ~u~t descrlbed allow~ fllter unit 10 to be employed for passing flltrate through the membranes in either d~rectlon, thereby allowlng a cleaning ! in place of the modules. This CIP feature prolongs the lifetlme s. ~l o~ the ~pirally-wound membrane module~ by allowing perlodic l cleaning thereof.

1 At the left-hand side of FIGURE 1, a system i~ provided for collecting the permeate forced into perforated tubes 40 through the spirally-wound module~. The connectors 56 have 10. , already been described as having elbows 58 connected thereto.
¦ Transparent æleeve~ 115 and 116 may be connected respectively to the elbows 58 of the m~ddle and lower ind~vidual membrane tubes and are connected at their remot~ end by elbows 118 to a series of T-fittings 120 at the top or upper portion of 15. 1 unit 10. An additional opening of T-fitting 120 i9 connected - ~I to a similar transparent sleeve 117 connected to elbow 58 of the uppermost ~ank of pressure ves~els. The final opening of I the T-fitting 120 i9 connected to a tubular manifold 122 which I serves to collect permeate from all locations of the pressure ; 20. vessels and passes the collected product out a hose 124 connected ; to one end of manifold 122. The number of transp~rent sleeves, ` T ~ 8 and elbow f~ttings i8 illustrative only a9 any method may be employed for collecting the permeate leaving each individual tubular pre~sure vessel 30. Of course the transparent sleeves ', 25. may be elim~nated 80 that the connectors would be attached di-rectly to their respective manifolds. As ~ust descrlbed, then, the permeate is collected through the ser~es of elbows and collecting means a~ the left-hand ~ide of the f~gure, while the prote~n concentrate wh~ch i~ not allowed to enter permeate tube3 30. ~ 40 passes progre~sively through each bank of membrane module~, j ¦ tbrough pl e~ 74 ~nd 80 to the vicinlty o~ the mlcrometer ~A1ves 1038~
and tho ptessurc gauge~ hcre1nbcfore dc~cribcd. The functlon of the clean in place operation and the operation of mlcrometer valves for determining thc solid content of the protein concen-,~ trate will next be described.
5. ! In the foregoing description of separating unit 10, refer-¦, ence was made to four valves 76, 90, 104 and 100, each of which ,¦ was described as ~eing a conventional dairy compression valve.
I The valves axe located, in the preferred embodiment, so as to ¦ provide the capability for passin~ concentrate through the 10. I various rows of filter banks in opposite directions to clcan the ~ filters and comply with dairy control la~s, and the valves may ¦ be automated so that the cleaning function is accomplished peri-odically at set intervals. A brief summary of the positioning I of the valves will be helpful in understanding the CIP capability.
; 15. Valve 100 ~s located near the output pipe 98 from pump 96. Valve - ~l 100 is connected to a T-fitting, the other two portions of the T being connected respectively to pipe 74 connecting outle~ mani-ji fold 68 and valve 76 and to pipe 102 connecting valves 100 and 1! 104. Valve 76 in turn connects pipe 74 to pipe 80 which extends 20. ji longitudinally across the top of unit 10. At the remote end of ¦ pipe 80 is a valve 90, and pipe 108 connects valve ~0 to valve ¦ 104 whose flnal outlet is connected to inlet manifold 24. If ¦ Yalve 100 is adjusted to close pipe 110, the cheese whey will ¦ flow into pipe 102 throu~h valve 104 into inlet manifold 24 25. ¦ and through the banks o~ membranes as hereinbefore described. I
The protein concentrate resulting from tlle filtration processl ¦ would then pa~s through valve 76 and pipe 80 to the vicinlt~
¦1 of micrometer valves 82 and 84. On the other hand, pipe 102 ¦¦ connecting valves 100 and 104 can be closed to proauct flow 30. where~n the whey would pass throu~h pipe 110 to pipe 74, and if i -valve 76 is also closed, product flow ~s rev~rsed so thnt . . ..

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I protein concentrate would lcave the 10~7er bank of mcmbranes through pipQ 106 and travel through open valves 104 and 90 to I the vicinity of micrometer valves 82 and 84.
I Unit 10 according to the present invent~on may be used as 5. l a continuous concentrating d~vice by ad ~usting mlcrometer valve ¦l 82 to a desired pressure of, for e~ample, 160 psi, and having the enriched product issue ~rom that valve to a separate ¦ receptacle (not shown) behind pump 96. Only enou~h fresh product I is added to compensate for the permeate removed. ~hen the 10. I desired level has been reached, the other micrometer valve 84 is opened to remove product of the desired concentration. A
higher concentration rate of protein may be obtained by routing I the flow through micrometer valve 82 hack to a hola~ng tan~
i~ (not shown), thereby allowing a full flo-~ of fxesh product over 15. , the membranes 44 and maintaining the lowest possible level of ? solids over membranes 44 for the longest possible time, and . ,, I having a ba~ch all reach the desired level at one time. This batch may then be concentrat~d by a si~ilar rerouting proccss.
, ~his latter method, however, is less desirable than the afore-20. l mentioned method since the product tends to acquire an acld ¦ flavor making it less desixable as a food substitutc, althou~h lts use as a feed product for animals is not impaircd. ~Sicro- ¦
metcr valves 8~ and 84 have been found to be prefcrred as ; opposed to other types of valves which could be employed. The 25. long, tapered needles of the micrometer valves allow a large surface over which the protein concentrate passes and reduces shearing of indivldual proteln molecules. `~
~eferring now to FIGURE 7 of the drawings, chcese whey i5 jj drawn off the checse vats which customarily run at a tempcraturc 30. approximating 103 F. The whey is then passed through a I separator to remove as much fat as possible, the scparator , l ..

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~038z26 prefera~ly bein~ of the conventional centrifu~al variety. The ey 18 then passed through a mesh having approxtmately 25 i micron openings to screen out gelat~nated particles wh~ch would - clog the filters if not removed. The next stcp in the proce~s 5. ¦, comprises passing the whey across a cooling plate whcre the whey is cooled to a temperature of und~r 80 to avoid clogging of membranes 44 during subsequent ultrafiltration. It has been found that if the ~iltxation temperature exceeds about 90 the 1 membrane~ will rapidly clog 2uring extended runs, even if the lO. CIP feature is utilized. It has also been found that the machine;
¦ itself heats the whey approximately 6 (pump heat), and accord- ¦
i ingly, it is necessary that the product be chilled to at least ; ~ 840 before bein~ introduced into the membrane banks. Seventy-li eight degrees has been found to be a preferred temperature to : I` I
15. I` avoid approaching the 90 ~igure as ~hey is pumped through the filter ban~s. It is also possible to use temperatures well i; below 78, successful runs having been made at temperatures approaching the freezing temperature of wl-ey. However, the ; I separation is slower as the temperature of the ~nput ~hey is j!
20. ` reduced even though finely flavored product3 are produced at the lower temperatures.
Pump 96 injects the cooled whey into the input mani~old ¦ 24 at a rate of approximately 8-1~2 gallons per pressure vcssel ¦
I at a pressure of 200 pounds per square inch. Depending on the 25. 1 particular material selected for the membranes, the number of membrane filter banks employed and the particular type of cheese whey being separated, the pressure and volume parametcrs can \
~e ad~usted to maximize output of the system. Micrometer j valve 84 i~ closed at the start of the process, micrometer 30. ! valve 86 is ad~usted to the desired back pressure, and the :~ ~ concentra e 1eaves the system thrcu~h pipe 86 and passes bac~

~ -13-,, ffZa6 to the inlet of pump 96. The only fluid le~ving the system i8 the permeate or BUgar water which 1~ being di~charged through pipe 124~ After a predetermined tlme, on the order of approxl-~ ¦~ ~ately 10 mlnutes, when suf~icient concentration of protein has S. i' been obtained, micrometer valve 84 i8 cracked and the solid ,j content of the product chec~ed by suitable analytic means, e.g., j by the use of a refractometer. It has ~een determined that when the refractometer indicate~ a 12~-14% solids content in the ~, product leaving pipe 84 a final product will be obtained upon 10. , drying which includes 36~ protein on dry matter basis. By suitable adjustment of micrometer valve 84, a const nt flow of product having a ~no~n solids content can be o~tained. For ¦, quality control, it is advantageous to recheck the solids I content at periodic intervals to insure that the machine is lS. ,i operating without increasing or decrea~ing the solid level~
~¦ of the protein concentrate.
The solid stream having a concentration of approximately 'I 12% solids is next transported to a balance tan~ and collected ! for holding prior to pasteurization. Pasteurization is accom-20. ' plished by heating the concentrate to around lG5 F for a period of approximztely 25 seconds, 23 seconds at 164 F being preferred. The concentrate is heated by pa~ing it o~er heated l plates at a~ rapid a rate a~ possible to avoid burn-on on the ¦ plate~ and consequent denaturization of the protein in the 25. l concentrate. After the heating step, the concentrate i9 ~mmediately chilled to well below 90, for example 36 F, ¦ preferably all in a total elapsed time of approximately 30 ¦ ~econds~ The di~clo~ed proces~ is not to be llmited to the6e ¦ operating parameters a~ the time and temperature hold~ng fsctorq 30. ¦ will vary dependlng on the concentration of the initlal con-¦ centrate. Higher temperatures and shorter holdlng times will .I
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accompll~h the a1m of bacter~l control of the concentr~te wlt~out 6ubstanti~1 denaturizat~on. It hAs al80 been noted that proteln concentrates having different ~ol~ds levels have ~ 1I dlfferent he~t tolerances and that as the percentage of protein 5. ~ ncre~$es a decrease ln heat tolerance ~ enco~ntered. The chilling step can be avoided if the evaporators and spray ¦ dryers used in the operation have sufficient capacity to treat ¦ protein concentrate at elevated temperatures lmmediately as lt leaves the pasteurizer.
10. I The flnal step in~olves drying the concentrate to produce ¦ a fine, powdered, m~lk-flavore~ product. Careful control ls ¦ necessary in this step to in~ure a desirable final flavor of the product and also the powder consistency thereo~. It has jl been determined that a two-stage vacuum evaporator preferably 15. '~ ls used to increase the concentration of the protein product to between 44 and 52~ solids, following which the final product ~s spray dried to a po~dered form. Through repeated experi-mentation, lt has also been determined that a high vacuum, low I! heat method of evaporation produces optimum final re6ults. The 20. 1 flr~t effect of the vacuum evaporator i8 preferably run at ; ¦ approx~mately 26 i~ches of vacuum and the second effect at ¦ approximately 29 inches of vacuum. An lnitial ef~ect evaporator ¦ te~perature of approximately 132 F is prefexred although the ¦ evaporators can be run at other temperatures, for example, 25~ ¦ between 130 and 165 F. Evaporators are kno~ to the art which include a 3exies of pumps which can take the concentrate from the cool~ng storage chest, heat it at various ~tages of 130 or more and in~ect it lnto the first effect tube chest t~rough compresslon valve that restricts the flow lnto the evapor~tor.
30. 1 The heat is given ~p qu~c~ly as the concentrate ~ introduced l lnto the vacuum atmosphere and evaporntion occurs. Preferred ~ ,'"' ~ I -15- ~ !
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, j . , ~ l 103~Z~6 ¦ evaporators are those whlch include a vapor heater betwoen thc \ flrst and secona effect~.
The concentrate leavlng the ~inal stage of the evaporator . ~ 19 in~ected into a spray dryer to produce the final product.
5. ~!l A low heat, high ~acuum method prevents denaturization and `1, balling of the product. In addition, a sweet milk-flavor~d ¦I product i~ produced u~ing the high vacuum, low tempexature ¦ method. A quality product, but with slightly less favorable i~ taste characteristics i8 produced if a lower vacuum i~ used. In - 10. l addition, using the high vacuum and low heat method, the solu-¦` bility lndex of the final product i8 higher. The method of ¦ the prefexred embodiment produces a powdered product having a ! solubility lndex of .05-.15 which, as ls well knownl is several Il times greater than the mo.st stringent requirements for extra 15. i grade mil~. In addition, the final product has a PER higher , than the finest available COW~3 mil~, a fine bulk denqity, a pH
~ of 5.8 to 6.3, and an ash content of 75-80% of milk (6-7~.
-; I While the instant invention has been described particularly ln connection with the apparatus of FIGURES 1-6, the invention 20~ ' is not to be limited to any particular apparatu~, but is generally applicable to sy6tems using membranes and the principle of ultrafiltration for concentrating and separating whey protein.
Further embodiment~ of the invention should be apparent to those s~111ed in the art. For example, should a particular separating I
25. unlt be located in an area where a ~pray dryer and eva~orator are not availa~le, it 1s possible to transport the chilled whey concentrate to another location for ~ubsequent drying. There are certa~n precautions which must be observed, however, in the transport of the whey concentrate. The material must be cooled 30. to around 40 or less and air must be carefully exclud~d ~rom the mlxture. Particularly if the pH of the product ls unde~
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6.0, the product wlll gel unleB8 these precautlons are observed and wlll not only be hard to handle but will yield a low ~ul~
density powder when dried. Further, ~ome ~nstall~t~ons m~y produce larger quantltie~ of whey than can be handled by the 5. ¦I fractionating equipment~ Thi~ whey may be transp~rted to . 1 suitable separating apparatus. In thie case, it i8 only necessary that the raw whey be cooled ~ufficiently to inhlblt bacterial growth and avoid freezing of the mixture. Bacteri~l I growth i8 inhibited sub~tantially below about 50~ F.
10. So while the foregoing invention has been de3cribed in connection with a particular preferred embodiment thereof, the ~nvention i8 not to be llmited by that description but is to be l~mited 801ely by the claim~ which follow.

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Claims (15)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A method for separating proteins from cheese whey comprising the steps of:
cooling raw whey below 90°F, concentrating the raw whey by the process of ultra-filtration at a temperature not substantially above said initial cooling temperature, pasteurizing the concentrated whey protein, cooling the pasteurized concentrated whey protein, and drying the protein concentrate.

2. The method set forth in claim 1 wherein the initial cooling step results in the raw whey being cooled below about 80°F.

3. The method set forth in claim 2 wherein the raw whey is initially cooled to 78°F.

4. The method set forth in claim 1 wherein said step of pasteurization includes heating said protein concentrate to a temperature which is high enough to destroy bacteria in said concentrate but low enough to avoid substantial denaturization of said protein, and holding said whey concentrate protein at the elevated temperature for a time sufficient to pasteurize the protein concentrate.

5. The method set forth in claim 4 wherein the steps of pasteurizing and subsequently cooling the concentrated whey are accomplished in a total elapsed time of approximately 30 seconds.

6. The method set forth in claim 5 wherein the pasteurization temperature is in the range of 162° F. to 170° F and the holding time at said temperature is in the range of 15-25 seconds.

7. The method set forth in claim 6 wherein said pasteurization temperature is 164° F and said holding time is 23 seconds

8. The method set forth in claim 4 wherein said step of drying said whey protein concentrate comprises the separate steps of partially evaporating volatile constituents from said concentrated whey protein and spray drying the partially evaporated concentrate.

9. The method set forth in claim 8 wherein said step of partially evaporating said concentrated whey protein includes vacuum evaporating said whey concentrate in a two-stage vacuum evaporator at a temperature of approx-imately 132° and a vacuum of between about 26 and about 29 inches of vacuum.

10. A method for separating proteins from cheese whey by ultrafiltration wherein cheese whey is concentrated by passing it through a plurality of serially arranged ultrafiltration modules whereby water, salt and sugar constituents of the whey are removed as permeate and the protein constituents thereof axe continually concentrated, the improvement in said method comprising the steps of:
cooling raw whey to a temperature below about 80° F
prior to introducing said whey into said ultrafiltration modules, maintaining the temperature of said whey below 90°
during the ultrafiltration of whey proteins, recirculating said concentrated whey through said ultrafiltration modules until the desired solid level of concentrate has been obtained, and continuously removing from said ultrafiltration modules a portion of the desired solids content product and simultaneously with the steps of recirculating concentrate and removing product, adding raw whey into said modules to maintain constant the liquid volume entering said ultrafiltration modules whereby the added raw whey compensates for permeate and product.

11. The method set forth in claim 10 including the further steps of pasteurizing said product to inhibit bacterial growth, said step of pasteurizing being accomplished for a time and at a temperature sufficient to pasteurize said product but insufficient to substan-tially denaturize said product.

12. The method set forth in claim 11 wherein the pasteurized product is cooled after said step of pasteurizing said product, whereby the total elapsed time of pasteurizing and cooling said product does not exceed 30 seconds.

13. The method set forth in claim 12 wherein said product is pasteurized at 164° F for 23 seconds and immediately cooled to a temperature of substantially less than 164° F.

14. The method set forth in claim 11 including the further steps of partially vacuum evaporating volatile constituents from said product and spray drying the resultant evaporated product to produce a powdered final product.

15. The method set forth in claim 14 wherein said step of vacuum evaporating is accomplished at a vacuum of between about 26 and 29 inches and at a temperature between 130° F and 165° F.