CA1173694A - Process for converting sour whey into sweet whey and product - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
Sour whey resulting from manufacture of cottage cheese or cream cheese is converted into a food product superior to either sweet whey or sour whey, by enzymatic splitting of the lactose to glucose and galactose, followed by deionization and preferably concentration.

Description

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B~CKGROUND OE T}IE INVENTION

The liquid whey remaining after removal of the curd in cheese making contains about half of the nutritive materials present in the whole milk, and consists principally of a water solution of lactose (milk sugar) along with proteins (other than the casein which makes up most of the curd), together with most of the calcium, and some lipids and vitamins.
The sweet whey pro~uced by curdling milk with rennet in preparing cured cheese can be concentrated or drled ~or addition to various food products, and large quantities of whey are pro-cessed in this manner.
Sour whey, produced by acidification o-f milk, in the preparation of cottage cheese or cream cheese, cannot be concen-trated or dried satisfactorily because of its acidity, which is accentuated by concentration, because of the peculiar properties of lactic acid. Neutralization of the lactic acid does not solve the problem because of the resulting increase in salinity.
Sour whey not only has found no use capable o:f absorb-ing the large quantities which are produced, but has had a nega-tive value because of the cost of finding some way to get rid o~
it. It cannot be used profitably as fertilizer because the cost 30 of transportation and application to the soil is greater than -3 ~) 9 ~
1 its value as a ~ertilizer. It cannot be dumped in streams because it pollutes them. It is not even permitted to be dumped in sewers, unless a substantial -fee is paid~ because it in-creases the cost of operation of sewage treatment -facilities.

OBJECTS OF THE INVENTION
The objects of the invention are to eliminate the problems and costs resulting from all of the previously known ways to dispose of sour whey, and instead to provide a way or ways to make practical and profitable use of the high quality food values present in the sour whey.

SUMMARY OF THE INV~NTION
This invention involves the discovery that sour whey can be modified to change its composition and properties in minor but very important respects so that its -food values will be palatable and can be economically recovered and profitably used.
The modification of the sour whey involves splitting or hydrolysis of the lactose into glucose and galactose by the action of an enzyme, without significant modification of other constituents, and also removal of at least a substantial pro-portion of the acid ions, and preferably also some of the ionsof mineral bases, by a suitable ion-exchange material.
A principal result of these operations is the elimina-tion of a high proportion of the mineral ions along with the ions of lactic acid and other soluble organic acids. The con-sequence is the reduction or elimination of the salty taste and particularly of the sour flavor of the lactic acid, which is un-palatable to many people and which makes sour whey unsuitable for many food purposes. A further result is to reduce or sub-stantially eliminate both lactic acid and lactose, which are the source of serious problems in concentration or drying of whey.
In addition, the splitting of most or preferably substantially ~ 9~
1 all of the lactose reduces or eliminates khe problem of in~ol-erance to milk sugar by many people, as well as improving the flavor because o-f the much greater inherent sweetness of the two monosaccharoses, glucose and galactose, than of the orig-inal disaccharose, lactose, contained in the milk.
These results are accomplished without significant loss of food value, since the only materials removed are ionsg and particularly ions of the lactic acid resulting from fermen-tation of a small part of the lactose. In addition, some min-eral ions such as calcium and phosphate may be removed, but aconsiderable part of these desirable constituents is retained in a combined, non-ionized, form. Almost all of the organic con-stituents are retained, including the sugar ~in an improved, more palatable, and more digestible form), the proteins, lipids, and vitamins.
When the modified whey is concentrated o~ dried, it becomes quite sweet and can be used in a great variety of foods in place of or in addition to other sweeteners. Nutritionally such use of the product is beneficial because of the presence of substantial proportions of other food elements and partic-ularly of proteins such as albumin and globulin, as well as vitamins. By contrast, previously known whey concentrates are not particularly sweet because of the low solubility and inherently low sweetness of lactose.
The splitting of most, that is, more than half of, of the lactose is an essential part of the invention since the low solubility and hygroscopicity of the lactose would` not only limit the desirability and usefulness o any product of which lactose is the major constituent~ but also would greatly com-plicate all subsequent operations. Splitting of the lactose ismost easily accomplished by use of a natural enzyme, of which only a very small amount is needed, and which does not introduce 3~ 4 1 constituents which could create subsequent problems.
The extent of hydrolysis or splitting of lactose is preferably as nearly complete as is economically attainable, but will generally be somewhat short of 100~ conversion. At least 50% conversion is generally desirable, and will result in at least as many molecules of glucose and of galactose as of resid-ual lactose, so that the properties o-f those two sugars will predominate. Preferably the conversion is carried further beyond 50% to splitting of two-thirds, or still better three-fourths, or in some cases substantially all of the lactose.
The other essential step of deionization may be car-ried out in various ways~ but should always involve at least partial deacidi:Eication with a suitable anion-exchange material to reduce substantially the lactic acid concentration in the whey. If more complete removal of the mineral salts is desired, the ions in the whey may be removed in two steps, preferably first a demineralization with a cation-exchange material to remove free metal ions such as calcium, magnesium and sodium, followed by deacidification with an anion-exchange material to remove lactic acid ions and other anions which contribute to an objectionable acidity.
I have found that deacidification is sometimes facil-itated by the two-step procedure, and that the two successive deionization operations just mentioned are very simple, ef~ec-tive, and inexpensive for removal of the troublesome lactic acid. On the other hand, if retention of most of the calcium is desired, a one-step procedure with anion-exchan~e material only should be used.
The first treatment in the two-step deionization pro-cess, with cation-exchange material, removes metal ions, pri-marily calcium, along with magnesium, as well as some sodium and potassium, and converts such lactic acid salts as ~3~g~
1 may be present ~ to free lactic acid, thereby temporarily increasing the acidity of the whey. Because of the relatively low dissociation constant of lactic acid~ the i~creased acid-ity does not interfere with removal of the metal ions.
The second treatment in the two-step deionization process, with anion-exchange material, removes the ions of the acids and particularly of lactic acid, which is wsually the primary acidic material present in the wheyg thereby reducing the acidity of the whey, preferably to approximate neutrality.
If lactose hydrolysis preceded the deionization, the essential operations for conversion of the sour whey to a use-ful food product are completed. However, other operations such as dewatering may be desirable for enhancing value of the prod-uct for food purposes.
If a one-step deionization treatment is chosen, the same anion-exchange material can be used. It removes most of the lactic acid, but some is retained in the form of salts, particularly as calcium lactate, which is not troublesome as long as the whey is nearly neutral.
It is not essential that the several steps of the pro-cess occur in any particular sequence, since splitting of lactose and deionization are distinct operations having only a minor effect one on the other. Neverthelessg it has been ~ound to be convenient to commence the splitting of the lactose at an early stage of the procedure, so that a small quantity of lactase enzyme will have time to split most of the lactose, at least 50% and preferably much more, before the ion-exchange part of the process.
For purposes for which the water content of the whey is not objectionableg the deacidified whey, in which most or nearly all of the original lactose is replaced by a mixtuTe of glucose and galactose, can be used without further treatment.

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1 Usually, though, the water content will b~ too great for con-venience, and it will be desirable to concentrate the whey.
This can be done by conventional methods, such as vacuum con-centration to produce a liquid concentrate, followed, if desired, by spray drying to produce a completely dry stable powder.
The sweet whey product, thus made from sour whey, is a desirable additive to a great many kinds of food products because of its sweetness and its almost entire absence of other flavors, as well as because of its content of easily digest-ible sugars and o-f desirable food proteins~ in addition to significant proportions of lipid materials and vitamins, and also minerals if anions only are removed. Moreover, the enzymes added to the milk or produced during the carrying out of the process have a significant benefit to consumers of foods con-taining the sweet whey product.
Thus the sweet whey product can be added to cereal products such as bread dough, cake mixes, pancake mixes, break-fast cereals, and similar products, and to desserts of many kinds such as ice cream, sherbet, milk drinks, pudding mixes, candies and many others, to enhance their flavor and nutritive value, and reduce their cost.

DETAILLD DESCRIPTION
_ _ _ As has been pointed out above, a considerable number of factors can be modified, in t~e practice of ~his invention, and the exact composition and condition of the immediate prod-uct, and also o~ the final food product of which it becomes a part, are therefore likewise subject to modification over wide ranges. Some of these variations will be describcd in the following examp].es.

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1 Example 1 Combined Preparation o~ Cottage Cheese and Modified Whey Pasteurized skim milk is brought to a temperature of about 88-90F (31-32C) and a commercial lactase enzyme prep-aration is added, such as the dry pow~ered lactase isolated from Saccharomyces lactis by Gist-Brocade in Delft, Holland and sold by ~nzyme Development Corp. in New York City. This enzyme is most active at approximate neutrality. Such enzymes are sup-plied with recommendations for the quantities needed for spec-ified percentages of conversion at particular temperatures and times. A quantity which will hydrolyze 90% of the lactose in six hours is suitable.
After the enzyme is distributed throughout the milk, it is allowed to stand for a time which may be as little as one hour or as much as a day, depending on the quantity of lactase enzyme added, to hydrolyze most and preferably as much as 75%
or more of the lactose. This may be in a holding tank or in the cheese vats, depending on the quantity o:~ enzyme used and the time required for its action.
A culture of acid-producing organisms is then added.
Suitably, a standard commercial culture containing Streptococcus lactus or similar culture is mixed into the milk in a volume of about 0.1%, in the cheese vats, and allowed to act or grow for approximately three hours until a pH of 5 to 4.5, preferably abou~ 4.7, is attained as the result of lactic acid production, which inactivates the enzyme. A small amount of rennet, on the order of 1 liquid ounce in 5000 gallons of milk (1 milliliter in 630 liters of milk) may be added along with the bacterial culture to supplement the gelling action of the acids produced by the bacterial culture.
The combined action of the i.nitially added lactase, plus further enzymes produced by the bacteria, splits ~ ~736~

1 substantially all of the lactose into glucose and galactose during the curdling of the milk.
After the milk has curdled, the curd is cut in the usual manner with wire knives and cooked to about 119-130F
~48-55C) to cause separation o~ the whey.
When the curds and whey have separated, the sour whey is withdrawn from the curds, and the curds can then be pre-pared for sale as cottage cheese. The whey usually contains a small remaining quantity of suspended solids which are pre-fer-ably removed from the whey by filtration or by centrifugalclarification, to avoid contam~nation of the ion-exchange materials in the next steps.
The ~iltered or centrifugally clarified sour whey is passed through a bed of cation-exchange material, suitably con-sisting of beads of a synthetic resin such as Amberlite IRC-84 made by Rohm and Haas Co., which consists of spherical particles of about 0.4mm diameter of a cross-linked acrylic resin with a carboxylic acid functionality having a p~ value of 5.3. The rate of passage of the sour whey through the cation-e~change resin is adjusted to accomplish removal of the desired propor-tion of the metal ions, preferably at least half of the calcium and magnesium ions, and desirably three-fourths or more, thereby changing lactic acid salts to free lactic acid and increasing the acidity to a pH of about 3.5.
The whey is next passed through a bed of an anion-exchange material, suitably consisting of beads of another syn-thetic resin such as Amberlite IR~-93 made by Rohm and Haas Co., which consists of spherical particles of abGut 0.4mm diameter of a polystyrene matrix cross-linked with divinyl benzene and con-taining a tertiary amine functionality. This treatment remo~eslactic acid and other acid ions, reducing the acidity to an approximately neutral condition, with a pH in the range of 6 r~

.~ ~73~9~1 1 to 8. Pre-ferably the time of contact is adjusted to produce a pH between 6 ana 7 However, for some purposes a faintly acid product with a pH somewhat less than 6 may be acceptable.
The finished, properly deacidified whey at this stage has completely lost its lactic acid sour 1avor and has become almost tasteless, except that it is somewhat sweeter than most milk because of the presence of the glucose and galactose derived from the original lactose.
The preferred procedure described above is particularly simple and economical, and results in a sweet whey product with properties superior to those of the natural sweet whey resulting from use of rennet alone in producing the neutral, non-acid curd in production of chedcdar cheese or other cured cheeses.
In this embodiment o~ the invention, the combination of enzyme action from the lactase added as such, with the action of enzymes produced by the organisms which sour the milk, results in a rapid and fairly complete conversion of lactose to its component sugars, glucose and galactose, at a lower cost than for conversion by added enzyme only.
Over 90% conversion o:E lactose is easily accomplishecl, so that the small residual-lactose content is easily tolerated by most people who have dif:Eiculty in digesting the lactose in milk.
Moreover, the deionization by ion exchange introduces only the ions of water to replace the mineral ions, and thereby avoids introduction of any forei~n materials, and particularly avoids the increased salinity which would result from neutrali-zation of acid ions by introduction of alkaline materials.
The consequence is that a previously almost useless waste product is economically converted to a food product supe-rior to sweet whey as it has heretofore been availab:Le.

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1 This modified sweet whey, containing all the -food elements of whey except for removal of some of the mineral ions, and involving c~nversion of the lactose to the -far more desir-able glucose and galactose, can be used as such as a beverage or component of a beverage, or can be used as the liquid component of any o:E a great many -foods, including soups~ puddings, baked goods, frozen desserts~ and many others. Moreover, it can be concentrated to produce a new kind of highly nutritiQus sweetener.

Example 2 Partial Demineralization of Sweetened Whey To produce a whey product or use as an ingredient of a citrus type fruit drink, it is desirable to retain some of the calcium and other mineral ions. Thus a partial demineralization can be carried out in the following manner.
Pasteurized skim milk is mixed with lactase enzyme, and after a few hours for hydrolysis of the lactose, a culture of acid-producing organisms is added, as in Example 1 above, to curdle the milk.
After cutting of the curds, the whey is withclrawn, clarified, and divided into two approximately equal parts. One part is then passed through a bed of cation-exchange material as in Example 1, following which it is remixed with the other part.
This procedure reduces the mineral content, principally calcium, by about a half, retaining the other half for its nutritive value and for its contribution to flavor of the final product.
The whey is then passed through a bed of anion-ex-change material for removal of lactic acid ions. Citric fruit flavorings are then added. The enhanced sweetness resulting from presence of the glucose and galactose derived from the hy-drolysis of lactose gives a pleasant -flavor to the product.
The procedure described above 7 of treating a measured fraction of a total batch, is a convenient way to bring about ~ 9ll 1 removal of a predetermined ~raction of an ingredient, since it involves only measurement o~ volume, which is very much simple'r than adjusting the extent of a remo~al procedure, and ~hen veri-fying it by an assay which can be quite complex and time-consuming.

Example 3 Modification o~--Freviously Made ~our~
Sour whey is prepared in the usual way by inoculating skim milk at room temperature with an acid-~orming organism and allowing the milk to curdle, after l~hich the curds are strained off for use as cottage cheese, and the whey is clarified.
The clarified sour whey is then passed through a bed of anion-exchange resin such as the Am'berlite ~ RA-93 described in Example 1, at such a rate that the effluent acquires a pH
;slightly higher than 6, which substantially elimin~tes the char-acteristic lactic acid sour flavor.
~The approximately neutral whey is then treated with one ;of the commercial lactase enzymes w'hich are produced by organis~
such as Saccharomyces fragilis. This lactase enzyme may be immobilized on the surface o-f a glass bead carrier. The whey is kept in contact with the enzyme until at least 50% of the lac-tose is hydrolyzed, and preferably 75% or more. Thereby the whey acquires a pronounced sweet flavor, modified by a slight saltiness from the mineral elements such as calcium present in original milk.
If the whey is to be used at a later ~ime, it is preferably pasteurized. It may be concentrated in any usual manner, as in a vacuum pan~ which greatly enhances its swee~ness and sterilizes lt so that it may be kept for subsequent use.
a cle rv~ k .~ :173~4 1 Example 4 Preparation of Sweet Syrup from Sour Whey Sour whey ~rom cottage cheese manufacture is inocu-lated with acid-active lactase enzyme produced by Aspergillus niger, and maintained at 35C until 90% of the lactose is hydrolyzed.
The whey is then de-acidified by passing it through a bed of anion-exchange material as described in Example l, to bring it to a nearly neutral pH value of about 6.
The whey containing glucose and galactose~ in place of the original lactose, is then vacuum concentrated to a syrupy consistency, which makes it reasonably stable. The prod-uct is a very sweet syrup, consisting primarily of a mixture of sugars, but containing also the proteins and other nutritive constituents of the whey.
The syrup can be used in almost any food product requiring sweetening, at a considerable saving over the use of pure sugar or other commercial sweeteners, or can be used as a table syrup.

Example 5 Whey Beverage Cottage cheese is made from pasteurized skim milk at about 90F (32C) by addition of diluted phosphoric acid to a pH of about ~.6. After the curd has set, it is cut and cooked to cause separation of the whey, and the curd is removed.
After clarification of the whey, an acid-stable lac-tase as used in Example ~ is then added and the whey is allowed to stand until about 80% of the lactose is hydrolyzed~ The whey is then partially de-acidified by passage through a bed of Amberlite IRA-93, as described in Example 1, at such a rate as to bring its pH value to 5 or more up to 7, depending on the intended use. It is found to have a pleasant sweet flavor.

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1 Addition of flavorings and additional sweetener produces agreeable beverages.
Similar beverages can be made from whey produced by the process of Example 1, if the treatment with an anion-exchange material is limited so as to produce a product with a mildly acid p~l level between 5 and 7. The flavor will then be slightly different because of the presence of lactic acid in-stead of phosphoric acid.

~xample 6 10Frozen Desserts Cottage cheese is made in the manner described in Example 1. The whey is then passed through a bed of IRA-93 anion-exchange material at such a rate as to raise its pH value to about 5. Lactase is added and the whey is allowed to stand until 90~ of the lactose is hydrolyzed. It is then vacuum con-centrated to about 50% total solids.
The material so produced has a mild, very sweet taste.
; When flavorings such as chocolate, or fruit flavors are added, and the mix is frozen, a dessert of good texture and pleasant flavor results. Such a dessert is more nutritious than sherbets because of the substantial quantity of high quality protein con-tained in it, along with significant quantities of several vitamins and minerals, in addition to the two sugars - glucose and galactose.

Example 7 Food Recipes As examples of the many kinds of food products that can be made from sour whey which has been at least partially de-acidified, and has had a major part of the lactose converted to glucose and galactose, the -following recipes are presented, in which "de-acidified sour whey" refers to the product of ~ ~73fi9~

1 Example 1 above. It should be understood that comparable good results are obtainable using products made by somew~at dif-ferent procedur~s, so long as most of the lactic acid is removed, and most of the lactose is hydrolyzed with the result that the sugars present are principally glucose and galac~ose.
~lthough improvements are obtained by any substan~
reduction in the quantity o-f lactose and of lactic acid, the problems resulting from presence of these two materials are still very troublesome unless most of the quantity originally present ~that is, more than hal~) is removed or replaced, and prefer-ably much more ~such as three-fourths or more), since many people dislike the flavor of lactic acid, and many others ex-perience digestive problems -from ingestion of even small amounts of lactose.

A. Wh te Bread 20 lbs. heated de-acidified sour whey 1-1/4 lbs. shortening 1-1/4 lbs. sugar 1/2 lb. salt 30 lbs. sifted bread flour 20 yeast cakes dissolved in 2-1/2 lbs. warm water Melt shortening, add sugar, salt, and whey. When lukewarm add yeast and half of the flour, mixing thoroughly. Add remaining flour gradually until no longer sticky. Knead thoroughly,cover, and let rise. Cut down, knead, shape into loaves and place in bread pans. When doubled in bulk, bake 15 minutes at 425F ~hen 30 to 35 minutes at 375F.

B. Whole Wheat Bread Same as White Bread replacing half of the flour with whole wheat flour and adding

2 lbs. molasses C. Rolls Same as White ~ead, adding 2 dozen beaten eggs, and shaping into rolls instead o-f loaves.

~ :L73fi~4 1 D. Griddle Cakes 5 lbs. de-acidified sour whey 5 lbs. -flour 1 lb. sugar 1 oz. salt

3 QZ. baking powder 1 doz. eggs, well beaten 1 lb. melted butter Mix well and drop tablespoonsful separately on hot greased griddle, turning when brown on bottom.

E. Biscuits 5 lbs. de-acidified sour whey 5 lbs. flour 6 oz. shortening 3 oz. baking powder 3 oz. salt Mix dry ingredients, work in shortening, add whey gradually, using more or less to proper consistency. Roll out, cut with biscuit cutter. Ba~è on buttered tin 10 to 15 minutes at 45QF.

F. Bran Mu-ffins 5 lbs. de-acidi-fied sour whey 2-1/2 lbs. flour 3 lbs. bran 3 lbs. molasses 10 eggs, well beaten

4 oz. soda 4 oz. salt Mix well and bake in buttered mu-Efîn tins 30 to 40 minutes at G. Corn Bread

5 lbs. de-acidified sour whey 5 lbs. flour

6 lbs. corn meal 2 lbs. sugar 1 lb. melted or liquid shortening eggs, well beaten 2 oz. salt 3 oz. baking powder Mix well and bake 20 minutes at 425F.

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1 H. ~egetable Soup 10 lbs. de-acidified sour whey 20 lbs. chîcken stock 6 lbs. chopped cooked green vege~able ~celery, peas, spin~.ch, etc.) l-l/Z lbs. butter 1 lb. flour salt and pepper to taste Melt the butter, add the ~lour, and mix into the soup while it is cooking.

; I. Omelet Allow 2 to 3 eggs per person. For each dozen eggs, slightly beaten ? add:
6 oz. de-acidified sour whey salt and pepper to taste For each 2 people, put 1 oz. butter in hot omelet pan, add mix-ture. Where it cooks, lift with spatula until aIl is o-f creamy consistency. Increase heat until light brown underneath. Fold and turn on hot platter. For a puffy omelet, separate eggs, beat whites separately, then other ingredients, and fold together before coo~ing, but don't stir during cooking. When bottom is browned, finish in oven to brown top.

J. White Sau~e 8 lbs. de-acidified sour whey 8 oz. flour l lb. bukter salt and white pepper to taste Melt butter, add flour mixed with seasoning7 stir until well blended, add whey gradually until well blended, bring to boil and cook 2 minutes.

K. Cheese Sauce Add 4 lbs. grated cheese to White Sauce.

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1 L. Lemon Cream Rice 6 lbs. de-acidified sour whey 8 eggs separated, yolks and whites separately beaten 1 lb. rice 1 lb. sugar 1/2 oz. salt 3 oz. lemon juice 4 oz. powdered sugar grated rind of 3 lemons Cook the rice in the whey in a double boiler until soft, add the sugar, lemon rind~ lemon juice, salt and egg yolks. Stir gently and cook until thickened. Turn into a buttered dish and cool. Add the powdered sugar to the beaten egg whites, and cover the top of the pudding with the meringue. Bake at 350 until top of meringue is browned.

M. Chocolate Pudding 18 lbs. de-acidified sour whey 2 lbs. unsweetened chocolate 2-1/2 lbs. sugar 1 lb. cornstarch 1/2 oz. salt 1 oz. vanilla Heat all but 2 lbs. of the whey and the chocolate in a double boiler and stir until blended. Mix the other ingredients, add them and stir constantly until the mixture thickens, then occa-sionally for a total time of 15 minutes. Pour into a dish and chill.

N. Citrus Sherbet 12 lbs. de-acidified sour whey 6 lbs. sugar 4 doz. egg yolks 6 oz. granulated gelatin 1 lb. water 9 lbs. orange juice 4 oz. lemon juice Gratings of one orange rind Put water, sugar, and grated rind in sauce pan, bring to boil~
add slightly beaten egg yolks 9 1cook 1 minute. Add gelatin soaked in water. Strain, cool, add fruit juices, and freeze.

O. Lemon Cream Sherbet -18 lbs. de-acidified sour whey 9 lbs. sugar 4 lbs. lemon juice 6 lbs. cream Mix and freeze.

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l P. Frozen Custard 20 lbs. de-acidlfied sour whey oz. -Elour lO lbs. sugar 20 eggs slightly beaten 112 oz. salt 3 oz. vanilla 49 lbs. thin cream Mix flour, sugar and salt, add ~eaten egg, and gradually add the whey. Cook lO minutes over hot water while stirring. When cool, add cream and flavoring, and freeze.

Q. Fruit Ice Cream 20 lbs. sour whey 40 lbs. heavy cream 6 doz. egg ~hites beaten stiff 20 lbs. canned fruit tpulp and juice) oz. lemon juice Mix ingredients except fruit, freeze to mush consistency, add fruit, finish freezing.

R. Chocolate Fudge 5 lbs. butter 15 lbs. chocolate 75 lbs. syrup of de-acidified sour whey Melt butter, add other ingredients while heating and stirring until well mixed. Cook at 23~~ until a portion forms a soft ball when tried in cold water. Cool on a greased sur:Eace and cut in squares.

Example 8 Chocolate Milk Drink A chocolate milk drink is prepared~ with equivalent properties o~tained by two different recipes, one of which con-tains only conventional ingredients and proportions while the other contains the new product of Example l.

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1 Conventional New Deacidified Sour Whey -- 9.7 Standard Milk 88.9 81.8 36% cream 0.6 1.1 Skim Milk Powder -- 0.6 ~hey Powder 1.1 --Sugar~ 7.0 4-4 Corn Sweetener 1.8 1.8 Cocoa 0.6 0.6 100 . O 100 . O
It is evident that in the second formula former waste material replaces nearly a tenth of the standard milk and more than a third of the sugar formerly required, with the only other required change being a slight increase in cream ~o keep the butter fat content in balance.

Example 9 Commercial Grade Ice Cream A standard commercial grade ice cream meeting the requirements of the local state law, and having a 10% milk fat content, contains the constituents listed in the left column bslow. A different composition, likewise meeting the require-ments, contains the somewhat different constituents listed in the right column. These constituents, in pounds, together with the water content of th~ milk, produce 9,260 pounds or 1,000 gallons of ice cream mix.
Conventional New Milk fat ~26 926 Non-fat Milk Solids 555 555 Dry Sweet ~ey 185 --Sucrose g26 g26 Corn Sweetener 971 436 De-acidified Whey Solids:
Sugars -- 360 Proteins, etc. -- 360 Stabilizer 37 37 3,600 3,600 It is noteworthy that replacement of about half of the corn sweetener and all of the dry sweet whey by a product con-taining galactose, which is a very sweet sugar, permits a ~ ~3~

1 significant increase in proteins and other nutrients. At the same time the cost is reduced.
Since the whey when properly prepared as described above has either a greatly reduced lactose content, or is essentially free from lactic acid, the problems previously encountered in concentration and drying of sour whey are largely eliminated.
The sweet whey produced in the foregoing manner is not only swee~ in the sense of being free from acidity, lacking the sour lactic acid flavor which is characteristic of cottage cheese whey, but is truly sweet in taste because of the pres-ence in it of approxima,tely one molecule of glucose and another molecule of galactose for each of the molecules of lactose in the original milk. When concentrated or dried, the whey becomes quite sweet because a major part of the solid content consists of this mixture of sweet flavored sugars.
For example, the sweet whey produced by the foregoing procedure is vacuum concentrated at a moderate temperature, to avoid denaturizing the lactalbumin and globulin, to a concen-tration of about 50~ solids. This liquid concentrate can bestored in bulk for reasonable periods if refrigerated. It is a highly nutritious material suitable for direct addition to ice cream or sherbet mixes or other sweet dairy products because of its pronounced sweet flavor.
While the procèdures described above are presently preferred, they can be modified by using other equivalent treatments at various stages of the process.
Thus the splitting of lactose into glucose and galac-tose can occur after the separation o-f the whey from the curd instead of being initiated before souring of the milk. In this variation of the procedure, the lactase should be ~ne of the commercially available kinds which is most active under 1 ~7.~
1 acid conditions.
A1SQ, instead o~ mixing a lactase enzyme through the entire volume of milk~ or of whey, the lactase can be immo-bilized on the surface of a suitable substrate such as porous glass or equivalent inert solid material, as is well known. In that case, the liquid is passed through or over ~he immobilized enzyme at such a rate as to bring about substantially complete reaction.
Similarly, instead of deionization by means of con-tact with pellets of ion-exchange material, deionization can be brought about by passing the whey over or through diaphragms having suitable ion-exchange properties, and in either event the ion-exchange products can be made from a wide variety of different kinds of materials.
The ion-exchange materials used in sweetening the sour whey are easily and quickly regenerated when exhausted.
The pellets or other form of cation-exchange resin~ may be regenerated with dilute hydrochloric acid, which is thereby con-verted into a solution of chlorides of the metals present in the original milk, principally calcium chloride, along with some magnesium, sodium, and potassium chloride.
The anion-exchange material may be regenerated by a dilute sodium hydroxide solution, which is thereby converted into a solution of the sodium salt of the lactic acid which was removed from the sour whey along with sodium salts or whatever other orgarlic or inorganic aci~s may have been present. Alter-natively, aqueous ammonia may be used for regeneration, if ammonium salts of the acids are not objectionable in the particu-lar effluent situation of the dairy plant.
These solutions of the alkali and alkaline earth salts and of the organic acid salts produced in regeneration o-f the ion-exchange resins are relatively innocuous and have a low 1 biological oxygen demand. They can be discharged into sewers or streams with little ef-fect, particularly when diluted with the normal wash waters and other effluents from the dairy plant.
The odors and the interference ~ith normal clari~ication of sewage which result from discharge o-f sour whey are essentially all eliminated.
At the same time, substantially all of the nutritional values of the whey, in particular the sugar, the proteins, the lipids, and the vitamins, are recovered for use in foods, and in an improved -form with greatly enhanced sweetness, and freedom from objectionable sour odor or taste, and also largely free or nearly completely free from lactose and the problems which its presence in food presents to so many people.
If a single stage de-acidification is preferred, the treatment with the cation-exchange material may be omitted.
This has the advantage of retaining the calcium which many peo-ple do not consume in ade~uate quantities, but the disadvantage of retaining a somewhat high total salt content.
Unless there is an immediate use for the nutritional materials in the rather dilute form contained in the whey, the product may be concentrated by any convenient process, such as vacuum drying, ultra-filtration, or reverse osmosis. The con-centration may be carried to any desirable extent, to produce a nutritional liquid of the proper water content for direct addi-tion to other constituents of a food product, or if it is not to be used immediately it can be dried further to produce either a syrupy concentrate or a completely dried whey powder~
This invention can be carried out in many different modifications. These include use of different kinds of lactase~
produced by different organisms~ and having maximum effective-ness under different conditions of temperature, acidity, and salinity. Other differences include use of ion-exchange 36~
1 materials having different chemical compositions and functioning best under various different conditions including presence and concentration of parcicular materials, or different temperatures.
The two essential operations, of hydrolysis of lactose, and of deionization, can be carried out simultaneously or separately, and in different orders of succession, or after various preliminary operations such as sterilization or concentration.

Claims (20)

The embodiment of the invention in which an exclusive property or privilege is claimed is defined as follows:

1. A process for converting sour whey, made by acidifying milk and removing the resulting curd, into sweet whey containing substantially all the food value of the whey, which process comprises splitting at least half of the lactose orig-inally present in the milk by a lactase enzyme, and de-acidifying the whey by contact of the whey with an anion-exchange material, while retaining the non-ionizable sub-stances in the whey.

2. A process as in claim 1 in which the enzyme is added to the milk be-fore the ion-exchange treatment.

3. A process as in claim 2 in which the enzyme is added to the milk be-fore it is acidified.

4. A process as in claim 3 in which the milk is acidified by the action of an acid-producing living organism.

5. A process as in claim 4 in which the organism also produces lactase.

60 A process as in claim 1 in which the ion-exchange material is a synthetic resin having anion-attracting functionality.

7. A process as in claim 5 in which the ion-exchange material is a synthetic resin having anion-attracting functionality.

8. A process as in claim 7 in which the whey is treated by successive contact with a cation-exchange resin and an anion-exchange resin.

9. A process as in claim 8 in which the cation-exchange resin has carboxylic functionality and the anion-exchange resin has amine functionality.

10. A process as in claim 9 in which the enzyme is added to the milk before it is curdled.

11. A process as in claim 1 in which the sweetened whey is at least partly dewatered.

12. A process as in claim 10 in which the sweetened whey is at least partly dewatered.

13. A process as in claim 1 in which nearly all of the lactose is split.

14. A process as in claim 12 in which nearly all of the lactose is split.

15. A sweet whey product made by the process of claim 1.

16. A sweet whey product made by the process of claim 14.

17. A process for converting sour whey into a palat-able food product lacking the pronounced lactic acid flavor of the sour whey, which process comprises hydrolyzing lactose in the whey by a lactase enzyme, de-acidifying the whey by contact of the whey with anion-exchange material while retaining the non-ionizable substances in the whey, and adding other nutritional and flavoring ingredients.

18. A palatable food product made from sour whey, containing substantially all the nutritional values of the sour whey including the functional values of the lactose and proteins, improved by enzymatic conversion of lactose to a mixture of glucose and galactose and by removal of anions to minimize the pronounced acid flavor of the sour whey, and containing also nutritional and flavoring food ingredients other than those present in the whey, when prepared by the process defined in claim 17.

19. A process as in claim 1 in which the whey is only partially de-mineralized, by dividing the whey into portions, de-mineralized one portion by contact with an ion-exchange material, and remixing the one portion with another portion which is not de-mineralized.

20. A process as in claim 19 in which the said one portion is about one-half of the whey, and after de-acidification it is remixed with the other half.