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the proportion of whey proteins in the end

product.

0014 The mineral content and low pH of casein wheys

severely limit their commercial exploitation. The

vast majority of whey-based products are manu-

factured commercially from low- or medium-acid

wheys.

0015 Whey has a very high biochemical oxygen demand

(BOD), which poses major difficulties for its

disposal. It should be noted also that a number of

options for whey processing, particularly those

that increase the proportion of protein in the prod-

uct, also result in the production of a waste pro-

duct, which contains most of the lactose originally

present. This stream, in turn, requires further pro-

cessing. Thus, the problems posed by the biochem-

ical oxygen demand of the original whey are often

only slightly affected by many of the whey-

processing options.

Processing Options

0016 The processing options for whey fall into four main

areas:

0017 Those concerned with simple removal of water

(spray or roller drying to yield whey powder).

0018 Those concerned with increasing the ratio of pro-

tein in the end product (ultrafiltration for the

manufacture of whey protein concentrates, frac-

tionation processes for the manufacture of protein

isolates, heat treatment for the production of

lactalbumin).

0019 Those concerned with utilization of the lactose in

whey (treatment with lactase or heat/acid for lac-

tose-hydrolyzed products, fermentation to a range

of products such as lactic acid, citric acid, and

single-cell protein).

0020 Those designed to alter the mineral composition of

the product (electrodialysis and ion exchange for

the manufacture of demineralized products).

Each of these is considered in turn below.

Drying of Whey

0021 The production of whey powder from whey is a

mature technology. Perhaps the major difficulty

involves the holding period required prior to drying

in the manufacture of nonhygroscopic whey powder.

Such a holding period (sometimes also involving

seeding) is required to allow for crystallization of

the lactose into a nonamorphous, nonhygroscopic

form prior to drying. The development of technology

to reduce this holding period could result in signifi-

cant savings to the industry.

0022The spray drying of whey is a fairly straight-

forward operation, with conditions employed similar

to those used for the spray drying of milk. Thus, the

whey is concentrated to 40–70% total solids and

spray (or roller) dried to a moisture content of less

than 5%. As indicated above, the drying of whey is

complicated by its high lactose content. Lactose exists

in two isomeric forms, a-lactose and b-lactose.

a-Lactose crystallizes as a hydrate, whereas solid

b-lactose contains no water of crystallization. How-

ever, when solutions of whey are dried rapidly, there

may be insufficient time for the a-lactose to form

as the monohydrate, and it forms as amorphous a-

lactose. The dry lactose in the whey product is then

essentially in the same form as in the liquid. Neither

a-lactose hydrate nor b-lactose is hygroscopic. How-

ever, amorphous a-lactose is highly hygroscopic and

will absorb moisture from the air, resulting in a

hydrate that occupies more space than the amorphous

form. This effect causes the commonly observed

lumping and caking in many whey powders.

0023Both hygroscopic and nonhygroscopic whey

powders are manufactured. The former are produced

by simple drying of the whey concentrate. The manu-

facture of nonhygroscopic whey powders relies on the

conversion of much of the lactose in the liquid con-

centrate to a crystalline form prior to drying. This is

achieved by holding the concentrate under appropri-

ate conditions to allow for extensive formation of

a-hydrate crystals. The traditional process requires

holding the concentrate for about 16–24 h after add-

ition of seeding crystals. This process requires holding

tanks of considerable size and is energy-intensive

(good agitation is required), and the viscosity of the

concentrate must be as low as possible (heat treat-

ment of the concentrate should be minimized). Re-

cently, a new process has been described, based on the

fact that most of the lactose is crystallized in 3–4h.In

this process, the whey is concentrated to 53–55% TS,

flash-cooled to about 30



C, and seeded. The product

is pumped to a conventional nonagitated tank, repre-

senting 2–3 h of production. The semicrystallized

concentrate is pumped to a second flash cooler and

cooled to 15



C, and then to a second crystallization

tank, where it is held ready for spray drying. Alterna-

tively, a process similar to instantizing may be used, in

which the surface of the partly dried whey powder

particles is partially humidified prior to completion of

the drying operation. This stage permits additional

crystallization of the a-lactose during drying.

0024The market for permeate powders is not as yet

well developed, probably because of difficulties in

obtaining a consistent product, and difficulties en-

countered during drying caused by the high-lactose/

low-protein content of the product. Worldwide, the

WHEY AND WHEY POWDERS/Production and Uses 6149

difficulties encountered in spray-drying permeate

have led some companies to cease production of per-

meate powder, and to adopt perhaps less profitable

alternative technologies. Research suggests that the

drying properties of permeate may be considerably

influenced by the pH and of course the crystallizing

conditions. The development of successful means for

the drying of permeate would be of particular value to

the industry, as the production of permeate powder

is a simpler option for many companies than, for

example, the production of crystalline lactose. In re-

sponse to this need, equipment supply companies are

continuing to develop systems specifically for perme-

ate drying.

Means for Increasing the Protein Content of the

End Product

0025 Whey solids contain about 11% protein. Many of the

most popular methods of whey treatment aim to

increase this level, with end products containing

between 35% and virtually 100% protein. It should

be noted that each of these methodologies results in a

waste stream high in lactose, which will pose separate

utilization or disposal problems.

0026 Ultrafiltration Ultrafiltration is the most common

method used by the dairy industry to produce a

range of whey products with an increased protein

content, known as whey protein concentrates

(WPCs). Ultrafiltration relies on the passage of whey

near a membrane with a pore size such that low-

molecular-weight materials such as lactose and

salts pass through the membrane, whereas higher-

molecular-weight components, such as proteins, are

retained. On ultrafiltration of whey, therefore, the

solids content of the product retained by the ultrafil-

tration membrane (the retentate) is higher in protein

and lower in lactose than the original whey, and the

solids content of the product that passes through the

membrane (the permeate) is high in lactose and ash,

and has minimal protein content. WPCs are produced

from a wide range of wheys, generally to protein

contents of 35%, 50% and 75% (Table 1).

0027 WPC containing 35% protein is often used as a

skim milk powder replacer in applications where the

specific functionality of skim milk powder is not im-

portant (a WPC of 35% protein content is generally

significantly less expensive than skim milk powder).

WPC with a protein content of 50% is not widely

manufactured and generally is used for specific appli-

cations only. WPCs containing 75% protein can have

very desirable functional properties, and these can be

readily manipulated by modifying the manufacturing

process. Such products often have excellent water-

binding, gelation, and emulsifying properties, making

them sought after by the food industry as functional

ingredients.

0028Production of lactalbumin Whey proteins are heat-

sensitive and can be precipitated by heat treatment

under appropriate conditions of pH and ionic

strength. This property is exploited in the manufac-

ture of lactalbumin. (Note that lactalbumin, the

product of heat precipitation of the proteins from

whey, contains a mixture of denatured a-lactalbumin,

b-lactoglobulin and other whey proteins. ‘Lactalbu-

min’ should not be confused with a-lactalbumin.) In

the manufacture of lactalbumin, whey is heated to

denature coagulate and precipitate the whey proteins;

the sediment is recovered by settling and decantation

(or centrifugation), washed to remove excess salts

and lactose, and the product recovered by centrifuga-

tion or filtration prior to drying, grinding, and bag-

ging. The heat treatment used in the manufacture of

lactalbumin results in extensive denaturation of the

whey proteins, resulting in a product of poor func-

tionality. Therefore, lactalbumin finds its best appli-

cations in products where protein fortification is

necessary, but it is not required to provide any func-

tional properties.

0029Isolation and fractionation of protein In contrast to

the precipitation of whey proteins by heat treatment

in the manufacture of lactalbumin, protein isolation

and fractionation methodologies aim to separate the

proteins from whey in such a form that they remain,

as far as possible, fully undenatured and thus retain

their functionally. These products (protein concen-

trates and isolates) have a high protein content and

can have exceptional functional properties of consid-

erable value to the food industry.

0030Protein concentrates contain the whey proteins in

about the same proportions as that in whey. (Note

that, in this article, the term ‘protein concentrates’ is

used for high-protein products containing the individ-

ual whey proteins in about the same ratio as that

present in whey, the term ‘whey protein concentrate’

is used for such products manufactured by ultrafiltra-

tion, and the terms ‘protein isolates’ and ‘protein

fractions’ are used to refer to high-protein products

with a higher ratio of a particular protein than that

present in whey.) Such protein concentrates are gen-

erally manufactured by the use of a nonspecific ab-

sorbent to bind the proteins in whey, followed by

elution of the proteins by treatment of the absorbent

with a specific eluent. Absorbents that have been

commercially used include carboxy-methylcellulose

and a range of mineral oxides. Although these ab-

sorbents are comparatively nonspecific, they can

show a preference for binding particular proteins

6150 WHEY AND WHEY POWDERS/Production and Uses

under set conditions of pH, temperature, and ionic

strength. Thus, these processes can be used to pro-

duce protein isolates, for example with a higher ratio

of b-lactoglobulin to a-lactalbumin than that present

in whey.

0031 Protein fractionation technology is also develop-

ing, which relies on separation of a-lactalbumin

from b-lactoglobulin on the basis of their different

solubilities under specified conditions of pH, tem-

perature, and ionic strength. It is therefore possible,

for example, to separate by sedimentation most of the

a-lactalbumin from whey by careful manipulation of

processing conditions. Both the a-lactalbumin that

has sedimented and the residual soluble protein

(mostly b-lactoglobulin) are comparatively undena-

tured and thus retain their high functionality. The

conditions employed in these processes are very mild

and do not result in any denaturation of the whey

proteins. With such processes, it is therefore possible

to produce isolates rich in b-lactoglobulin (with an

extremely high gel strength) and a-lactalbumin (a

product that may have considerable potential in non-

allergenic infant foods).

Lactose-processing Options

0032 The options for treatment of whey involving lactose

may be divided into three groups – those involving a

fermentation step, those involving separation of the

lactose and its utilization, and those involving enzym-

atic hydrolysis of the lactose to produce galactose and

glucose.

0033 Fermentation Many options for the fermentation of

whey are described in the literature, including the

production of biogas, biomass, ethanol, lactic acid,

and citric acid. However, the dairy industry world-

wide has not taken up such opportunities to any great

extent.

0034 Separation of lactose In many respects, this is a

most attractive option, as it can be used also as a

process for the treatment of waste streams from

other whey treatment operations such as ultrafiltra-

tion. The manufacture of lactose (normally a-lactose

hydrate) generally involves the removal of protein,

concentration, refiltration, further concentration, in-

duction of crystallization, and separation of crystals

with a basket centrifuge.

0035 The production of lactose in the major dairy coun-

tries is increasing rapidly – in the USA, production

has tripled in the past 14 years, with exports doubling

in the past 6 years, and in Australia, production has at

least doubled. Similar increases in Europe have benn

reported. Overall, the lactose market is holding

steady through increased applications for the prod-

uct, particularly in the confectionery field.

0036Hydrolysis of lactose The hydrolysis of lactose

yields the sweet soluble sugars, glucose and galactose,

thus increasing the applications of the product. Such

hydrolysis can be carried out by treatment of whey

with lactase (b-galactosidase) or by treatment of

deproteinized whey at an elevated temperature and

low pH. It should be noted that it is difficult to dry

hydrolyzed wheys, because of the tendency of the

monosaccharides formed by the hydrolysis to pro-

duce glasses on the surface of the drier.

0037It is often suggested that lactose-hydrolyzed prod-

ucts are attractive commercial options, first, because

hydrolyzed products will be in demand by lactose-

intolerant people, and second, the increased sweet-

ness of the products makes them attractive to

the general public. In fact, the demand by lactose-

intolerant members of the community has not been

significant, and the benefits of increased sweetness

are of only marginal commercial value.

0038Hydrolysis of lactose may be carried out by a

number of processes, including heat/acid treatment

(for permeate only) and enzymic hydrolysis (for

whey, permeate, and WPC). A number of hydrolyzed

whey products are manufactured, using both immo-

bilized and free enzyme technology. In Sweden, a

beverage (‘Nature’s Wonder’) is based on hydrolyzed

whey; in Finland, hydrolyzed whey is used by baker-

ies and in a flavored whey beverage. In the UK,

hydrolyzed whey has been used in confectionery

products, generally to replace sweetened condensed

milk. However, in spite of the apparent potential of

these products, market development appears to be

proceeding only slowly.

Changes in Mineral Composition

0039The mineral composition of whey, particularly casein

whey, is such that it deleteriously influences the taste

and applications of the product. Whole or partial

demineralization of whey is therefore a popular

option with manufacturers. In the past, this has

been accomplished most often by treatment of whey

by ion exchange (no preferential removal of ions) or

electrodialysis (preferential removal of monovalent

ions). However, these methods appear to be falling

into disuse both because of their high cost and be-

cause of large volumes of intractable effluents that

they produce.

0040More recently, an option for demineralization

using ‘open’ reverse-osmosis membranes has been

developed. This technique, known as ultra-osmosis,

uses membranes that allow the passage of ions and

WHEY AND WHEY POWDERS/Production and Uses 6151

water, whilst retaining all other whey components,

including lactose. Ultra-osmosis is rapidly gaining in

application, in spite of the fact that its ability to

reduce mineral content to much below 50% of ori-

ginal levels is limited. However, it does allow for

preferential removal of monovalent ions, a consider-

able advantage.

0041 Worldwide, demand for demineralized whey prod-

ucts is increasing rapidly, with emphasis on products

containing reduced monovalents.

Applications

0042 Whey solids may be used an ingredient in products

such as calf milk replacers, infant formulae, whey

cheese, beverages, baked goods, icecream and other

dairy products, comminuted meat products, and imi-

tation milk products. In most cases, the whey solids

contribute little to the functionality of the product,

offering only a comparatively low-cost source of

protein, carbohydrate, and calcium.

0043 Similarly, lactalbumin is used in foods where pro-

tein fortification is required, but additional function-

ality is not essential. Lactalbumin is commonly used

in products such as baked goods and comminuted

meat products.

0044 WPCs are used where both protein fortification and

functionality are required, although WPC of 35%

protein content is generally used directly as a cost-

effective skim milk powder replacer. WPC of 75%

protein content, with its excellent gelation properties,

is often used as a cost-effective egg white replacer.

0045 The main market for demineralized wheys is in the

formulation of cows’ milk-based infant formulae

with a composition closer to that of human milk.

Demineralized wheys also may be used effectively as

beverage ingredients, where the saltiness of the unde-

mineralized product might normally preclude its use.

0046 Lactose is used in sauces, instant drinks, and meat

products, where its low sweetness and ability to en-

hance flavor are advantages. Lactose is also used

extensively in the confectionery and baked goods

industries. Highly purified lactose is also used in the

pharmaceutical industry for tablet manufacture and

as a substrate for the manufacture of penicillin and

other fermented products.

0047 Applications of hydrolyzed wheys include ingredi-

ents in foodstuffs, such as beverages, and other prod-

ucts, such as most animal foods, where it can be used

as a humectant to replace the more expensive glucose

commonly used.

See also: Casein and Caseinates: Methods of

Manufacture; Uses in the Food Industry; Cheeses: Types

of Cheese; Drying: Spray Drying; Lactose; Membrane

Techniques: Principles of Ultrafiltration; Applications of

Ultrafiltration; Powdered Milk: Milk Powders in the

Marketplace; Characteristics of Milk Powders

Further Reading

Fox PF (ed.) (1985) Developments in Dairy Chemistry,

vol. 3. London: Elsevier.

IDF (1987) Trends in Whey Utilization. Bulletin No. 212.

Brussels: International Dairy Federation.

IDF (1988) Trends in the Utilization of Whey and Whey

Derivitives. Bulletin No. 223. Brussels: International

Dairy Federation.

Marshall KR (ed.) (1979) Proceedings of Whey Workshop

II 2–6 April, 1979. New Zealand Journal of Dairy

Science and Technology 14: 73.

Morr CC and Melachouris N (eds) (1984) Symposium:

Production and Utilization of Whey and Whey Compon-

ents (1983). Journal of Dairy Science 67: 11.

Robinson RK (ed.) (1986) Modern dairy technology. In:

Advances in Milk Processing, vol. 1. London: Elsevier.

Sienkiewicz T and Riedel C-L (1990) Whey and Whey

Utilization. Gelsenkirchen-Buer, Germany: Verlag Th.

Mann.

Zadow JG (ed.) (1992) Whey and Lactose Processing.

London: Elsevier.

Protein Concentrates and

Fractions

J G Zadow, Mount Martha, Victoria, Australia

Introduction

0001Over the past 20 years, whey processing has been

revolutionized by the development of methodologies

for the manufacture of highly functional food prod-

ucts containing a higher proportion of protein than

that found in whey. Functionality has been defined as

‘any property of a food or food ingredient, except its

nutritional ones, that affects its utilization.’ The main

functional properties of whey protein products used

for food applications include solubility, whipping,

flavor, water binding, thermal extrusion, viscosity,

gelation, foam formation, and emulsification. The

technology involved in the manufacture of functional

whey-based ingredients generally involves either

ultrafiltration or the selective separation of whey pro-

teins (either by adsorption technology or by utiliza-

tion of the different solubility characteristics of whey

proteins under specified conditions of pH and tem-

perature). This article will discuss the properties of

the major proteins of whey, whey protein products

6152 WHEY AND WHEY POWDERS/Protein Concentrates and Fractions

and methods for their manufacture, and the applica-

tion of such products in the food industry.

Characteristics of Whey Proteins

0002 Whey proteins are those which remain in solution

after removal of the caseins from milk, either by

treatment with chymosin or by acidification. The

distribution of proteins in milk is shown in Table 1.

0003 b-Lactoglobulin is the principal protein in whey,

comprising about one-half of the total protein pre-

sent. It occurs as a number of variants, and has a

monomer molecular weight of about 18 000. It should

be noted that b-lactoglobulin exists as a monomer

only outside the pH range 3.5–7.5. Inside this range,

it generally exists as a dimer although, under certain

circumstances, some variants may form an octomer.

b-Lactoglobulin is comparatively heat-sensitive and

may be denatured by heat treatment much above



C. a-Lactalbumin has a monomer molecular

weight of about 14 000, and is somewhat more heat-

resistant than is b-lactoglobulin. There are many other

serum proteins (including immunoglobulins) in whey,

most of which are readily heat-denaturable. For

example, heat treatment of skim milk at 70



C for

30 min denatures only 6% of the a-lactalbumin, but

32% of the b-lactoglobulin, and 89% of the immuno-

globulins; cumulatively, such a heat treatment results

in denaturation of about one-third of the total serum

proteins. In whey, heat treatment is often carried at a

pH quite removed from that of milk. It should be

noted that the pH of heat treatment of whey has a

considerable influence on the magnitude of the degree

of denaturation of each of the whey proteins.

0004 As globular proteins, both a-lactalbumin and b-

lactoglobulin have the potential to be highly func-

tional food ingredients. Unfortunately, many of the

processes used for whey protein recovery result in

their partial denaturation, which generally reduces

the functionality of the product.

Major Products and Applications

Whey Protein Concentrates

0005Whey protein concentrates are manufactured by the

ultrafiltration of whey. In this process, whey is passed

against a semipermeable membrane, which selectively

allows passage of low-molecular-weight materials

such as water, ions, and lactose, whilst retaining

higher-molecular-weight materials such as protein in

the retentate. The retentate is then further concen-

trated by evaporation and spray-dried to yield whey

protein concentrates (WPCs). WPCs are generally

available commercially with a protein content of

about 35, 50, or 75%. For the higher protein prod-

ucts a process known as diafiltration is employed, in

which water is added to the retentate during manu-

facture to wash out more of the low-molecular-weight

materials from the retentate.

0006The development of markets for WPCs has been

slowed by the inconsistent quality and composition of

the product, particularly during the early years of

development. WPC 35% is often considered to be a

skim milk powder analog, and for many skim milk

powder applications, it may be utilized as a direct

replacement. However, it is only in recent years,

with improved product consistency and quality, that

markets for this product have firmed. It should also

be noted that this is not a particularly lucrative

market for whey producers, as 35% WPC is generally

priced at a significant discount to skim milk powder.

0007A WPC with a higher protein content, particularly

the 75% product, is generally required by the end

user to have defined and reproducible functionality.

Again, however, inconsistent quality, due perhaps to

a lack of understanding of processing conditions

on functionality development, has slowed market

acceptance. In some cases, however, supplies of 75%

WPC have outstripped demand and this highly nutri-

tional product has been sold for animal feed on the

basis of its protein content.

0008A further problem with WPC development is the

need to develop markets for the products of permeate

processing. Whilst lactose markets are strong and

continuing to increase, significant concerns about

the ability of the industry to continue to cope with

the increasing levels of permeate production world-

wide remain.

0009There appears to be a slowing in the rate of instal-

lation of ultrafiltration membrane processing for the

production of WPC by the industry. This is probably

the result of a number of factors, including:

0010Such technology is only applicable to major whey

producers, and many have already installed this

technology (although some of these are reverting

tbl0001 Table 1 Typical protein composition of milk

gper100gmilk

Colloidal casein

2.36

Serum casein

0.26

b-Lactoglobulin

0.32

a-Lactalbumin

0.12

Bovine serum albumin

0.03

Total immunoglobulins

0.075

Other proteins

0.06

Nonprotein nitrogen components

0.08

Data from Farrell HM Jr and Thompson MP (1974) Physical equilibria in milk

proteins. In: Webb BH, Johnson AH and Alford JA (eds) Fundamentals of

Dairy Chemistry, p. 465. Westport, CT: AVI Publishing.

Data from Walstra P and Jenness R (eds) Dairy Physics and Chemistry,

p. 71. New York: John Wiley.

WHEY AND WHEY POWDERS/Protein Concentrates and Fractions 6153

to the production of whey powder for whey

utilization).

0011 The market response to the products has to date

been disappointing. The early promise of ex-

tremely high returns for high-protein (> 75% pro-

tein) WPC has often not been achieved, mostly

because of inconsistent functionality of such prod-

ucts. However, there is the potential for good

returns provided that quality and functionality

can be maintained consistently. Products contain-

ing 35% protein have in general not proven par-

ticularly commercially attractive.

0012 Adopting this technology does not solve any dis-

posal problems – the permeate still requires pro-

cessing or disposal. Further, given the fact that it is

virtually free of protein, permeate is generally a

less commercially attractive product to utilize than

whey.

0013 The inclusion of WPC into foodstuffs may confer a

wide range of potential functionality. Important func-

tional properties include solubility, foaming, gelation,

emulsification, elasticity, viscosity, and organoleptic

characteristics. It is possible, by manipulating com-

positional factors and processing conditions, to

manufacture WPCs with a wide range of functional-

ity, combining many of the above attributes. In

general, WPCs of lower protein content have more

limited functionality than those of higher protein

content. In many cases, WPCs serve more than one

functional purpose in foods. For example, as whey

proteins remain soluble over a wide pH range, in

particular near pH 4.5, they may be used in acidic

drinks as protein fortifiers. WPCs can be used as

water binders in products such as baked goods and

processed meats. In such cases, processing tempera-

ture must be sufficiently high to denature the whey

proteins, but not so high as to disrupt their water-

binding properties. WPCs can also have excellent

gelation characteristics, and can assist in the forma-

tion of heat-induced gels in meat products and baked

goods. WPCs with good emulsification properties

would find applications in products such as sausages,

salad dressing, coffee whitener, and soup. WPCs may

also have useful foaming properties, producing very

stable foams on whipping. Applications for such

products again vary depending on the functionality

required in the end product, but would include

desserts, cakes, and whipped products.

0014 A major challenge to whey protein researchers and

producers is to determine precisely the compositional

and processing properties which influence the final

functionality of WPC. It is well known that factors

such as the source of whey, its protein content, the

heat treatment applied to the whey or ultrafiltration

retentate during manufacture, and the lipid content

and mineral content of the product influence func-

tionality, but detailed knowledge of mechanisms is far

from complete. The manufacture of WPCs with such

widely varying and yet specific functional properties

certainly requires the careful control of manufactur-

ing conditions. Currently, much ultrafiltration pro-

cessing of whey is carried out on an ad hoc basis,

with little understanding of the effects of individual

processing parameters on the conformation or struc-

ture of the individual proteins, or on the functionality

of the product. It should also be noted that the func-

tionality of the whey products can be permanently

impaired by the use of excessive temperatures or

extremes of pH during processing.

0015Mineral composition is also an important factor

determining whey protein functionality. Many of the

functional properties of WPCs are considerably influ-

enced by either demineralization or by the addition of

calcium salts. Clearly, the manufacturing process

used in the whey production process will influence

the mineral content of the product, and thus its

functionality.

Whey Protein Isolates

0016There have been some commercial developments

recently in the manufacture of whey protein isolates.

Generally these products are manufactured by the use

of specific complexing agents which bind with the

proteins, allowing their removal from the whey. The

processes use absorbents such as carboxy-methyl-

cellulose (such as in the Bi-Pro process), or inorganic

oxides (such as with Spherosil reagents) or complex

formation (with reagents such as polyphosphates).

The end products may then be sold in the form of

these complexes, or the proteins eluted and dried for

sale as protein isolates. The products of these oper-

ations are highly functional, high-value-added whey

protein fractions which have high specific functional-

ity and generally sell for a high premium. Those prod-

ucts sold as complexes have less general applicability,

and attract reduced profit margins. However, in spite

of their availability, the market for these products has

proved to be somewhat limited, and demand has not

been as high as expected. It is believed that some

difficulties have been experienced in insuring that

the products of such processes have consistent

functionality when utilized in foods.

Whey Protein Fractions

0017Whey proteins can be recovered as mixtures of the

proteins in whey by use of the technologies out-

lined above. Commercially, ultrafiltration technology

is dominant for such processes. However, WPCs

6154 WHEY AND WHEY POWDERS/Protein Concentrates and Fractions

manufactured by ultrafiltration have not, in general,

lived up to their promise of offering reliable highly

functional cost-effective ingredients to the food in-

dustry. In particular, the functionality of WPCs is

often poor and/or highly variable. Further, the func-

tional properties of WPCs are often well below those

expected from their protein composition. This may be

due to mechanical or heat damage to the proteins

during manufacture, or to the presence of other com-

pounds in whey which inhibit the development of full

functionality.

0018 To overcome such difficulties, a number of alterna-

tive options for whey protein fractionation have been

developed. These aim at the manufacture of protein

fractions containing a higher proportion of a particu-

lar protein than that present in whey solids.

0019 Ion exchange Ion exchange or adsorption was dis-

cussed briefly above as a means for the separation of

proteins from whey. However, the adsorbents used

can also selectively adsorb proteins from whey under

specified conditions of pH and temperature. For

example, under appropriate conditions, certain Spher-

osil adsorbents can selectively remove a significant

proportion of the b-lactoglobulin from whey, leaving

a fraction rich in a-lactalbumin as the effluent from

the adsorption process.

0020 Such processes generally use batch operation,

involving adsorption, elution, and regeneration.

0021 Ion depletion This technology relies on the fact that

b-lactoglobulin is insoluble in solutions of low ionic

strength, particularly in the vicinity of its isoelectric

point. This principle has been used in a number of

studies which have led to pilot-scale separation pro-

cedures. The products in general were substantially b-

lactoglobulin, although other proteins were present.

However, the yield of the process was poor, with only

about 30% of the protein present in whey recovered

as the precipitate.

0022 Thermal separation A series of studies have recently

shown that the solubility of a-lactalbumin decreases

very markedly under certain conditions of pH,

temperature (below that of denaturation), and ionic

strength. These conditions have no effect on the solu-

bility of b-lactoglobulin. Clearly, this difference in

solubility characteristics may be exploited as a

means of preparing whey protein fractions. Two pro-

cesses based on this principle have reached the stage

of near commercialization – one in France, the other

in Australia. The major difference between the two is

the starting material – the French process uses un-

treated whey while the Australian process uses whey

concentrated to 12% solids by ultrafiltration. In the

Australian process, the pH of the ultrafiltration reten-

tate is adjusted to 4.2, and the process of aggregation

initiated by heating of the mixture to 64



C for 5 min.

During this process, the a-lactalbumin aggregates

into small particles. The product is then diluted with

water to assist in the formation of larger aggregates,

and the sediment (which is mostly a-lactalbumin)

separated, for example, by centrifugation or microfil-

tration. The separated sludge is evaporated and dried,

to yield a fraction rich in a-lactalbumin (a fraction).

The supernatant is subjected to ultrafiltration and

diafiltration (to assist in the removal of ash and lac-

tose), and dried to yield a fraction rich in b-lactoglo-

bulin (b fraction). The a fraction contains about 50%

protein (mostly a-lactalbumin) and 40% lactose,

while the b fraction contains about 75% protein

(mostly b-lactoglobulin) and 15% lactose.

0023It is probable that the products from the French

and Australian processes have similar functionality –

in each case, the b fraction is low in lipid content. The

b fraction has been shown to have excellent gelation

characteristics (much greater than those shown by the

best 75% WPC). Further, the gel strength exhibited

by the b fraction can readily be manipulated by minor

modifications to processing conditions. Clearly, this

product has considerable potential as a highly func-

tional food ingredient, with applications similar to

those of egg white.

0024The a fraction contains most of the lipid and phos-

pholipid in whey, and should be expected to show

excellent emulsifying properties. A further application

for the a fraction is in (humanized) infant foods.

Although whey-based products are common com-

ponents of infant foods, whey contains a significant

amount of b-lactoglobulin, a protein which has no

analog in human milk. On the other hand, human

milk does contain an analog to bovine a-lactalbumin.

Clearly, therefore, infant foods based on (b-lacto-

globulin-free) a fraction may offer considerable

advantages in reducing allergenic response.

0025An alternative thermal procedure is used in the

manufacture of lactalbumin. In the manufacture of

this product, whey is heated to denature, coagulate,

and precipitate the whey proteins present, which are

recovered by settling and decanting, or by centrifuga-

tion. The product (which should not be confused with

a-lactalbumin) is generally virtually fully denatured,

and comprises a mix of the heat-labile proteins

present in whey. Given the fact the functionality is

generally associated with proteins being present in a

globular native state, it is not surprising that lactal-

bumin shows little functionality. However it finds

specific applications in the food industry, particularly

in biscuits and baked goods. Modified techniques for

the preparation of lactalbumin, involving somewhat

WHEY AND WHEY POWDERS/Protein Concentrates and Fractions 6155

less severe heat processing, have been reported, with

indications that such products show markedly

improved solubility and functionality.

0026 Ferric chloride fractionation Techniques have been

described in the literature for the treatment of par-

tially demineralized whey with ferric chloride to pre-

cipitate b-lactoglobulin selectively as a ferric complex

at near neutral pH. By contrast, at an acidic pH,

almost all proteins except b-lactoglobulin are prefer-

entially precipitated. In this case, the separated com-

plex can be solubilized by a change in pH to near

neutral, and the ferric ion separated by, for example,

ultrafiltration. Such processes do not appear to be

close to commercialization.

Removal of Lipid from Whey and Whey Protein

Fractions

0027 WPCs inevitably contain levels of residual lipid, in

spite of attempts by producers to remove as much

as possible As would be expected, levels of residual

lipid increase with increasing protein concentration.

Reports have suggested levels of about 2.1% fat in

35% WPC, 3.7% fat in 50% WPC, and 7.2% fat

in 80% WPC. As can be seen in the higher protein

content products, the level of lipid is quite significant.

Removal of the lipid from whey results not only in an

improvement in ultrafiltration flux, but also mark-

edly improves product functionality. For example,

higher levels of lipid have been shown to be detri-

mental to the foaming and flavor characteristics of

WPC. Removal of lipids increases overrun whipping

substantially, as well as increasing foam stability.

Higher levels of lipid also inhibit the heat gelation

properties of WPC.

0028 The composition of the lipid fraction in WPC is not

similar to that of bulk milk, being higher in phospho-

lipid and milk fat globule membrane material.

0029 Overall, therefore, the lipid fraction in whey is

believed to inhibit much of the potential functionality

of WPCs, and whey protein fractions. The lipid frac-

tion in whey is also partly responsible for the fouling

of the membranes on ultrafiltration processing of

whey. Removal of the lipid fraction can thus improve

processing efficiency (if ultrafiltration is employed) as

well as product functionality.

0030 Removal of such lipids from whey prior to ultrafil-

tration or fractionation can be achieved by microfil-

tration using membranes of an appropriate pore size

to remove the comparatively large lipid-containing

material. However, fouling of microfiltration mem-

branes (presumably also by the lipid-containing frac-

tion) in such processes has, as yet, mitigated against

extensive commercial adoption of this approach. It is

likely, however, that improvements in microfiltration

membranes coupled with appropriate adjustment of

processing conditions will result in increased com-

mercialization of such processes in the near future.

0031The addition of calcium to aggregate lipoproteins

in whey has also been proposed as an alternative to

microfiltration for lipid removal. Whilst this process

is technically effective, it may pose particular difficul-

ties on scaling up to commercial operation.

0032A number of the whey fractionation processes pre-

viously outlined result in the preferential transfer of

any lipid-containing portion of the whey into one

particular fraction. For example, the lipid fraction in

whey is preferentially found in the a fraction pro-

duced by the Australian process utilizing thermal ag-

gregation. Such lipid material may be removed from

whey fractions by, for example, microfiltration. This

would result in a protein fraction with increased

functionality, and a lipid fraction with excellent

emulsification characteristics.

Summary of Whey Fractionation Methodologies

0033Of the various whey fractionation processes outlined,

only the procedures based on adsorption/ion ex-

change involving the use of carboxymethylcellulose

or Spherosil are in commercial operation, and these

only in comparatively small-scale operations. The

thermal procedures for whey fractionation are nearing

commercialization. Of the remainder, the use of

microfiltration to pretreat whey to remove lipid-

containing material is likely to become further

developed over the next few years. The remainder of

the processes outlined seem unlikely to be of immedi-

ate commercial interest.

Functionality of Concentrates and

Individual Whey Fractions

0034It is likely that whey protein fractions will have much

greater and more reliable functionality than will

WPCs, even WPCs containing 75% protein. Although

the existing production of whey protein fractions is

limited in the main to those from the Bi-Pro and

Spherosil processes, and is of comparatively small

tonnage, the ongoing development of the thermal

aggregation processes will likely see the production

of whey fractions increase sharply in the next few

years. Already whey protein fractions attract much

higher returns than WPCs and, with increased pro-

duction, it is probable that increased applications will

be identified, resulting in increased demand. Some

products in which WPCs and whey fractions have

been commercially utilized are listed in Table 2.

0035The individual proteins in whey can offer certain

specific functional advantages. a-Lactalbumin is in

demand for formulae which mimic human milk.

6156 WHEY AND WHEY POWDERS/Protein Concentrates and Fractions

However, currently the product is very expensive, and

some of the technologies available for production

have not yet come on stream. b-Lactoglobulin has

been shown to possess valuable functional properties,

and this product has been developed in Australia as

the basis of a solid fat-substitute, with initial develop-

ment as an ingredient in reduced- or low-fat luncheon

meats and salami. Lactoferrin is also a significant

component in whey, and various technologies have

been described for its isolation. However current

medical/nutritional claims for the product still have

to be fully verified, and existing production capacity

probably exceeds market demand. This situation

could, however, change dramatically if the benefits

of the product are verified in clinical trials. Extracts

containing growth factor from whey are also cur-

rently being commercially developed. An Australian

consortium of private, university, and medical organ-

izations is planning to undertake clinical trials to

assess the benefits of whey growth factor in wound

healing and repair, including application to ulcers,

burns, and incision wounds.

0036 Whey fractions and WPCs offer many valuable

functional properties as food ingredients. They can

modify some or all of the organoleptic, visual, hydra-

tion, surfactant, structural, textural, and rheological

properties of the food, resulting in improved con-

sumer acceptance of the product. It is probable that

the further development of specialized whey fractions

with reliable and well-defined functional properties

will see a marked increase in the application of these

products over the next few years. While the technol-

ogy for the production of such concentrates and frac-

tions is now well known, the commercial success of

this technology will turn to a large extent on develop-

ing means for the utilization of the lactose-rich

byproduct streams emanating from such processes.

See also: Whey and Whey Powders: Production and

Uses; Fermentation of Whey