Does homogenization
affect the human
health properties of
cow’s milk?
Marie-Caroline Michalski*,1
and Caroline Januel&
UMR INRA 1253, Science et Technologie du Lait et
de l’Œuf, Agrocampus Rennes, 65 rue de
Saint-Brieuc, 35042 Rennes Cedex, France
During the processing of marketed milk, homogenization
reduces fat droplet size and alters interface composition by
adsorption of casein micelles mainly, and whey proteins.
The structural consequences depend on the sequence of the
homogenization and heat treatments. Regarding human
health, homogenized milk seems more digestible than
untreated milk. Homogenization favors milk allergy and
intolerance in animals but no difference appears between
homogenized and untreated milk in allergic children and
lactose-intolerant or milk-hypersensitive adults. Controver-
sies appear regarding the atherogenic or beneficial bioactiv-
ity of some casein peptides and milk fat globule membrane
proteins, which might be enhanced by homogenization. In
children prone to type I diabetes, early cow’s milk
consumption would be a risk but no link was observed in
the general population and the effect of homogenization has
not been studied. In the current context of obesity and
allergy outbreaks, the impact of homogenization and other
technological processes on the health properties of milk
remains to be clarified.
0924-2244/$ - see front matter q 2006 Elsevier Ltd. All rights reserved.doi:10.1016/j.tifs.2006.02.004
* Corresponding author.1 Now present at: INRA UMR 1235/INSERM U 449, MecanismesMoleculaires du Diabete, Faculte de Medecine R. Laennec,Universite Claude Bernard Lyon I, 8 rue Guillaume Paradin,69372 Lyon cedex 08, France. Tel.: C33 47 877 1046; fax: C3347 877 8762; e-mail: [email protected]
IntroductionMilk is a complex biological fluid composed of water,
fat, proteins (mainly casein micelles and whey proteins),
carbohydrates (mainly lactose) and quantitatively minor
though bioactive components: minerals, vitamins and
enzymes (Jensen, 1995). Cow’s milk is a nutritive food
regarding human health and a functional food on a
technological viewpoint. Fat is present in milk in the form
of fat globules in suspension in the aqueous phase. Milk fat
is composed mainly of triacylglycerols and some diglycer-
ols, complex lipids and unsaponifiable lipophilic com-
pounds (Table 1). The milk fat globules are surrounded by a
native biological membrane (Fig. 1) composed mainly of
phospholipids, proteins and enzymes, cholesterol, glyco-
proteins, vitamins: the milk fat globule membrane (MFGM;
Mather, 2000). Saturated fatty acids represent 60–70%
(w/w) of total milk fatty acids and unsaturated fatty acids
30–35% (mainly mono-unsaturated). Moreover, each fatty
acid has a preferential position on the triglycerol backbone
so that thousands different triacylglycerols are found in milk
fat (Jensen, 2002). The role of milk fat in contributing to
health and disease is quite controversial (Berner, 1993a).
While saturated fatty acid and cholesterol contents are
suspected to take part to the risk of coronary heart disease,
some milk lipids such as conjugated linoleic acids (CLA),
sphingomyelin and butyric acid would present anti-
carcinogenic properties (Parodi, 1997).
Regarding proteins, four casein classes coexist (as1, as2,b, k) with similar composition, rich in glutamic acid, leucin,
serine, lysine and prolin. They are all phosphoproteins of
150–200 amino acids, differing in the number of phospho-
seryl groups, the presence of cystein, carbohydrates and
content in some amino acids. Caseins, that do not present
secondary structure, are organized as so-called micelles via
hydrogen bonds, hydrophobic, electrostatic and disulfide
bonds, and different salts are involved (calcium, phos-
phorus, magnesium, citrate). The k-casein is located at the
surface of the micelle, which is held together by calcium
phosphate bonds. The soluble proteins (whey proteins)
represent only 15–22% of milk proteins but form a complex
group consisting of albumins, immunoglobulins and
proteose–peptones. They are globular proteins (presenting
secondary—a-helix and b-pleated sheet—to quaternary
structure) whose high lysine, tryptophan and cysteine
content provide a great nutritional value. They contain
less proline than the caseins and are compact molecules.
Trends in Food Science & Technology 17 (2006) 423–437
Review
Table 1. Gross composition of milk lipids (adapted from Walstra, Geurts, Noomen, Jellama, & van Boekel, 1999; Jensen, 2002)
Content in totalfat (%, w/w)
Fraction inglobule core (%)
Fraction inMFGMa (%)
Fraction in skimphase (%)
Neutral glyceridesTriacylglycerol 95.8–98.3 100Diacylglycerol 0.28–2.25 z90 z10 ?Mono-acylglycerol 0.03–0.38 Traces Traces Traces
Free fatty acids 0.10–0.44 60 z10 30
Phospholipids (incl. sphingomyelin) 0.20–1.11 – 65 35Cerebrosides 0.1 – 70 30Gangliosides 0.01 – z70 z30
Sterols 80 10 10Cholesterol 0.30–0.46Cholesteryl ester %0.02
CarotenoidsCvitamin A 0.002 z95 z5 Traces
a Native milk fat globule membrane.
M.-C. Michalski, C. Januel / Trends in Food Science & Technology 17 (2006) 423–437424
They are more heat sensitive than caseins (the latter are
stable until 100 8C): heat treatments cause their denatura-
tion, aggregation and insolubilization. The denaturation and
insolubilization rates depend on the protein class and
physico-chemical conditions. b-Lactoglobulin (b-Lg) is
the most abundant whey protein (51%) and can bind and
transport small hydrophobic molecules such as retinol
(vitamin A precursor). a-Lactalbumin (a-La) represents
22% of whey proteins and is involved in lactose synthesis
(Jensen, 1995; Whitney, 1988). Individual milk proteins
have a wide range of beneficial health and functional effects
via bioactive peptides, such as anti-carcinogenic effects,
enhancement of certain physiological functions (Meisel,
2005; Silva &Maltaca, 2005), improved iron bioavailability
(Bouhallab & Bougle, 2004) or prevention of dental caries
(Aimutis, 2004). On the other hand, milk proteins are also
important food allergens (Host, 2002) and are suspected to
be involved in some diabetes cases (Schrezenmeir & Jagla,
2000). In this respect, the issue of milk as a healthy or
deleterious foodstuff remains controversial in many aspects.
Marketed milk is manufactured from raw milk obtained
from sane cows, subjected to various processing steps in
order to collect and preserve milk along the supply chain:
machine milking, cooling, cold storage, homogenization,
heat treatment, packaging and storage. Each one of
these processing steps induces changes in the intrinsic
quality of milk (Table 2). This article will focus on
homogenization, which results in the most profound
changes in the physical structure of milk and might result
in altered health properties. Homogenization is defined as
the process of subdividing the relatively large polydisperse
oil globules of a coarse oil-in-water emulsion into a large
number of smaller globules of narrow size range. Milk is
pressurized in order to destroy milk fat globules into fine
lipid droplets, thereby preventing the cream separation
(Mulder & Walstra, 1974). Though, homogenization does
not kill microorganisms, so that intensive heat treatments
(pasteurization or UHT, ultra high temperature process) are
necessary in order to preserve product microbiological
quality (Hui, 1993, Chapter 5). Pasteurization consists in
heating milk at 72 8C for 15 s then cooling it immediately. It
is sometimes necessary to heat milk up to 85 8C during 20 s.
The UHT process allows shortening of the heating step:
140–150 8C during a few seconds. Extended shelf-life of
chilled product can also be achieved by bacteria removal
using microfiltration (Saboya & Maubois, 2000). Heat
treatments are used to preserve milk easier, but they
enhance the impact of homogenization on the organization
of milk, and possibly on its quality and health properties.
Firstly, the different homogenization processes will be
summarized. The consequences of homogenization and heat
treatment sequences on milk structure will be described.
Finally, we will evaluate the possible effects of homogen-
ization on the health properties of milk through literature
evidence or suggestions and highlight research area that
should be further explored.
Principles of homogenizationThroughout the Western world, commercial milk is
homogenized and heat-treated. Homogenization has been
set-up by August Gaulin at the early 20th century; it consists
in forcing pressurized milk (8–20 MPa) between a valve
needle and seat (Gaulin-type homogenizer), resulting in a
dramatical reduction in fat globule size due to shear stress,
inertial forces and cavitation. A second stage processed at
lower pressure dissociates aggregates formed at the first
stage (Pouliot, Paquin, Robin, & Giasson, 1991). Homo-
genization is usually operated at 60 8C, though pressure and
temperature conditions vary according to apparatus and
valve type (Paquin, 1999; Wilbey, 2002). Homogenization
efficiency increases with temperature from 42 to 72 8C and
stabilizes around 72–77 8C (Hui, 1993, Chpater 5).
According to Stoke’s law, the smaller milk fat globule
size dramatically decreases the cream separation rate that is
due to the density difference between milk fat and
the aqueous phase. To some extent, it also prevents
coalescence; the milk emulsion is thus more stable and
shelf-life increases.
Fig. 1. Organization of the native milk fat globule membrane (MFGM) compared with the interfacial organization of an homogenized fatdroplet, and proposed general organization of lipid particles in homogenized milk: ( ) native milk fat globule, ( ) casein micelle, ( ) fragmentof casein micelle, ( ) whey protein, ( ) fragments of MFGM (structure and location of the latter in the skim phase remain to be characterized).
Adapted from Michalski et al. (2001, 2002b).
M.-C. Michalski, C. Januel / Trends in Food Science & Technology 17 (2006) 423–437 425
Microfluidization is another homogenization technique
by which the fluid is forced under high pressure
in the reaction chamber and is divided into two jets
colliding at 1808 at high speed. At a given pressure, a
microfluidizer produces significantly narrower fat globule
size distributions compared with a regular homogenizer and
the mean diameter is also smaller (Hardham, Imison, &
French, 2000; Pouliot et al., 1991). This improves emulsion
long-term stability, therefore, microfluidization is advan-
tageous for long shelf-life such as UHT products (Hardham
et al., 2000; Pouliot et al., 1991).
High pressure homogenization (HPH) is based on the
regular homogenization technique but is operated at higher
pressure (O50–100 MPa). It is used to disperse non-miscible
Table 2. Major milk changes induced by the processing chain (adapted from Korhonen and Korpela, 1994; Morr & Richter, 1988)
Unit process Related reaction Consequences
Machine milking Lipid oxidation Peroxides, oxidized tasteLipolysis Free fatty acids, rancid taste
Cooling, agitation, coldstorage
Dissolution of casein micelles Aggregation of casein and calcium phosphateFat crystallization Alteration of the milk fat globule membraneLipolysis Free fatty acids, rancid taste, oxidative off-flavorProteolysis Peptides, free amino acids
Homogenization Fat globule disruption Smaller fat globules with a new interfaceDispersion of casein micelles Formation of fat-protein complexesActivation of some enzymes Oxidized taste, rancid taste
Heat treatment Destruction of microorganisms Increased microbiological quality and shelf-lifeWhey protein denaturation Formation of casein–whey protein complexesLactone formation Enhanced flavor and tasteEnzyme inactivation Increased quality and shelf-life
Pasteurization Destruction of water-soluble vitamins !10% Vitamin B; !25% Vitamin CUHT Destruction of water-soluble vitamins !20% Vitamin B; !30% Vitamin C
Maillard reaction Lactose–protein complexes, partial loss of lysineLactose isomerization Formation of lactulose
Storage of packed: Reactivation of enzymes Organoleptic defects (proteolysis, lipolysis)Pasteurized milk Growth of psychrotrophic bacteria Bitter taste due to proteolysis
Destruction of water-soluble vitamins !30% of Vitamins B and CUHT milk Age gelation Formation of protein-mineral complexes
Destruction of water-soluble vitamins !50% Vitamin B; O90% Vitamin C
M.-C. Michalski, C. Januel / Trends in Food Science & Technology 17 (2006) 423–437426
phases, stabilize emulsions and/or prepare products with
appropriate rheological properties (Floury, Desrumaux, &
Lardieres, 2000). The fat droplet size decreases when the
HPH pressure increases (50–200 MPa) and at given tempera-
ture and pressure, the HPH fat droplets are significantly
smaller than regularly homogenized ones (Hayes & Kelly,
2003a). However, HPH (40–60 MPa) results in off-flavors in
milk, probably due to oxidation. Homogenization at 20 MPa
does not cause such off-flavor (Humbert, Driou, Guerin, &
Alais, 1980). One advantage of HPH is to reduce bacterial
microflora (Hayes, Fox, & Kelly, 2005; Thiebaud, Dumay,
Picart, Guiraud, & Cheftel, 2003). The size of casein micelles
decreases at pressures greater than 200 MPa. HPH inactivates
plasmin (Hayes & Kelly, 2003b) and reduces alcaline
phosphatase and lactoperoxidase activities (Hayes et al.,
2005). The major drawback of high-pressure treatment is the
high cost of the equipment required. HPH is suggested to be
possible novel milk processing technique-combining advan-
tages of homogenization and pasteurization in a single
process (Hayes et al., 2005).
Consequences of homogenization on milkcomponents
The composition of the MFGM is altered by heat
treatments and homogenization (Mulder & Walstra, 1974).
The effects of these treatments on milk organization are
often controversial. Fig. 1 schemes the organization of the
native MFGM and the solely homogenized fat droplet.
Moreover, the consequences of homogenization on the
organization of milk depend on the sequence and type of
homogenization and heat treatments, as also pointed out
using HPH with skim milk (Sandra & Dalgleish, 2005).
Effect of homogenization and heat treatments onproteins, phospholipids and vitamins
The main effect of homogenization on soluble milk
components is the disruption of casein micelles while
adsorbing at the interface, in micellar form or as fragments.
Moreover, at least one of the agglutination factors is
inactivated (Walstra, 1980) and some MFGM components
are displaced to the skim milk phase during homogenization
(Keenan, Moon, & Dylewski, 1983). Bovine xanthine
oxidase (BXO) and butyrophilin are covalently bound to
fatty acids, contributing to the lipophilicity of these proteins
and the preservation of their affinity with the interface
despite the physical stress caused by homogenization. The
phospholipid content of the new membrane appears slightly
lower than that of the MFGM (McPherson, Dash, &
Kitchen, 1984a). The material loss appears not to be
selective. HPH decreases the casein micelle size in skim
milk, e.g. from w209 nm at 41 MPa down to w190 nm at
186 MPa (Sandra & Dalgleish, 2005); though, it is not
known whether micelle size decreases in HPH homogenized
whole milk.
During milk heating, chemical and enzymatic reaction
rates increase, as well as bacteria disruption (Renner, 1988).
Whey proteins are more heat sensitive than caseins. The
extent of denaturation depends on heat treatment type
(neglectable during pasteurization; 20% of whey proteins
denatured at 80 8C for 1 min vs 60% with UHT process) and
protein type, b-Lg being more heat sensitive than a-La(Kinsella & Whitehead, 1989). Moreover, in skim milk,
heat-induced binding of denatured proteins to casein
micelles provokes pH-dependent increased micelle size
and inter-micelle interactions (Anema & Li, 2003; Jeurnink
M.-C. Michalski, C. Januel / Trends in Food Science & Technology 17 (2006) 423–437 427
& De Kruif, 1993). Caseins are much more heat resistant,
particularly b-casein. Several studies have shown that milk
heating induces complex formation between k-casein and a-La via a b-Lg–a-La complex (Elfagm & Wheelock, 1978).
Other studies have shown, using in vitro models (Haque,
Kristjanssan, & Kinsella, 1987; Jang & Swaisgood, 1990)
and skimmed milk (Dalgleish, 1990), that heat-induced
b-Lg–k-casein interactions are mainly due to hydrophobic
interactions and disulfide bond formation. During the
formation of such k-casein–whey protein complexes, both
soluble and micelle-linked aggregates are formed (Anema
& Li, 2003; Guyomarc’h, Law, & Dalgleish, 2003;
Vasbinder, Alting, & de Kruif, 2003). Primary b-Lg–a-Laaggregates seem to be implied in micellar aggreates as well
as k and as2-caseins. Heat-dissociated micellar k-casein is
implied in the formation of soluble aggregates and a
significant part of k-casein is not complexed after heat
treatment.
Heat also favors glycation (also called non-enzymatic
glycosylation or Maillard reaction): the initial reaction
consists in nucleophilic condensation of a sugar free-
aldehyde group and a protein amine group (terminal or
often from lysine). Heated milk is sensitive to glycation
due to its lactose content (Morgan, Leonil, Molle, &
Bouhallab, 1999). Among vitamins, only vitamins B1, B6,
B12 and C and folic acid are heat sensitive, but water-
soluble vitamins are sensitive to storage time (Renner,
1988; Table 2).
Effect of homogenization and heat treatmentson fat droplet size and z-potential
Shear stress and inertial forces induced by pumping are
maximal during homogenization (Corredig & Dalgleish,
1996). This induces fat globule disruption since the former
are greater than the Laplace pressure of the native milk fat
globules. In the following, we will thus refer to fat droplets,
different from the native milk fat globules. The native milk
fat globule size distribution spans from !1 to w20 mm,
with an average volumic size initially around 3–5 mm. Upon
homogenization, the latter is reduced to around 1 mm,
resulting in a 4-to 10-fold increase of the interface between
fat droplets and the aqueous medium (Keenan et al., 1983).
A relationship is given between the volume–surface average
diameter of the fat droplets (d32) and the homogenizing
pressure P: log10 d32ZaKb log10 P, with parameters such
as aZK2 to K1.8 and bZ0.6–0.71 (Michalski, Michel, &
Briard, 2002; Walstra, 1995). Particles between 100 and
400 nm even appear during regular homogenization
(Michalski, Michel, & Geneste, 2002), while the smallest
native milk fat globules (w100–200 nm; Walstra (1969))
should not be affected due to their higher Laplace pressure.
Heat treatment, when not associated with homogenization,
does not induce changes in the milk fat globule size. When
both processes are operated, regardless of order, fat droplets
tend to be smaller than in milk solely homogenized,
resulting in a greater droplet surface area (Lee, 1997;
Sharma & Dalgleish, 1994). In commercial pasteurized or
UHT full-fat milk, the d32 is in the range 0.20–0.25 mm,
calculated from the measured specific surface area (S) of
27–33 m2 gK1 (Lopez, 2005); the corresponding volumic
average diameter (d43) is in the range 0.37–0.49 vs 4.07 mmfor raw whole milk. Fave, Coste, and Armand (2004) report
d43Z0.46–1.02 mm in half-skimmed commercial UHT milk
vs 4.36 mm in whole pasteurized organic milk. In
microfluidized milk, d32 values of 0.30 and 0.24 mm are
reported at 50 and 200 MPa, respectively (Olson, White, &
Richter, 2004).
The electrokinetic potential (z-potential) of a particle is
defined as the potential at the shear layer located farther out
the Stern layer. For native milk fat globules, average znativeis K13.5 mV (Michalski, Michel, Sainmont, & Briard,
2001). The absolute value of z increases with homogenizing
pressure for milk fat droplets, up to a plateau value of
z around K20 mV for strongly homogenized ones
(PO30 MPa). This value corresponds to the z-potential of
casein micelles adsorbed at the droplet interface (Fig. 1).
Indeed, z of homogenized droplets is linked to the surface
fraction F that is not covered by the native MFGM
anymore: zZznative½1C ðKLnð1KFÞ=10:82Þ1=2� (Michalski
et al., 2001). Heating at 80 8C (15 min) results in only small
changes in the micellar z (Anema & Klostermeyer, 1997).
The z-potential of whey protein–k-casein complexes is
reported to be K17 mV (Jean, Renan, Famelart, &
Guyomarc’h, 2006).
According to these structural measurements, homogen-
ized milk is found to be composed of three types of particles
(Michalski et al., 2002b): (i) regular homogenized milk fat
droplets (disrupted globules from the main population,
whose surface fraction covered by caseins can be calculated
from their increase in specific surface area, the rest of
the surface being still covered by MFGM); (ii) small
(!500 nm) lipid–protein complexes having a new
membrane, presumably mainly composed of caseins; and
(iii) tiny native milk fat globules around 100 nm (that were
originally present in milk as a separate population and
should not be affected by homogenization due to their
small size).
Effect of homogenization and heat treatmentson the fat droplet interface
The rupture of fat globules occurring during homogen-
ization creates a new interface that cannot be entirely
covered by the MFGM and can be measured by the
increased S of fat droplets. Therefore, other surface active
components adsorb and form a new membrane (Darling &
Butcher, 1978). Casein micelles are the major protein
fraction adsorbed, even if part of the native MFGM remains
associated to the fat droplets (Jackson & Brunner, 1960). In
a proportion increasing with P (Fox, Holsinger, Caha, &
Pallansch, 1960; Henstra & Schmidt, 1970), casein micelles
would spread onto the fat surface when colliding during
homogenization.
M.-C. Michalski, C. Januel / Trends in Food Science & Technology 17 (2006) 423–437428
A fourfold increase of total proteins occurs in the
membrane when milk is either solely homogenized or
homogenized and heated (regardless of the sequence of
both treatments) compared to the total membrane proteins in
untreated or solely heated milk (Lee, 1997). After heating at
80–85 8C (10 min), total protein increases in the fat droplet
membrane (Dalgleish & Banks, 1991; Houlihan, Goddard,
Kitchen, & Masters, 1992). Heating increases the ability of
whey proteins to interact with MFGM proteins and/or caseins
adsorbed onto the membrane during homogenization. This
would not always be compensated by the desorption of
MFGM proteins that was highlighted by Houlihan et al.
(1992). If milk is homogenized (50 8C, 17 MPa) then
pasteurized (HTST), caseins represent 99% of adsorbed
proteins, among which b-casein represents 40.8%, as-casein35.7% and k-casein 23.5% (Zahar & Smith, 1996). This does
not reflect untreated milk (Table 3): a preferential adsorption
of k- and b-caseins occurs during homogenization. Signifi-
cant amounts of para-k-casein (N-terminal fragment of
k-casein) were detected in homogenized droplet membranes
(McPherson, Dash, & Kitchen, 1984b). This could be partly
explained by the action of heat stable proteinases on the
b-Lg–k-casein complexes associated with the membrane
(Garcia-Risco, Ramos, & Lopez-Fandino, 2002). However,
the relative amount of para-k-casein compared to b-Lg is
higher than observed in pasteurized milk (McPherson et al.,
1984b). Para-k-casein could also be formed by direct
k-casein hydrolysis at the fat droplet surface during
homogenization. It could preferentially adsorb onto lipid
droplet surface due to its higher hydrophobicity compared
with k-casein. However, several teams have found the b-Lg–k-casein complexes formed during heat treatments in the
membranes of homogenized milk (Houlihan et al., 1992).
Denatured b-Lg is linked to the casein micelles adsorbed on
the fat droplets via k-casein (Dalgleish & Sharma, 1993).
Heat not only causes whey protein binding to adsorbed
micelles, but also reorganizations among casein micelles
themselves (Dalgleish & Sharma, 1993).
Caseins are the major protein fraction adsorbed.
Regarding whey proteins, b-Lg is the main one associated
with the lipid droplets but a small quantity of a-La was alsodetected (Lee & Sherbon, 2002). Using infant formula
pasteurized then homogenized, the pasteurization step
favors b-Lg–k-casein interactions. The caseins and whey
proteins interact with the fat droplet membrane after
homogenization of these formulae (Guo, Hendricks, &
Table 3. Distribution of casein species in untreated milk (Hui,1993, Chapter 5) and at the interface of homogenized andpasteurized milk fat droplets (Zahar & Smith, 1996)
Untreatedmilk (%)
Homogenized and pasteurizedmilk fat droplets (%)
as1-Casein 3735.7
as2-Casein 11b-Casein 34 40.8k-Casein 12 23.5
Kindstedt, 1998). At average homogenization applied to
pasteurized milk, whey proteins make up about 5% of the
adsorbed protein and about 20% of the surface area covered;
for higher pressures, the proportion becomes increasingly
smaller (Sharma & Dalgleish, 1994). In commercial UHT
milk, about 25% of the droplet surface would still be coated
with MFGM (Lopez, 2005). The casein layer around fat
droplets appears thinner when milk is microfluidized rather
than regularly homogenized, suggesting micelle fragmenta-
tion (Dalgleish, Tosh, & West, 1996).
Observed differences depending on the sequence ofhomogenization and heating steps
The differences depending on the sequence of homogen-
ization and heating steps are rather controversial due to the
various treatments applied and to the sample preparation
procedure. Van Boekel and Walstra (1989) did not detect
whey proteins in the membrane of homogenized fat droplets
before the heating step. On the other hand, these proteins
associate to lipid droplets from 70 8C when denaturation
begins. Several reactions can take place: (i) interaction with
other denatured whey proteins, (ii) interactions with
k-casein on the surface of casein micelles in the skim
milk phase, (iii) interactions with k-casein located at the
exterior of the casein micelles adsorbed on the fat globule
surface, (iv) interactions with residual native MFGM
material, and (v) direct interaction with the fat droplet
surface. The availability of k-casein is crucial in these
different phenomena. In homogenized milk, the interface
between the adsorbed micelle fragments and the fat surface
is formed of non-k-caseins. Therefore, k-casein is exposed
on the outside, which favors interactions between whey
proteins and proteins at the interface (Dalgleish & Banks,
1991). When milk is homogenized then heated, less caseins
and whey proteins would be adsorbed onto the lipid droplet
surface than when milk is heated then homogenized (Lee,
1997). This is conflicting with the study of Sharma and
Dalgleish (1994) highlighting more whey protein–lipid
droplet membrane interactions when milk is homogenized
then heated, suggesting that the newly formed fat droplet
membrane offers more available binding sites for whey
proteins after homogenization than under its native MFGM
conformation.
Heat treatment at 80 8C (3–18 min) induces incorpor-
ation of whey proteins, particularly b-Lg, in the MFGM
(Lee & Sherbon, 2002). This implies increased membrane
protein concentration. The glycoproteins PAS-6 and PAS-7
(so-called lactadherin) would disappear and the linkage of
b-Lg to the MFGM could be due to disulfide bonds with
membrane proteins. Homogenization (two stages, 50 8C, 17
and 3.5 MPa) causes casein adsorption onto the MFGM, but
no whey protein adsorption if not associated to heat
treatment (Lee & Sherbon, 2002). The total protein amount
(caseins and whey proteins) at the MFGM is not
significantly different whether homogenization is performed
before or after heat treatment. In another study (Lee, 1997),
M.-C. Michalski, C. Januel / Trends in Food Science & Technology 17 (2006) 423–437 429
whey protein amount in the lipid droplet membrane
increases when milk is heated then homogenized. This
suggests that the k-casein–whey protein complexes formed
during heat treatment adsorb onto the newly formed
membrane during homogenization. Conversely, if heating
is performed before homogenization, then the proteins are
already denatured and are less prone to take part to
interactions at the fat droplet surface (Dalgleish & Sharma,
1993). The membrane of homogenized droplets is thus
thinner and globule aggregation is favored. Two-stage
homogenization limits this phenomenon (van Boekel &
Walstra, 1989). If heat treatment is performed prior to HPH
of skim milk (41–186 MPa), more micellar material and
b-Lg–k-casein complexes are displaced to the skim milk
phase (Sandra & Dalgleish, 2005); this would turn them
potentially available for adsorption at the fat interface if the
same occurred in whole milk but this hypothesis is not
justifiable to date.
Briefly, when heat treatment is performed prior to
homogenization: (i) whey proteins are denatured and
interact with the native proteins of the MFGM and the
micellar caseins, particularly k-casein, and (ii) the casein–
whey protein complexes adsorb onto the lipid droplet
interface. When homogenization is performed prior to heat
treatment: (i) the semi-intact casein micelles or micellar
fragments cover the fat droplet interface, and (ii) the
denatured whey proteins link to the native MFGM proteins
and adsorbed caseins via disulfide bonds. However, the
compositional changes in the fat droplet membrane
depending on the order of homogenization and heat
treatments do not seem to influence cream separation.
Cream separation is identical whether milk is (i) homogen-
ized, (ii) heated then homogenized, or (iii) homogenized
then heated, and always lower than for unhomogenized milk
(Hillbrick, Mcmahon, & Mcmanus, 1999; Lee, 1997). The
homogenization step can thus be performed prior to UHT
treatment, allowing lower asepsis rules and thus lower
industrial costs.
Current data related to homogenization effectson the health properties of milkTaste and digestion
A link exists between sensory stimulation and post-
prandial lipid metabolism (Mattes, 1996): the amount of
post-prandial plasma triacylglycerols after the ingestion of
oil capsules was measured in subjects exposed to various
oral stimuli masticated but not ingested. Higher plasma
triacylglycerols were observed in subjects in contact with
the fattest stimulus (cream cheese). Therefore, the sensory
properties homogenized vs unhomogenized milk could
affect the metabolic response. Due to increased photo-
chemical sensitivity and lipolysis, homogenized milk is
more sensitive to off-flavor formation during storage
(Humbert et al., 1980). Combined homogenization and
heat treatment also increase the viscosity of whole milk
(Lee, 1997). The possible sensory-stimulated effects of
these differences on milk digestion should be investigated.
During digestion of homogenized milk, a simultaneous
coagulation of caseins and lipid droplets occurs in the
stomach. The structure of coagulated matter is much finer
than for untreated milk and the protein transfer to the small
intestine is easier: for subjects suffering intestinal disease,
homogenized milk is more easily digestible than untreated
milk (Sieber, Eyer, & Luginbuhl, 1997). In minipigs, raw
milk and pasteurized milk give a very firm curd and present
slower gastric emptying rate than pasteurized homogenized
milk, UHT milk or cultured milk (Meisel & Hagemeister,
1984). Moreover, the proteolysis of casein is enhanced with
pasteurized homogenized milk and UHT milk (Pfeil, 1984).
UHT milk also results in a greater absorption in this animal
model (Kaufmann, 1984).
Regarding lipid digestion, the gastric step is crucial since
it facilitates subsequent triacylglycerol hydrolysis by the
pancreatic lipase (Fave et al., 2004). This is particularly
important in infants and in adult patients suffering
pancreatic insufficiency. In minipigs, Buchheim (1984)
found extended lamellar structures of mono-glycerides in
the gastric coagulum of pasteurized milk (homogenized and
non-homogenized) and of UHT milk, but only rarely in raw
milk and cultured milk, providing direct evidence for
lipolysis that occurs to a considerable extent in the former
milks. After feeding raw milk and (pasteurized and
homogenized) cultured milk, only slight gastric lipolysis
is observed in minipigs (Timmen & Precht, 1984). In
humans, the lipid droplet size is a key physico-chemical
factor governing fatty acid bioavailability: smaller droplets
result in greater lipolysis via their surface excess on a larger
interface area (Armand et al., 1999; Fave et al., 2004). The
small sized droplets in homogenized milk would thus favor
milk fat lipolysis. But in premature infants, human milk fat
globules (surrounded by a human native MFGM similar to
Fig. 1) result in a more efficient gastric lipolysis than the
much smaller homogenized lipid droplets of infant formula
(Fave et al., 2004). Human milk fat globules are larger in
colostrums (d32Z4.3 mm) than in mature breastmilk (d32Z3.5 mm), and much larger than infant formula droplets
(d32Z0.3 mm; Michalski, Briard, Michel, Tasson, &
Poulain, 2005). The ultrastructure of milk fat droplets
appears thus to be of utmost importance (Fave et al., 2004);
it can be related to the above-mentioned changes in
z-potential that could affect lipase access to the interface.
In rats, small homogenized fat droplets fed as a cream result
in a slower triacylglycerol metabolization than large
phospholipid-coated droplets or unemulsified fat
(Michalski, Briard, Desage, & Geloen, 2005; Michalski
et al., 2006). The slower metabolization can be linked to the
delayed gastric emptying due to the gastric clot structure,
even if small droplets are more efficiently lipolyzed. The
discrepancies with minipig studies can be due to the
different animal models and the different fat content of the
gastric clots. Long-term effects of these metabolization
M.-C. Michalski, C. Januel / Trends in Food Science & Technology 17 (2006) 423–437430
differences compared with untreated milk fat globules
remain to be elucidated in humans.
Atherosclerosis and coronary heart diseaseIn atherosclerosis, arteries are partially or totally
obstructed due to the formation of plaques rich in
cholesterol at the internal face of the vascular wall. Along
time, clotting can occur, obstructing arteries and depriving
vital organs of oxygen. This is why it is advised to control
cholesterol level by limiting saturated fat consumption via
butter, milk and fat meat. However, the role of these foods
in promoting cardiovascular diseases is controversial. The
amount of absorbed cholesterol via dairy products con-
sumed daily only represents 15% of the daily recommended
cholesterol intake and the beneficial role of milk fat has
been highlighted in an in-depth review by Berner (1993b).
Studies that used single dietary fat sources to compare
effects of fats on blood lipids should be taken with caution
since the effects of any single fat source will be diluted when
in a mixed diet. The food energy intake as lipids should be
7.5% saturated fatty acids, 15% mono-unsaturated fatty
acids and 7.5% polyunsaturated fatty acids (PUFA). But
within one group, different fatty acids do not act the same
way, and the impact of milk products on plasma lipids and
on the risk of cardiovascular disease is different from
expected considering their lipid content and composition
(Berner, 1993b).
Atherosclerosis develops during the post-prandial lipe-
mia stage and some studies have recently shown that
different structured dairy products result in different lipemia
profiles. Consequently, it is not justified to qualify milk as
anti- or pro-atherogenic regarding solely its lipid compo-
sition. Milk, mozzarella–cheese and butter in test meals do
not result in the same timing of triacylglycerol peak in type
II diabetic patients (Clemente et al., 2003). Fermented milk
results in a slower gastric emptying rate than regular milk
(certainly both homogenized although not stated), and in a
greater increase and a quicker decrease of the triacyl-
glycerol content in all lipoprotein fractions (Sanggaard
et al., 2004). Controlled dietary studies in humans have
shown no difference in the effect on plasma cholesterol of
milk and butter with equal fat content and adjusted
regarding lactose and casein content (Tholstrup, Høy,
Normann Andersen, Christensen, & Sandstrom, 2005). In
a careful review, Tholstrup (2006) concludes that there is no
strong evidence that dairy products (i.e. including hom-
ogenized milk) increase the risk of coronary heart disease in
healthy men of all ages or young and middle-aged healthy
women. Overall, studies would be needed in humans to
investigate the effect of homogenization on the anti- or pro-
atherogenic properties of milk.
Oster (1972) hypothesized that BXO released from the
MFGM due to homogenization would favor atherosclerosis.
The role of BXO in the generation of reactive oxygen
species in the cardiovascular system was also emphasized
(Berry & Hare, 2004). However, the former hypothesis is
criticized on many grounds such as the inactivation BXO at
the acidic gastric pH (Mangino & Brunner, 1976). The
possibly harmful effects of BXO have finally been the
subject of questions to the European Parliament in
September 2000 and April 2001 (written questions
E-2907/00 and E-0864/02). In both cases, the Commission
responded (i) not to have sufficient proofs regarding harmful
enzyme effects and (ii) not to consider new labelling rules.
Today, even if this hypothesis is often discussed, the
possible atherogenic role of BXO enhanced by homogen-
ization appears to be rejected by the scientific community.
Coronary diseases are due to the development of
arteriosclerosis in coronary arteries (arteries that bring the
oxygen necessary for the heart to the myocardium).
Arteriosclerosis is characterized by the deposit of more or
less calcified plaques in the internal wall of coronary
arteries. Gradual narrowing (stenosis) of arteries results,
possibly until their final destruction. Some casein-derived
peptides present anti-thrombotic and anti-hypertensive
features; e.g. the k-casein fragment f103–111 can prevent
blood clotting through inhibition of platelet aggregation
(Silva & Maltaca, 2005). Also, recent studies point out that
(i) milk drinking may be associated with a small but
worthwhile reduction in heart disease and stroke risk
(Elwood, Pickering, Hughes, Fehily, & Ness, 2004; even
though the definition of ‘milk intake’ presents some
difficulties, Tholstrup, 2006), and (ii) milk product intake
is negatively associated with cardiovascular disease risk
factors (Warensjo et al., 2004). Overall, no unfavorable
effect of dairy product could be found in these studies
involving the consumption of heat-treated and homogenized
milk. Since, these treatments involve the reorganization of
casein components (especially k-casein) within the milk
structure, one could suggest that the effect of milk
processing factors should be examined in respect with the
desirable bioactivity of casein-derived peptides.
On the other hand, Moss and Freed (2003) recently
studied the link between coronary disease occurrence and
circulating antibodies against the MFGM proteins. The
latter might by atherogenic by causing the aggregation of
lymphocytes and platelets. However, Spitsberg (2005)
criticizes this suggestion on analytical grounds. Besides,
we should stress that some populations, such as in the
French region of Brittany, use to consume high amounts of
buttermilk that is rich in MFGM fragments, while they are
not associated with the highest coronary mortality within
Northern France (Oberlin, Moquet, & Folliguet, 2004).
Also, hard cheese consumption is negatively correlated with
coronary heart disease (Moss & Freed, 2003; Tholstrup,
2006), although this product is rich in MFGM. Though, we
should highlight that buttermilk and hard cheese are
manufactured from unhomogenized milk. Since, homogen-
ization changes the organization of the MFGM and the
exposure of its proteins, this treatment might trigger the
putative atherogenic effect of these proteins. Studies are
needed to elucidate this point.
M.-C. Michalski, C. Januel / Trends in Food Science & Technology 17 (2006) 423–437 431
Finally, the A1 variant of b-casein in cow’s milk yields
b-casomorphin 7 (Jinsmaa & Yoshikawa, 1999), a bioactive
peptide with the ability to catalyze the oxidation of LDL that
is implicated in the cardiovascular risk (Allison & Clarke,
in press). The issue of the A1-b–casein variant effect on
coronary heart disease appears to be highly controversial
(Truswell, 2005; Woodford, 2006). Since homogenization
has an effect on milk structure, particularly regarding casein
distribution, we should wonder whether milk processing has
an impact on the possible role of A1-b-casein in coronary
heart disease.
Lactose intolerance and milk allergyLactose intolerance results from a lack of lactase
necessary for its proper digestion. Delayed gastric
emptying has been proposed as one possible explanation
for improved lactose tolerance after ingestion of milk with
a meal instead of milk on its own (Vesa, Marteau, &
Korpela, 2000) but no clear conclusion can be drawn
(Korhonen & Korpela, 1994; Vesa et al., 2000). Paajanen,
Tuure, Poussa, and Korpela (2003) studied adults tolerant
to lactose, with a subjective tolerance to unhomogenized
milk but describing subjective intolerance to homogenized
milk. This study revealed no symptom difference between
homogenized and unhomogenized milk consumers. A
following study dealt with adults intolerant to lactose
(Korpela, Paajanen, & Tuure, 2005). No significant
difference is observed in the symptomatic response
between unprocessed organic milk and processed milk.
Even though some subjects subjectively experience a better
tolerance of unhomogenized than homogenized milk, this
is not the case in lactose intolerant subjects in general
(Korpela et al., 2005).
Cow’s milk protein allergy (CMPA) is an abnormal
reaction of the immune system to proteins contained in
cow’s milk. The incidence of allergy in early childhood is
2–3% (Host, 2002). The major allergizing proteins are b-Lg,a-La and caseins, causing anaphylactic reactions (immune
phenomena induced by a type I hypersensitivity reaction to
the IgE mediation). Decreasing levels of milk-specific IgE
might signify allergy resolution. In animal models,
homogenization seems to favors hypersensitivity. Hom-
ogenization and pasteurization enhance the humoral
immune response of rats charged intraperitoneally with
milk (Feng & Collins, 1999). Homogenized milk orally fed
to hypersensitive mice induces an anaphylactic chock
(Poulsen & Hau, 1987), increases milk-specific IgE
production (Nielsen, Poulsen, & Hau, 1989), increases the
mass of intestinal segment and induces mastocyte degranu-
lation (Poulsen, Nielsen, Basse, & Hau, 1990). Moreover,
the allergenicity of homogenized milk in mice increases
with increasing fat content (Poulsen, Hau, & Kollerup,
1987). On the other hand, unhomogenized cow’s milk
induces few or no such symptoms and immune responses.
However, when milk is given intravenously (Poulsen &
Hau, 1987) or subcutaneously (Poulsen et al., 1990), the
same reactions are observed regardless of milk treatment.
In Northern countries, many consumers and also parents
of allergic children state that they tolerate untreated cow’s
milk and pasteurized non-homogenized milk, conversely to
homogenized milk. The explanation could be that during
homogenization, the milk fat presents a dramatically
increased surface onto which allergenic milk proteins
adsorb. In untreated milk, many of the antigenic proteins
are located inside casein micelles. In homogenized milk, the
amount of exposed antigenic proteins increases (Poulsen &
Hau, 1987). Besides, there is also some release of MFGM
proteins (listed in Table 4) in the aqueous phase (the latter
were suggested to be potential allergens, though with no
clear-cut evidence, in a viewpoint by Riccio, 2004).
However, the amount and exposure of allergenic proteins
in untreated milk appear to be sufficient to induce allergic
reactions in some subjects. Moreover, clinical studies reveal
no difference between homogenized and unhomogenized
milk in children allergic to milk (Host & Samuelsson, 1988)
or in adults intolerant to lactose or hypersensitive to milk
(Pelto, Rantakokko, Lilius, Nuutila, & Salminen, 2000). In
one study, homogenized pasteurized milk was found less
suitable than unhomogenized milk in 10% of the children
subjects with milk protein allergy (Hansen, Host, &
Osterballe, 1987). But few studies concern subjects with a
better milk tolerance. No difference was found in the
immunological responses to homogenized and unhomogen-
ized milk in healthy adults with a good tolerance of milk
(Paajanen, Tuure, Vaarala, & Korpela, 2005). Accordingly,
a recent review points out that homogenization does not
change the allergenic potency of cow’s milk (Paschke &
Besler, 2002). However, Paajanen et al. (2005) point out the
possibility that homogenized and unhomogenized milk
could induce different types of primary immunization to
cow’s milk antigens in immunologically intact individuals,
i.e. in infants. Moreover, most milk proteins, even minor
proteins, are potential allergens (Wal, 2004). This can
explain why the effect of homogenization may be difficult to
observe, since individuals can be sensitive to various
epitopes and since some human groups can be more
sensitive than others. The available evidence is not sufficient
to predict reliably the effect of food processing on allergenic
potential of milk proteins (Wal, 2004).
Food processing and interactions between constituents
and additives are strongly suspected to be responsible for at
least part of the increase of allergy incidence (Sanchez &
Fremont, 2003). Heating may have no effect or it may
decrease or increase allergenicity. Even in the absence of
heating, interactions between proteins and other com-
ponents of food can cause conformational changes in
allergens, thereby affecting their thermal stability. The
effect of such interactions on the allergenicity of proteins is
practically unknown today (Sanchez & Fremont, 2003). The
most important consequence of heating at common milk
processing temperatures seems to be the increased
Table 4. Major proteins and other components of the bovine MFGM, according to the nomenclature proposed by Mather (2000), withclaimed functions and health effects (benefits: C, or adverse effects: K)
Proteins Mw (kDa) Function Health effect
Mucin 1 (MUC1) (glycoprotein) O160a, 50–500b Protects from physical damage andinvasive pathogensb
?
Butyrophilin (BTN) (glycoprotein) 56b–66a Milk fat globule secretion Belongs to immunoglobulinsb
(K) Induces or modulates experimentalallergic encephalomyelitisb
(C) Suppression of multiple sclerosisa
Xanthine oxidase (XDH/XO) 150a Structural, lipid secretiona (C) Bactericidal agenta
Role in purine metabolismb (K) Risk factor for coronary heartdisease?b
Cluster of differentiation (CD36)(glycoprotein)
53b–78a Fatty acid transportera ?Macrophage markerb
Phagocytosis by neutrophilsb
Fatty acid binding protein (FABP) 13b–15a Fatty acid metabolism (C) Cell growth inhibitora
Increase of lipid droplets in thecytoplasmb
(C) Anti-cancer factor (as a seleniumcarrier)a
(K) Similar to P2 myelinprotein involved in experimental allergicneuritisb
BRCA1 210 Cancer suppressora (C) Inhibition of breast cancer (alsoBRCA2)a
Lactadherin (PAS 6/7) 43–59b Belongs to cadherinsb
Calcium-dependent adhesive prop-ertiesb
Role in the epithelialization, cellpolarization, cell movement andrearrangement, neurite outgrowth,synaptic activity in the central nervoussystemb
Phospholipid bindingb (C) Protection from viral infection inthe gutb
Adipophilin (ADPH) 52b Uptake and transport of fatty acidsand triacylglycerols
?
Other components Health effect
b-Glucuronidase inhibitora (C) Inhibition of colon cancera
Helicobacter pylori inhibitora (C) Prevention of gastric diseasesa
Cholesterolemia-lowering factora (C) Anti-cholesterolemica
Vitamin E and carotenoids (C) Anti-oxidantsa
Phospholipids (C) Inhibition of colon cancera
(C) Anti-cholesterolemica
(C) Suppression of gastrointestinal pathogensa
(C) Anti-Alzheimer, anti-depressant, anti-stressa
Phosphoproteins (C) Source of organic phosphorus and Ca-phosphatea
a Spitsberg (2005).b Riccio (2004).
M.-C. Michalski, C. Januel / Trends in Food Science & Technology 17 (2006) 423–437432
immunoreactivity (capacity to bind IgE) of some milk
allergens (Besler, Paschke, & Paschke, 2001). This can be
due to epitope exposure after conformational changes or to
changes in aminoacids due to Maillard reactions with sugars
enhanced by heating (Sanchez & Fremont, 2003). Protein–
fatty acid interactions can also change the secondary
structure of b-Lg upon heating or even at room temperature
with oleic acid (Ikeda, Fogeding, & Hardin, 2000). Since
some b-Lg can be present at the lipid interface in
homogenized milk, such interactions can occur and their
effect on protein allergenicity should be investigated,
independently from heat treatments.
DiabetesType I diabetes is an auto-immune disease initially
characterized by the infiltration of Langerhan’s islets by
macrophages and lymphocytes. Consequently, the insulin
producing cells (pancreatic b-cells) are selectively
destroyed, causing an absolute and definitive insulin
deficiency. Dietary factors such as milk consumption have
been discussed as being involved (Schrezenmeir and Jagla,
2000): 50% of type I diabetics consumed cow’s milk before
the age of 3 months (Kostraba et al., 1993). The risk of type
I diabetes is higher for children who were breast fed less
than 4 months and who received cow’s milk at younger than
M.-C. Michalski, C. Januel / Trends in Food Science & Technology 17 (2006) 423–437 433
5 months and interactions between these factors are
important (Sipetic, Vlajinac, Kocev, Bjekic, & Sajic,
2005). Early exposure to cow’s milk is not associated with
increased risk of type I diabetes development in low risk
subjects. However, cow’s milk is suspected to be a risk
factor in subjects genetically prone to diabetes (Dahl-
Jorgensen, Joner, & Hanssen, 1991; Fava, Leslie, &
Pozzilli, 1994) even if this was not confirmed by the study
of Meloni et al. (1997). Karjalainen et al. (1992)
hypothesized that a particular region of BSA (a 17-residue
peptide called ABBOS) would be the reactive, trigger
epitope for genetically prone subjects. Heating milk above
85 8C would be sufficient to denaturate BSA, more
specifically its reactive epitope regarding type I diabetes
(Strand, 1994). More recently, the implication of A1-b-casein in type I diabetes incidence was suggested (Elliott,
Harris, Hill, Bibby, & Wasmuth, 1999). Truswell (2005)
rules out the hypothesis of different effects of A1 and A2
variants of b-casein; however, his viewpoint is criticized
(Allison and Clarke, 2006; Woodford, 2006): studies often
fail to provide a true control devoid of diabetogenic effects.
Schrezenmeir and Jagla (2000) point out the need for
intervention studies in humans, and particularly, what
impact consumption of cow’s milk has beyond infancy.
Studies usually deal with the consumption of commercial
homogenized milk. Further studies appear to be necessary to
finally state whether cow’s milk consumption is linked to
type I diabetes development and examine the impact of
homogenization in this respect.
In contrast to type I diabetes, the etiology of type II
diabetes is still unclear. It is part of the so-called
metabolic syndrome, which besides diabetes comprises
abdominal obesity, hypertension, dyslipoproteinemia and
precocious atherosclerosis. Type II diabetes is character-
ized by the insulinoresistance of peripheral tissues
associated with hyperinsulinemia, followed by the
secondary qualitative and quantitative deficiency of
pancreatic insulin secretion due to glucose (Schrezenmeir
& Jagla, 2000). The early stage of type II diabetes is
characterized by insulinoresistance of peripheral muscular
and adipose tissues. Insulin resistance usually corresponds
to the reduced hypoglycemic effect at a usually efficient
concentration. High saturated fatty acid consumption is
associated with glucose intolerance or insulin resistance
and type II diabetes. Now, milk contains 60–70 g of
saturated fatty acids per 100 grams of total fatty acids. On
the contrary, unsaturated fatty acids (30–35% of total fatty
acids) are inversely associated to diabetes risk (Mann,
2002), and milk also contains beneficial minor com-
ponents such as CLA (Schrezenmeir & Jagla, 2000).
Epidemiological data about a relationship between milk
consumption and type II diabetes are rare (Schrezenmeir
& Jagla, 2000); moreover, milk processing parameters are
not controlled. Randomized controlled trials are required
to establish whether milk avoidance is causally associated
with the lower occurrence of type II diabetes observed in
non-milk consumers (Lawlor, Ebrahim, Timpson, &
Davey Smith, 2005) and the effect of milk processing
parameters should be examined.
Other health effects linked to the milk fat globulemembrane components
Proteins and other components of the native MFGMwere
found to present various health effects, listed in Table 4.
Riccio (2004) claims that MFGM proteins could possibly be
involved in autoimmune and neurological diseases, such as
multiple sclerosis and autism. Butyrophilin, the main
MFGM protein, shows more than 50% amino-acid
homology with a corresponding domain of the myelin
oligodendrocyte glycoprotein (MOG). The latter is a minor
component of the myelin membrane in the central nervous
system. MOG induces experimental allergic encephalomye-
litis (EAE), related to human multiple sclerosis, in many
experimental animals (Riccio, 2004). Spitsberg (2005)
reviewed recent studies demonstrating that butyrophilin
can trigger the development of EAE or suppress the disease.
The treatment of specific mice with butyrophilin either
before or after immunization with MOG prevents or
suppresses the clinical manifestation of EAE, suggesting
that the consumption of dairy products enriched with
MFGM could modulate the pathogenic response to MOG
in a positive direction. Riccio (2004), however, points out
that butyrophilin induces inflammatory responses in the
central nervous system when injected alone into animals.
This author advises cautious removal of MFGM from dairy
products. On the contrary, the thorough review by Spitsberg
(2005) highlights many health benefits of MFGM com-
ponents such as: (i) anti-cancer effects via the absorbed
peptides from proteins FABP and BRCA1, the b-glucuroni-dase inhibitor and the phospholipids (mainly sphingomye-
lin), (ii) anti-cholesterolemic effects mainly via
phospholipids, (iii) prevention of gastric diseases via
sialyated glycoproteins. This author suggests the use of
MFGM as a potential nutraceutical. The issue of MFGM
components contributing to health and disease still appears
controversial.
Due to the physical stress caused by homogenization, a
rearrangement of the MFGM components occur and some
fragments are released to the aqueous phase, while in whole
milk the MFGM is native at the globule surface (Fig. 1).
Due to its lipophilicity, butyrophilin should remain at the
lipid interface. It would be important to investigate the
effect of MFGM fragments on the above-mentioned health
effects when dispersed in an aqueous phase or adsorbed at a
lipid interface. Indeed, changes in the physico-chemical
arrangement of bioactive molecules may affect their activity
and suggest different effects of unhomogenized and
homogenized milk in this respect.
ConclusionChanges caused by homogenization on milk organization
were broadly investigated. The size of milk fat globules
M.-C. Michalski, C. Januel / Trends in Food Science & Technology 17 (2006) 423–437434
dramatically decreases and caseins become the main protein
fraction adsorbed onto the newly formed interface, together
with some whey proteins. Heat treatment changes the
impact of homogenization on milk structure. When milk is
heated then homogenized, complexes of caseins with heat-
denatured whey proteins adsorb onto the new expanded
lipid droplet interface. When milk is homogenized then
heated, heat-denatured whey proteins link to the proteins
already located at the homogenized droplet interface
(MFGM proteins and casein micelles or fragments thereof).
There are much less studies dealing with the impact of
homogenization and milk processing in general on the
human health properties of milk. Homogenization seems to
improve milk digestibility for subjects suffering intestinal
disease, however, infants digest better native human milk fat
globules than homogenized droplets from infant formula.
Presently, there seems to be no strong evidence that dairy
products, including homogenized milk, increase the risk of
coronary heart disease in healthy men of all ages or middle-
aged healthy women. Moreover, some casein peptides
present anti-thrombotic and anti-hypertensive features, and
milk drinking might be associated with a small reduction of
stroke risk. Though, the effects of milk homogenization and
heating regarding the bioactivity of casein peptides and the
cardiovascular impact of milk consumption should be
elucidated. Studies found to date do not show any impact
of homogenization on milk allergy or intolerance in
humans, except for a few percent of children allergic to
milk who would tolerate less homogenized milk. However,
differences of primary immunization could be much more
important in infants since most milk proteins are potential
allergens, especially when heated. Early exposure to cow’s
milk in genetically prone children could also be a risk for
type I diabetes but this result still seems controversial.
Studies are also required to establish whether milk
avoidance is causally associated with the lower occurrence
of type II diabetes observed in non-milk drinkers. The
impact of homogenization in the latter results has not been
investigated. A role of A1-b-casein is presently suspected intype I diabetes and coronary heart disease. Some authors
also claim that MFGM proteins could be atherogenic and
implied in autoimmune and neurological diseases. How-
ever, many other studies highlight beneficial health effects
of MFGM components that could be used in the prevention
of cancer, gastric diseases or hypercholesterolemia. The
distribution and conformation of caseins and MFGM
proteins changes in homogenized milk, which could alter
or enhance their bioactivity and allergenicity, as well as
those of other components of health interest.
The structure of milk is greatly altered depending on
the various mechanical and thermal steps of the
processing chain. Studies dealing with the health proper-
ties of milk and other dairy products should use samples
whose physico-chemical properties are well character-
ized. In the current context of obesity and allergy
outbreaks, interdisciplinary studies on the impact of
processing parameters on the nutritional and health value
of milk appears to be a challenging and necessary
research area for the future.
AcknowledgementsThe authors thank the steering committee for Nutrition of
Arilait Recherches for undertaking and financing this
literature review. M. Armand, D. Dalgleish, F. Guyomarc’h
and H. Vidal are acknowledged for their critical comments
on the manuscript. In a discussion of many health research
studies, some works were cited indirectly through reviews.
The authors apologize to those not cited.
References
Aimutis, W. R. (2004). Bioactive properties of milk proteins withparticular focus on anticariogenesis. Journal of Nutrition, 134(4),989S–995S.
Allison, A. J., & Clarke, A. J. (2006). Further research forconsideration in ‘the A2 milk case’. European Journal of ClinicalNutrition, doi: 10.1038/sj.ejcn.1602276.
Anema, S. G., & Klostermeyer, H. (1997). The effect of pH and heattreatment of the kappa-casein content and the zeta-potential ofthe particles in reconstituted skim milk. Milchwissenschaft,52(4), 217–223.
Anema, S. G., & Li, Y. (2003). Association of denatured wheyproteins with casein micelles in heated reconstituted skim milkand its effect on casein micelle size. Journal of Dairy Research,70, 73–83.
Armand, M., Pasquier, B., Andre, M., Borel, P., Senft, M., Peyrot, J.,et al. (1999). Digestion and absorption of 2 fat emulsions withdifferent droplet sizes in the human digestive tract. AmericanJournal of Clinical Nutrition, 70, 1096–1106.
Berner, L. A. (1993a). Defining the role of milkfat in balanced diets.Advances in Food and Nutrition Research, 37, 131–257.
Berner, L. A. (1993b). Roundtable discussion on milkfat, dairy foods,and coronary heart disease risk. Journal of Nutrition, 110, 1175–1184.
Berry, C. E., & Hare, J. M. (2004). Xanthine oxidoreductase andcardiovascular disease: Molecular mechanisms and pathophy-siological implications. Journal of Physiology, 555(3), 589–606.
Besler, M., Paschke, A., & Paschke, A. (2001). Stability of foodallergens and allergenicity of processed foods. Journal ofChromatography B, 756, 207–228.
Bouhallab, S., & Bougle, D. (2004). Biopeptides of milk: Case-inophosphopeptides and mineral bioavailability. ReproductionNutrition Development, 44(5), 493–498.
Buchheim, W. (1984). Influence of different technological treat-ments of milk on digestion in the stomach. IV. Electronmicroscopic characterization of the coagulum and of lipolyticprocesses in the stomach. Milchwissenschaft, 39(5), 271–275.
Clemente, G., Mancini, M., Nazzaro, F., Lasorella, G., Rivieccio, A.,Palumbo, A. M., et al. (2003). Effect of different dairy products onpostprandial lipemia. Nutrition Metabolism and CardiovascularDiseases, 13, 377–383.
Corredig, M., & Dalgleish, D. G. (1996). Effect of different heattreatments on the strong binding interactions between wheyproteins and milk fat globules in whole milk. Journal of DairyResearch, 63, 441–449.
Dahl-Jorgensen, K., Joner, G., & Hanssen, K. F. (1991). Relationshipbetween cow’s milk consumption and incidence of IDDM inchildhood. Diabetes Care, 14(11), 1081–1083.
Dalgleish, D. G. (1990). Denaturation and aggregation of serumproteins and caseins in heated milk. Journal of Agricultural andFood Chemistry, 38, 1995–1999.
M.-C. Michalski, C. Januel / Trends in Food Science & Technology 17 (2006) 423–437 435
Dalgleish, D. G., & Banks, J. M. (1991). The formation of complexes
between serum proteins and fat globules during heating of whole
milk. Milchwissenschaft, 46, 75–78.
Dalgleish, D. G., & Sharma, S. K. (1993). Interactions between
milkfat and milk proteins—The effect of heat on the nature of the
complexes formed. Protein & fat globule modifications—IDF
seminar (pp. 7–17).
Dalgleish, D. G., Tosh, S. M., & West, S. (1996). Beyond
homogenization: The formation of very small emulsion droplets
during the processing of milk by a microfluidizer. Netherlands
Milk and Dairy Journal, 50, 135–148.
Darling, D. F., & Butcher, D. W. (1978). Milk-fat globule membrane
in homogenized cream. Journal of Dairy Research, 45, 197–208.
Elfagm, A. A., & Wheelock, J. V. (1978). Heat interaction between
alpha-lactalbumin, beta-lactoglobulin and casein in bovine
milk. Journal of Dairy Science, 61, 159–163.
Elliott, R. B., Harris, D. P., Hill, J. P., Bibby, N. J., & Wasmuth, H. E.
(1999). Type I (insulin-dependent) diabetes mellitus and cow
milk: Casein variant consumption. Diabetologia, 42, 292–296.
Elwood, P. C., Pickering, J. E., Hughes, J., Fehily, A. M., & Ness, A. R.
(2004). Milk drinking, ischaemic heart disease and ischaemic
stroke II. Evidence from cohort studies. European Journal of
Clinical Nutrition, 58(5), 718–724.
Fava, D., Leslie, R. D., & Pozzilli, P. (1994). Relationship between
dairy product consumption and incidence of IDDM in childhood
in Italy. Diabetes Care, 17(12), 1488–1490.
Fave, G., Coste, T. C., & Armand, M. (2004). Physicochemical
properties of lipids: New strategies to manage fatty acid
bioavailability. Cellular and Molecular Biology, 50(7), 815–831.
Feng, C. G., & Collins, A. M. (1999). Pasteurisation and
homogenisation of milk enhances the immunogenicity of milk
plasma proteins in a rat model. Food and Agricultural
Immunology, 11, 251–258.
Floury, J., Desrumaux, A., & Lardieres, J. (2000). Effect of high-
pressure homogenization on droplet size distributions and
rheological properties of model oil-in-water emulsions. Inno-
vative Food Science and Emerging Technologies, 1, 127–134.
Fox, K. K., Holsinger, V. H., Caha, J., & Pallansch, M. J. (1960).
Formation of a fat protein complex in milk by homogenization.
Journal of Dairy Science, 43, 1396–1406.
Garcia-Risco, M., Ramos, M., & Lopez-Fandino, R. (2002).
Modifications in milk proteins induced by heat treatment and
homogenization and their influence on susceptibility to pro-
teolysis. International Dairy Journal, 12, 679–688.
Guo, M. R., Hendricks, G. M., & Kindstedt, P. S. (1998). Component
distribution and interactions in powdered infant formula.
International Dairy Journal, 8, 333–339.
Guyomarc’h, F., Law, A. J., & Dalgleish, D. G. (2003). Formation of
soluble and micelle-bound protein aggregates in heated milk.
Journal of Agricultural and Food Chemistry, 51(16), 4652–4660.
Hansen, L. G., Host, A., & Osterballe, O. (1987). Allergic reactions
to unhomogenized milk and raw milk. Ugeskrift for Laeger,
149(14), 909–911.
Haque, Z., Kristjanssan, M. M., & Kinsella, J. E. (1987). Interactions
between k-casein and b-lactoglobulin: Possible mechanism.
Journal of Agricultural and Food Chemistry, 35, 644–649.
Hardham, J. F., Imison, B. W., & French, H. M. (2000). Effect of
homogenisation and microfluidisation on the extent of fat
separation during storage of UHT milk. Australian Journal of
Dairy Technology, 55(1), 16–22.
Hayes, M. G., Fox, P. F., & Kelly, A. L. (2005). Potential applications
of high pressure homogenization in processing of liquid milk.
Journal of Dairy Research, 72(1), 25–33.
Hayes, M. G., & Kelly, A. L. (2003a). High pressure homogenisation
of raw whole bovine milk (a) effects on fat globule size and other
properties. Journal of Dairy Research, 70(3), 297–305.
Hayes, M. G., & Kelly, A. L. (2003b). High pressure homogeneisa-tion of milk (b) effects on indigenous enzymatic activity. Journal
of Dairy Research, 70(3), 307–331.Henstra, S., & Schmidt, D. G. (1970). On the structure of the fat–
protein complex in homogenized cow’s milk. Netherlands Milk
and Dairy Journal, 24, 45–51.Hillbrick, G. C., Mcmahon, D. J., & Mcmanus, W. R. (1999).
Microstructure of indirectly and directly heated ultra-high-temperature (UHT) processed milk examined using transmission
electron microscopy and immunogold labelling. LebensmittelWissenchaft und Technologie, 32(8), 486–494.
Host, A. (2002). Frequency of cow’s milk allergy in childhood.Annals of Allergy, Asthma and Immunology, 89(6-S1), 33–37.
Host, A., & Samuelsson, E.-G. (1988). Allergic reactions to raw,pasteurized, and homogenized/pasteurized cow milk: A com-
parison. A double-blind placebo-controlled study in milkallergic children. Allergy, 43, 113–118.
Houlihan, A. V., Goddard, P. A., Kitchen, B. J., & Masters, C. J.(1992). Changes in structure of the bovine milk fat globule
membrane on heating whole milk. Journal of Dairy Research,59(3), 321–329.
Hui, Y. H. (1993). Dairy science and technology handbook:Applications science, technology and engineering. New York:Wiley.
Humbert, G., Driou, A., Guerin, J., & Alais, C. (1980). Effets del’homogeneisation a haute pression sur les proprietes du lait et
son aptitude a la coagulation enzymatique. Le Lait, 40, 574–594.Ikeda, S., Fogeding, E. A., & Hardin, C. C. (2000). Phospholipid/fatty
acid-induced secondary structural changes in beta-lactoglobulinduring heat-induced gelation. Journal of Agricultural and Food
Chemistry, 48, 605–610.Jackson, R. H., & Brunner, J. B. (1960). Characteristics of protein
fractions isolated from fat/plasma interface of homogenizedmilk. Journal of Dairy Science, 43, 912–919.
Jang, H. D., & Swaisgood, H. E. (1990). Characteristics of theinteraction of calcium with casein submicelles as determined by
analytical affinity chromatography. Archives of Biochemistry andBiophysics, 283(2), 318–325.
Jean, K., Renan, M., Famelart, M. H., & Guyomarc’h, F. (2006).Structure and surface properties of the serum heat-induced
protein aggregates isolated from heated skim milk. InternationalDairy Journal, 16(4), 303–315.
Jensen, R. G. (1995). Handbook of milk composition. San Diego,CA: Academic Press.
Jensen, R. G. (2002). The composition of bovine milk lipids: January
1995 to December 2000. Journal of Dairy Science, 85, 295–350.Jeurnink, T. J. M., & De Kruif, K. G. (1993). Changes in milk on
heating: Viscosity measurements. Journal of Dairy Research, 60,139–150.
Jinsmaa, Y., & Yoshikawa, M. (1999). Enzymatic release of neo-casomorphin and b-casomorphin from bovine b-casein. Pep-
tides, 20(8), 957–962.Karjalainen, J., Martin, J. M., Knip, M., Robinson, B. H., Savilahti, E.,
Akerblom, H. K., et al. (1992). A bovine albumin peptide as apossible trigger of insulin-dependent diabetes mellitus. New
England Journal of Medicine, 327(5), 302–307.Kaufmann, W. (1984). Influence of different technological treat-
ments of milk on digestion in the stomach. VI. Estimation ofamino acids and urea in blood; conclusions regarding nutritional
evaluation. Milchwissenschaft, 39(5), 281–284.Keenan, T. W., Moon, T. W., & Dylewski, D. P. (1983). Lipid globules
retain globule membrane material after homogenization. Journalof Dairy Science, 66(2), 196–203.
Kinsella, J. E., & Whitehead, D. M. (1989). Proteins in whey:
Chemical, physical and functional properties. In J. E. Kinsella(Ed.), Advances in food and nutrition research (pp. 433–438).
San Diego, CA: Academic Press.
M.-C. Michalski, C. Januel / Trends in Food Science & Technology 17 (2006) 423–437436
Korhonen, H., & Korpela, R. (1994). The effects of dairy processes onthe components and nutritional value of milk. Scandinavian
Journal of Nutrition, 38, 166–172.Korpela, R., Paajanen, L., & Tuure, T. (2005). Homogenization of
milk has no effect on the gastrointestinal symptoms of lactose
intolerant subjects. Milchwissenschaft, 60(1), 3–6.Kostraba, J. N., Cruiskshanks, K. J., Lawler-Heavner, J., Jobim, L. F.,
Rewers, M. J., Ga, E. C., et al. (1993). Early exposure to cow’smilk and solid foods in infancy, genetic predisposition, and risk
of IDDM. Diabetes, 42(2), 288–295.Lawlor, D. A., Ebrahim, S., Timpson, N., & Davey Smith, G. (2005).
Avoiding milk is associated with a reduced risk of insulinresistance and the metabolic syndrom: Findings from the British
Women’s Heart and Health Study. Diabetic Medicine, 22(6),808–811.
Lee, S. J. (1997). Chemical changes in milk fat globule membranedue to heat treatment and homogenization of whole milk. Thesis,
Cornell University, USA.Lee, S. J., & Sherbon, J. W. (2002). Chemical changes in bovine
milk fat globule membrane caused by heat treatment andhomogenization of whole milk. Journal of Dairy Research, 69(4),
555–567.Lopez, C. (2005). Focus on the supramolecular structure of milk fat
in dairy products. Reproduction Nutrition Development, 45,
497–511.Mangino, M. E., & Brunner, J. R. (1976). Homogenized milk: Is it
really the culprit in dietary-induced atherosclerosis? Journal ofDairy Science, 59(8), 1511–1512.
Mann, J. I. (2002). Diet and risk of coronary heart disease and type 2diabetes. The Lancet, 360, 783–789.
Mather, I. A. (2000). A review and proposed nomenclature for themajor proteins of the milk fat globule membrane. Journal of
Dairy Science, 83(2), 203–247.Mattes, R. D. (1996). Oral fat exposure alters postprandial lipid
metabolism in humans. American Journal of Clinical Nutrition,63, 911–917.
McPherson, A. V., Dash, M. C., & Kitchen, B. J. (1984a). Isolationand composition of milk fat globule membrane material. I. From
pasteurized milks and creams. Journal of Dairy Research, 51(2),279–287.
McPherson, A. V., Dash, M. C., & Kitchen, B. J. (1984b). Isolationand composition of milk fat globule membrane material. II. From
homogenized and ultra heat treated milks. Journal of DairyResearch, 51(2), 289–297.
Meisel, H. (2005). Biochemical properties of peptides encrypted in
bovine milk proteins. Current Medicinal Chemistry, 12(16),1905–1919.
Meisel, H., & Hagemeister, H. (1984). Influence of differenttechnological treatments of milk on digestion in the stomach. II.
Gastric passage of different milk constituents. Milchwis-senschaft, 39(5), 262–266.
Meloni, T., Marinaro, A. M., Mannazzu, M. C., Ogana, A., LaVecchia, C., Negri, E., et al. (1997). IDDM and early infant
feeding. Sardinian case–control study. Diabetes Care, 20(3),340–342.
Michalski, M. C., Briard, V., Desage, M., & Geloen, A. (2005). Thedispersion state of milk fat influences triglyceride metabolism in
the rat: A 13CO2 breath test study. European Journal of Nutrition,44, 436–444.
Michalski, M. C., Briard, V., Michel, F., Tasson, F., & Poulain, P.(2005). Size distribution of fat globules in human colostrum,
breast milk, and infant formula. Journal of Dairy Science, 88,1927–1940.
Michalski, M. C., Michel, F., & Briard, V. (2002). On the size
distribution and zeta-potential of homogenized milk fatglobules. In M. Anton (Ed.), Food emulsions and dispersions (pp.
49–65). Kerala, India: Research Signpost.
Michalski, M. C., Michel, F., & Geneste, C. (2002). Appearance ofsubmicronic particles in the milk fat globule size distribution
upon mechanical treatments. Le Lait, 82, 193–208.Michalski, M. C., Michel, F., Sainmont, D., & Briard, V. (2001).
Apparent z-potential as tool to assess mechanical damages to themilk fat globule membrane. Colloids and Surfaces B: Biointer-
faces, 23, 23–30.Michalski, M. C., Soares, A. F., Lopez, C., Leconte, N., Briard, V., &
Geloen, A. (2006). The supramolecular structure of milk fatinfluences plasma triacylglycerol and fatty acid profile in the
rat. European Journal of Nutrition, doi: 10.1007/s00394-006-0588-9.
Morgan, F., Leonil, J., Molle, D., & Bouhallab, S. (1999).Modification of bovine b-lactoglobulin by glycation in a
powdered state or in an aqueous solution: Effect on associationbehavior and protein conformation. Journal of Agricultural and
Food Chemistry, 47(1), 83–91.Morr, C. V., & Richter, R. L. (1988). Chemistry of processing. In N. P.
Wong (Ed.), Fundamentals of dairy chemistry (pp. 739–766).New York: Van Nostrand Reinhold.
Moss, M., & Freed, D. (2003). The cow and the coronary:Epidemiology, biochemistry and immunology. International
Journal of Cardiology, 87, 203–216.Mulder, H., & Walstra, P. (1974). The milk fat globule. Farnham
Royal/England: Bucks/Commonwealth Agricultural Bureaux.Nielsen, B. R., Poulsen, O. M., & Hau, J. (1989). Reagin production
in mice: Effect of subcutaneous and oral sensitization withuntreated bovine milk and homogenized bovine milk. In Vivo,
3(4), 271–274.Oberlin, P., Mouquet, M.C., & Folliguet, T. (2004). Le traitment
invasif des maladies coronariennes. Etudes et Resultats de laDREES, 289, 1–12. http://www.sante.govv.fr/drees/etude-resul-
tat/er-pdf-er289.pdfOlson, D. W., White, C. H., & Richter, R. L. (2004). Effect of pressure
and fat content on particle sizes in microfluidized milk. Journalof Dairy Science, 87, 3217–3223.
Oster, K.A. (1972). Evaluation of serum cholesterol reduction andxanthine oxidase inhibition in the treatment of atherosclerosis.
In N.S. Dhalla (Ed.), Mycardial metabolism, vol. 3. Recentadvances in studies on cardiac structure and metabolism.
(pp. 73–80). Baltimore, MD: University Farm Press.Paajanen, L., Tuure, T., Poussa, T., & Korpela, R. (2003). No
difference in symptoms during challenges with homogenizedand unhomogenized cow’s milk in subjects with subjective
hypersensitivity to homogenized milk. Journal of DairyResearch, 70, 175–179.
Paajanen, L., Tuure, T., Vaarala, O., & Korpela, R. (2005).Homogenization of milk has no effect on milk-specific
antibodies in healthy adults. Milchwissenschaft, 60(3), 239–241.Paquin, P. (1999). Technological properties of high pressure
homogenizers: The effect of fat globules, milk proteins, andpolysaccharides. International Dairy Journal, 9, 329–335.
Parodi, P. W. (1997). Cow’s milk fat components as potentialanticarcinogenic agents. Journal of Nutrition, 127, 1055–1060.
Paschke, A., & Besler, M. (2002). Stability of bovine allergens duringfood processing. Annals of Allergy, Asthma and Immunology,
89(S1), 16–20.Pelto, L., Rantakokko, H.-K., Lilius, E.-M., Nuutila, J., & Salminen, S.
(2000). No difference in symptoms and receptor expression inlactose-intolerant and in milk-hypersensitive subjects following
intake of homogenized and unhomogenized milk. InternationalDairy Journal, 10, 799–803.
Pfeil, R. (1984). Influence of different technological treatments ofmilk on digestion in the stomach. III. Proteolysis in the stomach.
Milchwissenschaft, 39(5), 267–270.Pouliot, Y., Paquin, P., Robin, O., & Giasson, J. (1991). Etude
comparative de la microfluidisation et de l’homogeneisation sur
M.-C. Michalski, C. Januel / Trends in Food Science & Technology 17 (2006) 423–437 437
la distribution de la taille des globules gras du lait de vache.International Dairy Journal, 1, 39–49.
Poulsen, O. M., & Hau, J. (1987). Homogenization and allergenicityof milk. Some possible implications for the processing ofinfant formulae. North European Food and Dairy Journal, 53(7),239–242.
Poulsen, O. M., Hau, J., & Kollerup, J. (1987). Effect ofhomogenization and pasteurization on the allergenicity ofbovine milk analysed by a murine anaphylactic shock model.Clinical Allergy, 17(5), 449–458.
Poulsen, O. M., Nielsen, B. R., Basse, A., & Hau, J. (1990).Comparison of intestinal anaphylactic reactions in sensitizedmice challenged with untreated bovine milk and homogenizedbovine milk. Allergy, 45(5), 321–326.
Renner, E. (1988). Storage stability and some nutritional aspects ofmilk powders and ultra high temperature products at highambient temperatures. Journal of Dairy Research, 55, 122–142.
Riccio, P. (2004). The proteins of the milk fat globule membranein the balance. Trends in Food Science and Technology, 15,458–461.
Saboya, L. V., & Maubois, J. L. (2000). Current developments ofmicrofiltration technology in the dairy industry. Le Lait, 80,541–553.
Sanchez, C., & Fremont, S. (2003). Consequences of heat treatmentand processing of food on the structure and allergenicity ofcomponent proteins. Revue Francaise d’Allergologie etd’Immunologie Clinique, 43(1), 13–20.
Sandra, S., & Dalgleish, D. G. (2005). Effects of ultra-high-pressurehomogenization and heating on structural properties of caseinmicelles in reconstituted skim milk powder. International DairyJournal, 15(11), 1095–1104.
Sanggaard, K. M., Holst, J. J., Rehfeld, J. F., Sandstrom, B., Raben,A., & Tholstrup, T. (2004). Different effects of whole milk and afermented milk with the same fat and lactose content ongastric emptying and postprandial lipaemia, but not onglycaemic response and appetite. British Journal of Nutrition,92(3), 447–459.
Schrezenmeir, J., & Jagla, A. (2000). Milk and diabetes. Journal ofthe American College of Nutrition, 19(2), 176S–190S.
Sharma, S. K., & Dalgleish, D. G. (1994). Effect of heat treatments onthe incorporation of milk serum proteins into the fat globulemembrane of homogenized milk. Journal of Dairy Research, 61,375–384.
Sieber, R., Eyer, H., & Luginbuhl, W. (1997). L’homogeneisation dulait. Le Laitier Roman, 123(15), 7–9.
Silva, S. V., & Maltaca, F. X. (2005). Caseins as source of bioactivepeptides. International Dairy Journal, 15(1), 1–15.
Sipetic, S., Vlajinac, H., Kocev, N., Bjekic, M., & Sajic, S. (2005).Early infant diet and risk of type 1 diabetes mellitus in Belgradechildren. Nutrition, 21, 474–479.
Spitsberg, V. L. (2005). Invited review: Bovine milk fat globulemembrane as a potential nutraceutical. Journal of Dairy Science,88, 2289–2294.
Strand, F. T. (1994). Primary prevention of insulin-dependentdiabetes mellitus: Simple approaches using thermal modifi-cation of milk. Medical Hypotheses, 42, 110–114.
Thiebaud, M., Dumay, E., Picart, L., Guiraud, J. P., & Cheftel, J. C.
(2003). High-pressure homogenisation of raw bovine milk.
Effects on fat globule size distribution and microbial inacti-
vation. International Dairy Journal, 13(6), 427–439.
Tholstrup, T. (2006). Dairy products and cardiovascular disease.
Current Opinion in Lipidology, 17(1), 1–10.
Tholstrup, T., Høy, C. E., Normann Andersen, L., Christensen,
R. D. K., & Sandstrom, B. (2005). Does fat in milk, butter
and cheese affect blood lipids and cholesterol differently?
Journal of the American College of Nutrition, 23(2),
169–176.
Timmen, H., & Precht, D. (1984). Influence of different techno-
logical treatments of milk on digestion in the stomach. V.
Lipolysis in the stomach. Milchwissenschaft, 39(5), 276–280.
Truswell, A. S. (2005). The A2 milk case: A critical review. European
Journal of Clinical Nutrition, 59, 623–631.
Van Boekel, M. A. J. S., & Walstra, P. (1989). Physical changes in the
fat globules in unhomogenized and homogenized milk. Bulletin
of the International Dairy Federation, 238, 13–166.
Vasbinder, A. J., Alting, A. C., & de Kruif, K. G. (2003).
Quantification of heat-induced casein–whey protein inter-
actions in milk and its relation to gelation kinetics. Colloids and
Surfaces B: Biointerfaces, 31, 115–123.
Vesa, T. H., Marteau, P., & Korpela, R. (2000). Lactose intolerance.
Journal of the American College of Nutrition, 19(2),
165S–175S.
Wal, J. M. (2004). Bovine milk allergenicity. Annals of Allergy,
Asthma and Immunology, 93(5-S3), 2–11.
Walstra, P. (1969). Studies on milk fat dispersion. II. The globule-
size distribution of cow’s milk. Netherlands Milk and Dairy
Journal, 23, 99–110.
Walstra, P. (1980). Effect of homogenization on milk plasma.
Netherlands Milk and Dairy Journal, 34, 181–190.
Walstra, P. (1995). Physical chemistry of milk fat globules. In P. F. Fox
(Ed.), Advanced dairy chemistry Lipids (Vol. 2) (pp. 131–178).
London: Chapman & Hall.
Walstra, P., Geurts, T. J., Noomen, A., Jellama, A., & van Boekel,
M. A. J. S. (1999). Dairy technology. Principles of milk properties
and processes. New York: Marcel Dekker.
Warensjo, E., Jansson, J. H., Berglund, L., Boman, K., Ahren, B.,
Weinehall, L., et al. (2004). Estimated intake of milk fat is
negatively associated with cardiovascular risk factors and does
not increase the risk of a first acute myocardial infarction. British
Journal of Nutrition, 91, 635–642.
Whitney, R. M. (1988). Proteins of milk. In N. P. Wong (Ed.),
Fundamentals of dairy chemistry (pp. 81–169). New York: Van
Nostrand Reinhold.
Wilbey, R. A. (2002). Homogenization of milk. In H. Roginski, J. W.
Fuquay, & P. F. Fox (Eds.), Encyclopedia of dairy sciences (pp.
1346–1349). Paris: Academic Press.
Woodford, K. B. (2006). A critique of Truswell’s A2 milk review.
European Journal of Clinical Nutrition, 60, 437–439.
Zahar, M., & Smith, D. E. (1996). Adsorption of proteins at the lipid–
serum interface in milk systems with various lipids. International
Dairy Journal, 6(7), 697–708.