HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Michalski, M. C. Articles by Garnier, C. Search for Related Content PubMed PubMed Citation Articles by Michalski, M. C. Articles by Garnier, C.

Native vs. Damaged Milk Fat Globules: Membrane Properties Affect the Viscoelasticity of Milk Gels

M. C. Michalski^*, R. Cariou^*, F. Michel^* and C. Garnier

^* Laboratoire de Recherches de Technologie Laitière, INRA 65, Rue de Saint-Brieuc, 35042 Rennes cedex, France; and
Laboratoire de Physico-Chimie des Macromolécules, INRA Rue de la Géraudière, BP 71627, 44316 Nantes Cedex 3, France

Corresponding author:
M. C. Michalski; e-mail:
mcmichal{at}labtechno.roazhon.inra.fr.

The storage modulus G' of rennet and acid milk gels filled with milk fat globules was measured as a function of the fat globule surface composition (native milk fat globule membrane, caseins and whey proteins, or a mixture of the three due to mechanical treatments) and surface area (i.e., the fat globule size). By different technological procedures, it was possible to obtain fat globules of constant surface composition but various sizes, and vice-versa, which had never been done. For both rennet and acid gels, a critical fraction of the fat globule surface covered by caseins and whey proteins was identified (40%), beyond which G' increased. Below this threshold, the gel viscoelasticity was unaffected by mechanical treatments. When the diameter of native milk fat globules decreased, the G' of rennet gels increased slightly, whereas that of acid gels decreased sharply. For both types of gels, G' increased when the diameter of partially disrupted fat globules decreased. For recombined globules completely covered with caseins and few whey proteins, G' increased with fat globule surface area for rennet gels whereas it decreased for acid gels. With the help of confocal microscopy and in the light of general structural differences between rennet and acid gels, a mechanism is proposed for the effect of fat globule damage and diameter on G', depending on the interactions the globules can undergo with the casein network.

Key Words: milk fat globule membrane • gel • viscoelasticity • mechanical treatment

Abbreviation key: A = total surface area of the fat globules per unit mass of a milk sample (m²•kg^–1 milk), AMF = anhydrous milk fat, CLSM = confocal laser scanning microscopy, d₃₂ = Sauter average diameter (µm), F = fat content (g•kg^–1), G' = storage modulus of a milk gel (Pa), MFGM = milk fat globule membrane, NCN = noncasein nitrogen, S₀ = initial specific surface area of the native milk fat globules (m²•g^–1 fat), S_d = specific surface area of the milk fat globules that are mechanically damaged (m²•g^–1 fat), v_i = volume of particles in a size class of diameter d_i (µm³), = fraction of the fat globule surface that is new and covered by proteins (mainly caseins plus whey proteins) due to mechanical treatments (%), TN = total nitrogen, ULH-SMP = ultra-low-heat skim milk powder, = particle zeta-potential (mV)

This article has been cited by other articles:

				A. Zamora, V. Ferragut, P. D. Jaramillo, B. Guamis, and A. J. Trujillo Effects of Ultra-High Pressure Homogenization on the Cheese-Making Properties of Milk J Dairy Sci, January 1, 2007; 90(1): 13 - 23. [Abstract] [Full Text] [PDF]

				S. Couvreur, C. Hurtaud, P. G. Marnet, P. Faverdin, and J. L. Peyraud Composition of Milk Fat from Cows Selected for Milk Fat Globule Size and Offered Either Fresh Pasture or a Corn Silage-Based Diet J Dairy Sci, January 1, 2007; 90(1): 392 - 403. [Abstract] [Full Text] [PDF]

				M. C. Michalski, N. Leconte, V. Briard-Bion, J. Fauquant, J. L. Maubois, and H. Goudedranche Microfiltration of Raw Whole Milk to Select Fractions with Different Fat Globule Size Distributions: Process Optimization and Analysis. J Dairy Sci, October 1, 2006; 89(10): 3778 - 3790. [Abstract] [Full Text] [PDF]

				S. Couvreur, C. Hurtaud, C. Lopez, L. Delaby, and J. L. Peyraud The linear relationship between the proportion of fresh grass in the cow diet, milk fatty acid composition, and butter properties. J Dairy Sci, June 1, 2006; 89(6): 1956 - 1969. [Abstract] [Full Text] [PDF]

				F. Abeni, L. Degano, F. Calza, R. Giangiacomo, and G. Pirlo Milk Quality and Automatic Milking: Fat Globule Size, Natural Creaming, and Lipolysis J Dairy Sci, October 1, 2005; 88(10): 3519 - 3529. [Abstract] [Full Text] [PDF]

				M. C. Michalski, V. Briard, F. Michel, F. Tasson, and P. Poulain Size Distribution of Fat Globules in Human Colostrum, Breast Milk, and Infant Formula J Dairy Sci, June 1, 2005; 88(6): 1927 - 1940. [Abstract] [Full Text] [PDF]