On the Stability of Casein Micelles

Walstra, P.

doi:10.3168/jds.s0022-0302(90)78875-3

Cited by 483 publications

(307 citation statements)

References 44 publications

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“…At pH of about 4.6, isoelectric point of the casein micelle was reached, resulting in self-association of micelles. Therefore, average particle size sufficiently increased to alter light-reflecting properties (Walstra 1990).…”

Section: Discussionmentioning

confidence: 99%

Combined effects of replacement of sucrose with d-tagatose and addition of different probiotic strains on quality characteristics of chocolate milk

Rouhi

Mohammadi

Mortazavian

et al. 2014

Dairy Sci. & Technol.

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Nowadays, tendency to improve human nutrition and consume new healthful foods such as low-calorie and functional ones has been increased. In this study, effects of ratios of sucrose/D-tagatose (100:0, 0:100, or 50:50) as well as type of commercial probiotic strains (Lactobacillus acidophilus LAFTI L10, Lactobacillus casei LAFTI L26, Lactobacillus rhamnosus HN001, and Bifidobacterium animalis subsp. lactis LAFTI B94) on biochemical and microbiological characteristics, percent of residual sugar, color, and sensory attributes of synbiotic chocolate milk were investigated during 21 days of refrigerated storage (5°C). The treatments inoculated with L. acidophilus, L. casei, L. rhamnosus, and B. lactis showed significantly higher biochemical and color changes compared to non-probiotic ones. The greatest viability at the end of storage was related to the treatment of D-tagatose

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Section: Discussionmentioning

confidence: 99%

Combined effects of replacement of sucrose with d-tagatose and addition of different probiotic strains on quality characteristics of chocolate milk

Rouhi

Mohammadi

Mortazavian

et al. 2014

Dairy Sci. & Technol.

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“…In addition, micellar calcium phosphate crosslinks the casein molecules and neutralises negatively-charged phosphoseryl groups, allowing the formation of hydrophobic interactions between caseins. In milk, the micellar calcium phosphate is in equilibrium with the aqueous phase that is supersaturated with respect to calcium phosphate salts [24,25].…”

Section: Changes In the State Of Ionisation Of Proteinsmentioning

confidence: 99%

“…Hydrophobic and electrostatic interactions, hydrogen bonding and presence of calcium phosphate linked to casein molecules are the forces responsible for the structure and the stability of casein micelle. Cleavage of these forces by pH decrease, addition of calcium chelatants or urea, cooling, high pressure treatment and alkalinisation induce disruption of micelles into smaller units [24,25].…”

Section: Introductionmentioning

confidence: 99%

Physico-chemical changes in casein micelles of buffalo and cow milks as a function of alkalinisation

Ahmad

Piot

Rousseau

et al. 2009

Dairy Sci. Technol.

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-By modifying the forces (hydrophobic and electrostatic interactions, hydrogen bonding and presence of micellar calcium phosphate) responsible for the structure and the stability of casein micelles, alkalinisation induces a disruption of casein micelles in milk. The objective of this work was to compare the alkalinisation-induced physico-chemical changes of casein micelles of buffalo and cow milks with a special attention to the mineral fraction. The whiteness and viscosity were determined as global characteristics of milk. The aqueous and micellar phases of milks were ascertained for the distributions of the concentrations of nitrogen, casein molecules, calcium, inorganic phosphate and water as their supramolecular and molecular characteristics. These parameters were measured at six pH values between pH 6.7 and 10.8. Between pH 6.7 and 10.8, the whiteness decreased from 73.5 to 50.9 and from 71.3 to 50.9 units and the viscosity increased from 1.8 to 10.2 and from 1.5 to 4.8 mPa·s for buffalo and cow milks, respectively. Simultaneously, > 90% of nitrogen contents were in the supernatants of ultracentrifugation at pH 9.7 and 8.6 for buffalo and cow milks, respectively. Chromatographic analyses showed that caseins were totally solubilised at these pH values. Calcium and inorganic phosphate concentrations progressively increased in the supernatants of ultracentrifugation and decreased in the ultrafiltrates. At alkaline pH, the negative charge of caseins increased and the inorganic phosphate ion changed its ionisation state from HPO 4 2− to PO 4 3− form. This form has a greater affinity for calcium and can demineralise casein micelles. The consequences were modifications of protein-protein and protein-minerals interactions resulting in micellar disruption. The dissociations took place at pH 9.7 and 8.6 for buffalo and cow milks, respectively. These differences were due to higher concentrations of casein and minerals in buffalo than in cow milk, which were also our criteria of selection of the former as a model. casein micelle / buffalo milk / cow milk / mineral / alkalinisation 摘要 -碱化作用对水牛乳和牛乳酪蛋白胶束物理化学性质的影响○ 分子间作用力 (疏水和静电作用、氢键和胶束磷酸钙的存在) 的改变会影响酪蛋白胶束的结构和稳定性，碱化作用使得乳中酪蛋白胶束破坏○ 本研究比较了碱化作用对水牛乳和牛乳物理化学性质和酪蛋白胶束中矿物元素的影响○ 以白度和黏度作为综合指标来评价乳的表观特性○ 并测定了乳水相和胶束相中氮、酪蛋白分子、钙、无机磷酸盐和水分的分布○ 这些参数的测定是在 pH 6.7-10.8 (6 个 pH 间隔)○ 在 pH 6.7-10.8, 水牛乳的白度从 73.5 单位降到 50.9 单位，牛乳的白度从 71.3 单位降到 50.9 单位，而水牛乳的黏度从 1.8 mPaAEs 增加 10.2 mPaAEs，牛 *Corresponding author (通讯作者): frederic.gaucheron@rennes.inra.fr Dairy Sci. Technol. 89 (2009)

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“…If it was, then -casein would be expected to be almost as good a steric stabiliser on the surface of oil droplets as is -casein, taking up the ideal diblock type configuration on the surface of the droplets. Our calculations suggest that the asymmetrical distribution of charge, hitherto not accounted for in the conventional "hairy" -casein layer models (Walstra, 1990), may be just as important in determining the functional behaviour of -casein.…”

Section: Discussionmentioning

confidence: 93%

Interactions between casein layers adsorbed on hydrophobic surfaces from self consistent field theory: κ-casein versus para-κ-casein

2014

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Interactions mediated by layers of -casein and para--casein have been calculated and compared using the self consistent field (SCF) approach, at pH and electrolyte concentrations found in milk. Our results show the interaction potentials at close separation distances to be repulsive for -casein, while they are attractive for para--casein. We have also studied -casein chains stripped of their sugar moieties and highlighted the important role that the carbohydrate side chains play in the provision of steric forces. The point of transition from a repulsive to an attractive interaction is found to be rather sensitive to the degree of coverage of the surface by the protein chains. At =0.0025 chains per unit monomer area, the value is just over 40%, whereas at =0.0032 this increases to 87%. At the coverage values higher than those we estimate for the surface of casein micelles, no transition is detected and the interactions remain repulsive even when all of -casein has been converted to para--casein, as already shown by Mellema, Leermakers, & de Kruif (1999). At lower surface coverage values, the interaction potential curves for otherwise uncharged surfaces, covered with para--casein, posses an energy barrier. We have demonstrated that the origin of this energy barrier is electrostatic, with para--casein contributing a net positive charge to the surface.We have also explored the importance of the asymmetry in the distribution of charge between the para--casein and the glycomacropeptide sides of the protein. The glycomacropeptide is net negative while para--casein side is net positive at neutral pH. Our results suggest that on a negatively charged surface, such as the surface of casein micelles, this uneven distribution of charge is just as important in determining the conformation of -casein chains as is the difference in the hydrophobic and hydrophilic nature of the two sides of this protein.

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On the Stability of Casein Micelles

Cited by 483 publications

References 44 publications

Combined effects of replacement of sucrose with d-tagatose and addition of different probiotic strains on quality characteristics of chocolate milk

Combined effects of replacement of sucrose with d-tagatose and addition of different probiotic strains on quality characteristics of chocolate milk

Physico-chemical changes in casein micelles of buffalo and cow milks as a function of alkalinisation

Interactions between casein layers adsorbed on hydrophobic surfaces from self consistent field theory: κ-casein versus para-κ-casein

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