Skip to main content Accessibility help

Study of acid milk coagulation by an optical method using light reflection

  • Sylvie Banon (a1) and Joël Hardy (a1)


A turbidimetric method, based on light reflection, was used to study acid coagulation of reconstituted skim milk at low temperature. Capillary viscosimetry, gelograph and laser granulometer techniques were also employed. Acidification of milk was produced by hydrolysis of glucono-δ-lactone. The general shape of the turbidimetric signal as a function of pH or time can be divided into three stages: a lag phase followed by a significant decrease and then a final rise. Two factors have a great influence on the development of milk turbidity, pH and temperature. Dynamic viscosity measurements can be related to the turbidimetric signal while laser granulometrie measurements cannot be correlated with changes in turbidity: the micelle size distribution remains constant until the first signs of gelation. As previous work showed, dynamic viscosity diminishes with acidification until a particular pH is reached (pH 5·9 at 15°C and pH 5·75 at 20°C). We have related this latter period to the turbidimetric lag phase. As milk turbidity became lower than its initial value (pH 5·75 at 15°C and pH 5·55 at 20°C), dynamic viscosity increased significantly. The release of material from micelles (β-casein and Ca) could explain this phenomenon. In the same way, further increase of turbidity at a particular pH value (pH 5·3 at both 15 and 20°C) coulcl be partly due to the reincorporation of soluble casein monomers in the micelle framework. As the onset of gelation was approached, turbidity still increased as a result of gel network formation.



Hide All
Brulé, G. & Fauquant, J. 1981 Mineral balance in skim-milk and milk retentate: effect of physicochemical characteristics of the aqueous phase. Journal of Dairy Research 48 9197
Creamer, L. K. 1985 Water absorption by renneted casein micelles. Milchwissenschaft 40 589591
Dalgleish, D. G. & Law, A. J. R. 1988 pH-Induced dissociation of bovine casein micelles. I. Analysis of liberated caseins. Journal of Dairy Research 55 529538
Davies, D. T. & White, J. C. D. 1960 The use of ultrafiltration and dialysis in isolating the aqueous phase of milk and in determining the partition of milk constituents between the aqueous and disperse phases. Journal of Dairy Research 27 171190
Downey, W. K. & Murphy, R. F. 1970 The temperature-dependent dissociation of β-casein from bovine casein micelles and complexes. Journal of Dairy Research 37 361372
Hallstrom, M. & Dejmek, P. 1988 a Rheological properties of ultrafiltered skim milk. I. Effects of pH, temperature and heat pretreatment. Milchwissenschaft 43 3134
Hallstrom, M. & Dejmek, P. 1988 b Rheological properties of ultrafiltered skim milk. II. Protein voluminosity. Milchwissenschaft 43 9597
Hardy, J. & Scher, J. 1986 [Continuous measurement of milk coagulation by an optical method.] In Automatic Control and Optimisation of Food Processes [Eds Renard, M. & Bimbenet, J. J.] pp. 357369. London: Applied Science Publishers
Holt, C. 1975 In Proceedings of the International Conference on Colloid and Surface Science (Ed. Wolfram, E.) p. 641. Budapest: Akademiai Kiado
Holt, C. & Dalgleish, D. G. 1986 Electrophoretic and hydrodynamic properties of bovine casein micelles interpreted in terms of particles with an outer hairy layer. Journal of Colloid and Interface Science 114 513524
Jablonka, M. S., Munro, P. A. & Duffy, G. G. 1988 Use of light scattering techniques to study the kinetics of precipitation of mineral acid casein from skim milk. Journal of Dairy Research 55 179188
Lin, S. H. C., Leong, S. L., Dewan, R. K., Bloomfield, V. A. & Morr, C. V. 1972 Effect of calcium ion on the structure of native bovine casein micelles. Biochemistry 11 18181821
Little, L. 1967 Techniques for acidified dairy products. Journal of Dairy Science 50 434
Mabbitt, L. A., Chapman, H. R. & Berridge, N. J. 1955 Experiments in cheese making without starter. Journal of Dairy Research 22 365373
Munyua, J. K. & Larsson-Raznikiewicz, M. 1980 The influence of Ca2+ on the size and light scattering properties of casein micelles. 1. Ca2+ removal. Milchwissenschaft 35 604606
Patel, R. S. & Chakraborty, B. K. 1985 Acid curd cheese by direct acidification. Japanese Journal of Dairy and Food Science 34 453459
Payens, T. A. J. 1978 On different modes of casein clotting; the kinetics of enzymatic and non-enzymatic coagulation compared. Netherlands Milk and Dairy Journal 32 170183
Pierre, A. & Brulé, G. 1981 Mineral and protein equilibria between the colloidal and soluble phases of milk at low temperature. Journal of Dairy Research 48 417428
Roefs, S. P. F. M. 1987 Structure of acid casein gels. A study of gels formed after acidification in the cold. Netherlands Milk and Dairy Journal 41 99101
Roefs, S. P. F. M., Walstra, P., Dalgleish, D. G. & Horne, D. S. 1985 Preliminary note on the change in casein micelles caused by acidification. Netherlands Milk and Dairy Journal 39 119122
Rose, D. 1968 Relation between micellar and serum casein in bovine milk. Journal of Dairy Science 51 18971902
Scher, J. & Hardy, J. 1987 [Effect of method of preparation of milk samples on their coagulability studied by a turbidimetric method.] Science des Aliments 7 (hors série VIII) 159165
Snoeren, T. H. M., Damman, A. J. & Klok, H. J. 1982 The viscosity of skim milk concentrates. Netherlands Mille and Dairy Journal 36 305316
Snoeren, T. H. M., Klok, H. J., Van Hooydonk, A. C. M. & Damman, A. J. 1984 The voluminosity of casein micelles. Milchwissenschaft 39 461463
Tarodo de la Fuente, B. & Alais, C. 1975 Solvation of casein in bovine milk. Journal of Dairy Science 58 293300
Trop, M. 1984 Simulation of bacterial fermentation of milk and possible acylation of its proteins by acidogen hydrolysis. Journal of Dairy Science 67 13811389
Van Hooydonk, A. C. M., Hagedoorn, H. G. & Boerrigter, I. J. 1986 pH-Induced physico-chemical changes of casein micelles in milk and their effect on renneting. 1. Effect of acidification on physico-chemical properties. Netherlands Milk and Dairy Journal 40 281296
Visser, J., Minihan, A., Smits, P., Tjan, S. B. & Heertje, I. 1986 Effects of pH and temperature on the milk salt system. Netherlands Milk and Dairy Journal 40 351368


Full text views

Total number of HTML views: 0
Total number of PDF views: 0 *
Loading metrics...

Abstract views

Total abstract views: 0 *
Loading metrics...

* Views captured on Cambridge Core between <date>. This data will be updated every 24 hours.

Usage data cannot currently be displayed