Separation of Milk

Because milk fat has a lower density than milk plasma, it tends to rise under the influence of a gravitational or centrifugal force. For perfect spheres, the rate of rise, v, is given by Stokes Law  

To predict v correctly, several prerequisites must be met (Mulder and Walstra, 1974 Walstra and Oortwijn, 1975 Walstra, 1995), most notably  

Troy and Sharp (1928) found that, in milk highly diluted with milk plasma, the rise of individual milk fat globules, as well as roughly spherical clusters of milk fat globules, correlated well with Stokes law. However, Walstra and Oortwijn (1975) observed that the rate of rise of fat globules in undiluted milk systems under the influence of gravity was lower than 

The creaming rate (defined as the proportion of the fat arriving in the cream layer per unit time) is proportional to the creaming parameter, H (Walstra and Oortwijn, 1975)  

This parameter shows a linear relationship with the creaming rate if the effect of aggregation of the globules is excluded (Riiegg and Blanc, 1981) it can be seen that larger globules in particular affect H, and thus the creaming rate. 

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Yaguchi, M. and Rose, D. 1971. Chromatographic separation of milk proteins A review. J. Dairy Sci. 54, 1725-1743. 

B Manji, A Hill, Y Kakuda, DM Irvine. Rapid separation of milk whey proteins by anion exchange chromatography. J Diary Sci 68 3176-3179, 1985. 

Parodi, P.W. 1980. Separation of milk fat triglycerides into classes by silver ion adsorption thin-layer chromatography. Austr. J. Dairy Technol. 35, 17-22. 

Punidadas, P. and Rizvi, S.S.H., Separation of milk proteins into fractions rich in caseins or whey proteins by crossflow microfiltration. Food Res. Int., 31, 265, 2001. 

Separation of milk into the curd and whey fractions prior to cheese manufacture causes a partition of water-soluble substances (whey) from the curd. More than 80% of the vitamin C and thiamine is removed with the whey fraction (111). Desalting of the brine during pickle manufacture results in a 100% vitamin C loss. When desalting is not practiced, losses of ascorbic acid are about 40-50% (110). 

The third major concept of the kosher laws concerns the separation of milk and meat. 

Figure 15.14 presents a separation of milk proteins. Draw a calibration curve which corresponds to this chromatogram. 

Figure 15.14 Separation of milk proteins [reproduced with permission from B.B. Gupta, J. Chromatogr., 282, 463 (1983)]. Conditions sample, 100 pi of whey from raw skimmed milk (casein precipitated at pH 4.6) column, 60 cm x 7.5 mm i.d. stationary phase, TSK 3000 SW (silica, 10pm) mobile phase, 0.5 ml min buffer containing 0.1 M NaH2PO4, 0.05 M NaCl and 0.02% NaNa (pH 6.8) UV detector, 280 nm. Peaks (with molecular masses) 1 = high molecular weight proteins 2 = -y-globulin (150000) 3 — bovine serum albumin (69000) 4 = /3-lactoglobulin (35000) 5 = a-lactalbumin (16500) other components not identified.

Wheying off The phase separation of milk proteins and stabilizers in the matrix. 

Fairise, J. F., and Cayot, R, New nltrarapid method for the separation of milk proteins by capillary electrophoresis, J. Agric. Eood Chem., 46, 2628, 1998. 

Wine too consisted of heterogeneous particles according to Sennert it was this that accounted for the separation of tartar from the wine by mere settling and the extraction of alcohol by means of distillation. To Sennert, such substances as wine, blood, and milk are made of corpuscles that have, in Geberian fashion, been mixed per minima of smaller corpuscles and possess a certain amount of interparticular coherence. Hence he views the separation of milk into whey, butter, and cheese, the destructive distillation of blood, or the distillation of spirit of wine to have separated the preexisting particles of the fluid. 

Lucas JM, Kaneko JJ, Hirohara K, Kleiber M (1959) Separation of milk components. Chromatographie isolation of citric acid and lactose from skim milk. J Agric Food Chem... 

However, even without external mechaifical stress imposed by shear flow, reorganization of the agglomerates occurs. In dairy science, the separation of milk into curd and whey and the conversion of amorphous starch into a crystalline state with expulsion of physically bonded water are known examples. Silica, aluminum oxide and latex represent industrially produced compounds that show reorgaiuzation. The reason for reorgaiuzation of silica is the same polymerization reaction which is responsible for gelation. After the gel network has formed, there are still uncondensed silanol groups. A zoom of two solid silica particles is shown in Fig. 2. 

Figure 3. Separation of milk proteins using a weak anion-exchanger. Column, 7.75 mm x 100 mm, 15 micron BAKERBOND WP-PEI mobile phase, initial buffer (A) 10 mM Tris, pH 7.0 final buffer (B) 2 M sodium acetate, pH 6.0 gradient, 0—100% B over 60 min flow-rate, I ml/min detection UV (280 nm), 0.5 AUFS sample, 0.05 ml (LIPOCLEAN -extracted skim milk, diluted three times with buffer A). Peaks c, conalbumin b, 6-lactoglobulin B a, p-lactoglobulin A.

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